WO2019076909A1 - Equipment for injection of a dispersion in a fabric and method of manufacturing a fabric containing nanostructure particle powder - Google Patents

Abstract

An equipment for injection of a dispersion in a fabric, said equipment comprising: a supply of a fabric and a transport system for moving said fabric in a movement direction X; a supply of an nanostructure particle powder; a supply of a solvent; an in-line mixer, positioned in a pipeline through which said solvent and said nanostructure particle powder are circulated and provided for mixing said nanostructure particle powder and said solvent to provide a dispersion; and an injection unit for injecting said dispersion in said fabric.

Description

Equipment for injection of a dispersion in a fabric and method of manufacturing a fabric containing nanostructure particle powder

Field of the invention

[0001] The present invention relates to an equipment for injecting a dispersion in a fabric and to a method of manufacturing a fabric containing an nanostructure particle powder.

Background art

[0002] Nanostructure particle materials are highly porous, low density materials that are manufactured by forming a gel and by removing the liquid therefrom, whilst retaining the gel structure to a large extent. Nanostructure particles are unique materials with many fascinating properties such as low mean free path of diffusion, high specific surface area (for a non-powder material), low thermal conductivity, low sound speed, low refractive index and low dielectric constant. As nanostructure particles have such diverse chemical and physical properties, it is no surprise that it has a wide range of applications.

[0003] The extremely low density and low thermal conductivity of nanostructure particle materials make these materials attractive as insulating material. Although many efforts have been undertaken to manufacture flexible insulation sheets comprising nanostructure particles, it remains a challenge to manufacture such sheets in an economic interesting process.

[0004] From EP3023528, a method of manufacturing insulation sheets is known, wherein a dispersion of nanostructure particle powder in a solvent is prepared in a buffer tank and the dispersion is then injected in a fabric by means of needles. The method known from EP3023528 has the disadvantages that the process is not continuous and that the homogeneity of the dispersion is low.

Summary of the invention

[0005] It is an object of the present invention to provide an improved equipment for injection of a dispersion in a fabric.

[0006] It is another object of the present invention to provide an equipment for injection of a dispersion allowing to provide a continuous supply of the dispersion to the injection unit.

[0007] It is another object of the present invention to provide an equipment for injection of a dispersion in a fabric allowing to prepare the dispersion with a high homogeneity.

[0008] It is another object of the present invention to provide a method of manufacturing a fabric using such equipment. The fabric is in particular suitable as insulation material. [0009] According to a first aspect of the present invention, an equipment for injection of a dispersion in a fabric is provided. The equipment comprises: a supply of a fabric and a transport system for moving said fabric in a movement direction X; a supply of an nanostructure particle powder; a supply of a solvent; an in-line mixer, positioned in a pipeline through which said solvent and nanostructure particle powder are circulated, and provided for mixing said nanostructure particle powder and said solvent to provide a dispersion; and an injection unit for injecting said dispersion in said fabric.

[0010] The equipment according to the invention is provided for mixing the nanostructure particle powder into the solvent using an in-line mixer in a pipeline through which the solvent is circulated. It has been found that this can reduce the preparation time and provide a continuous process, i.e. a continuous supply of the dispersion to the injection unit, as opposed to prior art systems wherein a volume of dispersion is prepared using a mixer in a tank. Further, it has been found that the use of the in-line mixer can lead to an improvement in the homogeneity of the dispersion.

[0011] In preferred embodiments, the equipment according to the invention is provided for mixing a fumed silica powder into the solvent using an in-line mixer in a pipeline through which the solvent is circulated. The use of an in-line mixer unit with fumed silica resulted in an extremely high homogeneity of the dispersion. This synergetic effect of high speed and better homogeneity of the dispersion resulting from the combination of fumed silica as an nanostructure particle powder and mixing by means of an in-line mixing unit, was not obvious. Indeed, the prior art only teaches mixing fumed silica dispersions with standard mixers or with standard high shear mixers, by means of which it takes hours to days before a homogeneous dispersion of silica particles is obtained. Moreover, the homogeneity of the resulting dispersion is not optimal. Indeed, fumed silica is a very light weight material, which tends to float when added to a solvent.

[0012] In embodiments according to the invention, the in-line mixer may be a high-shear in-line mixer, which is typically used in the food industry, i.e. for mixing different ingredients. The mixer is preferably a high-shear rotor-stator mixer. In such mixers, the rotor-stator array is contained in a housing with an inlet at one end and an outlet at the other, and the rotor is driven through a seal at a predetermined rotation speed to reduce particle size in the dispersion and/or achieve a dispersion with a predetermined particle size.

[0013] In embodiments according to the invention, the equipment comprises a buffer system for temporary storage of a volume of the solvent and/or the dispersion, for example comprising one or more buffer tanks. The provision of a buffer system can ensure an uninterrupted supply of the dispersion to the injection unit. [0014] In embodiments according to the invention, the equipment further comprises a recirculation system for recirculating the solvent and/or the dispersion from an exit port of the buffer system through the in-line mixer and back to an inlet port of the buffer system. By the recirculation system a multi-pass system is created whereby the in-line mixer discharge is sent back to the in-line mixer and the recirculation can be continued until the dispersion in the first intermediate tank meets certain characteristics, for example until the required homogeneity of the suspension of the nanostructure particle material in the solvent is obtained, and to maintain the homogeneity thereafter. By provision of the recirculation system it is possible to prepare the dispersion (which may take some time) without causing interruptions in the process of injection. Furthermore, the provision of the buffer system with the recirculation system makes it possible to mix the nanostructure particle powder gradually into the solvent, for example by supplying an amount of the nanostructure particle powder from its supply to the in-line mixer at regular instances.

[0015] In embodiments according to the invention, a control unit may be provided for controlling the recirculation system and the in-line mixer. The control unit may be equipped with an algorithm for controlling the components of the equipment to gradually mix the supply of nanostructure particle powder into the volume of solvent. The provision of such a controller has the advantages of automation, avoidance of human error, and possibility to provide multiple different algorithms, pre-programmed for different nanostructure particle materials and solvents or the like. The algorithm can define the recirculation to be continuous or temporary, for example during a certain time interval (predetermined or until certain homogeneity is obtained) or repeatedly during a certain (predetermined) time interval.

[0016] In embodiments according to the invention, the buffer system may comprise a first buffer tank and a second buffer tank downstream of the first buffer tank. The provision of the second buffer tank can further ensure continuous availability and supply of the dispersion to the injection unit. By the provision of the second buffer tank, a preparation stage separate from a supply stage can be obtained wherein the dispersion is first prepared by means of the first tank and the recirculation system through the in-line mixer and subsequently the prepared dispersion is transferred from the first tank to the second tank, vacating the first tank for preparation of a new volume of dispersion.

[0017] In embodiments according to the invention, the recirculation system may be connectable to an outlet port of the second buffer tank. In this way, a volume of dispersion stored in the second tank may be transferred back to the preparation stage to be recirculated through the in-line mixer. [0018] In embodiments according to the invention, the first and/or second buffer tank may be provided with a (low-shear) stirring element for stirring the dispersion stored therein. The stirring element is preferably mounted in an inclined position. It has been found that such inclined position can improve the stirring action of the stirring element.

[0019] In embodiments according to the invention, the equipment may further comprise a drying unit for drying the injected fabric and/or a collecting unit for collecting the injected fabric.

[0020] According to a second aspect of the invention, which may be combined with the other aspects and embodiments described herein, a method for fabrication of a fabric containing an nanostructure particle powder is provided. The method comprises the steps of: providing a supply of a fabric and moving said fabric in a movement direction X; providing a supply of an nanostructure particle powder; providing a supply of a solvent; mixing said nanostructure particle powder and said solvent to provide a dispersion, said mixing being performed using an in-line mixer which is positioned in a pipeline through which said solvent and nanostructure particle powder are circulated; and injecting said dispersion in said fabric by means of an injection unit.

[0021] In embodiments according to the invention, the solvent may comprise an organic solvent.

[0022] In embodiments according to the invention, the nanostructure particle powder comprises particles with a particle size ranging between 1 and 100 nm.

[0023] In embodiments according to the invention, the supply of solvent is provided in a first buffer tank and the solvent is circulated from said first buffer tank to said in-line mixer and back to said first buffer tank, while gradually adding said supply of nanostructure particle powder.

[0024] In embodiments according to the invention, the nanostructure particle powder is gradually added at a rate of 0.2 to 2.0 kg per minute, preferably at a decreasing rate within this range, while said solvent is circulated through the in-line mixer at a rate of 5 to 10 m³/h, preferably 6 to 8 m³/h. It has been found that nanostructure particle does not mix very well with organic solvents, so adding the nanostructure particle in smaller doses and circulating the solvent may facilitate the provision of dispersion with a sufficiently high dosage of nanostructure particle powder.

Brief description of the drawings

[0025] The present invention will be discussed in more detail below, with reference to the attached drawings, in which: Figure 1 shows a schematic illustration of an embodiment of an equipment for injection of a dispersion in a fabric;

Figure 2 shows a schematic illustration of an embodiment of an injection unit of an equipment for injection of a solution in a fabric,

- Figure 3 shows a schematic illustration of the orientation of a hollow needle with respect to the fabric;

Figure 4 shows a schematic illustration of a preferred hollow needle;

Figure 5, Figure 6 and Figure 7 show schematic illustrations of alternative embodiments of equipments for injection of a dispersion;

- Figures 8 and 9 show schematic illustrations of embodiments of mixing systems for mixing an nanostructure particle powder and a solvent to provide a dispersion, each comprising a preparation unit and a storage unit;

Figure 10 shows a schematic illustration of an alternative embodiment of an injection unit.

Description of embodiments

[0026] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not necessarily correspond to actual reductions to practice of the invention.

[0027] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the invention can operate in other sequences than described or illustrated herein.

[0028] Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. The terms so used are interchangeable under appropriate circumstances and the embodiments of the invention described herein can operate in other orientations than described or illustrated herein.

[0029] Furthermore, the various embodiments, although referred to as "preferred" are to be construed as exemplary manners in which the invention may be implemented rather than as limiting the scope of the invention. [0030] The term "comprising", used in the claims, should not be interpreted as being restricted to the elements or steps listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising A and B" should not be limited to devices consisting only of components A and B, rather with respect to the present invention, the only enumerated components of the device are A and B, and further the claim should be interpreted as including equivalents of those components.

[0031] An equipment for injection of a dispersion in a fabric, an example of which is schematically illustrated in Fig. 1 , comprises:

a supply of a fabric 1 10 and a transport system 120 for moving said fabric in a movement direction X, said fabric defining a plane P;

a supply of a dispersion 130, said dispersion comprising a suspension of an nanostructure particle powder in a solvent; and

an injection unit 140 for injecting said dispersion in said fabric, said injection unit being located above said fabric, said injection unit comprising a needle holder and moving means for moving said needle holder in directions parallel and/or perpendicular to said plane P, said needle holder being provided for holding at least one hollow needle having a longitudinal axis L and having a tip for discharging said dispersion in said fabric;

a drying unit 150 for evaporating said solvent from said fabric injected with said dispersion; and

a collecting unit 160 for collecting said fabric.

[0032] The fabric 1 10 may comprise any type of textile structure, such as a woven, nonwoven, knitted or braided structure.

[0033] The fabric 1 10 preferably comprises organic or inorganic fibers, filaments or yarns. Organic fibers, filaments or yarns comprise for example polyethylene, polypropylene or polyethylene terephthalate (PET). Inorganic fibers, filaments or yarns comprise for example glass.

[0034] The fabric 1 10 has preferably a density between 90 g/cm³ and 150 g/cm³ and more preferably between 100 g/cm³ and 1 10 g/cm³.

[0035] Thickness of the fabric preferably ranges between 3 mm and 50 mm, for example between 5 mm and 30 mm, preferably between 10 mm and 25 mm.

[0036] In preferred embodiments, the fabric 1 10 comprises a nonwoven structure. A nonwoven structure is a sheet of fibres, continuous filaments, or chopped yarns of any nature or origin, that have been formed into a web by any means, and bonded together by any means, with the exception of weaving or knitting. The fibres, filaments or yarns are for example formed into a web by a wet laid process or a spun laid process. The fibres, filaments or yarns are for example bonded by chemical, mechanical, heat or solvent treatment. Examples of non-woven structures comprise for example felts, such as needle-punched felts.

[0037] The non-woven fabric preferably comprises organic or inorganic fibers, filaments or yarns. Organic fibers, filaments or yarns comprise for example polyethylene, polypropylene or polyethylene terephthalate (PET). Inorganic fibers, filaments or yarns comprise for example glass.

[0038] The fabric as for example the non-woven fabric has a planar structure defining a plane P.

[0039] The textile fabric layer of the present thermally insulating fabric containing the fumed silica is generally a flexible material consisting of a network of fibres and is preferably pliable around a tubular object having a bending radius of 1 .5 inch (3.81 cm) or less.

[0040] According to some embodiments, the textile fabric layer may have a thickness in the range of 5 to 40 mm, preferably 5 to 20 mm, most preferably about 10 mm. Thickness is measured herein according to ISO 9073, using 0.5 kPa pressure.

[0041] The textile fabric may comprise a woven, nonwoven, kitted or braided textile fabric.

[0042] According to some embodiments, the textile fabric layer may comprise a nonwoven textile fabric.

[0043] According to some embodiments, the textile fabric prior to the addition of the fumed silica may have a density in the range of 100 to 180 kg/m³, preferably in the range of 1 10 to 150 kg/m³, such as in the range of 1 10 to 130 kg/m³, e.g. about 1 10 to 120 kg/m³. The density of the textile layer containing the fumed silica will generally be in the range 160 to 260 kg/m³.

[0044] According to some embodiments, the textile fabric may have a surface weight of 1000 to 1800 g/m², such as in the range of 1 100 to 1800 g/m², more preferred in the range of 1 100 to 1500 g/m², e.g. in the range of 1 100 to 1300 g/m², such as about 1 100 g/m². Surface weight is measured herein according to EN 12127.

[0045] The textile fabric preferably comprises high temperature resistant fibers, i.e. having a glass transition temperature of more than 200°C, such as more than 500°C, even more than 800°C.

[0046] According to some embodiments, the textile fabric may comprise glass fibers. [0047] As an example, the textile fabric comprises fibers selected from the group consisting of E glass fibers, C glass fibers, S glass fibers, silica fibers, ceramic fibers, and organic fibers, such as PE or PET fibers.

[0048] The fibers of the textile fabric may even comprise only glass fibers.

[0049] The fibers may have a diameter in the range of 5 to 20 μηη, such as in the range of 6 to 20 μηη, more preferably in the range of 9 to 13 μηη, such as in the range of 9 to 1 1 μηη. The fibers preferably may be staple fibers with an average length of less than 15 mm, and preferably about 10 mm. The fibers preferably may have a maximum length of less than 15 mm, and preferably about 10 mm.

[0050] Suitable textile fabric layers are based on glass fiber needle felts F01 , F21 and F40 of JSC Valmiera Glass Fiber, Latvia.

[0051] The textile fabric layer preferably contains a binder, in particular when being a nonwoven layer, which binder content is preferably less than 10 %w, most preferably from 1 to 3 %w. This %w is expressed over the total weight of the textile fabric layer. Examples of suitable binders include functional silanes such Dynasylan commercially available from Evonik, tetraethylorthosilicate (TEOS), water glass, silicone, siloxane, colloidal silica and acrylics.

The benefit of adding a binder is that dust formation is further reduced and that it is easier to inject the fumed silica into the textile fabric layer.

[0052] A thermal insulating fabric according to the invention generally has a thermal conductivity in the range 35 to 50 mW/m^*K. This thermal conductivity is the thermal conductivity at 300°C, measured according to ASTM C177.

[0053] A product is understood thermally insulating when it has a thermal conductivity of less than 50 mW/m^*K.

[0054] The thermally insulating fabrics according to the invention are still flexible while releasing less to no dust during installation and/or use. The fabric is substantially noncombustible and may have a thickness up to 25 mm, even up to 50 mm thick.

[0055] The textile fabric layer of the thermally insulating fabric according to the invention is filled with fumed silica preferably making use of the technique as described in EP 3023528A1 , hereby incorporated in its entirety by reference. By means of hollow needles, the fumed silica powder, in suspension in a solvent, e.g. hexane, is injected in the textile fabric, after which the solvent is removed from the textile fabric, leaving the fumed silica powder in the textile fabric.

Alternatively the textile fabric layer may be filled with fumed silica by dipping techniques, or by applying electrical charges to impregnate the fabric layer with the fumed silica powder or by layered composite method wherein composites are formed by a sandwich technique of a layer of fumed silica powder between textile fabric layers interlocked by stiches or hot rolling.

[0056] The thermally insulating fabric of the present invention can further be provided with a first and/or a second outer textile layer laminated to the fumed silica containing textile fabric layer, said first outer textile layer preferably having an air permeability of less than or equal to 40 cc/sec^*5cm², said second outer textile layer preferably having air permeability of less than or equal to 40 cc/sec^*5cm².

[0057] The air permeability is measured using any suitable apparatus, measuring the volume of air passing through a surface of a sample at 98 Pascal pressure drop between the surfaces of the sample, typically using a circular surface of 25 mm diameter.

[0058] More preferably the air permeability of the first and/or second outer textile layer is less than or equal to 35 cc/sec^*5cm², such as less than or equal to 20 cc/sec^*5cm² or even less than or equal to 5 cc/sec^*5cm².

[0059] According to some embodiments, the first and/or the second outer textile layer may have a thickness in the range of 0.05 to 3 mm. According to some embodiments, the first outer textile layer may have a thickness in the range of 0.05 to 3 mm. According to some embodiments, the second outer textile layer may have a thickness in the range of 0.05 to 3 mm.

[0060] The first and/or the second outer textile layer may have a thickness in the range of 0.1 to 3 mm, such as in the range of 0.1 to 0.5 mm, more preferred in the range of 0.2 to 0.3 mm.

[0061] Optionally the thickness of the first and the second outer textile layer are identical.

[0062] According to some embodiments, the first and/or the second outer textile layer may have a density in the range of 3 to 1300 kg/m³. According to some embodiments, the first outer textile layer has a density in the range of 3 to 1300 kg/m³. According to some embodiments, the second outer textile layer has a density in the range of 3 to 1300 kg/m³. Optionally the density of the first and the second outer textile layer are identical.

[0063] According to some embodiments, the first and/or the second outer textile layer may have a surface weight of 10 to 30 g/m². According to some embodiments, the first outer textile layer may have a surface weight of 10 to 30 g/m². According to some embodiments, the second outer textile layer may have a surface weight of 10 to 30 g/m².

[0064] The first and/or the second outer textile layer may have a surface weight of 15 to 25 g/m², more preferred in the range of 17 to 21 g/m². Optionally the surface weight of the first and the second outer textile layer are identical.

[0065] The first and second outer layers are textile layers, i.e. they should be pliable around a tubular object having a bending radius of 1 .5 inch (3.81 cm) or less. [0066] The fibers of the first and the second outer layer may be selected from the group consisting of E glass fibers, C glass fibers, S glass fibers, silica fibers, ceramic fibers, and organic fibers, preferably PE or PET fibers.

[0067] The fibers used for the first and second layer may have a diameter in the range of 5 to 20 μηη, such as in the range of 6 to 20 μηη, more preferably in the range of 9 to 13 μηη, such as in the range of 9 to 1 1 μηη. The fibers preferably may be staple fibers with an average length of less than 15 mm, and preferably about 10 mm. The fibers preferably may have a maximum length of less than 15 mm, and preferably about 10 mm.

[0068] The first and the second layer may comprise high temperature resistant fibers, i.e. having a glass transition temperature of more than 200°C, such as more than 500°C, even more than 800°C.

[0069] According to some embodiments, the first and/or second outer textile layer may comprise glass fibers.

[0070] The fibers of the first and/or second outer textile layer may even comprise only glass fibers.

[0071] Optionally the fibers of the first and the second outer textile layer and/or the fumed silica containing textile fabric layer are provided out of identical material, such as either E glass fibers, C glass fibers, S glass fibers, silica fibers or ceramic fibers.

[0072] The first and/or second outer layer preferably have a binder content, in particularly when being a nonwoven layer, which binder content is preferably less than 15 %w, most preferably less than 12 %w, typically 10 to 1 1 %w. This %w is expressed over the total weight of the outer layer. The preferred binder is polyvinylalcohol (PVA) binder.

[0073] The first and/or second outer layer preferably have a tensile strength in machine direction (MD) and cross direction (CD) in the range of 20 to 100 N/5cm, measured according to IS01924/2.

[0074] The first and/or second outer textile layer is generally provided with an adhesive in order to be able to laminate the layers to the textile fabric layer. The preferred adhesive is a hot melt adhesive. Preferred adhesives are polyamide, polypropylene or thermally setting polyurethane based adhesives. The adhesive may be applied as a coating to the first and/or second layer. In an alternative, a film of adhesive, such as a hot melt adhesive, may be applied between the first and/or second outer layer, and the textile fabric layer. An adhesive, optionally applied as a coating, in an amount of 4 to 20 g/m² is preferred, more preferred in an amount of 4 to 10 g/m², such as about 8 g/m². Preferably this adhesive is applied on only one side of the first and second layer. The side being provided with adhesive is used to contact the textile fabric matrix.

[0075] The first and second layer and textile fabric layer may be laminated to each other by thermal or solvent lamination. Most preferred, the layers are laminated to each other using thermal or heat lamination, e.g. in a calendering.

[0076] The first outer textile layer may comprise a woven, nonwoven, kitted or braided textile fabric.

[0077] The second outer textile layer may comprise a woven, nonwoven, kitted (both warp or weft knitted fabrics) or braided textile fabric.

[0078] The woven first and/or second outer layer may be plain woven textile fabrics, twill woven textile fabrics, satin woven textile fabrics, atlas or basket woven textile fabrics, or alike.

[0079] According to some embodiments, the first and second outer textile layer may be identical.

[0080] According to some embodiments, the first outer textile layer may comprise a nonwoven textile fabric.

[0081] According to some embodiments, the first outer textile layer may have a density in the range of 3 to 300 kg/m³. According to some embodiments, the first outer textile layer may have a surface weight of 10 to 30 g/m².

[0082] Optionally the second outer textile layer comprises a nonwoven textile fabric.

[0083] Optionally the nonwoven textile fabric of the first and the second outer textile layer are identical.

[0084] According to some embodiments, the second outer textile layer may be a woven textile layer. According to some embodiments, the second outer textile layer may have a density in the range of 300 to 1300 kg/m³. According to some embodiments, the second outer textile layer may have a surface weight of 100 to 300 g/m².

[0085] Suitable first and second outer textile layers, also being referred to as veils, are layers provided as fleeces AD-stick E2016.4, available from ADLEY NV, Belgium.

[0086] Other suitable veils are the Optiveil™ series of veils of Technical Fibre Products Ltd, UK , such as 20103A Eglass veils, with areal weight of 10 g/m², 17 g/m², 22 g/m², 30 g/m² or 34 g/m².

[0087] According to a second aspect of the invention, the thermally insulating fabrics are used as thermal insulation.

[0088] The fabrics may be used to thermally insulate product for various applications such as pipes and building applications. The pipes may be used for the oil sector where temperature applications will be within 200 to 800°C. Fabrics according to the invention may be used in cryogenic applications with temperature limits of less than 10°C. The fabrics may be used in the building sector for e.g. roofing, ceiling and floor applications where mineral wools, polystyrene (PS), or polyurethane (PU) shortfalls in performance in thermal insulation properties.

[0089] When used to cover e.g. a tubular pipe by bending the fabric around the outer surface of said tube, e.g. a tube of 1 m diameter, little to no dust is released. The textile layers remain undamaged and do not show cracks.

[0090] Any fabric supply equipment to supply the substrate to the equipment can be considered. Examples comprise unwinding coils or reels.

[0091] As transport system 120 any system that is suitable to transport a fabric in the equipment, more particularly to transport a fabric from the supply to the injection unit of the equipment can be considered. Examples comprise belts, such as conveyor belts.

[0092] The transport system 120 preferably moves the fabric in movement direction X with a speed ranging between 0.05 m/min and 1 .00 m/min, and more preferably between 0.10 m/min and 0.50 m/mm. The speed of the movement can be constant or can be variable.

[0093] The dispersion 130 comprises nanostructure particle powder suspended in a solvent.

[0094] The solvent comprises preferably an organic solvent such as hexane, heptane, toluene, xylene or an alcohol as for example methanol or ethanol. In a preferred embodiment the solvent comprises hexane.

[0095] The nanostructure particle powder has preferably a particle size ranging between 1 and 100 nm.

[0096] The nanostructure particle powder preferably comprises silica particles (Si0₂ particles).

[0097] The nanostructure particle may also be a carbon nanostructure particle or a metal oxide nanostructure particle.

[0098]

[0099] In certain specific embodiments, the nanostructure particle powder is aerogel powder.

[00100]

[00101] In certain specific embodiments, the nanostructure particle powder is fumed silica powder.

[00102] The concentration of nanostructure particle powder ranges preferably between 0.01 and 0.2 g/mL solvent and more preferably between 0.03 and 0.1 g/mL solvent. [00103] A preferred dispersion comprises silica particles in a hexane solution, with a concentration of silica particles preferably ranging between 0.01 and 0.2 g/mL solvent and more preferably between 0.03 and 0.1 g/mL solvent.

[00104] To optimize the thermal insulation properties it can be preferred to add additional components, such as additional powder components to the dispersion. Such additional components may comprise opacifying compounds, infrared absorbing compounds, infrared reflecting compounds, thermally conductive compounds and/or electrically conductive compounds.

[00105] Preferred additional components comprises carbides and oxides such as metal oxides. Examples comprise boron carbide, titanium carbide, tungsten carbide, silicon carbide, carbon black, nickel oxide, tin oxide, titanium oxide, zirconium oxide, iron oxide, manganese oxide, aluminum oxide, chromium oxide, iron titanium oxide or combinations thereof.

[00106] The pore size of the nanostructure particle powder for use according to the present invention is between 0.01 and 200 nm on average.

[00107] In particular embodiments, the nanostructure particle powder is an aerogel powder, wherein the pore size of the aerogel powder for use according to the present invention is between 0.01 and 30 nm on average.

[00108] In particular embodiments, the nanostructure particle powder is a fumed silica powder, wherein the pore size of the fumed silica powder for use according to the present invention is between 50 and 200 nm on average, such as between 50 and 100 nm and preferably between 50 and 70 nm.

[00109] Pores within fumed silica are generally located between the primary particles (inter-particle pores), not within the primary particles themselves (intra-particle pores).

[00110] The pore size can be measured and analysed by gas adsorption/desorption. Gas adsorption analysis is commonly used for surface area and porosity measurements. This involves exposing solid materials to gases or vapors at a variety of conditions and evaluating either the weight uptake or the sample volume. Analysis of these data provides information regarding the physical characteristics of the solid including skeletal density, porosity, total pore volume and pore size distribution. Usually nitrogen gas is used for the pore size determination of fumed silica. Pore size measurement is generally carried out according to standard ISO 15901 -2.

[00111] The %w of the fumed silica powder is based upon the weight of the textile fabric layer in which it is present. [00112] More preferred, the thermally insulating fabric comprises a textile fabric layer, which comprises fumed silica powder in an amount range of 15 to 50 %w, such as in a range of 40 to 50 %w.

[00113] The fumed silica content of the thermally insulating fabric according to the invention may be more than or equal to 20 kg/m³, more preferably more than or equal to 50 kg/m³ such as in the range of 50 to 80 kg/m³, e.g. about 50 kg/m³ or about 60 kg/m³ or about 70 kg/m³.

[00114] The fumed silica within the textile fabric layer is preferably uniformly distributed over the surface and/or the thickness of the textile fabric layer.

[00115] The fumed silica preferably is hydrophobic and causes no corrosion under insulation (CUI).

[00116] The fumed silica powder for use according to the present invention may be any fumed silica with an average pore size within the above ranges.

[00117] Preferably the fumed silica for use according to the invention has a surface area in the range 50 to 380 m²/g, preferably 100 to 300 m²/g, most preferably about 200 m²/g. The specific surface area is generally determined on the basis of the BET method (Brunauer, Emmett and Teller) according to standard ISO 9277.

[00118] Fumed silica, also known as pyrogenic silica because it is produced in a flame, consists of microscopic droplets of amorphous silica (the primary particles) fused into branched, chainlike, three-dimensional secondary particles (aggregates) which then agglomerate into tertiary particles, resulting in a fluffy powder. The resulting powder has an extremely low bulk density and high surface area. Primary particle size is generally 5 to 50 nm. The particles are non-porous and generally have a surface area of 50 to 600 m²/g. The bulk density is generally 30 to 100 kg/m³, preferably 40 to 60 kg/m³, such as about 60 kg/m³.

[00119] Fumed silica is made from flame pyrolysis of silicon tetrachloride or from quartz sand vaporized in 3000°C electric arc. Major global producers are Evonik (who sells it under the name AEROSIL), Cabot Corporation, Wacker Chemie, Dow Corning, Heraeus, Tokuyama Corporation, OCI, Orisil and Xunyuchem.

[00120] The fumed silica for use in the present invention is preferably a hydrophobic fumed silica.

[00121] Hydrophobic fumed silica's are produced by chemical treatment of the hydrophilic grades obtained directly from the flame hydrolysis and having freely accessible silanol groups (Si-OH) on the particle surface with hydrophobic property- imparting agents such as silanes, silazanes or siloxanes (e.g. halogen silanes, cyclic dimethylsiloxane). Hydrophobic fumed silicas are characterized by a low moisture adsorption. Also they are especially suitable for corrosion protection of e.g. the pipes to be insulated.

[00122] The hydrophobic fumed silica powder preferably has a hydrophobic agent content of between 1 and 15 %w, preferably between 1 and 5 %w, most preferably between 1 and 3 %w, the %w based upon the total weight of the fumed silica powder. The hydrophobic agent content is generally also being referred to as silane content; the silane content as used herein meant to include the content of any organic derivative of a silicone containing at least one covalent silicon-carbon bond such as silane-based compounds, siloxane-based compounds and silazane-based compounds. Preferably the silane content is kept low so as to keep combustibility low.

[00123] Thermal insulation fabrics containing fumed silica powder according to the present invention generally obtain a Euroclass A1 performance in the non-combustibility test ISO 1 182 whereas thermal insulation fabrics containing aerogel generally only obtain a A2 classification due to the much higher silane content of aerogels (generally above 15 %w, such as 20 %w).

[00124] Suitable hydrophobic fumed silica's for use according to the present invention include the following products, commercially available from Evonik under the tradename AEROSIL: R 972, R 974, R 104, R 106, R 202, R 208, R 805, R 812, R 812 S, R 816, NAX 50, NY 50, RX 200, RX 300, RX 50, RY 200, RY 200 L, RY 200 S, RY 300, RY 50, NX 90 G, NX 90 S, NX 130. Other suitable hydrophobic fumed silica's are commercially available from Wacker under the tradename HDK such as H13L, H 15, H17, H18, H20, H2000, H20RH, H30, H30LM, H30RM. Further the hydrophobic fumed silica's available from OCI Company under the tradename KONASIL, e.g. K-P15, K-P20, K-D15, K-T30 and K-T20. Hydropbic fumed silica's are also available from Tokuyama under the tradename REOLOSIL (e.g. DM-10).

[00125] Particularly AEROSIL R 974 and RX 200 are preferred. AEROSIL R 974 is a hydrophobic fumed silica of specific surface area 150-190 m²/g aftertreated with dimethyldichlorosilane based on a hydrophilic fumed silica with a specific surface area of 200 m²/g.

[00126] Instead of adding a hydrophobic fumed silica as such to the textile fabric layer the hydrophobization of the fumed silica can also take place once the fumed silica is added to the textile fabric layer e.g. by sprinkle coating with silicones or using the technique as described in EP 2622253.

[00127] According to some embodiments, the fumed silica powder may have a thermal conductivity at room temperature of less than 30 mW/m^*K. This thermal conductivity is measured according to ASTM C518. The fumed silica powder may have a thermal conductivity in the range of 22 to 25 mW/m^*K..

[00128] Adding infrared opacifiers such as suitable titanium dioxide, Zircon, lllmenite,Zirconia, clays, graphite, carbon black, silicon carbide, iron oxide or magnetite powders allows to reduce the thermal conductivity of the fumed silica even more, especially at higher temperatures such as at more than 300°C or more than 500°C. A preferred IR opacifier is silicon carbide. Preferably the particle size of the IR opacifier is in the range 2 to 7 μηη.

This IR opacifier or mixture of IR opacifiers is generally added in an amount of up to 20 %w, preferably up to 10 %w, most preferably in the range of 3 to 7 %w, the %w based upon the weight of the fumed silica present.

[00129] Further additives for the textile fabric layer include flame retardants such as flame retardant minerals, e.g. AIOH, MgOH, MgC0₃.3H₂0 or any hydrated minerals (synthetic or natural) with endothermic nature or zinc borates, or functional mineral additives such as sound absorbers, or combinations of those.

Preferably, the concentration of additional components ranges between 1 and 30 % of the concentration of nanostructure particle powder in solvent, preferably between 1 and 10 % of the concentration of nanostructure particle powder in solvent.

[00130] The dispersion 130 is preferably supplied to the injection unit from a tank 131 for holding the dispersion, an example of which is shown in Fig. 5. The tank for holding the dispersion is preferably provided with means 133 to stir, mix and/or homogenize the dispersion.

[00131] Alternatively, or in combination, the equipment may comprise an in-line mixer 135 for mixing the solvent and the nanostructure particle powder whereby the dispersion is supplied to the injection unit from the in-line mixer either directly, as shown in Fig. 6, or through one or more intermediate or buffer tanks, as shown in Fig. 7.

[00132] The injection unit 140 for injection of the dispersion in the fabric is preferably, though not necessarily, located above the fabric and preferably above the transport system. The injection unit, an embodiment of which is shown in Figs. 2 and 3, comprises a needle holder 142 and moving means (not shown) for moving the needle holder in directions parallel and/or perpendicular to the plane P. The needle holder is provided for holding at least one hollow needle 144. The at least one hollow needle has a longitudinal axis L and has a tip 148 for discharging the dispersion in the fabric. The at least one hollow needle is preferably positioned in an inclined position towards the plane P of the fabric. The tip of the at least one hollow needle is thereby preferably pointing towards the movement direction X. [00133] Preferably, the at least one hollow needle comprises a tubular section 146, possibly connected to a hub.

[00134] The tubular section 146 of the hollow needle may comprise a polymer material, a metal or metal alloy, such as an iron alloy for example a stainless steel, a nickel alloy as for example brass. The tubular section may be coated for example with a metal or metal alloy coating, such as a nickel plated coating layer or a polymer coating such as a PTFE coating. It may be desired to apply a coating to increase the life cycle of a hollow needle, to increase the lubricity of the needle or to give the needle additional protection such as corrosion protection.

[00135] Suitable hollow needles 144 for use in equipment according to the present disclosure are injection needles which are used for medical purposes, such as for example the commercially available BD Microlance 3 16G or BD Microlance 3 18G manufactured by Becton, Dickinson and Company.

[00136] The tip 148 of the hollow needle can have a blunt tip surface, i.e. the hollow needle is cut in an angle of 90°. Alternatively, the hollow needle may have a beveled tip surface. In case the hollow needle has a beveled tip surface, the tip surface is preferably oriented in an angle ranging between 145° and 1 5° with respect to the longitudinal axis L. More preferably, the tip surface is oriented in an angle ranging between 160° and 170° with respect to the longitudinal axis L.

[00137] The hub may be designed to facilitate the positioning in the needle block and may comprise a polymer material, a metal or metal alloy material.

[00138] The needle holder 142 comprises at least one hollow needle. More preferably, the needle holder comprises at least one row of needles, with the needles preferably spaced 5 to 20 cm from each other.

[00139] In case the injection unit comprises more than one hollow needle, the hollow needles are preferably positioned in a mutual parallel or mutual substantially parallel position, preferably in a row. The needles may be arranged in a single row or in multiple (staggered) rows.

[00140] The at least one hollow needle 144 is preferably positioned in an inclined position towards the plane P of the fabric with the tip of the at least one hollow needle pointing forwards with respect to the movement direction X. Preferably the at least one hollow needle is aligned with a plane which is perpendicular to the plane P and parallel to the movement direction X, i.e. the projection of the longitudinal axis L of the needle onto plane P is preferably parallel to the movement direction X. In preferred embodiments, the angle between the at least one hollow needle and the plane P of the fabric ranges between 10 and 80°, preferably between 30 and 60°, more preferably around 45°. The angle between the at least one hollow needle and the fabric is hereby defined as the (enclosed) angle between the longitudinal axis L of the at least one hollow needle and the projection of the longitudinal axis L on said plane P of said fabric. By positioning the at least one hollow needle in an inclined position towards the fabric, i.e. towards the plane P of the fabric with the tip of the at least one hollow needle pointing forwards with respect to the movement direction X of the fabric, the risk of causing damage to the fabric can be considerably reduced.

[00141] In embodiments where the at least one needle 144 has a beveled tip surface, the needle is preferably oriented such that the sharp side of the needle tip contacts the fabric first, for example as shown in Fig. 3. This can facilitate penetration of the needle(s) into the fabric and/or minimize damage to the surface layer of the fabric as a result of penetration. In order to facilitate the placement of the needles in the correct orientation on the needle holder and to ensure the correct orientation afterwards, a clamping mechanism may be provided on the needle holder to clamp the needles after they have been placed on the needle holder in the desired position.

[00142] To obtain a substantially uniform distribution of the dispersion over the thickness of the fabric, the dispersion is preferably injected at different levels in the fabric, i.e. at different depths in the fabric, for example every 3 to 6 mm, so e.g. at 2 or 3 levels for a fabric of 10 mm thickness and at 4 or 5 levels for a fabric of 20 mm thickness. The injections at multiple different levels can be located aligned vertically above each other or can alternatively be located at different positions along the axis defined by the movement direction X of the fabric.

[00143] In case the injection of the dispersion comprises injections at multiple different levels of the fabric, it is particularly preferred to position the at least one hollow needle in an inclined position as described above.

[00144] The injection unit may comprise moving means (not shown) for moving the needle holder in directions parallel to and/or perpendicular to the plane P of the fabric. Preferably, the injection unit comprises moving means to move the needle holder in such a way that the positions of subsequent injections at multiple levels in the fabric are vertically aligned above each other. The longitudinal spacing (in direction X) between the injection locations is preferably 5 to 15 mm. Subsequent lines of injection points may also be staggered, which may for example be achieved by using a needle holder with two rows of needles, staggered with respect to each other, or with two separately movable needle holders. The amount of dispersion per injection is preferably controlled to achieve 1 ml/cm³, i.e. that each cm³ of fabric contains about 1 ml of dispersion, and/or to achieve that after drying the fabric the dried fabric contains 90 to 100 kg powder (nanostructure particle material and possible additives) per m³ fabric.

[00145] The dispersion 130 may be supplied by means of a mixing system, examples of which are shown in Figs. 7-9.

[00146] In an embodiment, the mixing system may comprise a supply of an nanostructure particle powder 137, a supply of a solvent 136 and an in-line mixer 135 for mixing said nanostructure particle powder and said solvent to provide the dispersion. The use of an in-line mixer may allow a continuous supply of the dispersion, may reduce the preparation time of the dispersion and/or may allow to obtain a better mixing.

[00147] The in-line mixer preferably comprises a high-shear in-line mixer. The mixer is preferably a high-shear rotor-stator mixer. In such mixers, the rotor-stator array is contained in a housing with an inlet at one end and an outlet at the other, and the rotor is driven through a seal at a predetermined rotation speed to reduce particle size in the dispersion and/or achieve a dispersion with a predetermined particle size.

[00148] The dispersion may be temporarily stored in a buffer system comprising one or more buffer tanks 138, 238. The mixing system may be provided with at least one recirculation system for recirculating the dispersion from the buffer tank(s) 138, 238 to and from the in-line mixer. In case of multiple buffer tanks, the recirculation system may be partly common for the buffer tanks, or separate recirculation systems may be provided for each buffer tank or sets of buffer tanks.

[00149] By the (re)circulation system, a multi-pass system is created whereby the in-line mixer discharge is sent back to the in-line mixer and the recirculation can be continued until the dispersion in the buffer tank 138, 238 meets certain characteristics, for example until the required homogeneity of the suspension of the nanostructure particle material in the solvent is obtained, and to maintain the homogeneity thereafter.

[00150] The operation of the recirculation system can be continuous or temporary, for example during a certain time interval until a predetermined level of homogeneity is obtained, or repeatedly during a certain predetermined time interval. As an example, for the first mixing of the nanostructure particle powder and the solvent, the nanostructure particle powder can be gradually introduced into the mixture at the in-line mixer 135 which is circulated from the in-line mixer 135 through a recirculation circuit, for example comprising a first buffer tank 138 and a recirculation pump 139, back to the inlet side of the in-line mixer.

[00151] The recirculation system and the in-line mixer may be controlled by means of a controller 125, which is equipped with at least one appropriate algorithm for controlling the mixing process. Such algorithm may define the flow rate of the recirculation, the rate at which nanostructure particle powder is added to the solvent, and/or other parameters.

[00152] In the first buffer tank 138, a volume of the dispersion may be temporarily stored. If necessary, for example after a period of interruption, recirculation may be restarted.

[00153] Preferably, the mixing system comprises a second buffer tank downstream from the first buffer tank, the second buffer tank being provided for temporary storage of a volume of the dispersion before supply to the injection unit. The dispersion is then supplied to the injection unit from the second buffer tank. In this way, it is possible to first prepare the dispersion by the in-line mixer and the first recirculation system and temporary storage in the first buffer tank 138, without causing interruptions in the process of injection which takes its supply from the second buffer tank 238.

[00154] The mixing system is thus preferably divided into a preparation unit 101 and a storage unit 102, as further shown in Figs. 8 and 9. The preparation unit is connected to the supply of nanostructure particle powder 137 and the supply of solvent 136 and is generally provided for preparing a homogeneous, or substantially homogeneous batch of dispersion, for example by use of one or more in-line mixers 135, preferably high-shear in-line mixers, and a first buffer tank 138 with a recirculation system as described above. The storage unit is provided downstream of the preparation unit and upstream of the injection unit 140, and is generally provided for tapping from the batch of dispersion that has been prepared in the preparation unit and temporarily storing the tapped volume of dispersion before supply to the injection unit, for example by use of a second buffer tank 238 which is connected to the preparation unit 101 via a transferring means, such as a tap and/or a pump 239.

[00155] Each of the buffer tanks 138, 139 may be equipped with an inclined stirrer 133, 233 as described elsewhere herein. The second buffer tank 238 may also be provided with a recirculation circuit to return dispersion to the preparation unit 101 , if necessary, as shown in Fig. 8, or may be equipped with its own recirculation circuit as shown in Fig. 9.

[00156] Both buffer tanks 138 and 238 may be provided with a pressure sensor and/or pressure control unit, and/ or a liquid level control system keep the liquid level above a lower level and/or under an upper level (not shown).

[00157] The equipment for injection of a dispersion in a fabric, according to preferred embodiments, comprises at least one tank 131 , in particular an intermediate or buffer tank 138, 238, for temporary storage of the dispersion. As shown in the example of Fig. 5, the at least one tank preferably has a vertical central axis 132 and preferably comprises at least one stirrer 133 having a longitudinal main axis 134, said stirrer being oriented in a predetermined, non-parallel or inclined position with respect to said vertical central axis of the tank. Such positioning of the stirrer means that the stirring element rotates according to a plane which is inclined with respect to the axis of the tank. In this way, a stream can be created which reaches into area at the bottom of the tank. This can avoid that the nanostructure particle suspension can subside to the bottom area of the tank, so can avoid a "dead zone" and can ensure that the mixture stays more homogeneous. The dead zone can be avoided by creation of a predetermined flow as a result of the non-parallel/inclined position of the stirrer, or by an actual rotation of the stirrer through the zone.

[00158] The non-parallel or inclined position of the stirrer is preferably such that the vertical central axis 132 of the tank and the longitudinal main axis 134 of the stirrer extend in a predetermined angle β with respect to each other, which preferably ranges between 30 and 80°, preferably is about 60°.

[00159] The stirrer 133 preferably comprises at least one stirring blade and the inclined position is preferably such that the at least one stirring blade is during operation rotated into and out of a bottom area of said tank, in particular the area which would otherwise form the dead zone.

[00160] The at least one tank 131 preferably has a bottom wall which is inclined with respect to the vertical axis. The bottom wall may for example be conical, or otherwise tapered. The at least one stirrer 133 is preferably oriented with its axis 134 substantially perpendicular to said bottom wall.

[00161] The equipment for injection of a dispersion in a fabric, according to preferred embodiments, see for example Fig. 7 and Fig. 10, comprises a buffer tank 238 for buffering the dispersion at a first pressure P1 . The injection unit 140 is located downstream from said buffer tank and provided for injecting the dispersion 130 in the fabric 1 10. The injection unit comprises a buffer tank 238, and a pressurizing means (i.e. a volumetric pump) for pressurizing the dispersion to the injection needles at a pressure P2 higher than P1 . The use of a volumetric pump has the advantage that only small volumes of dispersion are pressurized before injection and not the entire volume present in the buffer tank. This can lead to a higher efficiency (less power consumption) and, in case of explosive mixtures (e.g. when hexane is the solvent), a reduced risk of explosion.

[00162] In an embodiment, for example as shown in Fig. 10, the injection system comprises a needle holder 142 for holding a plurality of injection needles 144 and two pressure dampeners, the latter of which control and stabilize the pressure at the injection beam. This structure has the advantage that a more uniform distribution of the dispersion to the needles 144 can be achieved.

[00163] Preferably, P1 ranges between 1 .0 and 1 .5 ATM and P2 ranges between 1 .5 and 8.0 ATM, more preferably between 2.0 and 5.0 ATM.

[00164] As drying unit 150 any drying equipment suitable to evaporate the solvent from the fabric injected with the dispersion can be considered.

[00165] As collecting unit 160 any unit suitable to collect the dried fabric can be considered. Collecting units comprise any type of winding or coiling units and any type of units for cutting the fabric in sheets of a predetermined size and for collecting these sheets on a pile.

[00166] In operation, the equipment for injecting a dispersion in a fabric, according to embodiments disclosed herein, implements a method for manufacturing a fabric which comprises the following steps:

preparing a dispersion;

- supplying a fabric, said fabric defining a plane P;

moving said fabric by means of a transport system in a movement direction X, injecting said dispersion in said fabric by an injection unit, said injection unit being located above said fabric, said injection unit comprising a needle holder and moving means for moving said needle holder in directions parallel and/or perpendicular to said plane P, said needle holder being provided for holding at least one hollow needle having a longitudinal axis L and having a tip for discharging said dispersion in said fabric;

drying said fabric injected with said dispersion to evaporate said solvent from said fabric;

- collecting said dried fabric by means of a collecting unit.

[00167] The step of preparing the dispersion preferably involves the use of an inline mixer, preferably a high-shear in-line mixer, wherein a supply of nanostructure particle powder and a supply of solvent are gradually mixed, while recirculating the mixture through the in-line mixer, as described elsewhere herein, preferably with a preparation step in a preparation unit that is separate from the (temporary) storage and supply of the dispersion to the injection unit.

[00168] The preparation and supply of the dispersion to the injection unit may involve one or more intermediate or storage tanks, preferably with inclined stirrers, and preferably pressurizing means, as described elsewhere herein.

[00169] The step of injecting the dispersion in the fabric may involve positioning the at least one hollow needle in an inclined position towards the plane P of the fabric with the tip of the at least one hollow needle pointing forwards with respect to the movement direction X, as described elsewhere herein. The at least one needle preferably has a beveled tip, as described elsewhere herein.

[00170] Figure 1 shows a schematic illustration of an equipment 100 for injection of a dispersion in a fabric 1 10. The equipment 100 comprises a supply 120 of a fabric 1 10 and a supply 130 of a dispersion. The dispersion comprises nanostructure particle powder and an organic solvent such as hexane. The equipment 100 furthermore comprises an injection unit 140 for injecting the dispersion in the fabric 1 10, a drying unit 150 for evaporating the solvent from the fabric injected with the dispersion and a collecting unit 160 for collecting the dried fabric 1 1 . The fabric 1 10 moves from the supply of the fabric 1 10 to the collecting 160 in movement direction X. The injection unit 140 is located above the fabric 1 10.

[00171] Figure 2 shows a schematic illustration of an injection unit 140. The injection unit 140 comprises a needle holder 142 and moving means (not shown) for moving the needle holder 142 in directions parallel and/or perpendicular to the plane P. The needle holder 142 is provided for holding hollow needles 144. Each hollow needle 144 has a longitudinal axis L and comprises a tubular section 146 provided with a tip 148 for discharging the dispersion in the fabric. The hollow needles 144 are positioned in a mutual parallel or substantially mutual parallel position in a row. The row of hollow needles 144 is preferably oriented perpendicular to the direction perpendicular to the movement direction X.

[00172] Figure 3 shows a schematic illustration of the injection unit 140 above the plane P defined by the fabric 1 10 which is moved in the movement direction X. The hollow needles 144 are oriented in an inclined position towards the fabric 1 10 with the tip 148 of the hollow needle 144 pointing forwards with respect to the movement direction X. Preferably, the angle a between the hollow needles 144 and the fabric 1 10 ranges between 10° and 80°, preferably between 30° and 60°, more preferably around 45°. The angle a is thereby defined as the (enclosed) angle between the longitudinal axis L of the at least one hollow needle 144 and the projection of the longitudinal axis L the plane P of the fabric 1 10.

[00173] Figure 4 shows a detail of a preferred hollow needle 144 for use in the equipment for injecting a dispersion in a fabric according to the present disclosure. The hollow needle 144 comprises a tubular section 146 having a longitudinal axis L and a beveled tip surface 149. The beveled tip surface 149 is preferably oriented in an angle ranging between 145° and 175°, preferably between 160° and 1 0° with respect to the longitudinal axis L. [00174] Figure 5 shows a particular embodiment of an equipment 100 for injection of a dispersion in a fabric 1 10 as shown in Figure 1 . The dispersion is supplied to the injection unit 140 from a tank 131 . The tank has a vertical central axis 132. In preferred embodiments the tank 131 is provided with a stirrer 133 to mix and/or homogenize the dispersion. The stirrer 133 has a longitudinal main axis 134 and is preferably oriented with its longitudinal main axis 134 in an inclined position, i.e. non-parallel with respect to the vertical central axis 132. The stirrer 133 is for example positioned in such a way that the enclosed angle β between the longitudinal main axis 134 of the stirrer 133 and the vertical central axis 132 of the tank 131 is about 60°.

[00175] Figure 6 shows a particular embodiment of an equipment 100 for injection of a dispersion in a fabric 1 10 as shown in Figure 1 . The dispersion is supplied from an in-line mixer 135. A solvent is supplied to the in-line mixer 135 from a supply 136; nanostructure particle powder is supplied to the in-line mixer from supply 137. The supply 137 of the nanostructure particle powder comprises preferably a hopper. The in- line mixer 135 here provides a continuous supply of dispersion 130 to the injection unit 140.

[00176] Figure 7 shows a particular embodiment of an equipment 100 for injection of a dispersion in a fabric 1 10 as shown in Figure 1 . A solvent is supplied from a supply 136 to a first buffer tank 138, from which it is (re)circulated through a pipeline in which an in-line mixer 135 is provided. Nanostructure particle powder is supplied to the in-line mixer 135 from a hopper 137. The first buffer tank 138 may be provided with a stirrer 133 in an inclined position. A volume of the dispersion can be temporarily stored in the first buffer tank. The recirculation system comprises a recirculation pump 139 for recirculating the solvent/dispersion from the first buffer tank 138 through the in-line mixer 135. By such first recirculation system 139 a multi-pass system is created whereby dispersion temporarily stored in the first buffer tank 138 is sent back to the in-line mixer 135. The recirculation can be continued until the dispersion in the first intermediate tank 138 meets certain characteristics, for example until the required homogeneity of the suspension of the nanostructure particle in the solvent is obtained, and to maintain the homogeneity thereafter. The recirculation can be continuous or temporary or interrupted, for example during a certain time interval (predetermined or until a certain homogeneity is obtained) or repeatedly during a certain (predetermined) time interval. The recirculation is controlled by a control unit 125, which is equipped with one or more algorithms for controlling the mixing process. This control unit 125 may be dedicated for the preparation stage, or may be integrated in a general control unit which controls also the other parts of the equipment 100. [00177] The first part of the supply forms a preparation unit, comprising the mixer 135, the first buffer tank 138 and the recirculation pump 139. The supply of the dispersion may furthermore comprise a storage unit, comprising a second circulation pump 239 and a second buffer tank 238, possibly provided with a stirrer 233 in an inclined position. The second buffer tank 238 is used to tap a volume of prepared dispersion from the first tank 138 and temporarily store said volume as supply for the injection unit 140.

[00178] Figure 8 shows an alternative embodiment of the mixing system which supplies the dispersion for an equipment 100 for injection of a dispersion in a fabric 1 10 as shown in Figure 1 . The mixing system comprises a preparation unit 101 and a storage unit 102. The preparation unit comprise, in the same way as in Fig. 7, the supply of solvent 136, the supply of nanostructure particle powder 137, the in-line mixer 135, the first tank 138 with inclined stirrer 133 and the recirculation pump 139, and is provided for preparing the dispersion in a first, separate stage from the storage and injection stage. The storage unit 102 is provided downstream of the preparation unit and upstream of the injection unit 140, and is generally provided for tapping from the batch of dispersion that has been prepared in the preparation unit 101 and temporarily storing the tapped volume of dispersion before supply to the injection unit 140. Thereto, the storage unit has a second buffer tank 238, preferably with inclined stirrer 233, which is connected to the preparation unit 101 via a pump 239. Figure 9 shows an alternative embodiment of the mixing system of Figure 8. In this embodiment, the storage unit 102 is provided with its own recirculation system, comprising a pump 439 and an in-line mixer 439.

[00179] In the embodiment of Fig. 9, a second recirculation system is provided, comprising a feedback line with a pump 439, for recirculating the dispersion from the second buffer tank 238 back to the preparation unit.

[00180] Fig. 10 shows an embodiment of the injection system 140 for an equipment 100 for injection of a dispersion in a fabric 1 10 as shown in Figure 1 . The injection system 140 comprises a needle holder 142 for holding a plurality of injection needles 144 and two pressure dampeners, such that a more uniform distribution of the dispersion to the needles 144 can be achieved.

Example

[00181] By way of example, a process of mixing aerogel powder containing Ti02 into hexane is described.

[00182] The hexane was supplied to the first tank. The in-line mixer as described herein was used; not all aerogel was mixed at once into the hexane. The hexane was pumped around from the first buffer tank to the in-line mixer and back. The pumping around was done at a flow rate of about 7 m³/h. The powder was added at a rate of 10 kg per 25 minutes or 400 g per minute, which means that 0.4 kg was added to 250 to 500 I, or that the addition was done at a ratio of 1 kg per 625 to 1250 I. This was continued until a ratio of 1/15.6 was reached.

[00183] Once all the aerogel powder was mixed into the hexane, the resulting dispersion was pumped around for another few minutes to increase homogeneity. Thereafter, the pumping around was repeated at regular intervals for the same duration so as to maintain the homogeneity.

[00184] It is to be understood that although preferred embodiments and/or materials have been discussed for providing embodiments according to the present invention, various modifications or changes may be made without departing from the scope and spirit of this invention.

Claims

An equipment for injection of a dispersion in a fabric, said equipment comprising a supply of a fabric and a transport system for moving said fabric in a movement direction (X);

a supply of an nanostructure particle powder;

a supply of a solvent;

an in-line mixer, positioned in a pipeline through which said solvent and said nanostructure particle powder are circulated, and provided for mixing said nanostructure particle powder and said solvent to provide a dispersion; and an injection unit for injecting said dispersion in said fabric.

The equipment according to claim 1 , wherein said in-line mixer comprises a high- shear in-line mixer.

The equipment according to any of claims 1 or 2, wherein said nanostructure particle powder is a fumed silica powder.

The equipment according to any one of claims 1 to 3, further comprising a buffer system for temporary storage of a volume of a mixture of said solvent and said nanostructure particle powder, and/or said dispersion.

The equipment according to claim 4, further comprising a recirculation system for recirculating said mixture and/or said dispersion from an exit port of said buffer system through said in-line mixer and back to an inlet port of said first buffer system.

The equipment according to claim 5, further comprising a control unit for controlling the recirculation system and the in-line mixer, the control unit being equipped with an algorithm for controlling components of said equipment to gradually mix said supply of nanostructure particle powder into said volume of said solvent.

The equipment according to claim 4, 5 or 6, wherein the buffer system comprises a first buffer tank and a second buffer tank downstream of the first buffer tank.

The equipment according to claim 7, wherein the recirculation system is connectable to an outlet port of the second buffer tank. The equipment according to any one of the claims 4 to 8, wherein the buffer system comprises at least one buffer tank with a stirring element, the stirring element preferably being mounted in a non-parallel position with respect to a longitudinal axis of the buffer tank.

A method for fabrication of a fabric containing an nanostructure particle powder, comprising the steps of:

providing a supply of a fabric and moving said fabric in a movement direction (X); providing a supply of an nanostructure particle powder;

providing a supply of a solvent;

mixing said nanostructure particle powder and said solvent to provide a dispersion, said mixing being performed using an in-line mixer which is positioned in a pipeline through which said solvent and said nanostructure particle powder are circulated; and

injecting said dispersion in said fabric by means of an injection unit.

The method according to claim 10, wherein said solvent comprises an organic solvent. 12. The method according to claim 10 or 1 1 , wherein said nanostructure particle powder comprises particles with a particle size ranging between 1 and 100nm.

13. The method according to any one of the claims 10 to 12, wherein said supply of solvent is provided in a buffer system and wherein said solvent is circulated from said buffer system to said in-line mixer and back to said buffer system, while gradually adding said supply of nanostructure particle powder.

14. The method according to claim 13, wherein, at said in-line mixer, said nanostructure particle powder is gradually added at a rate of 0.2 to 2.0 kg per minute while said solvent is circulated at a rate of 5 to 10 m³/h, preferably 6 to 8 m³/h.

15. The method according to any one of the claims 10 to 14, wherein said fabric comprises a nonwoven structure.