EP2595934A1

EP2595934A1 - Method of metallizing mineral fibers and their use

Info

Publication number: EP2595934A1
Application number: EP11743480.3A
Authority: EP
Inventors: Hagen HÜNIG; Michael Schumm; Ulrich Passon
Original assignee: Saint Gobain Isover SA France
Current assignee: Saint Gobain Isover SA France
Priority date: 2010-07-21
Filing date: 2011-07-21
Publication date: 2013-05-29
Also published as: WO2012010655A1; DE102010036535A1

Abstract

A method of metallizing mineral fibers, wherein the mineral fibers a) are contacted for a predetermined time period to an N-, P-, or S-functionalized silane and to the metal ions intended for the metallization, so as to deposit on the mineral fibers a first metal layer which includes the metal corresponding to said metal ions; and b) incubating the mineral fibers pre-coated in accordance with step a) with an aqueous solution of the metal ions intended for the metallization and with a reducing agent, so as to reinforce the first metal layer.

Description

METHOD OF METALLIZING MINERAL FIBERS AND THEIR USE

Description

The present invention relates to a method of metallizing mineral fibers in accordance with the preamble of claim 1 , metal-coated mineral fibers according to claim 1 1 , a use thereof for the manufacture of insulation material products according to claim 13, as well as an insulation material product according to claim 16.

For the purpose of the present invention, the term "mineral fibres" includes any kind of mineral fibers, in particular "man-made mineral fibers", preferably "(refractory) ceramic fibers" or "glass fibers" including "optical glass fibers", "drawn glass fibers", "glass wool", "rock wool", and "slag wool".

The use of man-made mineral fibers for the thermal insulation of buildings and industrial facilities has been state of the art for many decades.

Several processes were found to be suited for the manufacture of mineral fibers from siliceous starting materials, among which the so-called TEL process for the production of glass wool as well as the nozzle blast process and the REX process for the production of rock wool have gained particular importance. The processes are described, e.g., in Ullmann's Encyclopedia of Industrial Chemistry, Vol. A1 1 , Fibers, 5. Synthetic Inorganic.

In the TEL process, a jet of molten material is conducted into a rotating drum having a perforated annular jacket. The fibers are formed by centrifugal ejection and further attenuation with the aid of pressurized air.

In the nozzle blast process, a suitable molten material is conducted through platinum nozzles to be divided there into individual primary filaments of molten liquid. These are subsequently accelerated with the aid of high-velocity air streams, multiplied, and attenuated into homogeneous long fibers in the process.

In the cascade spinning process, the molten material flows onto the revolving surface of a rapidly rotating disk having a horizontal axis whereby it is accelerated and spun off onto one or more subsequent disks whilst being attenuated into fibers. As a rule, during fiberization in these three processes a suitable binder dissolved in water, for instance a phenol-formaldehyde binder, is sprayed from nozzles onto the fibers while they are still hot inside the chute, and the fibers are deposited in the form of a mineral wool web. From this mineral wool web the various insulation material products are then produced according to demand and may be present, e.g., in the form of rolls, mats and panels which may be employed in various areas of civil engineering such as, for example, in roof insulation, facade insulation, and in ceiling and floor insulation.

Mineral wool products are offered in the form of panels or rolls having a thermal conductivity that corresponds to a thermal conductivity classification of 032 to 040. The requirements to the thermal conductivity classification which are described in German Industrial Standard DIN 18165 continue to be highly important in practice, despite the fact that this standard has in the meantime been withdrawn.

Thermal conduction of a mineral wool product is made up of three components: firstly, thermal conduction through the stationary air enclosed in the porous structure of the mineral wool product ("gas conduction"), secondly, the component of heat dissipation by way of the very material of the fibers (conduction), as well as the radiation component. Besides other parameters, the radiation component depends in particular on the temperature and the bulk density of the mineral wool product so as to increase with a decreasing bulk density. At a bulk density in the range from 20 to 30 kg/m³, the radiation component at room temperature may be as high as 7 imW/mK.

In order to counteract this lowered insulation effect owing to the comparatively high heat transfer in the form of radiation through such mineral wool products, for example unilateral aluminum linings were in the past applied on the mineral wool on its side facing away from the heat source. This technique is employed particularly in the industrial high-temperature insulation field, for example in the insulation of pipes transporting hot media. Here the pipe insulation shells in accordance with DE 27 24 147 C3 include a lining consisting of a metal foil, in particular aluminum foil, for suppressing the infrared radiation loss. At room temperature this measure was found to be of limited effect.

From the prior art it is known to add athermanous materials to an insulation material, in particular to a fiber-type or foam-type insulation material, in order to enhance - i.e. reduce - thermal conductivity by radiation. Materials referred to as athermanous materials generally are materials possessing IR absorption or IR reflection properties. Customary materials are graphite, (industrial) carbon black, metal powders, and organic dyes or pigments whose effectivity is founded in an electrically conductive surface.

By way of example, EP 1 127 032 B1 discloses a thermal insulation product of a man-made fiber material in which graphite is distributed homogeneously for the purpose of reducing the radiant heat transfer. In accordance with EP 1 127 032 it is possible, depending on application temperature and added concentration of graphite, to obtain improvements in the thermal conductivity on an order of 2 to 4 imW/mK as compared to mineral wool products without graphite.

Apart from this, there are a number of documents in the prior art which deal with metal coating of fibers and in particular of mineral fibers that are added to a polymer material as electrically conductive fillers whereby, for instance, a casing for electronic equipment is capable of protecting the electronic circuits inside it against undesirable electromagnetic fields.

Thus, e.g., US 3,148,107 describes conductive papers which may be used, for example, for electrostatic printing or may be employed for cable insulation and shielding. Apart from the paper fibers, these conductive papers additionally contain metal- coated glass fibers, in particular silver-coated glass fibers, wherein the glass fibers are initially activated with 5% SnCI₂ solutions, the fibers then are added to an ammoniacal silver solution, and the silver ions are reduced to elemental silver with dextrose.

Document DE 10 2007 030 861 A1 describes metal-coated, electrically conductive glass fibers for embedding in a resin and/or rubber mat.

There, a silver or nickel coating is disclosed without giving any details, however in accordance with this prior art, activation on the one hand appears to be effected with SnCI₂, and on the other hand a defined ratio of fiber length to fiber diameter must be provided.

Furthermore, German laid-open publication 1 720 977 of July 18, 1967 discloses a polymer material and a method for its manufacture. Various recipes for the reduction of metal ions from their solutions, in particular silver, copper and nickel, by means of sugar and their depositions on glass fibers are described there. The glass fibers are prepared for the metallization by washing with organic solvents, chromic acid and water, as well as by SnCI₂ or PdCI₂ or TiCI₃.

DE 1 720 977 A clearly points out that a possibly existing silanization of the glass fibers must be destroyed prior to metallization by heating the fibers to 400 to 500 °C.

None of the named documents disclose insulation materials based on mineral fiber or glass fiber containing these metallized fibers.

Before this background it was therefore an object of the present invention to even further improve the hitherto excellent thermal insulation properties of mineral wool products.

This object is achieved through a method according to claim 1 .

The metal-coated mineral fibers according to claim 1 1 equally achieve the object.

In terms of use, the object is achieved through the features of claim 13.

With regard to an insulation material product having improved properties, the object is achieved through the features of claim 16.

The present invention concerns in particular a method of metallizing mineral fibers, for example glass fibers, wherein the mineral fibers are contacted for a predetermined time period to an N-, P-, or S-functionalized silane and to the metal ions intended for the metallization in a wet chemical process, so as to deposit on the mineral fibers a first metal layer which includes the metal corresponding to said metal ions; and incubating the mineral fibers thus pre-coated with an aqueous solution of the metal ions intended for the metallization and with a reducing agent, so as to reinforce the first metal layer.

As a result of this two-stage reaction it was surprisingly found that the mineral or glass fibers are coated with the metal in an extremely homogeneous manner.

Without being bound hereby, it appears in a mechanistic view that what takes place initially is complexing of the metal ions on the nitrogen, phosphorus, or sulfur of the silane, while the silane with its remaining organic residues couples to the glass surface via an Si-O bond. This complex is then decomposed in the course of time, or for example by heating, with the metals depositing in their elemental form or being fixed as a mixed oxide, respectively, on the glass surface.

This metal layer, which obviously still is very thin and defective, appears to have a catalytic effect for the further deposition of metal during incubation of the pre-coated glass fibers or mineral fibers with an aqueous solution and a reducing agent, resulting in the formation of a homogeneous, thicker metal layer which reinforces the first metal layer and thus brings about very good IR radiation reflection properties.

For the purposes of the present invention, the expression "N-, P- or S- function- alized silane" is understood to be a silane or alkoxysilane intramolecularly and/or terminally carrying a functional group which contains N, P, or S. In the case of intramolecular functional groups, for N this may be an NH group or a C1 to C10 N-alkyl group, for P it may be a PH or PR group, with R being a C1 to C10 alkyl residue, and for S this may be a thioether group.

For terminal functional groups of the silane in question, a NH₂ group, a NHR group, or a NR₂ group is applicable for N. For P, the PR₂ group and for S the SH or SR group is applicable, with R being a C1 to C10 alkyl residue in these cases.

The nitrogenous silanes are preferably selected from the group consisting of mono-, di-, and trialkoxysilanes having a C1 to C8 alkoxy group, wherein the alkoxysilane carries at least one C2 to C10 aminoalkyl group or a C2 to C10 N-aminoalkyl group, 3(2-aminoethylamino)propyltrimethoxysilane; (MeO)3-Si-(CH₂)₃-NH-(CH₂)₃-Si- (OMe)₃; 3-aminopropylsilanetriol; aminosilanes with ethoxylated nonylphenolate;

phenyl-CH₂-NH-(CH₂)₃-NH-(CH₂)₃-Si-(OMe)₃ ^*HCI; corresponding silanes having P and/or S functionality, in particular those where at least one intramolecular NH group is replaced with PH or PR, with R being a C1 to C10 alkyl residue, or S; corresponding silanes where at least one NH₂ group is replaced with PR₂, SH, or SR, with R being a C1 to C10 alkyl residue; as well as their mixtures.

It was found in practice that a desired first metallization takes place with 3-amino- propyltriethoxysilane, with 3-aminopropyltriethoxysilane having the advantage of being commercially available at a favorable pricing. The metal coating in accordance with the method of the present invention may be carried out with metals selected from the group consisting of: Ag, Ni, Cu, Pd, Pt, Au, Cr, Fe, Mn, Zr, and Ti, with a silver coating being preferred as the metal coating because it may be obtained easily and because silver salts, beside nickel, copper, and chromium salts, are relatively low-cost.

As aqueous solutions of metal salts for incubating the previously pre-coated mineral fibers with an aqueous solution of the metal ions intended for the metallization and with a reducing agent for the purpose of reinforcing the first metal layer, particularly those metal salts are employed which are selected from the group consisting of:

AgNO₃, Ag₂SO₄, NiCI₂, Ni(NO₃)₂, PdCI₂, PtCI₄, AuCI₃ {Au₂CI₆}, CrCI₃, FeCI₃, MnCI₂, ZrOCI₂, TiCI₄.

It is furthermore preferred to employ glass fibers as the mineral fibers which are then provided, in accordance with the invention, with a metal layer.

As reducing agents, in particular for the deposition of the noble metals in the second step of the method of the invention, sugars, in particular saccharose and glucose, as well as aldehydes, in particular formaldehyde, are applicable, with an aqueous saccharose solution (sucrose solution) preferably being employed as the reducing agent. Alternatively, the metallized fiber material may be reduced under a gas flow. In this case, CH₄, H₂, or CO are preferably applicable as reducing agents.

For the case that the metal-coated mineral fibers in accordance with the invention are provided with a silver coating, they preferably contain between 200 and 1000 mg Ag/kg fiber, preferably 800 to 900 mg Ag/kg fiber.

A preferred use of the metal-coated mineral fibers in accordance with the present invention resides in the manufacture of insulation material products having an improved thermal insulation capacity. The particular advantage of the insulation material products lies in the fact that owing to the athermanous properties of the metal-coated mineral fibers, they exhibit a thermal conductivity corresponding to a thermal conductivity class of lower than or equal to 031 , preferably lower than or equal to 030 in accordance with DIN 18165.

In principle, it is possible to manufacture fiber-based insulation material products of metallized mineral fibers only. Such a product can not be realized economically, however, for with an increasing proportion of the metal-coated mineral fibers the improvement of the thermal insulation capacity exhibits a tendency to approach a limit value in an asymptotic manner.

Preferably, the proportion of the metal-coated mineral fibers of the invention in the total mass of an insulation material product on the basis of non-coated mineral fibers is 0.5 to 8% (wt.), more preferably 1 to 5% (wt.), and in a particularly preferred manner 2 to 4%.

The metal-coated mineral fibers may be introduced via the binder subsequently to the actual fiberization process inside the chute. As an alternative it is also possible to directly supply the metal-coated mineral fibers there via separate feeding means, to thereby obtain a homogeneous distribution in the product.

Further advantages and features of the present invention result from the description of practical examples.

Manufacture of mineral fibers having a suitable size

Mineral wool is manufactured in accordance with one of the processes represented at the outset, however only quenched with water after its passage through the fiberizing unit. First of all, the binder-free raw nonwoven is dried. Drying is not indispensable but contributes to economy of the process. The raw nonwoven treated in this way is crushed by means of a roller, and the desired fiber length predetermined by the purpose of use is adjusted by means of a cutting mill. For the wet chemical coating process per se, the geometry of the fibers to be coated is not of importance. The required amount of coating material can be found by determining the real surface area or estimated by measuring the mean fiber diameter under the hypothesis of a mean fiber length.

Wet chemical process

The presently described metallizations only constitute a very small selection of the coatings that are possible by this technique and should thus only be considered to be examples. What is presently being shown are selected techniques on a laboratory scale. Transposition to technical magnitudes is readily possible.

Pre-treatment of the glass fibers 1000 ml of toluene and 50 g of fibers are placed in a 2-liter distillation apparatus. At first, this is heated to the boil, and about 100 ml of the solvent is removed by distillation. 5.25 g = 25 imMol 3-aminopropyltriethoxysilane is added to the mixture that was dried by steam entraining, and distilling is continued slowly until the boiling temperature of the pure toluene is reached at the still head. Once the reaction is completed, it is allowed to cool.

With the exception of reactively functionalized silanes such as acrylic or methacrylic silanes, most compounds of this type may be converted in this way.

Treatment of the mixture for direct complexinq

The cooled mixture of toluene and glass fibers is filtered off, the filtration residue is washed with a small quantity of toluene and suction-dried. The filtrate may be used for further reactions of glass with a silane. The filtered glass fibers are dried to weight constancy.

Reaction with aqueous salt solutions of silver

10 g of the silanized fiber powder is stirred into 120 ml of deionized water, and 10 ml 0.1 M silver nitrate solution is added in the absence of light. Stirring is then carried out during 10 minutes, followed by evacuation and washing with a small quantity of water. The silver is subsequently fixed by thermal decomposition of the complex at 100 - 300 °C. In order to establish the quantity of silver contained on the fibers, 1 g of the material is treated with fuming nitric acid, and following filtration and dilution to volume under standard conditions, the solution is examined for metal content by AAS (Atomic Absorption Spectroscopy). In the case of the silver solution, 810 mg/kg was found.

Success of the reaction may be checked in a simple manner in a tentative experiment by heating the correspondingly coated fiber material in a diluted ascorbic acid solution. The metal which is partly present on the surface in the oxidic state is reduced, which is visually well discernible by a bathochromic shift. For an examination of layer homogeneity it is also possible to carry out tempering during several hours at 400 °C in air. In contrast with the pure metal, the metal layer is transformed quantitatively to the well- visible, yellow-brown oxide.

Reaction with aqueous copper salt solutions

250 mg of CuSO₄ ^* 5H₂O is dissolved in 120 ml of deionized water, and 10 g of the silanized fiber powder is introduced under stirring. After 10 minutes, suction-drying, washing with a small quantity of water, and drying are performed. Subsequently the copper is fixed by tempering at 100 - 300 °C with concurrent decomposition of the complex. The metal content was determined in analogy with the silver solution and was 2720 mg/kg in this case.

Reaction with salts of gold and platinum

The corresponding salt solutions are expediently prepared fresh by dissolving the respective metal in nitrohydrochloric acid (Aqua regia), in the case of gold 197 mg, in the case of platinum 195 mg in one milliliter of nitrohydrochloric acid. Subsequently dilution to about 10 ml and careful buffering with caustic soda solution are performed. The respective solution is reacted with 10 g of the silanized fiber powder in 1 10 ml of water. Working up takes place in analogy with the previous metals. Verification of the metal content was carried out by dissolving in nitrohydrochloric acid and yielded the result of 710 mg/kg for gold and 845 mg/kg for platinum.

The effectivity of the method can, of course, be enhanced by the use of less-diluted solutions to thereby approach complete loading. In this case, unused solutions and washing filtrates are re-circulated as a matter of fact.

Reinforcing the metal layer

To this end, following fixation of the metal, the respective fibers are stirred in 100 ml of a 0.1 M ammonia solution during about 10 minutes, sharply vacuum filtered, but not dried. Subsequently, stirring out in the respective metal salt solution is performed, and further processing takes place in analogy with the previous steps. In cases of base metals, this step is necessary prior to reducing as the simple layers are pyrophoric. By this simple method step it is also possible to realize intermetallic coatings.

It is a further possibility to start out from fiber powders with reduced metal and boiling these in the known manner with a reducible metal salt and a corresponding reducing agent such as a glucose solution or an aldehyde. In order to avoid metal being separated out from the solution, however, it is necessary to start with diluted solutions or separate the adding steps.

Reduction to the metal

In cases of noble metals it is readily possible, following fixation of the metal, to add a wet chemical process. To this end, the corresponding fiber powder is boiled in aqueous solutions of sugar or formaldehyde. In the course of the tests it was, however, found far more simple to transform the metal into its elemental form under a gas flow. To this end, the respective fiber powder is transferred into a quartz glass tube, the oxygen is displaced from the apparatus at room temperature, and then stepwise heating to 400 °C under a gas flow is performed. Hydrogen, carbon monoxide and particularly methane (dry natural gas) are suited as gases having a reducing effect for the noble metals. It should be noted, however, that platinum metals form hydride phases, and carbon monoxide is unsuited for ferrous metals / chromium.

Modification of the nitrogen function by reacting with compounds of phosphorus and sulfur

In order to convert the nitrogen function of the silane, dispersing in toluene as described at the outset may be used following removal of the alcohol by distillation. Working up is not performed in this case, but a halogen alkane hetero compound in quanitites equi- molar to the silane is added to the dispersion. It is possible, for example, to obtain functionalization with phosphorus by the addition of diethylchloromethylphosphonate (CAS 3167-63-3) or functionalization with sulfur by the addition of 2-chloroethyl- ethylsulfide (CAS 693-02-2). As it is not possible to proceed in the customary manner by employing a scavenger base, the toluene in turn serves as an entraining agent for the released hydrogen chloride. The end of the reaction may be determined by shaking out several drops of distillate with an aqueous indicator solution. In analogy it is possible by this method to convert the nitrogen function to the amide by addition of the respective carboxylic acid anhydride, or to the imine by addition of the corresponding aldehyde / ketone.

Further preferred embodiments of the invention

A further preferred embodiment of the present invention is

I) A method of metallizing mineral or glass fibers,

wherein

the mineral or glass fibers

a) are contacted for a predetermined time period to an N-, P-, or S-functionalized silane selected from the group consisting of: mono-, di- and trialkoxysilanes having a C1 to C8 alkoxy group, wherein the alkoxysilane carries at least one C2 to C10 aminoalkyl group or a C2 to C10 N-aminoalkyl group; 3(2- aminoethylamino)propyltrimethoxysilane; (MeO)3-Si-(CH₂)₃-NH-(CH₂)₃-Si- (OMe)₃; 3-aminopropylsilanetriol; aminosilanes with ethoxylated

nonylphenolate; phenyl-CH₂-NH-(CH₂)3-NH-(CH₂)₃-Si-(OMe)3^*HCI;

corresponding silanes having P and/or S functionality, in particular those where at least one intramolecular NH group is replaced with PH, PR, with R being a C1 to C10 alkyl residue, or S; corresponding silanes where at least one NH₂ group is replaced with PR₂, SH, or SR, with R being a C1 to C10 alkyl residue; as well as their mixtures;

and to the metal ions intended for the metallization, so as to deposit on the mineral fibers a first metal coating layer which includes the metal corresponding to said metal ions; wherein said metal is selected from the group consisting of: Ag, Ni, Cu, Pd, Pt, Au, Cr, Fe, Mn, Zr, and Ti; and b) incubating the mineral or glass fibers pre-coated in accordance with step a) with an aqueous solution of the metal ions intended for the metallization and with a reducing agent, so as to reinforce the first metal coating layer; wherein said reducing agent is selected from the group consisting of: sugars, in particular saccharose, glucose; aldehydes, in particular formaldehyde; ascorbic acid and phenols; reducing gases, in particular CH₄, H₂, and CO.

The method according to embodiment I, wherein 3-aminopropyltriethoxysilane is used as said silane.

The method according to embodiment II, wherein a silver coating is employed as said metal coating.

The method according to any one of embodiments l-lll, wherein for step a) and/or b), the aqueous solutions of metal salts are employed which are selected from the group consisting of: AgNO₃, Ag₂SO₄, NiCI₂, Ni(NO₃)₂, PdCI₂, PtCI₄, AuCI₃ {Au₂CI₆}, CrCI₃, FeCI₃, MnCI₂, ZrOCI₂, TiCI₄.

The method according to any one of the embodiments I- IV, wherein an aqueous saccharose (sucrose) solution is employed as a reducing agent.

The method according to any one of the embodiments l-V, wherein insulation material products are manufactured of the metallized mineral fibers.

Metal-coated mineral or glass fibers, obtained in accordance with a method according to any one of the embodiments I- VI . VIII) . Metal-coated mineral fibers, in particular glass fibers, according to embodiment

VII, wherein they are provided with a silver coating, wherein they preferably contain 200 to 1000 mg Ag/kg fiber, in a preferred manner 800 to 900 mg Ag/kg fiber.

IX) . Use of metal-coated mineral fibers, in particular glass fibers, according to any one of embodiments VII or VIII for the manufacture of insulation material products.

X) . Use according embodiment IX, wherein the insulation material products of metal- coated mineral fibers have a thermal conductivity class of lower than or equal to 031 , preferably lower than or equal to 030 in accordance with DIN 18165.

XI) . Use according to embodiment IX or X, wherein the insulation material products contain a proportion of metal-coated mineral fibers according to embodiment VII, wherein the proportion relative to the total mass of the insulation material products on the basis of mineral fibers not coated with metal is 0.5 to 8% (wt.), preferably 1 to 5% (wt.), and in a particularly preferred manner 2 to 4%.

XII) . Insulation material product on the basis of mineral wool, wherein it contains a proportion of metal-coated mineral fibers according to embodiment VII, wherein the proportion relative to the total mass of the insulation material product on the basis of mineral fibers not coated with metal is 0.5 to 8% (wt.), preferably 1 to 5% (wt.), and in a particularly preferred manner 2 to 4%.

Claims

A method of metallizing mineral fibers,

characterized in that

the mineral fibers

a) are contacted for a predetermined time period to an N-, P-, or S-function- alized silane and to the metal ions intended for the metallization, so as to deposit on the mineral fibers a first metal layer which includes the metal corresponding to said metal ions; and b) incubating the mineral fibers pre-coated in accordance with step a) with an aqueous solution of the metal ions intended for the metallization and with a reducing agent, so as to reinforce the first metal layer.

The method according to claim 1 , characterized in that the silane is selected from the group consisting of: mono-, di- and trialkoxysilanes having a C1 to C8 alkoxy group, wherein the alkoxysilane carries at least one C2 to C10 aminoalkyi group or a C2 to C10 N-aminoalkyl group; 3(2-aminoethylamino)propyltrimethoxysilane; (MeO)3-Si-(CH₂)3-NH-(CH₂)3-Si-(OMe)3; 3-aminopropylsilanetriol; aminosilanes with ethoxylated nonylphenolate; phenyl-CH₂-NH-(CH₂)₃-NH-(CH₂)₃-Si- (OMe)₃ ^*HCI; corresponding silanes having P and/or S functionality, in particular those where at least one intramolecular NH group is replaced with PH, PR, with R being a C1 to C10 alkyl residue, or S; corresponding silanes where at least one NH₂ group is replaced with PR₂, SH, or SR, with R being a C1 to C10 alkyl residue; as well as their mixtures.

The method according to claim 2, characterized in that 3-aminopropyltriethoxy- silane is employed as a silane.

The method according to any one of claims 1 to 3, characterized in that the metal coating is selected from the group consisting of coatings with: Ag, Ni, Cu, Pd, Pt, Au, Cr, Fe, Mn, Zr, and Ti.

The method according to claim 4, characterized in that a silver coating is employed as a metal coating.

6. The method according to any one of the preceding claims, characterized in that for step a) and/or b), the aqueous solutions of metal salts are employed which are selected from the group consisting of: AgNO₃, Ag₂SO₄, NiCI₂, Ni(NO₃)₂, PdCI₂, PtCI₄, AuCI₃ {Au₂CI₆}, CrCI₃, FeCI₃, MnCI₂, ZrOCI₂, TiCI₄.

7. The method according to any one of the preceding claims, characterized in that glass fibers are employed as mineral fibers.

8. The method according to any one of the preceding claims, characterized in that the reducing agent is selected from the group consisting of: sugars, in particular saccharose, glucose; aldehydes, in particular formaldehyde; ascorbic acid and phenols; reducing gases, in particular CH₄, H₂, and CO.

9. The method according to any one of the preceding claims, characterized in that an aqueous saccharose (sucrose) solution is employed as a reducing agent.

10. The method according to any one of the preceding claims, characterized in that insulation material products are manufactured of the metallized mineral fibers.

1 1 . Metal-coated mineral fibers, obtained in accordance with a method according to any one of the preceding claims.

12. Metal-coated mineral fibers, in particular glass fibers, according to claim 1 1 ,

characterized in that they are provided with a silver coating, wherein they preferably contain 200 to 1000 mg Ag/kg fiber, in a preferred manner 800 to 900 mg Ag/kg fiber.

13. Use of metal-coated mineral fibers, in particular glass fibers, according to any one of claims 1 1 or 12 for the manufacture of insulation material products.

14. Use according to claim 13, wherein the insulation material products of metal- coated mineral fibers have a thermal conductivity class of lower than or equal to 031 , preferably lower than or equal to 030 in accordance with DIN 18165.

15. Use according to claim 13 or 14, characterized in that the insulation material

products contain a proportion of metal-coated mineral fibers according to claim 1 1 , wherein the proportion relative to the total mass of the insulation material products on the basis of mineral fibers not coated with metal is 0.5 to 8% (wt.), preferably 1 to 5% (wt.), and in a particularly preferred manner 2 to 4%.

16. Insulation material product on the basis of mineral wool, characterized in that it contains a proportion of metal-coated mineral fibers according to claim 1 1 , wherein the proportion relative to the total mass of the insulation material product on the basis of mineral fibers not coated with metal is 0.5 to 8% (wt.), preferably 1 to 5% (wt.), and in a particularly preferred manner 2 to 4%.