EP2408869A2

EP2408869A2 - Antimicrobially treated and/or stain-resistant planar substrates and method for producing the same

Info

Publication number: EP2408869A2
Application number: EP10710293A
Authority: EP
Inventors: Sabine Amberg-Schwab; Annett Halbhuber; Detlev Uhl; Karl-Heinz Haas
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2009-03-19
Filing date: 2010-03-18
Publication date: 2012-01-25
Also published as: WO2010106152A3; US20120015576A1; DE102009013884A1; WO2010106152A2

Abstract

The invention relates to a planar or shaped textile material comprising or constituted of fibers, at least part of the fibers being coated with a hydrolytically condensed inorganic/organic hybrid material having single-walled or multi-walled carbon nanotubes which are embedded therein, optionally covalently bound thereto. The carbon nanotubes are preferably functionalized, especially with carboxylic acid groups or sulfanilic acid groups. The textile material is suitable for producing protective clothing, barrier materials or the like. The invention further relates to the use of the above-defined hybrid material as a coating material which imparts stain-resistance and/or antimicrobial properties to the coated substrate.

Description

Antimicrobially treated and / or soil-repellent surface substrates and process for their preparation

The present invention relates to sheet substrates, and more particularly to textile materials having antimicrobial impregnation. This impregnation preferably consists of activated carbon nanotubes (CNTs) formed in a matrix of an inorganic-organic hybrid polymer (eg, a ORMOCER ^®) are embedded and covalently attached in special cases to this. The hybrid polymers have an inorganic network and organic components. In preferred embodiments, they may carry organic groups which, if appropriate with the aid of heat or actinic radiation (for example UV radiation) or redox-catalyzed, are organically postpolymerized or postpolymerizable.

It is known to use carbon nanotubes (single-walled tubes, SWNT, or multi-walled tubes, MWNT) as constituents of composites in order to strengthen them mechanically or to give them electrical conductivity or thermal conductivity (see Review Macromolecules 2006 S. 5194-5205 [2870] ) to rent. They may also be used as actuators (Jain S. et al "Building smart materials using carbon nanotubes" Proc. SPIE Smart Structures and Materials 2004: Smart Electronics, MEMS, BioMEMS, and Nanotechnology pp. 167-175 Vol. 5389 (2004)) or in aligned form eg for displays or microelectronic applications. Dispersions of CNT are commercially available (for example, BYK in cooperation with Bayer), sometimes with reactive functions. A study of suitable surfactants for such dispersions has been made by R. Rastogi et al. published in Journal of Colloid and Interface Science 328 (2008) 421-428.

Inorganic-organic hybrid polymers are known in a large number of variants, for example as multifunctional scratch-resistant layers, which are frequently UV-structurable. An important group of inorganic-organic hybrid polymers are the organically modified (hetero) polysiloxanes which can be obtained via a sol-gel process. These are known in wide variation. Basic building blocks of these materials are, in addition to tetraalkoxysilanes, especially organically modified silicon compounds of the type R'Si (OR) 3 and R'2Si (OR) 2, where R is, for example, alkyl and R 'is either R or aryl or an organically crosslinkable or substituted organic Rest can be. Examples are groups R 'which contain one or more acrylate or methacrylate groups, anhydride, vinyl, allyl, epoxy or Carry carboxylic acid (derivative) residues. The targeted hydrolysis of these precursors and condensation of the silanol groups formed builds up an inorganic network. This can be extended by the use of alkoxy compounds of certain metals such as aluminum, titanium or zirconium. Thus, the targeted influencing of physical matrix properties such as hardness, refractive index and density is possible. However, the type of organic modification used also has a significant influence on the material properties. Unreactive groups such as alkyl or phenyl radicals serve as network transducers and allow adjustment of the polarity and density of the matrix without altering the network density. With reactive groups (such as vinyl, methacrylic or epoxy radicals), which act as network formers, an additional organic network can be built up via photochemically or thermally induced polymerization reactions. There are covalent bonds between the inorganic and the organic phases. The coating sols obtained via the sol-gel process can be applied to various substrates by means of customary lacquer application methods. Areas of application of the hybrid polymers include, for example, scratch and abrasion resistant coatings of plastic surfaces, passivation layers for microelectronic elements, layers with antistatic and antiadhesive properties, anti-slip effect, with barrier to gases, vapors and volatile organic substances, but also the use as compact materials in the dental field. Hybrid polymers are also suitable for the physical incorporation of functional inorganic, organic and bioorganic molecules which can function, for example, as gas, pH, ion and biosensors or as light dosimeters (see eg DE 196 50 286 C1, EP 0 792 846 DE 196 07 524.6, DE 196 15 192 A1, EP 0 802 218 A2, DE 196 15 192.9).

Carbon nanotubes ("nanotubes", hereinafter referred to as CNTs) have already been incorporated in the past into organic paints (for example polyimides) for TCOs which are thermally curable, see the corporate brochure of Eikos, Paul J. Glatkowski, "Carbon nanotube based transparent conductive coatings "2004, in particular also Figure 5. Internet information on Eikos are accessible at wmv.eikgs.com In this document are filled with SWNTs (Single wall nanotubes) filled polyimides with a filling level of about 0.05 wt .-%. compared with the same material with a degree of filling of> 5 wt .-% ITO particles, with the result that the not yet optimized products in their properties (good transmission at 550 nm, low surface resistance) that of the ITO-filled material already very much so that further improvements in material properties and coating processes could at least be expected to produce equivalent products. Further known are: CNT-2D or 3D arrays prepared using a colloid treated with sol-gel technique, see US 6,749,712 B2; a coating of FET (field-effect transistors) with a semiconducting layer of glycerol-crosslinked, functionalized COOR-CNT in the region between the source electrode and the gate electrode, see US 2006/0138404 A1; CNTs in conjunction with Ormocer © s for the coating of golf balls, also in combination with phyllosilicates (barrier), see US 2006/0189412 A1; an electrically conductive composition made of an inorganic sol-GeI with LF CNTs, see US 2006/0240238 A1 (Dupont).

Uses of CNT dispersions or composites incorporated e.g. in polymeric materials are also spun fibers for textile materials (WO 2004/090204), materials which render surfaces antistatic and anti-adhesive (WO 2008/046165, EP 1914277 A1) and polysiloxane-based compositions which are useful as coatings for repelling the onset of marine organisms suitable for areas exposed to seawater. The polysiloxane used for this purpose is commercially available; it is an addition product of a polyhydrosilane to a vinyl group-containing polysilane. The polysiloxane is filled with a cylindrical nanofiller, which may be sepiolite or carbon nanotubes (WO 2008/046166 A2).

DE 102008039129.8 describes new coating materials which are dispersions of deagglomerated carbon nanotubes in polysiloxane matrices with an improved anchoring of the nanotubes in the matrices. These dispersions may contain particularly high amounts of nanotubes.

According to DE 102008039129.8, nanotubes (CNTs) are used for the preparation of the coating materials, to which functional groups are coupled. This leads to an improved dispersion in the corresponding matrix and thus to the possibility of achieving higher solids contents. In a preferred manner, ultrasound and / or strong shear gradients can be used as the deagglomeration process. For dispersing the use of adsorbing surfactants and polyelectrolytes are possible.

Object of the present invention is to make surfaces of any surface substrates and in particular textile materials dirt-repellent and / or antimicrobial effective. The invention accordingly treated Textile materials, for example for protective clothing or barrier materials, as well as coating materials, which are suitable for dirt-repellent or antimicrobial treatment.

The object is achieved on the one hand by the provision of flat or suitably shaped textile materials whose fibers have a coating which is a hydrolytically condensed, preferably organically crosslinkable or organically crosslinked, inorganic-organic hybrid material and dispersed therein, preferably functionalized, single or multi-walled carbon nanotubes contains. The invention also provides a corresponding method for the preparation of these materials. In this case, a suitable textile material is treated with a suspension which contains a hydrolytically condensed, preferably inorganic, postcrosslinkable and / or organically postcrosslinkable inorganic-organic polymer matrix (lacquer matrix) as well as preferably covalently bound, single-walled or multi-walled carbon nanotubes dispersed therein or covalently incorporated therein. This suspension is also referred to below as a paint. The treatment may be in any form known in the art, e.g. by soaking, spraying, dipping or coating. After treating the fabric, excess paint, if any, is removed and the material is dried to cure the paint, preferably with organic polymerization of organic groups present in the material to form said inorganic-organic hybrid polymer material.

On the other hand, the object of the invention is achieved by proposing the above-described lacquers for use as coating materials for flat substrates, which impart soil-repelling and / or antimicrobial properties to these substrates. These sheet-like substrates may likewise be textile material, but any other surface substrates should also be encompassed by the invention, including, in particular, flexible plastic films which, for B. as continuous material, d. H. in roll form, can be stored.

For the present invention suitable textile and other sheet materials are known in large numbers. Textiles can be composed of a wide variety of materials, for example of natural fibers (cellulose fibers, cotton), organic polymers, inorganic-organic copolymers, glass fibers, metal or ceramic fibers, mixed fibers of these materials or mixtures thereof. They can be in a variety of forms and, for example, be treated with substances that are theirs give targeted properties. They may, but need not, be high temperature stable and / or more or less highly compressed. The porosity can be adjusted by a variety of measures, for example, by impregnation of the fibers with sheaths, which make the fibers thicker and thus the pores smaller, or by the provision of porous, possibly hollow fibers. The pore size may be consistent throughout the fabric or may be selectively altered through the thickness of the fabric. The pore size is adjusted depending on the purpose of use in a suitable manner. All types of textiles are suitable from the mentioned materials, for example woven or knitted or laid fiber materials made of yarns or other threads. In the latter, the fibers are usually connected to one another either by needling or other mechanical measures and / or by gluing. If the fibers have thermoplastic properties, the bonding can be effected by heating the fibers; alternatively or additionally, they can be connected by means of a bonding suspension, with which the scrim, eg a felt, was impregnated. However, "shaped textile matehals" in the sense of the present application also mean yarns or non-spun or un-laid fibers. However, the invention is not only suitable for textiles, but also for other surface materials, for example continuous or perforated films made of plastics. Examples of these are polyethylene, polypropylene or polyethylene terephthalate films.

Most commercially available dispersions of CNTs (eg AquaCyl ™ from Nanocyl) are water-based and have a high CNT concentration; However, the pH is usually in the alkaline range. If the pH is changed (eg to below 7), the CNTs can quickly agglomerate again. This involves some difficulty in dispersing in a wide variety of matrices. Modification of the CNTs, but also the choice of suitable wetting and dispersing agents can facilitate incorporation into the paint matrix. Various investigations have shown, for example, DMF (dimethylformamide), N-methyl-2-pyrrolidone (NMP) or propylene carbonate (PC) as good solvents for CNT dispersions. However, since these have a very high boiling point of 153 ° C, 203 ⁰ C and 242 ° C and DMF is also classified as toxic, they are only very limited for use in Lackmatrices such as those that are useful for the present invention. Another limiting factor in dispersing is the high surface energy of CNT. As soon as the CNT agglomerates are broken up, for example by ultrasonic treatment, and the CNTs are present individually, the viscosity of the dispersion increases enormously. Therefore, the maximum concentration of CNT in such dispersions is usually about at most 1 wt .-%, based on the total paint composition. CNT Dispersions are usually not stable for long and agglomerates often form again after a short time. This can be z. B. by surfactants such as sodium dodecyl sulfate or Triton X-100 prevent, which also also improve the dispersion. Unfortunately, these surfactants foam very strong and are not suitable for all coating systems.

The invention takes advantage of the fact that CNTs can be incorporated much better than in the above-mentioned concentration in paints when they are composed of inorganic-organic hybrid material. The suspensions produced may be applied to fibrous or other surfaces and cured such that the CNTs are solid and long lasting on the respective surface, e.g. a fiber or a thread. According to the invention, however, it has also been found that the CNTs have to be incorporated in a significantly smaller amount than carbon black in order to achieve comparable effects, which may be due to the fact that many of the individual CNTs abut one another in the paint matrix because of their length in the μm range and thus longer form conductive areas. Without wishing to be bound by any theory, the inventors assume that a resulting permanent charge over larger areas causes the observed effect of the coating according to the invention. Therefore, according to the invention, transparent paints having the desired properties can optionally also be obtained, while paints filled with carbon black with otherwise the same properties are no longer transparent but cloudy.

The invention further makes use of the fact that a significantly larger proportion of CNTs can be incorporated into the matrix when the CNTs are used in the form of functionalized carbon nanotubes. For the purposes of the present invention, this expression is to be understood as meaning that carbon atoms bound to the nanotubes are converted into an organic group, these carbon atoms having thereby passed into the corresponding oxidation state. The simplest form of this functionalization is the oxidation to COO ^" groups, which can then be further reacted with conventional methods (esterified, amidated, possibly also reduced), so it is not so much a matter of transparency but of high effectiveness , the incorporation of functionalized CNTs is preferred, although the effect of functionalized CNTs on the incorporated amount is slightly lower than that of unfunctionalized CNTs, possibly because smaller CNT fragments are formed when CNTs are modified.

The functional groups of the CNTs may be in charged form (eg as -COO ^" ) or in neutral form (eg as -COOH). In a preferred embodiment of the present invention, CNTs are used which are functionalized as follows: Commercially available CNTs (examples being Industrial Grade Multiwalled CNT from Nanocyl, Belgium) are used for basic functionalization with COOH groups. The functionalization is usually carried out by standard methods, for example by reacting the CNTs at 40 ⁰ C for 3h in a mixture of HNO ₃ and H ₂ SO ₄ (ratio 1: 3) with stirring and ultrasound. After the reaction, it is expedient to neutralize the suspension in a basic solution (NaOH or KOH) with subsequent recovery and washing of the functionalized nanotubes by means of centrifugation or filtration. This yields carboxylate-modified nanotubes (hereinafter referred to as CNT-COOH).

In a further preferred embodiment of the invention, CNTs are used which have been further reacted starting from CNTs already functionalized with COOH groups, in which case either the COOH group has been modified or further functional groups have been formed on the walls of the nanotubes. The modification of the COOH group can be carried out with conventional reactants that can react with carboxylic acid functions. For example, the carboxylic acid group can be esterified or amidated, of course, the balance of the reaction must be shifted in the usual way in the product direction, e.g. by trapping emerging water.

An example of such an amidation reaction is the reaction with sulphanilic acid. For this, the previously obtained (or commercially purchased) CNT-COOH with a salt (eg the sodium salt of sulfanilic acid) or an optionally modified sulfanilic acid and with a coupling reagent, for example N, N ^{'dicyclohexylcarbodiimide} (DCC), (in a suitable solvent For example, DMF) implemented. The reaction is carried out with stirring and ultrasound at room temperature over a period of 24 hours. The product, hereinafter referred to as CNT-SuIf, accordingly arises in the salt form or as a free sulfanilic acid derivative. It is isolated, washed and dried.

The following two steps are shown schematically below: 1st step, functionalization with carboxylic acid groups:

2nd step, functionalization of CNT-COOHs with sulfanilic acid:

CNT sulfanilic

Both COOH-functionalized CNTs (CNT-COOH) and CNT-COOH, whose carboxylic acid residues have been further functionalized, and in particular CNTs reacted with sulfanilic acid (hereinafter referred to as CNT-sulfide), can be classified as inorganic-organic matrices (Lacke , Hybrid polymers) of the type mentioned incorporated. For incorporation of the functionalized CNTs in the paint, the CNTs usually have to be deagglomerated again and stirred by means of stirring and possibly ultrasound into the solvent associated with the paint or directly into the paint. To adjust the viscosity to prepare a coating suspension for the purposes of the invention, solvent may be added as needed.

Since many applications of the textile materials according to the invention can be provided for areas in which harmful substances should be avoided, aqueous solvents are preferred for the suspensions. For other areas, however, are readily suspensions in solvents such as alcohols or the like. As a lacquer base for lacquers filled with functionalized CNTs, a large number of different materials based on hybrid polymers of the type mentioned above can be used. For example, typical hybrid polymers can be used, as they are also used for barrier coatings. As a rule, they have a high degree of inorganic crosslinking. In addition, it may be beneficial to use hybrid polymers that are still flexible after drying or curing. These are particularly preferred because textile materials impregnated therewith are still flexible even after drying and, if necessary, curing, so that the fibers or filaments not yet brought into the final form can already be treated with the suspension according to the invention and then be brought into the appropriate form ,

The inorganic-organic hybrid polymers of the present invention are preferably prepared using silanes of the formula (I)

wherein R ^{1 is} a radical which is amenable to organic polymerization. By "polymerization" is meant a poly-reaction in which reactive double bonds or rings under the influence of heat, actinic radiation such as light or ionizing radiation, but optionally instead of redox catalysed, go into polymers (English: addition polymehzation or chain - growth polymerization). For example, cationic polymerization can be carried out with the aid of a cationic UV initiator, for example an epoxy system (see, for example, CG Roffey, Photogeneration of Reactive Species for UV Curing, John Wiley & Sons Ltd, (1997)). Examples of R are therefore radicals having one or more non-aromatic C =C double bonds, preferably a Michael addition accessible double bonds, such as Styryle or (meth) acrylates. Alternatively, crosslinking may be by other polyreactions such as ring-opening polymerization. An example is the reaction of an epoxide radical with a radical containing a carboxylic acid anhydride group. The radical R ¹ usually contains at least two and preferably up to about 50 carbon atoms.

R ² is an (at least predominantly) organic radical which is not accessible to organic polymerization. Preferably, this is an optionally substituted alkyl, aryl, alkylaryl or arylalkyl group whose substituents do not allow crosslinking, wherein the carbon chain of these radicals is optionally substituted by O, S, NH, CONH, COO, NHCOO or the like. can be interrupted. Preference is given to radicals R ² having 1 to 30 or even up to 50, more preferably 6 to 25 carbon atoms. X denotes OH or a leaving group which is hydrolyzed under hydrolysis conditions and at least partially contributes to inorganic crosslinking during sol-gel formation by binding to an oxygen atom of a further silicon compound. In particular, X may be an alkoxy, hydrogen, hydroxy, acyloxy, alkylcarbonyl, alkoxycarbonyl and, in specific instances, NR " ₂ with R", the same or different and being hydrogen or lower alkyl (preferably having from 1 to 6 carbon atoms). Preferably, X is an alkoxy group, most preferably a Ci-C ₄ alkoxy group.

a and b can each be 0, 1 or optionally also 2, 4-ab may in rare cases be 1, but is usually 2 or 3. It is inventively preferred that the silanes used for the preparation of the hybrid polymers at least partially are those in which a is 1 or - more rarely - 2. but a can be 0 instead. The presence of a certain number of radicals R ² is indeed also decisive for the properties of the coatings; Since R ² as a network converter has an influence on the physical properties such as flexibility or density, but not on the degree of crosslinking, the number of b is suitably chosen according to the desired properties.

The radicals R ¹ are also referred to as organic network formers, since they allow the formation of an organic network in addition to the inorganic, formed by hydrolytic condensation network. For this purpose, the same radicals R ¹ can react with one another; but also possible is the reaction of different radicals R ¹ , for example an epoxide with an amine radical or an (activated) acid radical with an alcohol radical. The radicals X are referred to as inorganic network formers.

The hybrid material can be prepared by using at least one further silane of the formula (II)

SiX ₄ (II) are produced, wherein X is the same or different and has the same meaning as in formula (I). A suitable compound for this purpose is tetraethoxysilane. By adding such silanes to the mixture to be hydrolyzed and condensed, from which finally the coating suspension is formed, the SiO content, ie the inorganic content, is increased. Instead or optionally additionally, the hybrid matehal which can be used according to the invention can be prepared by using at least one silane of the formula (III) in which R ¹ , R ² and X have the meaning given above for formula (I). This increases the organic content of the material, which can improve the elasticity of the material.

The hybrid materials of any one of the preceding embodiments may optionally be further hydrolytically condensed with the addition of further substances, e.g. of complexed or (chelate) ligand-containing metals of the III. Main group, germanium and metals of IL, III, IV, V., VI., VII. And VIII. Subgroup. In particular, boron, aluminum, zirconium, germanium or titanium compounds are favorable. Frequently, alkoxides, in particular C 1 -C 6 -alkoxides, which have been dissolved or recovered from such a solution in the presence of a complexing solvent, are frequently used for this purpose. In addition, the starting materials may comprise purely organic materials that can be polymerized into the organic network.

In particular, zirconium alkoxides are preferred for the reasons explained in more detail below.

The starting materials are hydrolytically condensed or partially condensed by the known sol-gel process, wherein usually a catalyst initiates or accelerates the condensation reaction and optionally a suitable catalyst or initiator, the organic polymerization. The sol-gel step is usually carried out in a suitable solvent, for the aforementioned reasons, preferably on an aqueous basis. The product is often referred to as a paint. Subsequently, this paint is brought to the appropriate viscosity, for example by dilution. Subsequently, it is possible to cure by evaporation of solvent, further inorganic post-crosslinking and / or organic crosslinking. The organic crosslinking can be effected thermally with the aid of catalysts and / or initiators, with the aid of actinic radiation (for example UV radiation) and / or redox-catalyzed. The inorganic post-crosslinking is often associated with the evaporation of solvent. All this has long been known and written down in a variety of publications.

Due to the variability of the starting materials used as well as, for example, the degree of crosslinking of the prepolymers produced therefrom (of the number of Groups X in the silanes of the formula (I) or the other additives depends) results in a potential variation, which can be used for the preparation of different paints, which are suitable for use with a variety of surfaces and in particular with textile materials.

For the preparation of the suspensions which can be used according to the invention, about 0.2-20% by weight of unfunctionalized or functionalized CNTs, based on the solids content of the paint, are generally stirred into the latter and preferably dispersed by means of ultrasound. The amount depends on the effect to be achieved in each case and may therefore also be lower or higher. Thus, in some cases, an antimicrobial effect can be detected as low as 1% by weight or even lower. For other applications, about 1.0 to 15, and preferably at least about 7.5, more preferably at least about 10 mass%, may be particularly beneficial. To adjust the viscosity and facilitate deagglomeration of the coating suspension, it can often be diluted with deionized water and / or ethanol. The functionalized CNTs are usually added to the paint after the hydrolytic condensation has been initiated; however, they can also be added at an earlier date. It has been found that the CNTs are particularly well dispersed in paints containing metal alcoholates or complexed metal compounds. As a result, very high levels of CNTs can be realized. In particular, the inventors were able to achieve good results in the presence of zirconium alcoholate (zirconium propylate): for example, 1, 2% by weight of sulfanilated CNTs, based on the total mass, could be incorporated in not yet optimized experiments, without having to resort to dispersing aids. After optimization and / or with such an agent, the amount should increase even further. Common dispersing aids can be used to facilitate dispersion and to further increase the amount of incorporable CNTs. This applies in particular to water-based paints. These are preferred on the one hand because of their environmental compatibility, on the other hand, but they are in special cases, the recoverable hardness of the post-crosslinked product because of especially for the application of the invention. Up to at least 0.5 wt .-% CNT-SuIf, based on the total amount of the paint, but often significantly more (eg to more than 5 wt .-% CNT-SuIf), can be incorporated into water-based paints, which are not only acid-catalyzed but also have a pH in the acidic range.

It is noteworthy that even an addition of 0.1 wt .-% sulfanilic acid modified CNTs can significantly increase the hardness of such paints (eg by about 30%). In a specific embodiment of the invention, functionalized CNTs are used which are covalently bonded into the lacquer via their functional groups. For example, the carboxylic acid group of carboxylated CNTs can react with free OH or NH ₂ groups of the paint to form ester or amide bonds. For this purpose, for example silanes with aminoalkyl or hydroxyalkyl groups are used for the paint base.

It should be noted that the presence of ammonium groups in the paint can be detrimental. Ammonium groups or other positively charged groups appear to interact with the functionalized CNTs, therefore the viscosity increases.

The crosslinking levels of the paints - the types of paints mentioned above differ greatly with respect to inorganic and organic crosslinking - can have a major impact on the resulting systems with the functionalized CNTs (e.g., directional alignment of the CNTs and percolation, respectively).

The intended textile or other sheet material is treated with the suspension, e.g. padded. For this purpose, it is impregnated with the suspension, which is then pressed between two rollers. Then the paint is cured as described above.

With the coating materials of the present invention, if necessary, very thin coatings can be achieved, e.g. B. of less than 5 microns, preferably less than 2 microns and in many cases even less than 1 micron in thickness, which nevertheless have excellent properties, including a greatly reduced surface resistance, such. Example from the examples. This is particularly - but not only - for textiles of particular importance because textiles are of course to be affected by a coating, of course, as little as possible in their haptic properties and in their flexibility. Another advantage of thin layers is that their transparency is high. Thus, the coatings of the invention may have a light transmission of well over 60%, usually over 80% and often even from 85% to 90% or even more in the visible range, depending on the thickness of the layer and the selected amount of CNTs. It could be shown that textile materials which were treated according to the invention have an antimicrobial effect, even with small amounts of incorporated CNTs. For other purposes, higher amounts of CNTs are particularly favorable, which is why a coating with a high amount of, in particular, functionalized CNTs may be preferred. Compared to hitherto customary antimicrobial substances such as octadecyldimethyl ^ S-thmethoxysilylpropyl ammonium chloride (OTA), the systems which can be used according to the invention have the advantage that they can be designed with a solvent system suitable for the respective system because the optionally functionalized CNTs are incorporated into the resin matrix independently of the chosen solvent while relying on customary substances to rely on specific, often toxicologically questionable solvents - OTA is offered for example in a 60% methanol solution.

The incorporation of CNTs in inorganic-organic matrices of the aforementioned type and application to textile or other planar structures, the surface resistance is lowered by several orders of magnitude; Good permanent electret properties are achieved. Probably for this reason, both antimicrobial and dirt repellent properties can be adjusted simultaneously; also the strong antistatic effect in combination with the other properties can be especially useful for protective clothing.

Overall, according to the invention, therefore, it is possible to produce coatings or coated materials which, despite the low degree of filling of CNTs (and thus with high transparency), have a more than satisfactory antimicrobial / soil-repelling effect or-at higher degrees of filling-are highly effective with regard to the stated properties and in both cases because of their very small thickness, they do not compromise desirable properties of the coated material, such as traction or flexibility.

Embodiment 1

A varnish was prepared from the following ingredients: 1140.3 mmol (85 mol%, 347.12 g) of 3- (triethoxysilyl) propyl succinic anhydride, 201.7 mmol (15 mol%, 89.43 g) of Zr-tetra- n-propylate 73.9%, 2 / 3m, based on the succinic anhydride, ethanol, 2113.9 mmol (about half-stoichiometric, for the hydrolysis, 38.09g) O ₁ I n HCI. The silane was initially charged, Zr alcoholate and ethanol were added with stirring. The resulting solution was yellow. Dropwise was hydrolyzed with the acid, wherein 20 ⁰ C were not exceeded. The mixture was stirred for 120 min at RT, whereby the solution became almost colorless. The product had a solids content of 41.68% by weight.

For the incorporation of the CNT-SuIf the paint was first diluted to 10 wt .-%. Then, the CNTs were dispersed therein. Based on the solids content of the paint matrix, dispersions having different proportions of CNTs were produced up to a content of 12% by weight of CNT. The following measurements of the surface resistance or the spec. Conductivities of coatings on films have shown that very good conductivities can be achieved, for example, from a concentration of 7.5% by weight of CNT derivative, based on the solids content. The antimicrobial testing was also positive.

4-point conductivity measurement:

Ten measurements per sample were made. Sample A had a CNT content of 7.5% by weight, sample B had a content of 12% by weight, based on the solids content.

The measured thickness of the samples was 100 μm; the distance of the four measuring points to each other was 2.77 mm.

The mean measured resistance R [MΩ] was 10.03 ± 4.2 for Sample A and 2.13 ± 0.6 for Sample B. This resulted in an estimated correction factor of 1.0 for both samples. The resistance Rs = CxC1xU / l (with C = ττ / ln2 ~ 4.53236) resulted for sample A at 45.45 MΩ and for sample B at 9.64 MΩ. the resistivity p (= Rsxt) was calculated to be 4636 Ωm for sample A and 984 Ωm for sample B; the specific conductance σ (1 / p) to 2,16E-04 for sample A and 1, 02E-03 for sample B. Test of antimicrobial action - surface resistance

The surface resistance of the samples was as follows:

The control sample consisted of the same lacquer in the same dilution without CNTs.

It has also been found that samples A and B have antimicrobial activity.

The measurement of the surface resistances of sample A, sample B and the comparative sample was repeated using a Keithley Electrometer / High Resistivity Fixture 8009. The samples were clamped in the form of a coating on PET film, which had been applied with a wire-wound rod to 50 microns and then thermally cured for 1 h at 130 ⁰ C without circulating air, with the coating down between two electrodes. Then a measuring voltage of 25V was applied. The surface resistance was determined from the current flow and expressed in ohms per (specified) area.

The surface resistance of the comparative sample was found to be 1.3E + 14Ω / area, that of Sample A was 8.3E + 6Ω / area, and that of Sample B was 7.5E + 5Ω / area.

Embodiment 2

A mixture of 3- (thethoxysilyl) propyl-succinic anhydride and γ-glycidoxypropyl-methoxysilane in a molar ratio of 2: 1 is gently hydrolyzed in 25% by weight of 2-butoxyethanol, based on the weight of the silanes, in the presence of methylimidazole as the catalyst. 2 to 15% by weight of CNT-COOH, based on the solids content of the sol (about 54%), are added and dispersed in various formulations to the resulting sol. During thermal curing This paint system add two Anhydridreste to form two free carboxylic acid groups on the opening epoxide.

Embodiment 3 (water-based paint system)

Another paint system was prepared based on aluminum tri (sec.Butylat), zirconium n-propylate, tetramethoxysilane and glycidylpropyltriethoxysilane. The hydrolysis was initiated with 0.1 N HCl. After condensation, the solvent was spun off and replaced with 0.1 HCl. It was then diluted with water to a solids content of 10 wt .-%.

With this paint system, the following dispersions were prepared:

Dispersion I:

300 g of the 10% water-based paint were admixed with 3 g of Triton X 100 (octylphenolpoly (ethylene glycol ether), nonionic detergent) as dispersing assistant. This was dissolved therein with stirring. Subsequently, 5 wt .-% (1, 5 g) of carboxylated CNTs, based on the solids content of the paint, gradually dispersed with an ultrasonic finger in the paint.

Dispersion II:

275 g of the 10% water-based paint were first admixed with 1% (6.875 g, 40% strength in H ₂ O) of a high-molecular block copolymer having pigment-affinic groups from Byk, Germany (deflocculant), and this was dissolved with stirring. Subsequently, 5 wt .-%, based on the solids content of the paint (1, 375g) CNT-SuIf gradually dispersed with an ultrasonic finger in this paint. This gave an agglomerate-free, uniform black-colored dispersion in which further CNT sulfonates could be incorporated.

Dispersion III:

275 g of the 10% water-based paint were first admixed with 1% (6.875 g, 40% strength in H ₂ O) of a high-molecular block copolymer having pigment-affinic groups from Byk, Germany (deflocculant), and this was dissolved with stirring. Subsequently, 5 wt .-%, based on the solids content of the paint (1, 375g) unfunctionalized CNTs are gradually dispersed with an ultrasonic finger in this paint.

Dispersion III was applied as a wet film in each case in a thickness of 10 .mu.m and 20 .mu.m to PET film; For comparison, the same coating system without CNTs in a thickness of 20 .mu.m was applied to PET film. After the drying / curing performed as for the samples A and B of the embodiment 1, the thickness of the obtained dry films was <1 μm and ~ 1.7 μm, respectively. The surface resistances were measured as described above for Example 1 using the Keithley electrometer under the same conditions as indicated therein. A surface resistance of 9.4E + 13Ω / area was obtained for the CNT-free sample, a surface resistance of 2.5E + 6Ω / area for the <1 μm thick sample and a surface resistance of 1 for the ~ 1.7 μm sample , 2E + 5Ω / area determined.

The lowering of the surface resistance correlates with an increase of the antimicrobial effect.

Embodiment 4

Another paint system was prepared similar to that described in Example 3 except that the zirconium n-propylate was omitted. With this paint system, the following dispersion was prepared:

Dispersion IV:

In the paint diluted to 10% by weight with water / ethanol (1: 1), 5% by weight of CNT sulfide was dispersed by means of ultrasound.

The dispersion IV and a comparative sample of the varnish of this example without CNTs were coated on a PET film as described above and, after drying / curing, were measured using the Keithley electrometer under the same conditions as indicated therein. For the CNT-free sample, a surface resistance of E + 14Ω / area and for the dispersion IV a surface resistance of E + 10Ω / area was determined.

Claims

Claims:

1. Flat or shaped textile material with or made of fibers, characterized in that at least a part of the fibers is coated with a hydrolytically condensed inorganic-organic hybrid material having embedded therein, single or multi-walled carbon nanotubes.

2. Textile material according to claim 1, characterized in that the inorganic-organic hybrid material contains organically polymerizable or organically polymerized groups.

A textile material according to any one of the preceding claims, characterized in that the inorganic-organic hybrid material is obtainable or obtained by using at least one silane of the formula (I)

wherein R ^{1 is the} same or different and is a radical accessible to organic polymerization, R ^{2 is the} same or different and is an organic radical which is not amenable to polymerization, X is the same or different and represents OH or a leaving group is hydrolyzable under hydrolysis and can contribute at least partially by an attachment to an oxygen atom of a further silicon compound to an inorganic crosslinking, a and b are each 0, 1 or 2, and 4- is 1, 2 or 3.

4. Textile material according to claim 3, the Hybhdmaterial living using at least one further silane of the formula (II)

SiX ₄ (II)

and / or at least one silane of the formula (III)

is available or was obtained wherein R ¹ , R ² and X are optionally the same or different and as well as a have the meaning given in claim 3 for formula (I).

5. Textile material according to one of the preceding claims, wherein the hybrid material was hydrolytically condensed with the addition of at least one substance, selected from solvent-soluble or water-soluble metal compounds or complexes of III. Main group of germanium and metals of the IL, III, IV, V., VL, VII. And VIII. Subgroup, wherein said metal compound / said metal complex is preferably selected from optionally complexed and / or stabilized by chelating ligands Ci -Cβ-alkoxides of boron, aluminum, zirconium, germanium and titanium.

6. Textile material according to one of the preceding claims, further comprising a purely organic material, which is preferably present in copolymerized form in the organic network.

7. Textile material according to one of the preceding claims, characterized in that the inorganic-organic hybrid material is free of cationic groups.

8. A textile material according to any one of the preceding claims, wherein the carbon tubes are functionalized with neutral or ionic groups and in particular with carboxylic acid groups and / or with sulfanilic acid groups, the latter being bonded via a carboxamide group to the carbon wall of the nanotubes.

9. Textile material according to one of the preceding claims, characterized in that the carbon tubes are functionalized and are covalently bonded via a functional group in the hybrid material.

10. Textile material according to one of the preceding claims, containing at least 5.0, preferably at least 7.5 and most preferably at least 10 mass% carbon tubes, based on the mass of the inorganic-organic hybrid material.

11. Textile material according to one of the preceding claims, characterized in that the hybrid material covalently adheres to the fibers.

12. Textile material according to one of the preceding claims, characterized in that it is a woven or knitted fabric, a yarn or a fabric insert.

13. Textile material according to one of the preceding claims, characterized in that the coating with the hybrid material has a thickness of

<5 microns, preferably of <2 microns and most preferably of 1 micron or less has.

14. Textile material according to one of the preceding claims, whose hybrid material coating has a surface resistance by a factor of 10 ⁴ , preferably by a factor of 10 ⁵ , more preferably by a factor of 10 ⁶ and most preferably by a factor of 10 ⁷ to the surface resistance an otherwise identical textile material whose coating is free of CNTs.

15. A method for producing a textile matehal according to any one of claims 3 to 14, comprising the steps:

Preparing a hydrolytic condensate from or using at least one silane of the formula (I) as defined in claim 3,

Incorporation of a suspension containing single- or multi-walled carbon nanotubes,

Applying the carbon nanotube hydrolytic condensate to at least part of the surfaces of the fibers of a sheet or formed textile material, and

- Hardening of the provided with the carbon nanotubes hydrolytic condensate.

16. The method according to claim 16, characterized in that the hardening of the hydrolytic condensate comprises the further inorganic crosslinking and / or a crosslinking of organically polymerizable groups contained therein.

17. The method according to any one of claims 15 or 16, wherein the hydrolytic condensate is prepared in an aqueous solvent or converted into such after its preparation.

18. The method according to any one of claims 15 to 17, characterized in that it is the suspension of single or multi-walled carbon nanotubes functionalized such tubes, which preferably contain carboxylic acid and / or Sulfanilsäuregruppen.

19. The method according to any one of claims 15 to 18, characterized in that prior to incorporation of the carbon nanotube suspension, a dispersant is added to the hydrolytic condensate.

20. Use of a hydrolytically condensed inorganic-organic hybrid material having embedded therein, single or multi-walled carbon nanotubes as a coating matehal for a planar substrate, which gives the coated substrate dirt-repellent and / or antimicrobial properties.

21. Use according to claim 20, characterized in that the inorganic-organic hybrid material contains organically polymerizable or organically polymerized groups and is preferably obtainable or obtained using at least one silane of the formula (I)

22. Use according to claim 21, wherein the hybrid material comprises at least one additional silane of the formula (II)

SiX ₄ (II)

and / or at least one additional silane of the formula (III)

wherein R ¹ , R ² and X may optionally be the same or different and have the same meaning as defined in claim 20 for formula (I).

23. Use according to any one of claims 20 to 22, wherein the hybrid material was hydrolytically condensed with the addition of at least one substance, selected from solvent-soluble or water-soluble metal compounds or complexes of III. Main group of germanium and metals of the IL, III, IV, V., VL, VII. And VIII. Subgroup, wherein the metal compound is preferably selected from optionally complexed and / or stabilized by chelating ligands Ci-Cβ-alkoxides of Boron, aluminum, zirconium, germanium and titanium.

24. Use according to any one of claims 20 to 23, further comprising a purely organic material, which is preferably present in copolymerized form in the organic network.

25. Use according to any one of claims 20 to 24, characterized in that the inorganic-organic hybrid material is free of cationic groups.

26. Use according to any one of claims 20 to 25, wherein the carbon tubes are functionalized with neutral or ionic groups and preferably with carboxylic acid groups lo and / or with sulphanilic acid groups, the latter being bonded via a carboxamide group to the carbon wall of the nanotubes.

27. Use according to any one of claims 20 to 26, characterized in that the carbon tubes are functionalized and are covalently bonded via a functional group i5 in the hybrid material.

28. Use according to one of claims 20 to 27, comprising at least 5.0, preferably at least 7.5 and very particularly preferably at least 10 mass% of carbon tubes, based on the mass of the inorganic

20 organic hybrid material.

Use according to any one of claims 20 to 28, wherein the hybrid material is obtained from a hydrolytic condensate present in water or in a water-containing solvent.

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