DE4237355A1 - Electroconductive pigment with shell of fluoride-doped tin oxide - and use in antistatic lacquer, plastics and fibre which is non-toxic and has good properties in use - Google Patents

Abstract

Electroconductive pigment (I) of the core-shell type has a conductive shell of F-doped Sn oxide (II). (I) is prepd. by: (1) suspending a slurry of the pigment (III) in water; (2a) opt. heating to 95 deg.C, adding a soln. contg. 40-500 (wt.)% Sn-IV cpd. (IV) w.r.t. (III) and 10-200% fluoride dopant (V) w.r.t. (IV); or (2b) adding a soln. contg. 20-200% (V) w.r.t. (III), heating 15-60 min. at 95 deg.C and adding a soln. contg. 50-300% (IV) w.r.t. (III); or (2c) adding a soln. contg. 20-200% (IV) w.r.t. (III); (3) pptg. Sn-IV cpd. on (III) by adding an alkaline or ammoniacal precipitant to pH 3.5-5; (4) adding a soln. contg. 10-100% (V) w.r.t. (III) and allowing this to react with the coated pigment at pH 3.5 or over; and (5) reacting for 30-240 min.; sepg. the coated (III) from the suspension; opt. washing and drying; and then calcining 5-30 min. at 400-600 deg.C, pref. 5-15 min. at 500 deg.C. A protective coating of SnO2 pref. is pptd. on (III) before the above procedure. (IV) is SnCl2, carboxylate, chlorocarboxylate of the formula ClxSn(OOCR)y; x + y = 4; alcoholate of the formula Sn(OR1)x(OR2)y(OR3)z; R1-3 = alkyl; x + y + z = 4; Sn-IV oxide hydrate sol (pref. with a particle size of 1-100 nm) or (IV) dispersions produced electrochemically. (V) is aq. HF soln., NH4HF2 or SnF2. USE/ADVANTAGE - (I) is used in antistatic lacquers, plastics and fibres (claimed). (I) has good properties in use and avoids the drawbacks (esp. toxicity) of pigments coated with F- and Sb-doped Sn oxide in various applications.

Description

The invention relates to a pigment with a conductive it enveloping gene layer and method for producing such a pigment and its use in the manufacture of anti-static Paints, plastics and fibers.

The manufacture of electrically conductive pigments has been around for a long time known. In principle there are two different methods available supply.

In the first process, the pigments are all over their cross cut made electrically conductive. This can be done in that Metal oxides, which have a semiconducting character, with a Dopants are added, which is the electrically conductive significantly improved. This process can either be done by a me chanic process, d. H. Mixing of the starting materials and subsequent Calcination, or by wet chemical precipitation suitable starting connections are made. Doped metal oxides of this type have in the Usually a continuous conductivity due to the dopant is statistically distributed throughout the oxide.

In the second method, pigments are coated with a layer of one electrically conductive material coated. Usually these are Stratified layers by wet chemical methods or by pyro vaporized lytic procedures. Tin is usually used as the metal oxide oxide used. Fluorine, anti are used to dope the tin oxide mon or phosphorus.  

For example, in DE-OS 40 06 044 the production becomes more electrically conductive Tin-IV-oxides are described which are divalent with a maximum of 2% by weight Tin and 0.1 to 1.0 wt .-% halides are doped. The production is carried out, for example, by grinding tin IV oxide with Tin-II fluoride with subsequent calcination.

DE-OS 40 34 353 is based on electrochemically produced Sus of tin oxalates containing fluorine-containing dopants mixed, then alkaline precipitated and worked up.

The synthesis of antimony-doped tin oxide is, for example, be written by Orel et al. in the Journal of Material Science 27, (1992), 313-318. The authors co-precipitate tin tetra chloride and antimony trichloride.

The coprecipitation can also be carried out in the presence of technically customary pigments, which then leads to a layer formation on the surface of the support. For example, EP-OS 0 415 478 describes how rutile mixed-phase pigments are provided with an Sb / SnO ₂ layer. Amorphous silicon dioxide is used in EP-OS 0 359 569 as a carrier material for the electrically conductive Sb / SnO ₂ layer. Electrically conductive barium sulfate is described in EP-OS 0 459 552. Here too, the conductivity comes from an Sb / SnO ₂ layer. The same applies to titanium oxide (EP-OS 0 267 535) and to mica (EP-OS 0 373 575).

The advantage of particles coated with conductive tin oxide is that the morphology and properties of the result pigments essentially determined by the carrier material the. These properties must be observed for pure doped tin oxides due to complex procedural steps be put.

Such electrically conductive pigments are increasingly in various which application areas used. Their use at the Manufacture of conductive lacquers (e.g .: DE-OS 40 11 867, color + Lacke 98, (1992) 19-24), antistatic plastics  (e.g. Journal of Electrostatics 23, (1989) 117-125), fibers (e.g.: EP-OS 0 407 960) and films (e.g. US Pat. No. 5,051,209), antistatic, ceramic components (e.g. Yogyo Kyokai-Shi 95, (1987) 102-107), Toners for photocopiers and antistatic coatings Glass.

Each of these applications requires a product that is optimally adapted to the requirements of the application area in terms of its application properties. When used in paints in particular, it is necessary to treat pigment surfaces that are tailored to the overall system in order to arrive at technically usable products. In this application area, however, fluorine-doped tin oxides show clear shortcomings. The fluorine-doped tin oxides produced by the previously known processes have an acidic character, which can lead to undesirable side reactions when incorporated into coating systems. The antimony-doped tin oxides that can be used in this application are to be classified as toxicologically unsafe because of their antimony content, which can go up to 9% by weight in the case of wet-chemical products. It must also be taken into account that Sb / SnO ₂ pigments with a high Sb content have a bluish shade which has a negative effect on the colorability of coating systems. This precludes the use of the paint systems equipped with it in certain sensitive applications.

The same applies to the use of plastic fibers or films, e.g. B. based on polyester. Here, too, the acidic character of the F / SnO ₂ pigments leads to a reduction in the system stability. The toxicological argument again applies to the Sb / SnO ₂ pigments. In addition, the use of conductive particles in fibers and foils requires a certain particle size and morphology, which must be set in the pure doped tin oxides by a complex process technology. The tin oxides also have a high specific weight, which makes their use at higher fill levels problematic.

The invention is concerned with the technical problem of an electrical conductive pigment, consisting of a pigment core and a conductive able to produce enveloping layer, which in addition to its electri  conductivity in its application properties can be coordinated that the disadvantages described so far be known fluorine and antimony-doped tin oxides in various applications avoids.

The invention is based on the idea, known per se and in the Areas of application used carrier materials with a fluorine-doped Coating tin oxide layer. Such products would be toxicological practically harmless. At the same time, the through the support part Chen given morphology and particle size can be used. Here However, a solution to the problem that the fluorhal term dopants preferably with the carrier materials, such as titanium dioxide or silicon dioxide, which reacts to metal fluorides during the necessary calcination step can easily escape. This would lead to non-conductive products.

An object of the invention is therefore an electrically conductive pig ment with a conductive layer enveloping the pigment, in which the conductive layer from a fluorine-doped tin oxide layer be stands.

Another object of the invention is to produce a such pigment.

A method according to the invention is characterized in that

• a) a slurry of the pigment is suspended in water,
• b) the suspension is optionally heated to a temperature of up to 95 ° C.,
• c) the suspension a solution of tin IV compounds in an amount from 40 g to 500 g, based on 100 g pigment, which additionally the dopant in an amount of 10 g to 200 g, based on Tin IV compound, contains, admits,
• d) the tin compounds by adding sufficient amounts of an alkali mixed or ammoniacal precipitant on the pigment separates; keeping a pH range of 3.5 to 5,
• e) the coated pigment after a reaction time of 30 to Separated from the suspension for 240 minutes, optionally washed out and dries, and then  
• f) at temperatures of 400 to 600 ° C for a period of 5 calcined for up to 30 minutes.

In this method according to the invention, the electrically conductive capable layer by depositing tin-IV-oxide on the pigment obtained a solution containing dopants, the to the next excreted layer was subjected to a calcination treatment will.

Another method according to the invention is characterized in that that he

• a) a slurry of the pigment is suspended in water,
• b) the suspension a solution of the fluorine-containing dopant in an amount of 20 to 200 g of fluoride, based on 100 g of pigment, admits
• c) the suspension for a period of 15 to 60 minutes Temperature warmed up to 95 ° C,
• d) the suspension a solution of tin IV compounds in an amount from 50 g to 100 g, based on 100 g of pigment,
• e) the tin compounds by adding sufficient amounts of an alkali mixed or ammoniacal precipitant on the pigment separates, keeping a pH range of 3.5 to 5,
• f) the coated pigment after a reaction time of 30 to Separated from the suspension for 240 minutes, optionally washed out and dries, and then
• g) at temperatures of 400 to 600 ° C for a period of 5 calcined for up to 30 minutes.

In this process variant, the pigment is first impregnated with the fluorine-containing dopant and then produces the tin IV oxide hydrate layer in which the doping agent is incorporated.

A third process variant is that

• a) a slurry of the pigment is suspended in water,
• b) the suspension a solution of tin IV compounds in an amount from 20 to 200 g, based on 100 g of pigment,  
• c) the tin compounds by adding sufficient amounts of an alkali mixed or ammoniacal precipitant on the pigment separates, keeping a pH range of 3.5 to 5,
• d) the suspension of the coated pigments a solution of the fluorhal term dopant in an amount of 10 g to 100 g, based per 100 g of pigment, and add the dopant at a pH Value 3.5 can act on the coated pigment,
• e) the coated pigment after a reaction time of 30 to Separated from the suspension for 240 minutes, optionally washed out, dries, and then
• f) at temperatures of 400 to 600 ° C for a period of 5 calcined for up to 30 minutes.

In this process variant, the tin IV is first generated oxide hydrate layer and this layer in a second step endowed.

Virtually any pig can be used as the starting material for the coatings ment that is used in the plastics and coatings sector finds, the chemical stability compared to that still to be described reaction conditions is a prerequisite for use. In the we The main types of connection are:

Silicates:

Suitable support materials for the F / SnO ₂ layer are: talc, kaolin, mica, feldspar, wollastonite, natural and synthetic silicon dioxide. These pigments are often offered with chemically modified surfaces. These are generally not disruptive in the coating according to the invention.

Heavy spade of natural or synthetic origin.

Metal oxides:

The main representative is titanium dioxide, it doesn't matter whether it is a natural or synthetic product. Be However, the rutile-crystallized form is preferred, since the up  precipitated tin oxide also occurs in this crystal form and therefore ensure a firm connection between the tin oxide layer and the carrier is steady.

In addition, inorganic colored pigments consisting of different metal oxides can also be provided with an F / SnO ₂ layer according to the invention.

The choice of the suitable temperature for the calcination depends essentially on the type of pigment used. It was found that when using metal oxides, especially TiO ₂ , it is possible to work at higher temperatures than when using silicic pigments. Depending on the type of silicate pigment, it may even be advantageous to do without heating. However, the calcination is preferably carried out at temperatures of about 500 ° C. and for a period of 5 to 15 minutes.

The choice of reaction temperature essentially affects the up rate of precipitation of the fluorine-doped tin oxide layer onto the Pigment surface. The reaction temperature is generally 50 to 95 ° C, preferably 50 to 80 ° C.

A defined pH range should be maintained during hydrolysis and precipitation not be left. The preferred pH range is depending on the ver Driving variant between 3.5 and 8.

After completion of the precipitation, the reaction mixture is left for react for a period of 30 minutes to 240 minutes and then separates the solvent. Depending on the type of used Tin output connection, additional washing operations will be necessary to remove any remaining soluble salts. Then the product dried.

To set the appropriate electrical conductivity, the Raw powder can be thermally treated. It is known that antimony doped Tin oxides to achieve their optimal conductivity temperatures of  800 to 1000 ° C must be exposed. For the fluorine-doped tin oxide, the thermal aftertreatment is 400 to 600 ° C, preferably about 500 ° C. If the temperature or tempera is not observed non-conductive pigments by evaporation of the Do agent arise.

The calcination can be carried out under a normal atmosphere, but preferably under N ₂ , CO ₂ or Ar as protective gas. The annealing time should not exceed 30 minutes, a time period between 5 and 15 minutes is preferred.

In order to avoid that the dopant can interact undesirably with the pigment surface, which leads to pigments which are not or only poorly conductive, a preferred embodiment of the process according to the invention is that one first starts on the pigment by precipitating tin IV compounds generates a protective layer of SnO ₂ and then carries out the method according to claim 2 or 3.

Aqueous hydrogen fluoride solutions are preferred as dopants gene, ammonium hydrogen fluoride or tin-II fluoride used, wherein the latter are particularly preferred.

Can be used as starting materials for the tin oxide layer become:

Tin IV halides, such as. B. tin tetrachloride, bromide, iodide, but preferably SnCl _{4 be} ;
Tin IV carboxylates, such as. B. tin tetraacetate, propionate, butyrate, octoate, stearate, but preferably tin tetraacetate;
Tin-IV-halogen carboxylates of the general empirical formula (Hal) _x Sn (OOCR) _y (x + y = 4), such as, for. B. dichlorotin diacetate, dibromo tin diacetate and corresponding higher dihalocarboxylates;
Tin IV alcoholates of the general empirical formula Sn (OR ¹ ) _x (OR ² ) _y (OR ³ ) _z , where R ¹ , R ² and R ^{3 are} alkyl radicals and x + y + z = 4,
Tin IV oxide hydrates obtained by oxidation of tin II compounds with hydrogen peroxide, in particular by oxidation of tin II chloride and tin II oxalate; the tin oxide hydrates thus obtained are in the form of sols (Gmelin Sn C1 p. 233);
electrochemically produced tin-IV salt dispersions, as can be synthesized according to DE-OS 40 34 353.

Tin IV salts which have a low salt content are particularly preferred Have halide content.

When using such compounds arise in the invention Process low or non-halogenated residual salts in the precipitation lung, which in contrast to highly halogenated after completion of the reaction Tin compounds can be removed with little effort.

The sols of the tin oxide hydrate are particularly preferred since SnO ₂ particles with particle sizes in the lower nm range, in particular in a range from 1 to 100 nm, are already present in these. These can be deposited particularly well on the pigments presented. Even before use, these brines can be doped in such a way that already fluorine-doped tin oxides are deposited during the precipitation. This also prevents possible side reactions with the pigment surface.

The F / SnO ₂ layer pigments produced according to the invention have a pH between 4 and 7. The pH value is measured from a 10% suspension of the pigment in water using commercially available measuring devices. The pigments thus produced thus have a significantly higher pH than pure fluorine-doped tin oxides, which were synthesized according to DE-OS 40 06 044 or DE-OS 40 34 353. They usually have a pH between 2 and 3.

The consequences of this higher pH value are significant: in contrast to the uncoated fluorine-doped tin oxides are according to the invention manufactured pigments for the production of antistatic finish Varnishes, plastics and fibers are suitable as there are no negative effects solution of the polymer matrix or the coating system occurs more.  

The process according to the invention is first described in the following examples ren explained in more detail. In further application engineering examples who the properties of the conductive pigments according to the invention shows.

I. Manufacturing examples example 1 Production of an F / SnO ₂ layer on titanium dioxide pigments

156.7 g of stannous fluoride are dissolved in 3 l of water. In this solution 80 g of titanium dioxide are added with vigorous stirring. The dispersion is heated to 85 to 90 ° C. At a pH of 3.5 to 4.5 a solution of 260.5 g of tin tetrachloride in 942 ml of ethanol is added drips. During the dropping in, the pH is changed by simultaneous Addition of 5% ammonia solution kept constant.

After the addition of SnCl _{4 has} ended, the temperature is kept constant for another hour and then filtered. The filter cake is washed several times with water. After the product has dried, it is annealed at 500 ° C. The annealing time is 10 minutes.

The powder has the following properties:

resistivity: 270 Ωm
Bulk density: 0.3 g / cm ³
BET surface area: 68 m ² / g
pH (10% in water): 4.

Example 2 Production of an F / SnO ₂ layer on modified mica

290 ml of a 0.35 mole Sn containing tin acid sol, which by Oxida tion of stannous chloride with hydrogen peroxide is obtained mixed with 10 g of stannous fluoride with stirring. The originally color  loose solution turns dark brown. By adding 1 ml of Was The peroxide is oxidized to tin IV by means of peroxide Solution turns light yellow. A suspension of 100 g iriodin (titanium dioxide coated mica) in 1.5 l of water is stirred to 60 to Heated 70 ° C and added dropwise with the doped tin acid sol. At the same time, the pH is kept at 5 with 32% NaOH.

After a reaction time of about 2 hours, the powder obtained is dissolved separated and dried. The product is at 15 minutes Annealed 500 ° C.

The specific resistance of the coated mica is: 90 Ωm.

Example 3 Production of an F / SnO ₂ layer on modified mica

The procedure is as in Example 2. Lowering the glow time in 5 minutes gives a product that has a specific counter of 120 Ωm.

Example 4 Production of an F / SnO ₂ layer on silicon dioxide

1000 g of an aqueous 25% NH ₄ OH solution are mixed with 2 l of water and 1 l of ethanol and heated to 20 to 25 ° C. by means of a cooling device. 184 g of Aerosil are stirred in with vigorous stirring. 5 l of a fluorine and 6.1 mol of Sn containing tin acid sol dispersion are added to the suspension.

The tin acid sol is made as follows:

1292 g of tin-II-oxalate are slurried in 1.5 l of deionized water and mixed with 710 ml of 30% H ₂ O ₂ so that the temperature does not rise above 20 ° C. After the addition, excess perhydrol is boiled and the resulting mixture is diluted with 2.25 l of water. Then 172 g of SnF _{2 are} added, the resulting dark color being removed with 111 g of H ₂ O ₂ . A yellowish, clear fluorine-doped tin acid sol is formed.

After the precipitation has taken place, the solvent is separated off and washed and dried.

The subsequent 30-minute calcination at 500 ° C gives a Powder, which has an F content of 2 wt .-% and a tin II content of 0.5% by weight. The pressure-free measurement of the specific resistance that gives 180 Ωm.

Example 5 Production of an F / SnO ₂ layer on mica

50 g of SnF ₂ and 225 g of mica are placed in 5 l of water and heated to 50 ° C. Via a pH-dependent control, 68.4 g of NaOH in 615.3 g of water and a tin acid sol are metered in with stirring at this temperature between pH 3.5 and 4.5. The tin acid sol is prepared from 81.01 g of SnCl ₂ in 1087 ml of water and 14.53 g of H ₂ O ₂ . The sol was added after about 10 minutes. Now the pH is increased to 7 with NaOH. The solvent is then separated off and the remaining powder is dried. Calcination at 500 ° C under a protective gas gives a pigment with a specific resistance of 500 Ωm after 15 minutes. The hydrolysis conductivity of a 10% suspension in water is 1500 mS / cm, the pH of this suspension is 5.6.

Example 6 Production of an F / SnO ₂ layer on TiO ₂

100 g of titanium dioxide are added to 2 l of water with vigorous stirring. A tin acid sol, which has been prepared from 81 g of tin (II) chloride in 1000 ml of water and 15 g of H ₂ O ₂ , is dripped into the dispersion, which is heated to 80 ° C. The pH of the dispersion is adjusted to 7 by simultaneous addition of NaOH. After the addition of sol has ended, the mixture is left to react for 30 minutes in order to complete the separation.

The doping solution, which has been prepared by dissolving 40 g of stannous fluoride in 300 ml of water and adding 10 g of 30% H ₂ O ₂ solution, is then added dropwise. The pH is kept at 7 to 8 by adding further sodium hydroxide solution.

After a reaction time of about 60 minutes, the solvent removed, the remaining pigment washed, dried and then at Annealed 500 ° C for 10 minutes.

The specific resistance of the coated TiO ₂ is 200 Ωm.

II. Examples of application technology

To demonstrate the application-related properties, use the Examples 7 and 8 used as pigment titanium dioxide, on its surface according to the invention fluorine-doped tin IV oxide has been noticed. The experiments are done with a varnish Water-based and a solvent-based varnish.  

Example 7 Water-based polyurethane paint

• - Polyurethane varnish ¹⁾ 100 g
• - Butyl glycol 4 g
• - DI water 32 g
• - pigment ²⁾ 40 g
  ¹⁾ commercially available under the name Witcobond W 234
  ²⁾ TiO ₂ coated with fluorine-doped SnO ₂ according to the invention

The electrically conductive pigment according to the invention is thereby used a laboratory dissolver (Dispermat type) at 15,000 rpm for 5 minutes in incorporated the paint system. After application to a glass plate using A 100 µm squeegee gives a coating with a smoother finish after drying Surface. The specific surface resistance of the almost white Lacquer, measured according to DIN 53 482, is 38 kΩ.  

Example 8 Solvent-based alkyd resin paint

• - Alkyd resin ¹⁾ (60% in white spirit) 112.2 g
• - Thickener ²⁾ (10% in white spirit) 2.2 g
• - Dispersing aid ³⁾ 0.3 g
• - White spirit 145/200 18.2 g
• - Desiccant ⁴⁾ 4.4 g
• - Paint aids ⁵⁾ 1.1 g
• - Leveling and lubricant ⁶⁾ 0.1 g
• Pigment ⁷⁾ 40.0 g
  ¹⁾ commercially available under the name rhenaldehyde MF 4028
  ²⁾ commercially available under the name Bentone 38
  ³⁾ commercially available under the name Tego-Dispers
  ⁴⁾ commercially available under the name combination dryer 17
  ⁵⁾ commercially available under the name Ascinin R (conc.)
  ⁶⁾ commercially available under the name Airex 980
  ⁷⁾ TiO ₂ coated with fluorine-doped SnO ₂ according to the invention.

The electrically conductive pigment according to the invention is by means of a Laboratory dissolver (Dispermat type) at 15,000 rpm for 2 minutes Dispersed paint system. After application to a glass plate using a 100 µm squeegee gives an almost white lacquer after drying with a smooth surface. The specific surface resistance, measured sen according to DIN 53 482, is 78 kΩ.

Claims (10)

1. Electrically conductive pigment with a conductive layer enveloping the pigment, characterized in that the conductive layer consists of a fluorine-doped tin oxide layer. 2. A process for producing an electrically conductive pigment with a conductive fluorine-doped tin oxide layer enveloping the pigment according to claim 1, characterized in that

• a) a slurry of the pigment is suspended in water,
• b) if necessary, the suspension is heated to a temperature of up to 95 ° C.,
• c) the suspension a solution of tin IV compounds in an amount of 40 g to 500 g, based on 100 g pigment, which additionally the dopant in an amount of 10 g to 200 g, based on tin IV compound , contains, admits
• d) the tin compounds are deposited on the pigment by adding sufficient amounts of an alkaline or ammoniacal precipitant, a pH range from 3.5 to 5 being observed,
• e) after a reaction time of 30 to 240 minutes, the coated pigment is separated from the suspension, optionally washed out and then dried, and then
• f) calcined at temperatures of 400 to 600 ° C for a period of 5 to 30 minutes.

3. A process for producing an electrically conductive pigment with a conductive fluorine-doped tin oxide layer enveloping the pigment according to claim 1, characterized in that

• a) a slurry of the pigment is suspended in water,
• b) adding a solution of the fluorine-containing dopant in an amount of 20 to 200 g of fluoride, based on 100 g of pigment, to the suspension,
• c) the suspension is heated to a temperature of up to 95 ° C. for a period of 15 to 60 minutes,
• d) adding a solution of tin IV compounds to the suspension in an amount of 50 g to 300 g, based on 100 g of pigment,
• e) the tin compounds are deposited on the pigment by adding sufficient amounts of an alkaline or ammoniacal precipitant, a pH range from 3.5 to 5 being observed,
• f) after a reaction time of 30 to 240 minutes, the coated pigment is separated from the suspension, optionally washed out and then dried, and then
• g) calcined at temperatures of 400 to 600 ° C for a period of 5 to 30 minutes.

4. A process for producing an electrically conductive pigment with a conductive fluorine-doped tin oxide layer enveloping the pigment according to claim 1, characterized in that

• a) a slurry of the pigment is suspended in water,
• b) adding a solution of tin IV compounds to the suspension in an amount of 20 g to 200 g, based on 100 g of pigment,
• c) the tin compounds are deposited on the pigment by adding sufficient amounts of an alkaline or ammoniacal precipitant, a pH range from 3.5 to 5 being observed,
• d) adding a solution of the fluorine-containing dopant to the suspension of the coated pigments in an amount of 10 g to 100 g, based on 100 g pigment, and allowing the dopant to act on the coated pigment at a pH of 3.5,
• e) after a reaction time of 30 to 240 minutes, the coated pigment is separated from the suspension, optionally washed out and then dried, and then
• f) calcined at temperatures of 400 to 600 ° C for a period of 5 to 30 minutes.

5. The method according to claim 2, 3 or 4, characterized in that the calcination at temperatures of about 500 ° C and during a period of 5 to 15 minutes. 6. The method according to claim 2, 3 or 4, characterized in that one first generates a protective layer of SnO ₂ on the pigment by precipitation of tin IV compounds and then carries out the method according to claim 2, 3 or 4. 7. The method according to one or more of the preceding claims, characterized in that tin-IV compounds are tin-IV-chlorides, tin-IV-carboxylates, tin-IV-chlorocarboxylates of the general formula Cl _x Sn (OOCR) _y , in which the sum of x and y has a value of 4, tin IV alcoholates of the general formula Sn (OR ¹ ) _x (OR ² ) _y (OR ³ ) _z , in which R ¹ , R ² and R ³ Are alkyl residues and the sum of x, y and z has a value of 4, tin IV oxide hydrates in the form of sols or electrochemically prepared tin IV salt dispersions used. 8. The method according to claim 7, characterized in that tin Use oxide hydrate brine with a particle size of 1 to 100 nm det. 9. The method according to one or more of claims 2 to 7, characterized characterized in that as a dopant aqueous fluorine water fabric solutions, ammonium hydrogen fluoride or tin-II-fluoride ver turns. 10. Use the pigments according to one or more of the preceding the requirements for the production of antistatic lacquers, Plastics and fibers.