DE2057731A1 - Finely divided oxides - of metals or silicon rendered hydrophobic by treatment with hydrolysable metallic compounds or silicones - Google Patents

Abstract

Finely divided oxides of metals and/or silicon are rendered hydrophobic by treatment under intensive mixing with hydrolysable compounds (a) M(OR1)4 (I) where M = Group IV element (esp. Ti or Si), R1 = 1-18C alkyl or aryl; (b) organoalkoxysilanes RnSi(OR1)4-n where R = 1-12C alkyl or aryl and R1 = 1-8C alkyl and n = 1-3; (c) organoalkoxyoligosiloxanes R-Si(X)(Y)(O-Si(R)(Y))nO-Si(X)(Y)-R where X = R or OR1, Y = R or OR1, R = 1-6C alkyl or aryl and R1 = 1-8C alkyl and n = 0 or 1; or (d) organoalkoxycyclosiloxanes (R-Si-Or1)n where n = 3 or 4. Esp. as fillers for silicone rubbers.

Description

Process for the waterproofing of highly disperse oxides.

The invention relates to a method for hydrophobing highly dispersed Oxides of metals and / or silicon by treating the oxide particles with Organosilicon compounds in the presence of ammonia as a catalyst.

It is known that finely divided silicas are precipitated or pyrogenic Type of production through chemical change of its surface permanently hydrophobic To give properties While the known method of hydrophobing precipitated Silicas use a "slurry technique", with the most varied of Hydrophobizing agents derived from silicon compounds are used, are different from the "Slurry technique" advantageously lifting hydrophobing processes in heterogeneous Known gas phase.

For example, pyrogenic products are obtained using the method according to DAS 1 163 784 Wiesel acids immediately after production in a downstream production process Fluidized bed can be converted into hydrophobic, finely divided fillers by means of e.g. alkylchlorosilanes.

According to an older proposal, silicas become more thermal after a previous one Activation also in a heterogeneous gas phase at higher temperature with the help of volatile ones or alkyl siloxanes brought into the gas phase, e.g. D4 (octamethylcyclo-tetra-siloxane), hydrophobized.

According to a further suggestion, silicas, regardless of which Form of production, after previous act;: ivation with Illife of alkyl- or aryl-alkoxysilanes or alkyl / arylalkoxysiloxanes are converted into finely divided hydrophobic products, the alkyl / arylalkoxysilanes or alkyl / arylalkoxysiloxanes required as hydrophobing agents can be used both in gaseous form, as well as a spray in heterogeneous Gas phases The first two processes mentioned lead to satisfactory products, but require a considerable technical outlay in terms of equipment. In contrast The latter method offers the great advantage that it actually works with one Minimum of outlay in terms of equipment. The one with full utilization of the slightest small amounts of alcohols still adhering to the products in terms of apparatus generally do not interfere. Still, it would be desirable to use hydrophobic products to obtain with the least technical effort that is as free as possible from volatile constituents resulting from the manufacturing process.

Now, however, it is possible to use such alkyl-alkoxy-silanes or alkyl-alkoxy-siloxanes as a water repellent to select, the alkoxy radicals of which are particularly easy derive volatile alcohols, e.g. methanol. However, experience has shown that hydrophobic silicas made with alkoxy derivatives that differ from height ru derived from alcohols, possess superior properties. Therefor for the disadvantage be accepted that the higher alcohols released during the hydrophobization can only be removed with difficulty and in some cases not completely from the finished product leave, whereby even the smallest amounts are annoying due to the odor perception considered wervletl.

On the other hand, particularly good hydrophobic properties of Silicic acids also by hydrophobing with alkylalkoxysilanes which have longer alkyl chains reach; here one is however already because of the with the alkyl chain length rapidly increasing boiling points on the use of never those alcohols for the alkoxy radical reliant.

There is now also the fact that the hydrophobization of silicas Usable alkyl (or aryl) alkoxysilanes react more difficult or slower, the more O atoms their alkyl radicals on the one hand and the more C atoms their alkoxy radicals on the other hand own.

Alkylalkoxysilanes or alkylalkoxysiloxanes with longer carbon chains On (n> 2) therefore require at normal temperature even when using highly active ones or highly active silicas, so long reaction times (if excluded, catalytic active substances) that they, at least for a technical use, in this simplest embodiment out of the question.

On the other hand, according to an earlier suggestion, they can benefit you technical water repellent process can be used if you have one at the same time Lane EC1, for example, 0.1% of the applied water repellent added. In this way obtained depending on the alkyl-alkoxy-silanes or altyl-alkoxy siloxanes used depending on their alkyl and alkoxy radicals within a few minutes up to one hour of hydrophobic silicas.

In many cases, e.g. for use in silicone rubber, but that of the method just mentioned, the product from its method of manufacture still adhering acidic character disadvantageous or even precludes the use of the product manufactured in this way.

It is true that the earlier proposal mentioned above stated that as well as advantageously silicas without catalysts with the aid of alkyl-alkoxy-silanes or alkyl-alkoxy-siloxanes can be converted into hydrophobic products, however this embodiment requires the use of a technical system for hydrophobing.

The problem was therefore to combine silicas with alkyl-alkoxysilanes or Alkyl-alkoxy-siloxanes or cyclo-siloxanes even at room temperature without use acidic catalysts with a speed sufficient for technical purposes to hydrophobize in the simplest embodiment, still undissolved.

From U.S. Patent 3,334,062 it is known to use finely divided inorganic substances e.g. silicas, which have a water content of at least 1% by weight, with cyclo-trisiloxane in the presence of ammonium compounds, i.a.

Ammonium hydroxide and ammonium carbonate, in the temperature range of 15 to 1700 C over a period ranging from 5 minutes to several hours treat, whereby hydrophobic products are obtained, which as fillers 111 Elastomeric rubber and synthetic resins are suitable. This procedure is jedocfi limited to hydrophobization with cyclotrisiloxane as a treatment with cyclotetrasiloxanes, e.g. D4, not too hydrophobic, but clearly hydrophilic Products.

The invention was based on the object of providing a method for Hydrophobization of finely divided oxides of metals and / or silicon by treatment the oxide particles with organosilicon compounds from the group of organoalkoxysilanes, Organosiloxanes and organocyclosiloxanes in the presence of ammonia as a catalyst indicate which, with the simplest procedure, becomes totally and stably hydrophobic Products that are neutral and completely free of volatile components, ie also alcohols, whereby the use of acidic catalysts is omitted and wherein both linear organosiloxanes, such as hexamethyldisiloxane (D2), and cyclic ones Organosiloxanes such as hexamethylcyclo-trisiloxane (D3) or octamethyl-cyclo-tetrasiloxane (D4) Find use without the application being restricted to the named ones.

The characteristic feature of the invention can be seen in the fact that the oxide particles after it by a temperature treatment in the range of 700 to 1000 ° C within a period of less than 60 seconds by means of a stream of inert gas in the fluidized bed activated and before, during or after their treatment with the organosilicon compound exposed to the action of NII gas for a few seconds.

3 From the group of organoalkoxysilanes there are compounds of the general Formula RnSi (OR) 4-n Use, in which R = an alkyl radical with 1 - 12 C atoms or an Arylrest.und R '= an alkyl radical with 1 - S carbon atoms, where n is a Number from 1 to 3 can be.

From the group of organoalkoxy-siloxanes and organoalkoxy-oligosiloxanes, compounds of the general formula are found Use in which X = R or OR ', YSR or OR' and R = an alkyl radical with 1 - 6 carbon atoms or an aryl radical and R '= an alkyl radical with 1 - R carbon atoms, where n is the number zero or 1 can be.

From the group of the organo-alkoxy-cyclo-siloxanes there are compounds of the general formula Use in which R and R 'have the abovementioned meaning and n can be the number 3 or 4.

Without the previous activation of the finely divided silicas, which according to the procedure according to the German patents ............... (patent applications P 17 67 226.3 and P 2004 443.3), the end products show otherwise same treatment either no hydrophobic properties or when applied increased amounts of water repellants only inadequate hydrophobic properties.

All possible types of compounds from the group of the organosiloxanes can be used or the organo-alkoxy-silane resp.

Organo-alkoxy-silanes according to the general ones given above Formulas are used. However, the use of such is of particular advantage Organo-alkoxy-silanes or organo-alkoxy-siloxanes, which are obtained by reacting with alcohols can be obtained from organo-trihalosilanes.

As in the production of these organo-alkoxy-silanes as alcoholic Components all conceivable alcohols - including mixtures of different alcohols - can be used, it is also not necessary that the for use according to the invention coming organo-alkoxy-silanes are uniform compounds that they are liquids are, or even have to be volatile; just as can namely with equally good Successful solids - provided they are available in a suitable form of distribution - used will.

Alkyltrichlorosilanes easily react with alcohols according to the scheme: R-Si Cl3 + 3 WbH - p- R - Si - (OR ') 3 + 1101 (I) to the altyl-trialkoxysilanes (I), the alkyl alkoxysiloxanes (II) derived from (I) often in the same reaction, as well as alkyl-alkoxy-polysilanes (III) arise.

Both the alkoxysilanes (I) and dic siloxanes (II) and (III) leave Use on their own or in mixtures for hydrophobing.

It is noteworthy that organoalkoxypolysiloxanes have been equally successful (III) can be used, depending on the alcohols used in the soft Production of the organoalkoxysilanes, as by-products in smaller or in can arise in a considerable amount.

Surprisingly, this can be done in the preparation of the organoalkoxysilanes or organoalkoxypolysiloxanes formed reaction mixture directly as lJydrophobierungsmittel use, whereby the process according to the invention is essential designed more economically, since complex process steps to separate the individual Reaction products can be omitted.

Since the inventive method uses ammonia catalysis, neutral hydrophobic silicas are obtained even if this is used for hydrophobing The reaction mixture used still contains residues of gaseous hydrogen chloride. For Purposes for which those incidentally arising during the hydrophobization with such mixtures The organoalkoxysilanes therefore need small amounts of ammonium chloride or organo-alkoxy-oligosiloxanes are not available as technically pure products.

However, for higher demands aii the hydrophobic products are also Traces of ammonium chloride undesirable. In a manner known per se, which is not the subject of the present invention, the alkyl alkoxysilanes to be used or Siloxanes in the preparation or in the separation of the reaction mixture by Treatment with ammonia also of the last residues of HC1 and / or chlorosilanes to be freed.

With such a breadth of application of the method according to the invention it is obvious that one has to choose both for the preparation of the water repellant required organohalosilanes as well as the alcohols to each by the least technical effort procurable raw materials can fall back.

So irl is the simplest form of making a hydrophobic one Products; possible in such a way that on the activated silicas in any Container the above-mentioned fiydi'ophobierungsmittel are given, these stirred in as such, sprayed in in droplet form or in the form of an elamp, if necessary im Mixture with an inert gas stream can be supplied.

Depending on the water repellants used and described above is obtained depending on their radicals R, ins'-especially R ', and depending on the temperature products that are completely hydrophobic within a few seconds to hours Addition of gaseous NI13. This is extremely surprising since experiments showed that other amines, e.g. pyridine, or n-dibutylamine still remain after weeks show no catalytic effect.

It is particularly surprising that when using the more volatile Alkyl-alkoxy-silanes completely hydrophobic products within even at room temperature from 3 - 30 'can be obtained. As more volatile alkyl-alkoxy-silanes in this The meaning of this is to consider those compounds whose boiling points are at normal pressure still below approx.

200 ° C, where the radicals R and R 'in the sense of the above general formula can have up to 6 or 8 carbon atoms, if only R are large and R 'are small or vice versa.

In many cases, e.g. for use in silica @@ rubber is a Desired product that is completely free of volatile compounds and also neutral is. The present method according to the invention fulfills this requirement in one Embodiment that uses alkyl-alkoxy-silanes, which are highly volatile Derive alcohols.

A particular element of surprise was the fact that after the above Process activated silicas also when using Akyl-alkoxy-silanes with longer alkyl chain even at room temperature in a few minutes without special technical device deliver completely hydrophobic products. So one obtains e.g. made of n-hexyl-trimethoxysilane and an activated pyrogenic silica inside 3 minutes after mixing, a completely hydrophobic product that easily - also at room temperature - by means of a stream of inert gas in a simple countercurrent fluidized bed can be freed of both NH3 and the methanol formed in the reaction Without The application of NH3 is obtained by treating the activated according to the above-mentioned procedure Silicas with organo-alkoxysilanes at room temperature without the use of a catalyst Totally hydrophobic products only after a very long exposure time; with organosiloxanes E.g. D4 can under the same conditions even after a very long exposure time no hydrophobic products are obtained.

It is therefore surprising that according to the process according to the invention also when using organosiloxanes (instead of organo-alkoxy-silanes or siloxanes) can be obtained with similar ease *).

Since this variant of the method according to the invention at the On the surface of the hydrophobized silicas, organic groups are located, it is a welcome addition to those available with the help of organo-alkoxy-silanes or organo-silozanes Hydrophobized silicas also have organic groups on their surface Organo-oxy groups can be located.

Of course, in the method according to the invention, a continuous production method are preferred.

In this case, the activated Kieset acids are mixed with the above-mentioned water repellants and NT13 in a manner known per se in one Fluidized bed.

The reaction mixture then goes through one of the above Said shorter or longer dwell zone, followed by a countercurrent fluidized bed be conducted en, in which the removal of ammonia and, if necessary, alcohol by means of an Incrtgasstromes is operated.

hydrophobic products that are free of volatile compounds and In addition, it has only been possible to react neutrally up to now by means of high-temperature hydrophobization to win.

In the following examples, the implementation of the invention Procedure explained in more detail: *) completely hydrophobic products example 1,500 g of a pyrogenic silica (surface area 120 m 2 / g BET) were activated after activation at normal pressure and normal temperature with 40 g («8% by weight) of n-propyl-triisopropoxysilane (MW 248.4) sprayed with stirring.

After 1 hour, a stream of dry NH3 gas was generated for 2-3 seconds the product passed, after which it was shaken once.

Ten minutes after the ammonia was added, the product became water no longer wetted.

A sample that was tested prior to abandoning the ammonia was completely wettable with water.

Example 2 500 g of fumed silica (surface area 120 m2 / g BET) were After activation, put in ulii vessel, put under vacuum and add 70 g (= 14 G% of a mixture of C6 - C8 - alkyltrimethoxysilanes (average MH 220, 36, bp3 54 - 56 ° C) was added dropwise within a short time, shaking vigorously. After this the vacuum was released under nitrogen, turned on for 2-3 seconds dry nitrogen gas stream introduced into the product.

All manipulations - with the exception of activation - were carried out at normal temperature (20 ° C) carried out.

After 1 hour the product was; no longer wettable by water, it had a surface area of 76 m² / g (BET) and a carbon content of 5.86%.

Example 3 500 g of a pyrogenic silica (surface area 120 m² / g BET) were placed in a vessel after activation, placed under vacuum and added at room temperature 100 g (^ 20% by weight) of n-propyl-tris-2ethylhexoxy-silane previously heated to 50 ° C (MW = 458.8; bp3 182/183 ° C) was added dropwise within a short time, with vigorous shaking became. After releasing the vacuum under N2, it lasted 2-3 seconds a dry NH3 gas stream is introduced into the product. A sample that takes 5 minutes After the ammonia was drawn through it was completely hydrophobic. Surface 70 m² / g (BET), C content 7.9%.

Example 4 500 g MOX 80 (surface area 80 m2 / g BET) were activated after activation while stirring with 35 g (= 7% by weight) n-propyl-trimethoxysilane (NG 164.3; Kp745 146 °) added at room temperature.

After 5 minutes a stream of dry NH3 gas became available for 2-3 seconds introduced into the product. A sample taken 3 minutes after passing the ammonia through was drawn was completely hydrophobic.

Example 5 500 g of a precipitated silica (surface 150 m² / g BET) were activated with 75 g (= 15% by weight) of n-propyltri-n-butoxy-silane (MW 290.5; Kp2 97 °) at room temperature while stirring.

After 5 minutes, the alkaline solution became a dry one for 2-3 seconds with stirring NH3 gas flow passed through the mixture. Then it was shaken vigorously.

Ten minutes after the ammonia was added, the product became water no longer wetted.

Example 6 500 g of a pyrogenic silica (surface area 120 m2 / g BET) were placed in a vessel after activation, placed under vacuum and added at room temperature 75 g (= 15% by weight) di-n-propyl-tetra-n-butoxy-disiloxane previously warmed to 60 ° C (MW 530.8; bp 0.5 174-184 °) was added dropwise within a short time with shaking.

After 1/2 etd. the vacuum was released below room temperature and A stream of dry NH3 gas is passed through the mixture for 2-3 seconds.

after shaking the product was free flowing, one after 6 hours. sample drawn was completely hydrophobic.

Example 7 To 300 g of a fumed silica (surface 200 m2 / g) was left after prior activation with shaking at normal pressure and room temperature Add 60 g of D4 (octamethylcyclo-tetrasiloxane) dropwise, then shake for another 10 minutes became. Then NH3 gas was poured into the mixture for 2-3 seconds while shaking initiated.

A sample taken after standing for 2 days at room temperature was not more wettable with water.

Example 8 500 g of a mixed oxide (surface 80 m2 / g BED) were placed in a vessel after activation, placed under vacuum and added to it Room temperature (20 ° C) 35 g (= 7% by weight) octamethylcyclo-tetrasiloxane (D4) within sprayed in for a short time while shaking.

After 1/2 hour the vacuum was released under dry N2 and 2 - A stream of dry NH3 gas is passed through the mixture for 3 seconds, with A significantly improved flow behavior was immediately evident.

A sample taken after standing for 3 days at room temperature was complete hydrophobic.

Claims (19)

P a t e n t a n s p r ü c h e 1.) Process for the hydrophobization of finely divided oxides of metals and / or the silicon by treating the oxide particles with organosilicon compounds in the presence of ammonia as a catalyst, characterized in that after Activation of the oxide particles by a temperature treatment in the range of 700 - looo C within a period of less than 60 seconds using a Inert gas stream in the fluidized bed on the oxide particles completely freed from water, dry NH3 gas during or after their treatment with the organosilicon compound is caused to act for a period of less than 6o Selciinden. 2.) The method according to claim 1, characterized in that PlS organosilicon compounds those from the group of the organoalkoxysilanes of the general formula Rn (SiOR ') 4-n can be used, where R = an alkyl radical with 1-12 carbon atoms or an aryl radical and R '= an alkyl radical with 1 to 8 carbon atoms, where n is a number of 1 - can be 3. 3.) Process according to claims 1 and 2, characterized in that that organoalkoxysilanes of the general formula R2 Si (OR ') 2 are used, in which R = an alkyl radical with 1 to 8 carbon atoms or an aryl radical and R '= = one Denote an alkyl radical with 1 to R carbon atoms. 4.) The method according to Ansprttchen 1 to 3, characterized in that that an organoalkoxysilane of the general formula R - Si (OR ') 3 is used, where R = an alkyl radical with 1-12 carbon atoms or an aryl radical and R '= one Denote an alkyl radical having 1 to 8 carbon atoms. 5.) The method according to claim 1, characterized in that the organosilicon compounds are those from the group of organo-alkoxy-siloxanes or organoalkoxy-oligosiloxanes of the general formula are used, in which -X - R or OR 'Y = R or OR', R = an alkyl radical with 1 to 8 C atoms or an aryl radical and R '= an alkyl radical with 1 to 8 C- Mean atoms, where n can be the number 0 or 1. 6.) Method according to response 1 and 5, characterized in that an organo-alkoxysiloxane or organoalkoxy-polysiloxane of the general formula is used, in which R and R 'have the meaning given above and n can assume a number from 0-2. 7.) Process according to claims 1 and 5, characterized in that an organo-alkoxy-siloxane or organoalkoxy-oligo-siloxane of the general formula where R = an alkyl radical with 1-12 carbon atoms or an aryl radical and R '= alkyl radical with 1-8 carbon atoms, where n can be the number 0 or 1. 8.) The method according to claim 1, characterized in that an organo-alkoxy-cyclo-siloxane of the general formula is used where R = an alkyl radical with 1-12 carbon atoms or an aryl radical and R '= an alkyl radical with 1- @ atoms and where n can be the number 3 or 4 9.) Process according to <ien claims 1 to 8, characterized in that such organo-alkoxy-silanes or Organoalkoxy-poly-siloxanes Find use in which the sum of the carbon atoms in each Kolenstoffkette R and in each case one carbon chain R 'does not exceed the number 9 or does not significantly exceed it. lo.) Process according to claims 1 to 9, characterized in that that in the organoalkoxysilanes used either the radical R or but the remainder fl 'has as high a number of carbon atoms as possible. 11.) Process according to claims 1 to 10, characterized in that that the organoalkoxy-silanes used are those whose radicals R are a carbon chain of 3 - 8 carbon atoms and whose radicals R 'have a carbon chain of 1 - 3 carbon atoms. 12.) Process according to claims 1 to 11, characterized in that that the organo-alkoxy-silano used are those whose radical R is a carbon chain of 6 -CTA atoms and the radical R '= CH3 (methyl). 13.) The method according to claim 1, characterized in that organosiloxanes as the organosilicon compound of the general formula R. R Si - 0 - Si - 0 - SiR 3 Si 3 R. n in which R = CH3 or an alkyl radical having 2 to 4 carbon atoms or an aryl radical and n is the number 0 to 8. 14.) Method according to claims 1 and 13, characterized in that that hexamethyl-disiloxane is used as the organosiloxane. 15.) Process according to claim 1, characterized in that the organosilicon compounds are organo-cyclo-siloxanes of the general formula in which R = CH3 or C2H3- and where n can be the number 3 to 5 can be used. 16.) Process according to claims 1 and 15, characterized in that that octamethylcyclo-tetrasiloxane (D4) is used as the organo-cyclo-siloxane. 17.) Process according to claims 1 and 16, characterized in that that the organoalkoxy-siloxane or organoalkoxy-polysiloxane and / or the organo-siloxane respectively. Organo-cyclo-siloxanes at a temperature above 20 ° C with the silicas or mixed oxides are mixed. 18.) Process according to claims 1 and 17, characterized in that that with the organo-alkoxy-silanes or organo-alkoxy-polysiloxanes and / or the organosiloxanes or organocyclosiloxanes at temperatures of more than 20 ° C mixed silicas or mixed oxides at normal temperature with anhydrous NH3 are fumigated. 19.) Method according to claims 1 - 18, characterized in that that the organoalkoxy-silanes or organoalkoxy-polysiloxanes and / or the organo-siloxanes respectively. Organo-cyclo-siloxane at normal pressure and at normal temperature with mixed with the silicas or mixed oxides and gassed with anhydrous NH3.