WO2009147025A2

WO2009147025A2 - Method for the production of organosols

Info

Publication number: WO2009147025A2
Application number: PCT/EP2009/056337
Authority: WO
Inventors: Imme Domke; Reiner WERKMÜLLER; Hartmut Hibst; Alexander Traut; Sachin Jain
Original assignee: Basf Se
Priority date: 2008-06-04
Filing date: 2009-05-26
Publication date: 2009-12-10
Also published as: WO2009147025A3

Abstract

The present invention relates to a method for the production of organosols containing at least one oxide and/or oxide hydrate of metals and/or semimetals, comprising the following steps: (a) providing an aqueous solution or dispersion of at least one starting compound containing at least one metal and/or semimetal M¹, (b) bringing the aqueous solution or dispersion from step (a) in contact with at least one acidic substance, (c) extracting the aqueous solution or dispersion from step (b) using at least one organic solvent or dispersion medium (L) and (d) raising the pH of the organic phase from step (c) to at least 7. The present invention additionally relates to a method for producing particles from the organosols and to the use of the organosols for producing polymer compositions or polymer coatings.

Description

Process for the preparation of organosols

description

The present invention relates to a process for the preparation of organosols comprising at least one oxide and / or hydrated oxide of metals and / or semimetals, comprising the following steps:

(a) providing an aqueous solution or dispersion of at least one starting compound containing at least one metal and / or semimetal M ¹ ,

(b) contacting the aqueous solution or dispersion from step (a) with at least one acidic substance,

(c) extracting the aqueous solution or dispersion from step (b) with at least one organic solvent or dispersing agent (L), and

(d) raising the pH of the organic phase from step (c) to at least

7th

Moreover, the present invention relates to a process for the production of particles from the organosols and the use of the organosols for the preparation of polymer compositions or coatings.

Processes for the preparation of sols containing particles of oxides and / or oxide hydrates are known from the recovery of aqueous SiO 2 sols from water glass. Such SiO 2 sols arise in particular as intermediates in the production of aerogels. The removal of the aqueous phase occurs in the prior art at the stage of ready formed sols or gels. The production of SiO 2 in the presence of organic solvents is also known in principle.

EP-A 0 236 945 discloses the hydrolysis of tetramethoxysilane or tetraethoxysilane in alcohol / water mixtures. By the method disclosed in said document, SiO 2 dispersions in glycols become accessible by exchanging the water / alcohol phase of the brine with a glycol.

US Pat. No. 6,110,439 discloses a method for producing silica gel by contacting an aqueous silica sol having a pH of> 7.5 with an acidic ion exchange resin which removes metal ions from the silica system and replaces them with protons. Subsequently, an organic liquid selected from among alcohols, acetone, dioxane, tetrahydrofuran, acetonitrile and ethylene glycol is added in an amount of up to 80% by weight. By the method disclosed in US 6,110,439 can be made a silica gel, which is characterized by its high content of organic solvent. However, the process does not lead to the formation of organosols.

EP-A 1 236 765 discloses a process for the preparation of SiO 2 dispersions from water glass. For this purpose, an aqueous solution of Na2Ü ^* n SiÜ2 is polycondensed and then set an alkaline pH. However, the process does not provide organosols.

US-P 5,759,506 discloses a process for the preparation of aerogels in which an aqueous solution of water glass is brought to a pH of <3 by the action of an acidic ion exchanger or a mineral acid and then a polycondensation of the water glass to SiO 2 gel by adding a base and if necessary, an exchange of the water with organic solvents. However, the process does not lead to the formation of organosols, but to agglomerated particles. Accordingly, an application of this method for the preparation of nanoparticulate substances is not suitable.

EP-A 0 409 083 describes a process for preparing aerogels from SiO 2, in which case the extract containing polysilicic acid, if appropriate with the addition of polysilicic acid esters and / or bases such as ammonia, is subjected to a supercritical treatment with simultaneous formation of a gel. However, the process does not lead to the formation of organosols.

For many applications, aqueous oxidic sols are unsuitable as such, so that the originating from the manufacturing process aqueous medium must be replaced by a suitable organic solvent.

For example, it is advantageous for a functionalization of SiO 2 particles to be carried out at the surface to be present in organic solution, since the functionalizing reagents are often soluble only in these solvents, but not in aqueous solvents. For example, e.g. 3- (glycido-oxy-propyl) trimethoxysilane not in water but only in organic solvents, e.g. Ethylene glycol or tetrahydrofuran (THF), soluble. Furthermore, it is often necessary to have available SiO 2 particles in organic solution in order to incorporate them in polymers, for example in polyurethanes or other formulations based on organic solvents. If, for example, polyurethanes are prepared in a reaction mixture which contains more than 0.7 to 1% by weight of water, the properties deteriorate significantly.

In the publication by P. Sozzani et al., Chem. Mater. 2002, 14, 3377-3381 a process for the preparation of SiÜ2 is described, wherein first by acidification of a aqueous alkali metal silicate solution by means of HCl, the resulting silica is extracted into an organic solvent. Subsequently, the polycondensation of the silica is carried out by evaporation of the organic solvent at ambient pressure and temperature. It is platelet-shaped SiÜ2 obtained, but no organosol.

DE-O 26 33 198 describes the acidification of alkali metal silicate solutions with organic acids in an organic solvent with octadecylamine as emulsifier, whereupon the resulting emulsion is stirred vigorously and heated. According to this disclosure, a hydrogel is obtained.

It would be desirable to provide a process for the preparation of oxidic organosols in which the formation of the particles occurs immediately in the presence of an organic solvent so that solvent exchange can be omitted.

It is therefore an object of the present invention to provide a process which makes available organosols comprising oxides and / or hydrated oxides of metals and / or semimetals in organic solution or dispersion without replacement of the aqueous phase by the organic phase in an additional process - step is necessary. The process should at the same time make available organosols having a water content of at most 0.01% by weight without carrying out a drying step or a solvent exchange. Furthermore, a method is to be provided which makes a complicated, costly and energy-intensive drying step unnecessary at the end of the method. The organosols should have a narrow particle size distribution. In the process, the formation of gels should be avoided, i. the process should lead to stable sols without further steps. The process should also make it possible to control the formation of stable sols while preventing the cross-linking or agglomeration of the particles. The sols thus obtained should have a high proportion of oxidic particles in the solvent, without carrying out a step of concentration. The resulting sols should also be stable over a long period of time. Finally, the resulting sols should be able to be used directly for the preparation of hybrid materials.

These objects are achieved by the method according to the invention. Preferred embodiments are described in the claims and in the following. Combinations of several preferred embodiments do not depart from the scope of the present invention. In particular, each preferred embodiment of a method step can be combined with a preferred embodiment of another method step. The process according to the invention for producing organosols comprising at least one oxide and / or hydrated oxide of metals and / or semimetals comprises the following steps:

(a) providing an aqueous solution or dispersion of at least one

Starting compound containing at least one metal and / or semimetal M ¹ ,

(c) extracting the aqueous solution or dispersion from step (b) with at least one organic solvent (L), and

(d) raising the pH of the organic phase from step (c) to at least 7.

For the purposes of the present invention, Sol is understood to mean a stable dispersion of isolated particles in a liquid phase. In SoI, the solid phase is particu- larly distributed in the liquid phase, i. H. dispersed, wherein isolated particles are present. Preferably, a sol is a stable colloidal solution.

For the purposes of the present invention, a sol is to be strictly distinguished from a gel. In a gel, the solid phase, which forms a three-dimensional network, and the liquid phase penetrate continuously (often called bicohärent).

A stable dispersion of isolated particles is to be understood as meaning a distribution of the isolated particles in the liquid phase which is constant in time. A system which undergoes temporal change by forming a three-dimensional network (gel) is thus not a sol in the sense of the present invention.

Preferably, the distribution of the particles in the sol is stable over a period of at least two hours, in particular at least 4, more preferably at least 8 hours, most preferably at least 12 hours.

Preferably, step (d) of the present invention comprises raising the pH of the organic phase of step (c) to a pH of at least 7 to obtain a dispersion of isolated particles containing at least one oxide and / or hydrated oxide of metals and / or or semimetals in the solvent (L), wherein the dispersion over a period of at least 2 hours, more preferably at least 4 hours, in particular 8 hours and most preferably 12 hours is stable. Oxide hydrates of metals and / or semimetals are to be understood as meaning oxides which also contain hydroxyl groups and / or chemically bound water. Preferably, however, the organosols of the present invention contain oxides.

For the purposes of the present invention, organosol is to be understood as meaning a sol in which the liquid phase contains at least one organic solvent or dispersant.

By reacting the starting compound or starting compounds containing at least one metal and / or metalloid M ¹ , which are provided as a solution or dispersion in step (a) of the method according to the invention, an organosol is obtained in the process according to the invention, in which the liquid Phase consists of at least one organic solvent or dispersant (L). The solid phase contains at least one oxide and / or hydrated oxide containing at least one metal and / or metalloid M ¹ as sol, ie in the form of isolated particles.

The organosols obtainable by the process according to the invention preferably comprise particles of oxides and / or hydrated oxides of metals and / or semimetals which correspond to the general formula (I):

wherein M ¹ , a and b have the following meanings:

M ¹ metal or semimetal selected from Groups 1 to 15 of the Periodic Table of the Elements (IUPAC) of lanthanides, actinides and mixtures thereof, a 1 to 4 and b 1 to 4, wherein a and b, depending on the oxidation state of M ¹ so are chosen such that the compound of the general formula (I) is neutrally charged.

In a preferred embodiment, M ^{1 is} selected from metals or semi-metals selected from Groups 4 to 15 of the Periodic Table of the Elements (I U-PAC). More preferably, M ^{1 is} selected from the group consisting of Ti, Zr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu, Ag, Zn, Cd, B, Al, Ga, In, Si, Ge , Sn and mixtures thereof. In a very particularly preferred embodiment, M ^{1 is} selected from the group consisting of Zn, Si and mixtures thereof, with M ¹ = Si being particularly preferred.

a and b are chosen so that, depending on the oxidation state of M ^1, the compound of general formula (I) is neutrally charged. For example, if M ¹ is a monovalent metal or semimetal, is a 2 and b is 1, M ^{1 is} a divalent metal or semimetal, so if a is 1 and b is 1, M ^{1 is} a trivalent metal, then a is 3 and b is 2, M ^{1 is} one tetravalent metal, is a 1 and b 2, etc.

It is clear to the person skilled in the art that the listed preferred embodiments with respect to M ¹ are to be understood as meaning that corresponding starting compounds containing at least one metal and / or semimetal M ^{1 are} preferred.

The volume-weighted average particle diameter D [4,3] of the particles of the organosols obtainable by the process according to the invention can be from 1 nm to approximately 10 μm. The upper limit with respect to the particle diameter is caused inter alia by the decreasing stability of the organosol. The particles in the organosols preferably have a volume-weighted average particle diameter D [4,3] of 1 to 500 nm, in particular of 1 to 300 nm.

The measurement of the volume-weighted mean particle size of the organosols obtainable according to the invention is carried out by means of dynamic light scattering. Corresponding methods are known to the person skilled in the art. Alternatively, the determination of a number-weighted average particle diameter by means of transmission electron microscopy and subsequent image-analytical evaluation on at least 500 individual pores can be carried out on the basis of a statistically meaningful sample. However, all particle diameters referred to in the present invention are volume weighted average particle diameters determined by dynamic light scattering.

The individual steps of the method according to the invention are explained in more detail below.

Step (a)

According to the invention, step (a) comprises providing an aqueous solution or dispersion of at least one starting compound containing at least one metal and / or semimetal M ¹ .

The term solution or dispersion encompasses both solutions in the true sense as well as colloidal solutions and dispersions of particles in a liquid phase.

The concentration of the starting compounds in the aqueous solution or dispersion is preferably from 10 to 25% by weight, in particular from 12 to 20% by weight. The starting compound or the starting compounds containing at least one metal and / or metalloid M ¹ are selected depending on the organo-nosols to be prepared or depending on the oxidic particles to be produced.

In the context of the present invention, an aqueous solution or dispersion is to be understood as meaning a solution or dispersion whose liquid phase comprises at least 50% by weight of water, preferably at least 90% by weight, in particular at least 99% by weight, of water consists.

Suitable starting compounds are those compounds containing at least one metal and / or semimetal M ¹ , which are soluble or dispersible in the aqueous phase and which can be reacted by hydrolysis and polycondensation.

Preferably, step (a) is carried out by providing an aqueous solution or dispersion of at least one compound of the general formula (II)

in which M ^{1 has} the abovementioned meaning, and M ² , x, y, z and n have the following meanings:

M ² alkali, alkaline earth metal or mixtures thereof, x 0.5 to 6, y 0.5 to 6, z 0.5 to 4, n 0 to 12 and

wherein x, y and z are selected depending on the oxidation states of M ¹ and M ² so that the at least one compound of general formula (II) is neutrally charged.

The general formula (II) means for some by the meanings of M ¹ , M ² , x, y, z and n used in the invention starting compounds only a formal consideration of the compounds actually used. For example, Na ₂ [Zn (OH) _4] used as starting compound in the inventive process, the Na compound is only a formal ₂ ZnO ₂ ^* H ₂ O before, however, as in substance

2 NaOH / Zn (OH) _{2 is} to be described. In general, the starting compounds used are oxides / hydroxy compounds which can be formally described by the general formula (II). These oxides / hydroxy compounds are then converted in the process according to the invention by hydrolysis and polycondensation into the corresponding oxides of the general formula (I). M ² is an alkali, alkaline earth metal or a mixture of two or more alkali or alkaline earth metals or of alkali and alkaline earth metals. M ² thus represents a metal selected from Groups 1 or 2 of the Periodic Table of the Elements (I U-PAC) and mixtures thereof. Examples of particularly preferred M ² are Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba and mixtures thereof. Alkali metals are particularly preferably used, so that very particularly preferred meanings for M ^{2 are} Li, Na, K or Rb.

x, y and z are selected so that, depending on the oxidation states of M ¹ and M ^2, the at least one compound of general formula (II) is neutrally charged. For example, if M ² is a monovalent alkali metal and M ¹ is a monovalent metal or metalloid, then x, y and z are 1. If M ^{2 is} a monovalent alkali metal and M ^{1 is} a divalent metal or semimetal, x 2, y 1 and z 2. These meanings for x, y and z are to be understood as examples only. It is known to a person skilled in the art how, depending on the oxidation states of M ¹ and M ² , x, y and z have to be determined so that the compound of the general formula (II) is neutrally charged.

In the context of the present invention, the starting compound or compounds preferably contain at least one M ¹ selected from Si and Zn, in particular Si.

In a preferred embodiment of the process according to the invention Na2SiC "3 ^* 5H 2 O or Na 2 [Zn (OH) 4], formally corresponding to Na 2 ZnC" 2 ^* H 2 O, is used as compound of the general formula (II).

In a very particularly preferred embodiment, for the preparation of SiC "2 nanoparticles, water glass of the formula Na 2 SiC" 3 ^* 5H 2 O is used as the compound of the general formula (II), or the corresponding compound without crystal water.

If a ZnO nanoparticle is produced by the process according to the invention, in a further preferred embodiment Na 2 [Zn (OH) 4] is used. This compound corresponds formally regarded Na2ZnÜ2 ^* 2 H2O corresponding to the general formula (II).

The solution or dispersion in step (a) of the process according to the invention is preferably carried out by mixing the starting compounds in dry form or in the form of concentrated aqueous solutions with water. Of course, the term "compounds in dry form" also includes compounds containing water of crystallization. Step (a) of the process of the invention is preferably carried out at a temperature of 5 to 50 ⁰ C, more preferably from 15 to 35 ° C. Pressure does not play a crucial role during step (a) unless it affects the dissolution properties of water. In order to carry out the process as simply as possible, step (a) is preferably carried out at a pressure of 900 to 1100 mbar, in particular at normal pressure.

Step (a) may be carried out in an inert atmosphere, depending on the substrates used. Suitable inert gases are preferably selected from the group consisting of nitrogen, noble gases such as helium or argon, and mixtures thereof. If the starting compounds used are not sensitive to atmospheric oxygen or moisture, it is advantageous to carry out step (a) of the process according to the invention in the presence of ambient air.

Step (b)

Step (b) of the process according to the invention comprises contacting the aqueous solution or dispersion from step (a) with at least one acidic substance. By acidic substance is meant a compound or substance which, in contact with water, lowers its pH.

Preferably, the pH is from 1 to 5, more preferably from 2 to 3.5, as a result of performing step (b). The person skilled in the art preferably selects the amount of the acid substance (s) preferably so that the aqueous solution has the above-indicated preferred pH values due to the contacting. The choice of the amount depends on the number of acid groups of the acidic substance and on the acidity.

Without being limited to theoretical considerations, there is the idea that as a result of the presence of protons from the acidic substance, electrically neutral proton-containing derivatives of the starting compounds are formed, ie the starting compound is in molecular form as the acid. For example, there is the notion that, starting from sodium silicate, the starting compound is so-called free silicic acid, which can be referred to simply as H ₄ SiO ₄ . The electrically neutral proton-containing derivatives of the starting compounds can also be present in oligomeric form. However, further hydrolysis and polycondensation at this time of the process according to the invention is undesirable. The starting compound in molecular form has an increased solubility in the organic solvent (L) compared to the starting compound.

As an acidic substance basically different types of proton sources come into consideration. The acidic substance can in principle be in the form of a solid, in particular as Solid phase, or be brought in contact with the aqueous solution in the form of a liquid. For example, the contacting with the acidic substance can be effected by adding a strong acid, in particular a mineral acid.

Corresponding methods are known to the person skilled in the art, in particular, from the production of aerogels. For example, in the so-called Kistler method (S.S. Kistler, J. Phys. Chem. 36, (1932), pages 52-64), water glass is used as the starting material. By acidification of water glass with HCl or H2SO4 a silica hydrogel is produced, which is then freed by washing with water of alkali metal ions. Water contained in the hydrogel is then completely replaced in one step with 95% alcohol (ethanol, methanol). Subsequently, supercritical drying of the resulting SiO 2 -alkogel takes place in an autoclave.

However, the maximum concentration of the starting compound according to step (a) of the process according to the invention is about 8 wt .-%, provided that the contacting with an acidic substance is effected by addition of inorganic acids.

It is preferred to use an acidic ion exchanger as the acidic substance according to step (b). Preferably, the acidic ion exchanger is separated following step (b). This is preferably done by decanting or filtration of the aqueous solution or dispersion following step (b). Filtration also leads to the separation of suspended matter and the smallest particles. Suitable filters are, for example, paper filters, membrane filters, metallic nets or ceramic filters. The filters used preferably have a pore size of 2 to 5 micrometers.

Preferred acidic ion exchangers are acidic ion exchange resins such as functionalized styrene-divinylbenzene copolymers with sulfonic acid groups or comparable acid groups on the surface or phyllosilicates (zeolites), in particular zeolite A (Sasil) according to the formula Nai 2 ((AIO ₂ ) i ₂ (SiO ₂ ) i2) ^* 27 H ₂ O.

It is in principle also possible, in addition to the at least one acidic ion exchanger in the context of step (a) to add at least one further acidic substance. The state of matter of the additionally used acid substance can be solid, liquid or gaseous. Examples of suitable acidic substances are mineral acids, for example HCl and / or H2SO4.

Step (b) of the process according to the invention can be carried out in an inert gas atmosphere, reference being made to the inert gases which have been mentioned with respect to step (a) of the process according to the invention. In a preferred embodiment, however, step (b) is not carried out in an inert gas atmosphere in order to keep the process technically as simple as possible. After and optionally during the addition of the at least one acidic substance, the reaction mixture is preferably stirred for the duration of step (b). The duration of step (b) is at least 0.5 hours, more preferably at least one hour, most preferably at least 2 hours. The person skilled in the art determines the time of completion of step (b) preferably according to one or more of the following criteria: no change in the pH and / or in the case of the addition of an ion exchanger, whereupon the temperature of the solution increases: re-cooling to room temperature.

Step (b) of the process according to the invention can be carried out at any temperature which ensures a sufficiently high reaction rate between the starting compound or the starting compounds and the at least one acidic substance. In a preferred embodiment, step (b) is carried out at a temperature of 15 ° C to 40 ⁰ C, more preferably at a temperature of 15 ° C to 30 ⁰ C.

After the reaction time, if the acidic substance is present in the solid phase, the at least one acidic substance, in particular the ion exchanger, through the

Technician known method separated from the mixture. Examples of suitable methods are filtration, decantation and / or centrifugation. The person skilled in the art knows which of the mentioned methods can be used, which in turn depends on the viscosity of the reaction mixture. Alternatively, however, the acidic substance may also remain in the mixture and be removed in the course of step (c). If an acid soluble in water was used as the acidic substance, then there is no separation at this point.

Step (c)

Step (c) of the process of the invention comprises extracting the aqueous solution or dispersion from step (b) with at least one organic solvent or dispersing agent (L).

The term extraction in the context of the present invention comprises contacting a first liquid with a second liquid which is subsequently separated and which at least partially contains at least one compound which was previously completely in the first liquid. The extraction as such is well known to those skilled in the art.

Preferably, the amount of the first liquid and the amount of the second liquid are of the same order of magnitude, preferably substantially the same. The organic solvent or dispersant (L), hereinafter referred to as solvent (L), preferably satisfies some conditions as set forth below. The solvent (L) is preferably liquid at room temperature and normal pressure.

Preferably, the at least one organic solvent or dispersant is selected so that it is substantially immiscible with water, either as such or after addition of at least one salt. It is thus likewise preferred to use a solvent (L) which is in principle miscible with water but which, after the addition of at least one salt, is substantially immiscible with water. The person skilled in this process is known as "salting out" in principle.

In the context of the present invention, two properties of the solvent (L) have proven to be particularly relevant: the polarity and the boiling point. A high polarity of the solvent favors the extractability of the compounds formed and to be extracted in step (b). However, high polarity solvents often have a high boiling point. A very high boiling point has been found in the context of the present invention to be unfavorable.

The polarity of the solvent (L) can in principle vary within a wide range. However, it is preferred to use a medium polarity or moderately high polarity solvent (L). A measure of the polarity of a substance is its dipole moment. The dipole moment of the organic solvent (L) which can be used according to the invention is preferably from (0.4 to 20) - 10 " ³⁰ cm, preferably from (1 to 15) - 10" ³⁰ cm, particularly preferably from (3 to 10) -10 ^{" 30} cm.

Suitable organic solvents are, in particular, those having 1 to 6 C atoms and at least one O atom. The viscosity of the solvents used in a preferred embodiment is 0.2 to 1300 mPa.s, more preferably 0.2 to 100 mPa.s, very particularly preferred are organic solvents having a low viscosity of <5 mPa.s, wherein a technically reasonable lower limit is approximately 0.2 mPa.s.

Preferred organic solvents (L) have a boiling point of at least 30 ⁰ C, in particular at least 40 ⁰ C. Suitable, usable in the process according to the invention organic solvent (L) have a boiling point of preferably at most 300 ⁰ C, in particular at most 200 ⁰ C and particularly preferably at most 150 ⁰ C. It is particularly preferred if the solvent (L) has a low boiling point, very particularly preferably from 30 ^° C. to 90 ^° C., especially from 40 to 70 ^° C. If a solvent (L) having a low dipole moment, in particular maximum 0.4-10 " ³⁰ cm, then it is all over particularly preferred that the solvent (L) has a boiling point of at most 150 ⁰ C, for example from 30 to 150 ⁰ C.

Preferably, the at least one organic solvent or dispersing agent is selected from the group consisting of ethers, ketones and aromatic hydrocarbons.

Preferred aromatic hydrocarbons are those having a boiling point of at most 150 ⁰ C, which have exclusively uncondensed aromatic rings, for example benzene or its derivatives such as toluene and the xylene.

Preferred ethers are those of the structure R ¹ -OR ² , wherein R ¹ and R ^{2 are} aliphatic groups of 1 to 12 carbon atoms and may be the same or different and are independently selected. Preferably, R ¹ and R ^{2 are} independently selected from methyl, ethyl, n -propyl, iso -propyl, n -butyl, iso -butyl and n -hexyl. Preferred ethers are also cyclic ethers, especially THF.

Preferred ketones are those of the general structure R ¹ -CO-R ² , wherein R ¹ and R ^{2 are} aliphatic groups of 1 to 12 carbon atoms and may be the same or different and are independently selected. Preferably, R ¹ and R ^{2 are} independently selected from methyl, ethyl, n -propyl, iso -propyl, n -butyl, iso -butyl and n -hexyl. Particularly preferred ketones are dimethyl ketone, methyl ethyl ketone and acetone.

Tetrahydrofuran is particularly preferred as the organic solvent or dispersant (L).

The abovementioned solvents (L) can be used individually or as a mixture of a plurality of the abovementioned solvents. The solvent or dispersant (L) can be used in anhydrous or hydrous form. If the solvent or dispersion medium (L) contains water, the corresponding amount of water in the solvent or dispersion medium (L) is preferably at most 10% by weight, particularly preferably at most 8% by weight.

Step (d)

Step (d) of the process according to the invention comprises increasing the pH of the organic phase from step (c) to at least 7, preferably at least 7.5. In step (d) of the process according to the invention, the pH of the organic phase from step (c) is preferably increased to a pH of from 7 to 10, particularly preferably from 7.5 to 9.

Bases are used to increase the pH. Suitable bases are both inorganic and organic bases.

Suitable inorganic bases are, in particular, ammonia or hydroxides of alkali metals, in particular NaOH and / or KOH. The inorganic bases are preferably used as aqueous solution and / or as alcoholic solution.

However, inorganic bases have the disadvantage over the organic bases that only organosols with a content of particles of at most 1 wt .-% are accessible, whereas the use of organic bases makes organosols with a particle content of up to 15 wt .-% accessible. Accordingly, organic bases are preferred in step (d) of the process according to the invention.

Suitable organic bases are, in particular, compounds containing at least one primary, secondary or tertiary amino group bonded to a carbon atom. The organic compounds thus defined are referred to below as organic amines.

It is preferred if the increase in the pH of the organic phase to at least 7, preferably to a pH of 7 to 10, in step (d) by adding at least one organic amine.

As the organic amine, preference is given in particular to a primary, secondary or tertiary aliphatic amine of the empirical formula C _n H 2n + 3N, where n is an integer from 6 to 24, preferably from 8 to 14, in particular n = 12. Dodecylamine is an organic amine particularly preferred.

As organic amine are also polyfunctional aliphatic amines into consideration. Polyfunctional amines are amines which have at least two amino groups per molecule.

Suitable organic amines are in particular the following polyfunctional amines: bis (2-aminoethyl) amine, also called diethylenetriamine, tris (2-aminoethyl) amine, triethylenetetramine and other derivatives of ethyleneimine, tetramethylenediamine, ethylenediamine, diamines of butane and of pentane , 2-methyl-1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,12-diaminododecane, 1-amino -3-aminomethyl 3,5,5-trimethylcyclohexane, 4,4'-methylenebis (cyclohexylamine), 4,4'-, 2,4'- and 2,2'-diaminodicyclohexyl-1, 2, and 1, 3 Propanediamine, 2-methyl-1,2-diaminopropane, 2,2-dimethyl-1,3-diaminopropane, bis (4-amino-3-methylcyclohexyl) methane, 1, 2 and / or 1, 4-diaminocyclohexane, Bis (1,3-methylamino) cyclohexane, bis-hydrazides, bis-semicarbazides, N, N, N-tris (2-aminoethyl) amine, guanidine, N- (2-aminoethyl) -1, 3-diaminopropane and ethoxylated and / or propoxylated compounds with amino groups as the end group.

Aliphatic polyfunctional amines having at least two primary amino groups are also suitable, in particular bis (2-aminoethyl) amine, tris (2-aminoethyl) amine, triethylenetetramine, ethylenediamine, tetraethylenepentamine, pentaethylenehexamine, diaminopropylenethylenediamine, propylenediamine, hexamethylenediamine, diaminocyclohexyl, triglycol diamine , Polymers of alkylene oxides such as ethylene oxide or propylene oxide, in which the hydroxyl end groups are replaced by amino groups, 1, 3-diaminopropan-2-ol, ω, ω "-Diaminodi-n-hexylamine, and dimethyl-1, 4-diaminoadipate.

The abovementioned aliphatic amines can be used individually or in mixtures.

In a particularly preferred embodiment, the organic amines used are those having a weight-average molecular weight of from 100 to 10,000 g / mol and two to three amino groups per molecule, if unequal amines are used. The weight-average molecular weight is determined by gel permeation chromatography.

As the organic amine having a molecular weight of 100 to 10,000 g / mol and two or three amino groups per molecule, particularly preferred are bis (2-dimethylaminoethyl) ethers and polyetheramines. Polyetheramines are to be understood as meaning polyalkylene oxides which have been functionalized with amino groups, in particular polymeric ethylene oxides and / or propylene oxides having primary amino end groups.

In a very particularly preferred embodiment, the organic amine used is a polyetheramine of the general structure R ¹ R ² N - (- CHR ³ -CH ₂ -O-) _n -CHR ³ CH ₂ -NR ¹ R ² , where R ¹ and R ² independently of one another are H or an alkyl radical having 1, 2, 3 or 4 carbon atoms, R ³ independently of one another corresponds to H or methyl and n is a number from 1 to 40. The polyetheramines mentioned may be uniform or non-uniform in their molecular weight, so that n corresponds to a number-weighted average.

Preference is given in particular to polyetheramines of the general structure H2N - (- CH (CH3) CH2θ-) n-CH (CH ₃₎ NH 2 with a number-average molecular weight of 150 to 1000 g / mol, particularly preferably from 150 to 300 g / mol and an amine content of 7 to 10 meq / g, especially 8 to 9 meq / g.

Without wishing to be bound by theoretical considerations, there is the notion that the above-mentioned polymeric organic amines additionally stabilize the surface of the particles and thus, among other things, lead to an increased stability of the sols.

In a preferred embodiment, in step (d) an increase in the pH of the organic phase to a pH of 7 to 10, in particular from 7.5 to 9, wherein preferably the temperature during step (d) from 0 to 5 ° C is. It is then preferably stirred at a temperature of 0 to 5 ° C over a period of a few minutes to several hours, preferably from 1 to 4 hours.

In a preferred embodiment, the process according to the invention comprising the steps (a) to (d) is followed by a further step (e):

Steps)

Functionalization of the particles containing at least one oxide and / or hydrated oxide of metals and / or semimetals.

This optional functionalization of the metal or semimetal oxide particles can be carried out according to processes known in principle to the person skilled in the art, in particular by adding at least one functionalizing agent. In a preferred embodiment, those functionalizing agents are added which contain the metal M ¹ already used in step (a) and which have further functional groups which are reactive with the surface groups of the oxide or hydrated oxide.

Preferred functionalizing agents are siloxanes, chlorosilanes, silazanes, titanates and zirconates as well as combinations of the aforementioned classes of compounds, with siloxanes, chlorosilanes and silazanes being particularly preferred. Preferred structures for the functionalizing agent are in particular M ¹ (OR ¹ ) _n (R ² ) 4-n, SiCl _n (R ² Kn, and ((R ² ) _m (OR ¹ ) ₃ -mSi) ₂ NH, where

M ^{1 has} the meaning described in step (a) and preferably corresponds to the metal or semimetal used in step (a), m = 1 or 2, - n = 1 or 2 or 3, and

R ¹ and R ^{2 are} independently linear or branched alkyl groups of from 1 to 12 carbon atoms optionally containing further functional groups Groups may be included, with methyl, ethyl, n-propyl, iso-propyl, n-butyl, n-hexyl, n-octyl and n-dodecyl being particularly preferred.

OR ¹ are water-hydrolyzable functional groups. R ^2, however, are not hydrolyzable in water and remain as a hydrophobic functional group in the oxidic particles. The person skilled in the art refers to the oxide particles thus obtained as surface-functionalized or -modified particles.

Other suitable functionalizing agents are aminopropyltrimethoxysilane, aminobutyltrimethoxysilane, aminopropyltriethoxysilane, aminobutyltriethoxysilane and the corresponding silanes which contain glycidyl groups, in particular 3-glycidopropyltrimethoxysilane, and also phenyltriethoxysilane and phenyltrimethoxysilane.

Alkyltrimethoxysilanes (R ² ) Si (OMe) 3 are particularly preferred as functionalizing agents, where R ^{2 has} the abovementioned meaning. Isobutyltrimethoxysilane is most preferred as a functionalizing agent.

Corresponding methods for carrying out the functionalization of oxidic particles, in particular of oxidic nanoparticles, are known to the person skilled in the art and are described, for example, in "Particulate Filled Polymer Composites (Polymer Science & Technology)", Editor: R.N. Rothon, 2nd edition, pages 26 et seq.

In a preferred embodiment, the functionalization in the optional step (e) is carried out in the same solvent or dispersion medium (L). To complete the functionalization reaction, the resulting reaction mixture is stirred at a temperature of from 20 to 200 ^° C., preferably from room temperature to 180 ^° C., for a period of from 2 to 48 hours, preferably from 6 to 18 hours. The person skilled in the art knows how to choose the reaction temperature as a function of the solvent used, the functionalization reagent and the desired particle size.

particle

Another object of the present invention is a process for the preparation of particles containing at least one oxide and / or hydrated oxide, wherein subsequent to steps (a) to (d) and optionally (e) a further step (f) is carried out, which comprises the separation of the particles obtained in step (d) or optionally in step (e) comprising at least one oxide and / or oxide hydrate from the organosol.

Suitable methods for separating solids from solutions or dispersions are widely known. Examples are decanting, filtering and / or centrifuging. fugieren. Particularly preferably, the particles are filtered off from the reaction mixture. This can be done using an increased pressure or vacuum. Suitable methods are also known to the person skilled in the art.

Another object of the present invention is the use of the organosols according to the invention for the preparation of polymer compositions, in particular polymer composites, or coatings.

The process according to the invention makes it possible to produce particles having a volume-weighted mean particle diameter in the nanometer range as organosol. The organosols obtainable in this way contain particles which can be further optimized by modification as described above with regard to good binding to a polymer in the organosol. The organosols may be used for the preparation of polymer composites preferably directly, d. H. without drying, be brought into contact with the polymer. As a result, an irreversible agglomeration of the particles can be avoided.

Examples

Example 1 :

300 g Na2Siθ3-5H2θ the company Alfa Aesar were dissolved in 1700 g of demineralized water. It turned to a pH of 12.5. At the same time, an acidic ion exchanger (Amberlyst® 15 Wet from Rohm & Haas) was slurried in demineralized water and then added to the silicate solution while stirring vigorously (450 revolutions per minute). As much ion exchanger was added until the silicate solution had a pH of 2.6. The mixture was then stirred at room temperature for 1 h, then the ion exchange resin was decanted off and 2100 g of tetrahydrofuran (THF) were added. The mixture was then stirred at room temperature for 20 h at 200 revolutions per minute. After addition of 250 g of NaCl, a phase separation of the aqueous and the organic phase took place. The organic phase was separated from the aqueous phase via a separating funnel and then the organic phase was freed from suspended matter using a coarse white-band filter. The THF phase had a pH of 2.3 and was then cooled to 2 ⁰ C. With vigorous stirring at 450 revolutions per minute, so much dodecylamine was added until the solution had a pH of 8.9. The system was stirred for a further 12 h at room temperature and freed of suspended matter by means of a coarse round filter. Subsequently, a volume-weighted mean particle diameter of the SiO 2 particles of 140 nm was detected by means of dynamic light scattering. The organosol was stable for a period of at least 8 hours. Example 2:

300 g Na2Siθ3-5H2θ from Alfa Aesar were dissolved in 1700 g demineralized water. It turned to a pH of 12.5. At the same time, an acidic ion exchanger (Amberlyst® 15 Wet from Rohm & Haas) was slurried in demineralised water and then added to the silicate solution while stirring vigorously (450 revolutions per minute). As much ion exchanger was added until the silicate solution had a pH of 2.6. The mixture was then stirred at room temperature for 1 h, then the ion exchange resin was decanted off and 2100 g of tetrahydrofuran (THF) were added. The mixture was then stirred at room temperature for 20 h at 200 revolutions per minute. After addition of 250 g of NaCl, a phase separation of the aqueous and the organic phase took place. The organic phase was separated from the aqueous phase via a separating funnel and then freed the organic phase with a coarse white-edge filter of suspended matter. The THF phase had a pH of 2.3 and was then cooled to 2 ⁰ C. With vigorous stirring at 450 revolutions per minute, so much dodecylamine was added until the solution had a pH of 7.8. The system was stirred for a further 12 h at room temperature and freed of suspended matter by means of a coarse white-edge filter. Subsequently, 146.2 g of 3-glycido-propyltrimethoxysilane Alfa Aesar were added for the modification of the SiO 2 surface and stirred at 0 ⁰ C for 4 h. Subsequently, the mixture was warmed to room temperature. The silane-modified SiO 2 particles had a volume-weighted mean particle diameter of 220 nm according to dynamic light scattering. The organosol was stable for a period of at least 12 hours.

Example 3:

50 g Na2Siθ3-5H2θ Alfa Aesar were dissolved in 200 g of demineralized water. It turned to a pH of 12.5. At the same time, an acidic ion exchanger (Amberlyst® 15 Wet from Rohm & Haas) was slurried in demineralised water and then added to the silicate solution while stirring vigorously (450 revolutions per minute). As much ion exchanger was added until the silicate solution had a pH of 2.6. The mixture was then stirred at room temperature for 0.5 h, then the ion exchanger resin was decanted off and 200 ml of tetrahydrofuran (THF) were added. The mixture was then stirred at RT at 200 revolutions per minute for 20 h. After addition of 60 g of NaCl, a phase separation of the aqueous and the organic phase takes place. The organic phase was separated from the aqueous phase via a separating funnel and then freed the organic phase with a coarse white-edge filter of suspended matter. The THF phase had a pH of 2.5 and was then cooled down to 2 ⁰ C. With vigorous stirring at 450 revolutions per minute, 12.0 ml of 1 M NaOH were added and the mixture was heated to 60 ^° C. for 2 h. After cooling to room temperature, the dispersion was over a coarse white edge filter freed of suspended matter. By means of dynamic light scattering, SiO 2 particles having a volume-weighted mean particle diameter of 3 nm were detected. The organosol was stable for a period of at least 8 hours. The content of SiO 2 particles in the organosol was 1% by weight. It was not possible to increase the content of SiO 2 in the organosol obtained by varying the amounts used and the experimental conditions beyond 1% by weight.

Claims

claims

1. A process for the preparation of organosols comprising at least one oxide and / or hydrated oxide of metals and / or semimetals comprising the following steps:

(c) extracting the aqueous solution or dispersion from step (b) with at least one organic solvent or dispersant (L), and

(d) raising the pH of the organic phase from step (c) to at least 7.

2. The method of claim 1, wherein in step (d) the increase in the pH of the organic phase to a pH of 7 to 10 takes place.

3. The method of claim 2, wherein the increase in the pH of the organic phase according to step (d) by adding at least one organic amine.

4. The method of claim 3, wherein as the organic amine, a primary, secondary or tertiary aliphatic amine of the empirical formula C _n H2n + 3N is used, wherein n is an integer from 6 to 24.

5. A process as claimed in claim 3, wherein at least one polyetheramine of the general structure R ¹ R ² N - (- CHR ³ -CH ₂ -O-) _n -CHR ³ CH ₂ -NR ¹ R ^{2 is} added as the organic amine, where R ¹ and R ² independently of one another are H or an alkyl radical having 1, 2, 3 or 4 carbon atoms, R ³ independently of one another corresponds to H or methyl and n is a number from 1 to 40.

A process according to claims 1-5, wherein the temperature during step (d) is from 0 to 5 ° C.

A process according to claims 1 to 6, wherein the pH is from 2 to 3.5 as a result of carrying out step (b).

8. The method according to claims 1 to 7, wherein the acidic substance according to step (b) is an acidic ion exchanger.

9. The method according to claims 1 to 8, wherein the concentration of the starting compounds in the aqueous solution or dispersion according to step (a) of 12 to 20 wt .-% is.

10. The method according to claims 1 to 9, wherein the acidic ion exchanger is removed following step (b).

1. The process according to claims 1 to 10, wherein the organosols comprise particles of oxides and / or hydrated oxides of metals and / or semimetals of the general formula (I):

wherein M ¹ , a and b have the following meanings:

M ¹ metal or semimetal selected from groups 1 to 15 of the Periodic Table of the Elements (IUPAC) of lanthanides, actinides and mixtures thereof, a 1 to 4 and b 1 to 4, wherein a and b, depending on the oxidation state of M ¹ are chosen so that the compound of general formula (I) is neutrally charged.

12. Process according to claims 1 to 11, wherein step (a) is carried out by providing an aqueous solution or dispersion of at least one starting compound of the general formula (II)

(II)

wherein M ^{1 has} the meaning given above and M ² , x, y, z and n are the following

Meanings have:

M ² alkali, alkaline earth metal or mixtures thereof, x 0.5 - 6, y 0.5 - 6, z 0.5 - 4, n 0 - 12 and wherein x, y and z are selected depending on the oxidation states of M ¹ and M ² so that the at least one compound of general formula (II) is neutrally charged.

13. The method according to claims 1 to 12, wherein the organosols contain nanoparticles having a volume-weighted average particle diameter of 1 to 500 nm.

14. The method according to claims 1 to 13, wherein M ^{1 is} selected from Si and Zn.

15. The method according to claims 1 to 13, wherein as the starting compound in step (a) Na ₂ SiO ₃ ^* 5 H ₂ O or Na ₂ [Zn (OH) ₄ ] is used.

16. The method according to claims 1 to 15, wherein the at least one organic solvent or dispersion medium (L) is selected so that it is substantially immiscible with water, optionally after the addition of at least one salt.

17. Process according to claims 1 to 16, wherein tetrahydrofuran is used as the organic solvent or dispersant (L).

18. Process according to claims 1 to 17, wherein step (e) follows at step (d):

(e) functionalization of the particles obtained in step (d) comprising at least one oxide and / or hydrated oxide of metals and / or semimetals.

19. A process for the preparation of particles containing at least one oxide and / or hydrated oxide by the organic solvent or dispersion medium (L) of the organosols according to claims 1 to 18 is separated from the particles.

20. Use of the organosols according to claims 1 to 18 for the preparation of polymer compositions or coatings.