Silicon dioxide dispersion

The invention relates to a silicon dioxide dispersion comprising contains:<sl><li>(A) an external flowable phase comprising:<sl><li>A1) polymerizable monomers, oligomers and / or prepolymers, Which are formed by non-radical transformations in Polymers are transferable; and or</li><li>A2) polymers,</li></sl></li><li>B) a disperse phase containing amorphous silica.</li></sl>

It is known to use polymeric materials such as, for example, polyurethanes, Polyureas or so-called reaction resins with fillers To provide certain properties of the polymeric material To modify. For example, In this way, impact strength, Flexural strength, hardness or electrical insulation be improved.

It is already known silica or silicon dioxide (SiO₂) As a filler in polymers. Various Process for the preparation of SiO₂Fillers are more obvious Prior use.

Natural (mineral) SiO₂ Can be carried out, for example, by grinding A desired particle size and with the polymer Or a polymer precursor. Ground SiO₂ Generally shows a very broad particle size distribution And irregular particle structure. particle sizes Of less than 1 μm are obtained by mechanical comminution of the SiO₂Difficult or impossible to achieve.

It is also known from aqueous alkali metal silicate solutions SiO₂ To precipitate by acidification and then to dry. This precipitated SiO₂ Is reacted with the polymer or a Product. Irregular ones are also obtained here Particle structures with very wide particle size distributions.

A further possibility is the production of fumed silica By flame hydrolysis of silicon halide compounds. This results in particles of very complex morphology and Extremely broad particle size distribution since the Flame hydrolysis are partially agglomerated And other associated superstructures. pyrogens Silica is also expensive to produce.

Further known is organofunctional silanes (In particular alkoxysilanes) to hydrolyze and condense, Thereby aqueous or aqueous-alcoholic silica sols And these sols are added with a polymer precursor mix. Subsequently, water or alcohol from the mixture Removed. This process is expensive and impenetrable Large technical scale difficult to control.

The described methods also have the disadvantage that The targeted production of SiO₂Fillers with monomodal, Narrow particle size distribution is not possible The disadvantage of the three first-mentioned methods is particular pronounced. This results in dispersions of the filler In polymer precursors already at relatively low Filler concentrations undesirable rheological properties, In particular a high viscosity Processability.

SUMMARY OF THE INVENTION The present invention is based on the object of providing a Silica dispersion of the type mentioned initially, Which can also be processed well at higher filler concentrations Which is a good mechanical and / or electrical Property improvement of the polymer end product and According to a likewise inventive method, from inexpensive Starting materials are.

The silica dispersion accordingly contains:<sl><li>(A) an external flowable phase comprising:<sl><li>A1) polymerizable monomers, oligomers and / or prepolymers, Which are formed by non-radical transformations in Polymers are transferable; and or</li><li>A2) polymers,</li></sl></li><li>B) a disperse phase containing amorphous silica,</li></sl>And is characterized in that the light scattered by means of neutron angle scattering (SANS) average particle size d_Max Of the silica is between 3 and 50 nm at a maximum Half-width of the distribution curve of 1.5 d_Max, And the dispersion contains silanes.

The process according to the invention for the preparation of such a process Dispersion is characterized by the following steps:<sl><li>A) providing an aqueous silicate solution,</li><li>B) Polycondensation of the silicate up to a particle size Of 3-50 nm,</li><li>C) adjusting the obtained silica sol to an alkaline PH value,</li><li>D) optionally concentrating the sol,</li><li>E) mixing the sol with components of the outer, flowable Phase of the dispersion, </li><li>F) optionally removing water and / or other solvent constituents From the dispersion.</li></sl>

Firstly, some terms used in the context of the invention explained:

The so-called outer phase of the silicon dioxide dispersion according to the invention Is flowable. This means that they can be used in the usual manner Processing temperatures (for example 18 to 300 ° C., preferably 18 to 100 ° C) is either liquid or sufficient Is flowable or viscous in order to achieve the desired further processing, In particular the mixture with further constituents Of the polymer material to be produced or the shaping in the Processing.

This outer phase comprises, according to one aspect of the invention Polymerizable monomers, oligomers and / or prepolymers. Prepolymers are smaller polymer units that are larger Polymers. "Polymerizable" Means that in this outer phase still polymerizable And / or crosslinkable groups contained within the framework The further processing of the dispersion is a polymerization- And / or crosslinking reaction. The outer Phase contains polymerizable components which are formed by non-radical Reactions into polymers. This Means that the polyreaction to polymers does not take place over a Radical mechanism. Preferred are instead Polycondensation (in stages with elimination of by-products Polyredition) or polyaddition (in Stages without elimination of by-products) The invention relates to anionic surfactants Or cationic polymerizable constituents in the outer layer Phase. The invention does not cover dispersions in any case With outer phases, the polymerisable acrylates Or methacrylates as an essential constituent. Polymerizable Acrylates or methacrylates are all monomeric, Oligomeric or prepolymeric acrylates or methacrylates, In the production of a material from the dispersion Can be subjected to a further polymerization in a targeted manner. As An example of polyaddition is the synthesis of polyurethanes From diols and isocyanates, for example For polycondensation the reaction of dicarboxylic acids with Diols to form polyesters.

According to a further aspect of the invention, Flowable phase contain one or more polymers. Polymers in this sense are macromolecules that are not Are more reactive and therefore not to larger polymer units react. In particular, it can be a molten one And / or dissolved material, which is formed by Cooling and / or removal of the solvent again physically Into this material. In this variant Of the invention thus cures the dispersion according to the invention Does not chemically evolve into a polymer; Phase, a finished polymer has already been used For the purpose of preparing the dispersion only physically (Thermally and / or by addition of solvent) into a liquid Or viscous aggregate state in order to achieve this Mixing of the disperse phase. After manufacture Of the dispersion can be reduced by cooling or removal of the A material containing the disperse phase The polymer composition of which is substantially Is unchanged from the original as external Phase polymer material. Substantially unchanged Means that in the course of the transfer of the original Material into the outer phase (thermally or through Solvent addition) and after the mixing in of the dispersed Phase to an inventive step Material (by cooling or solvent removal) No further polymerization is effected, but instead To a small extent polymer reactions as side reactions occur. Example 21 in Experimental Section Is an example of this variant of the invention.

The disperse phase contains amorphous silica. Preferably It consists essentially of amorphous silicon dioxide. As a method for measuring the amorphous silica particles The neutron angle scattering (SANS small Angle neutron scattering). This method of measurement Is familiar to a person skilled in the art and does not require any further explanation here. In the SANS measurement, a particle size distribution curve is obtained, Wherein the volume fraction of particles With a corresponding size (diameter) The particle diameter. An average particle size in the sense of The invention defines the peak of such a SANS distribution curve, Ie the largest volume fraction with particles Corresponding diameter.

The half-width of the distribution curve is the width (in Nm) of the distribution curve at half height, ie half Of the particle volume fraction at the distribution curve peak d_Max, Or, in other words, the width of the distribution curve At half height of the Y axis (relative to the height of the curve at d_Max).

The average particle size is preferably between 6 and 40 nm, more preferably between 8 and 30 nm, especially Preferably between 10 and 25 nm. Silica dispersions According to the invention can be well processed and shown Even at higher concentrations of the disperse phase, a rheology, Which approximates the ideal Newtonian flow behavior Is. At the given particle concentration, they have in the Generally have a lower viscosity than corresponding dispersions Of the prior art.

The half-value width of the distribution curve is according to the invention Preferably at most 1.2 × d_Max, More preferably They maximally d_Max, Particularly preferably it is at most 0.75 x d_Max.

The proportion of the outer phase at the dispersion may be within the scope Of the invention is between 20 and 90% by weight, preferably 30 to 30% by weight 80% by weight, more preferably 40 to 70% by weight. Accordingly The proportion of the disperse phase can be between 10 And 80% by weight, preferably 20 to 70% by weight, more preferably 30 to 60% by weight. The silica particles of the According to the invention are preferably essentially Spherical. The dispersion may additionally contain adjuvants Containing compound selected from the group consisting of solvents, Plasticizers, crosslinking agents, catalysts, stabilizers, Dispersants, curing agents, reaction promoters And means for influencing the flowability of the Dispersion.

The dispersion according to the invention is particularly preferably anhydrous, It thus contains only slight traces of water, which Also after carrying out the usual described below Methods for removing water remain.

The outer phase may be one of two or more reaction components For the preparation of a polymer. Both Polymers can be thermoplastic or thermosetting Plastics. Examples which may be mentioned are polyurethanes, Polyureas, epoxy resins, polyester resins, polysiloxanes (Silicones) and generally reaction resins for the production Thermosetting plastics. It can, for example, be a fabric By weight of a compound selected from the group consisting of polyols, Polyamines, linear or branched polyglycol ethers, polyesters And polylactones.

Suitable monomeric polyols for the purpose of the invention A variety of known compounds can be used. Because of The easy availability and the advantages, in particular of the Excellent compatibility and good processability Of the resulting products, are used for the outer phase of the According to the invention as polyols linear or branched Aliphatic glycols are preferably used, wherein the Outer phase of the SiO₂Dispersion particularly preferably ethylene glycol, 1,2- or 1,3-propanediol, 1,2- or 1,4-butanediol, 1,6-hexanediol, 2,2,4-trimethylpentanediol-1,3 and / or neopentyl glycol Respectively.

Furthermore, the aliphatic polyols used are preferably glycerol, Trimethylolpropane and also sugar alcohols, especially Erythritol, xylitol, mannitol and / or sorbitol. Further The outer phase as the preferred polyols can be one or more Alicyclic polyols, in particular 1,4-cyclohexanedimethanol, And / or sucrose.

As polymeric polyols, preference is given to the outer phase Those having an average molecular weight of from 200 to 20,000, wherein the polymeric polyol is preferably a Such on the basis of (polymeth) acrylic acid alkylene glycol esters Is. The outer phase of the dispersion according to the invention May further preferably comprise polymeric polyols which are By saponification or partial saponification of vinyl esters Polymers.

Suitable polyethers for the outer phase are, in particular, those obtained by Ring-opening polymerization of cyclic ethers in the presence Of polyols, for example the abovementioned polyols Linear or branched polyglycol ethers, Due to their relatively easy availability, polyethylene glycol, Polypropylene glycol and / or polytetramethylene glycol Or their copolymers are preferred.

Suitable polyesters are for the outer phase of the invention Dispersions based on polyols and aliphatic, Cycloaliphatic or aromatic multifunctional Carboxylic acids (for example dicarboxylic acids), and Although all corresponding, at temperatures of from 18 to 300 ° C., Preferably 18 to 150 ° C, liquid saturated polyester, Preferably succinic acid esters, glutaric acid esters, adipic acid esters, Citric acid esters, phthalic acid esters, isophthalic acid esters, Terephthalic acid esters and / or the esters of the corresponding Hydrogenation products, wherein the alcohol component From monomeric or polymeric polyols, for example From those of the aforementioned type.

Further polyesters which can be used according to the invention are aliphatic Polylactones, preferably ε-polycaprolactone, and / or polycarbonates, For example by polycondensation of diols with Phosgene are accessible. Preferably, for the outer Phase Polycarbonic acid ester of bisphenol A with a medium Molecular weight of from 500 to 100,000.

Instead of the abovementioned polyols, polyethers and saturated Polyesters can be used for the purpose of the invention Also mixtures of the abovementioned classes for the external substances Phase of the dispersion according to the invention. The Use of such mixtures can be carried out, for example, with a view to a Reduction of the glass or melting temperature of the resulting Products. The abovementioned polyethers And polyesters can be functional for the further reaction Groups, such as, for example, hydroxyl, carboxyl, amino- Or isocyanato groups.

For the purpose of influencing the viscosity of the outer phase, In particular the viscosity lowering or the liquefaction, Can be used for the outer phase according to the invention Polyols, and saturated polyesters Or mixtures thereof, if appropriate, also suitable auxiliaries, Especially solvents, plasticizers, thinners And the like.

In the context of the invention, the outer phase can comprise at least one, Reaction resin.

For the purposes of the present invention, reaction resins are used Precursors or prepolymers which are used before and During the processing or shaping process Or are plastic and, according to the normally formative Processing by polyreaction (polycondensation, polyaddition) Thermosetting plastics. Through the polyreaction A three-dimensionally cross-linked, hard one is not obtained Meltable resin, the thermosetting, which is thus fundamental Of thermoplastics Known to be repeatedly liquefied by re-heating Or can be plasticized.

As a result of the usually very high crosslinking density, Crosslinked reaction resins have a number of valuable properties Which are the reason for the fact that besides the thermoplasts Are among the most widely used polymers. To this Valuable properties include in particular hardness, strength, Chemical resistance and temperature resistance. Because of these properties, these reaction resins are based on In various fields, for example for the production Of fiber-reinforced plastics, for insulating materials In electrical engineering, for the manufacture of construction adhesives, Laminates, stoving enamels and the like.

According to the invention, all polymers or Oligomeric organic compounds which are compatible with a Suitable for a curing reaction Groups. For this purpose, Purpose irrelevant, which curing or curing mechanism In a specific case. Therefore, as Starting products for the production of the modified Reaction resins in general all reaction resins, Which can be processed to give thermosets By the respective crosslinking mechanism, which occurs during curing Of the respective reaction resin. Not object Of the invention are reaction resins which are free-radically polymerizable Double bonds due to their particular reactivity For the process according to the invention Are well suited. They can at most be regarded as optional additional Component in the outer phase.

In principle, the starting products according to the invention can be used as starting products Suitable reaction resins according to the nature of the Crosslinking by addition or condensation into two groups The

From the first group of the reaction resins crosslinked by polyaddition Are preferably one or more epoxy resins, Urethane resins and / or air-drying alkyd resins as starting materials selected. Epoxy and urethane resins are used in the Rule by adding stoichiometric amounts of a hydroxyl, Amino, carboxyl or carboxylic acid anhydride groups Hardener, the curing reaction being carried out by addition Of the oxirane or isocyanate groups of the resin to the corresponding Groups of the hardener. For epoxy resins Also the so-called catalytic curing by polyaddition Of the oxirane groups themselves. Air-drying alkyd resins Crosslinked by autooxidation with air oxygen.

Examples of the second group of polycondensation Crosslinked reaction resins are condensation products of aldehydes, For example formaldehyde, with aliphatic groups containing amine groups Or aromatic compounds, for example urea or Melamine, or with aromatic compounds such as phenol, resorcinol, Cresol, xylene, etc., furan resins, saturated polyester resins And silicone resins. The curing takes place here Usually by temperature elevation with elimination of water, Low molecular weight alcohols or other low molecular weight Connections. Preference is given to starting materials for the Modified one or more reaction resins according to the invention Phenol resins, resorcinol resins and / or cresol resins Both resols and novolaks, furthermore urea-formaldehyde- And melamine-formaldehyde precondensates, furan resins as well as Saturated polyester resins and / or silicone resins.

Not only the above-mentioned reaction resins, but Also all others, used for the manufacture of thermosetting plastics Plastics are suitable, can be used in the process according to the invention And, according to the Crosslinking and curing thermosets with significantly improved Fracture and impact strength, other essential materials being used for the Thermosetting characteristics such as strength, Heat resistance and chemical resistance, essentially Unaffected. In this connection, Or reaction resin mixtures At temperatures ranging from 18 to 100 ° C. Furthermore, the reaction resins used or the reaction resin mixtures are used An average molecular weight in the range of 200 to 500,000, preferably from 300 to 20,000. Continue As the outer phase according to the invention also monomers and Oligomers can be used. These include in particular those Monomeric or oligomeric compounds which are characterized by Polyaddition or polycondensation to form polymers.

The invention is particularly useful in the application Of reaction resins. reaction resins Of the prior art are due to the highly cross-linked state Brittle and have low impact strength, in particular At lower temperatures. The breaking and impact strength Such thermosetting plastic can be used according to the invention Can be considerably improved without hardness, strength And softening temperature can be adversely affected. According to the invention Thus reaction resins and thermoset Plastics are produced, on the one hand The liquid reaction resin despite a high proportion of filler Can still be processed well and, on the other hand, Filling addition of monomodal particles of small diameter Significant improvement in mechanical properties (In particular tensile strength, elongation at break or fracture toughness) Of the cured thermosetting plastic.

In a preferred embodiment of the invention The polymerizable monomers, oligomers and / or prepolymers Carbon, oxygen, nitrogen and / or sulfur atoms In the main chain. It is therefore organic Hydrocarbon polymers (optionally with heteroatoms), polysiloxanes Do not fall under this preferred embodiment.

Preferably, the outer flowable phase can be polymerizable Monomers without free-radically polymerizable double bonds As well as reaction resins.

The outer flowable phase contains silanes. The silanes may be hydrolyzable and non-hydrolysable, Optionally functional groups. Examples of hydrolysable Groups are halogen, alkoxy, alkenoxy, Acyloxy, oximino and aminoxy groups. Examples of functional, Non-hydrolysable groups are vinyl, aminopropyl, Chloropropyl, aminoethylaminopropyl, glycidyloxypropyl, Mercaptopropyl or methacryloxypropyl groups. Examples For non-hydrolysable, non-functional groups Are monovalent C atoms₁- to C_8thHydrocarbyl radicals. Examples For silanes which can be used according to the invention are: γ-aminopropyltrimethoxysilane, Γ-aminopropylmethyldiethoxysilane, γ-aminopropyldimethylmethoxysilane, glycidyloxypropyltrimethoxysilane, Glycidyloxypropyldimethylmethoxysilane, methacryloxypropyltrimethoxysilane, Chloropropyltrimethoxysilane, vinylmethyldimethoxysilane, Vinyltrispropenoxysilane, vinyldimethylbutanone oxime silane, Vinyltrisbutanone oxime silane, trimethylchlorosilane, Vinyldimethylchlorosilane, dimethylchlorosilane, vinylmethylchlorosilane.

The silanes are preferably used in a concentration of 40 to 200 mol% and more preferably from 60 to 150 mol% On the molar amount of silanol groups on the surface Respectively.

When carrying out the process according to the invention, Firstly an aqueous silicate solution. It can be To provide an alkali silicate solution, especially a sodium silicate solution Or potassium silicate solution. The concentration of these Aqueous silicate solution is preferably in the range between 20 and 50% by weight. The preferred ratio of SiO₂ to Na₂O Is between 2 and 3.

In the next step, the silicate becomes a particle size From 3 to 50 nm. This can be done, for example By treating the alkali silicate solution with acidic solution Ion exchangers containing the alkali ions against H⁺ions And thus trigger the desired polycondensation.

The resulting silica sol is adjusted to an alkaline pH (PH&gt; 8, preferably&gt; 9, more preferably&gt; 10, especially Preferably between 10 and 12) and in this way Against further polycondensation or agglomeration already Of existing particles.

Optionally, the sol can be concentrated, for example by distillation, Preferably to a SiO₂Concentration of 30 to 40% by weight.

In the next step, the sol is mixed with constituents of the outer, Flowable phase of the dispersion. The parts Of the outer, flowable phase can be either Simultaneously or in several partial steps successively Are added or blended.

Subsequently, water and / or others are particularly preferred Solvent constituents are removed from the dispersion, since From the dispersions according to the invention are particularly preferred Water-free plastics (so-called water-free nanocomposites) Should be produced. All conventional, As is known to the person skilled in the art For example distillation, preferably in vacuo, membrane separation, Optionally sedimentation, solvent extraction, use of a Molecular sieves, etc. In the case of the distillation, solvents, Which form an azeotrope with water And thus act as azeotropic entrainer. If different Solvent components can also be removed Simultaneously or through several sequential substeps be performed.

Within the scope of the invention it is also possible to carry out partial steps of the Process steps e) and f) of claim 16, so to speak, with one another to mix. It is therefore possible, after the addition of One or more constituents in step e) First one or more solvent constituents within the framework Of the step f), and then further (Substance addition) as part of step e) Other solvent constituents within the framework Of the step f), etc. Thus, partial steps Of process steps e) and f) of claim 16 with one another And mixed and interchanged.

It is preferred if the proportion of the silicon dioxide of a Dispersion exclusively and thus in its By the said method. in the However, it is also possible to provide a part of the invention Of the silica of the dispersion according to the method of the state Of the technique, so long as the disperse phase As a whole satisfies the criteria of claim 1. Especially Can be part of the disperse phase within the scope of the invention By the method described in the introduction to the description The hydrolysis and condensation of organofunctional Silanes (especially alkoxysilanes). It Can be mono-, di-, tri- or tetraalkoxysilanes, Wherein a sufficient proportion of silanes with three or four hydrolysable Groups. Preferred are in particular Mono-, di- or trimethoxy- or -ethoxysilanes One of the non-hydrolysable radicals is an aliphatic (Preferably having 1 to 18 carbon atoms) or more aromatic Hydrocarbon residue, which additionally has a functional Group, for example, a vinyl, allyl, (meth) acrylic, Glycidyl, halogen, hydroxyl or mercapto group. If necessary, Any further non-hydrolysable radicals are preferred Methyl or ethyl.

If a part of the dispersed phase in the manner mentioned Is prepared by silane hydrolysis, Solvents which are used as solubilizing agents Between silane and the outer phase of the dispersion can. Suitable solvents are, for example, water-miscible low-molecular-weight polymers Alcohols (preferably C₁- to C₄Alcohols), ketones, amines, Amides or heterocyclic compounds such as, for example, THF or Pyridine.

The invention also relates to the use of a process described above Defined dispersion for the production of a polymeric material. The polymeric material may be a thermoplastic Or thermosetting plastic. Examples are mentioned Polyurethanes, polyureas, epoxy resins, polyester resins, Polysiloxanes as well as all duroplastic, from reaction resins Plastics.

The polymeric material can, on the one hand, be a thermoplastic Plastic or, on the other hand, a chemically cross-linked, thermoset Or elastomeric plastic. For example For duroplastic and / or elastomeric plastics are mentioned: Polyurethanes, polyureas, epoxy resins, polyester resins, Polyimide resins, polysiloxanes, alkyd resins, styrene-butadiene rubber, Acrylonitrile-butadiene rubber, polybutadiene rubber.

Examples which can be used according to the invention in the outer phase Thermoplastic polymers can be mentioned: polyolefins, Polystyrene, styrene-acrylonitrile copolymers, polyamides, Polyvinyl chloride and its copolymers, polyvinyl alcohols, And -acetates and ethers, as well as copolymers of these substances, Polycarbonate, polymethyl acrylates and polymethyl methacrylates Including their copolymers, polyurethanes, polysulfones, Polyether ketones, polyesters.

The polymeric materials for the purposes of this invention are not Only compact materials, but rather the inventive Dispersions also advantageously as part of the binder In paints, varnishes and coatings will. This is particularly advantageous in these applications From the fact that by the content of silicon dioxide on the one hand The abrasion and scratch resistance as well as the barrier effect The penetration of the coating by gases and moisture But on the other hand by the narrow particle size distribution The viscosity is increased considerably lower Than in the case of silicon dioxide fillers according to the conventional State of the art. This is especially for surface coatings A considerable advantage.

Furthermore, the polymers according to the invention can be modified Materials also closed cell or open cell Foams, for example based on polyurethanes, polysiloxanes, Polyolefins or polystyrene. The special advantage Of the dispersions according to the invention results from the The fact that due to the small particle size and the narrow Distribution of the particles in the thin lamellas of the Foam may be present without the foam structure As such. This makes it possible, for example, for the Hardness and the compressive strength of the foam at the same time Foam density, or despite decreasing Density.

A further embodiment of the inventive modified Polymeric materials are liquid, curable potting and Impregnating compositions, eg for the production of electrical insulating resins Or fiber composite materials. For many applications Of electrical insulation resins, for example, when casting coils Or transformers, it is important that the impregnating resin As easily and error-free as the often only few Μm of the coil windings Fillers filled with fillers according to the prior art Because of their particle size and irregular distribution is possible. In principle the same applies to the application Of impregnating resins in fiber composite materials, in particular In the case of highly stressed parts, the individual reinforcing fibers So tightly packed that according to the state of the art No filled systems can be used. In both Applications can be carried out using the dispersions according to the invention Prepared impregnation resins due to the extremely low Particle size and the narrow diameter distribution of the silica To the interstices of the windings or Fibers. Thus, the advantageous mechanical And thermal properties of the silicon dioxide filled Resin in the entire component.

A further advantageous property of the process described with the invention Dispersions-modified polymeric materials Whose optical clarity, which in turn results from the extremely small Particle size and the narrow diameter distribution of the Silica. Especially in the case of plastics By nature are optically clear, there is according to the state of the Technology no way to more than a very small one Proportion of inorganic fillers to the polymer, Without affecting its optical properties to be pulled. Thus, in the case of plastic applications, In which optical clarity is important, hardly one Possibility of applying properties such as hardness or modulus of elasticity, Scratch resistance, breaking strength, thermal conductivity, Coefficient of expansion, diffusion barrier effect, etc., What is usually used in non-transparent systems By the addition of inorganic fillers would. In principle this affects a great many polymeric materials And their applications, for example polymethyl methacrylate, Polycarbonate, polyalkylene terephthalates, various clear lacquer systems Eg for topcoats of vehicles, furniture, Flooring, printing etc.

For example, The dispersion according to the invention can be polyols or polyamines Of the type described in more detail above, from which Polyurethanes or polyureas can be prepared. The Dispersion is then carried out in known manner with polyisocyanates Mixed and reacted to obtain the desired polymeric Materials whose properties are determined by the dispersed SiO₂Phase are modified accordingly. The polymerization reaction Can be carried out in a manner known to the person skilled in the art Single or multi-stage, possibly at elevated temperature will.

If the dispersion according to the invention contains a reaction resin, This can be carried out in a known manner according to the known methods of Multistage process of the reaction resin technique to a preferably Duroplastic plastic. Preferably with addition of catalysts, hardeners Or crosslinkers finds the formation of a three-dimensional Polymer network. Other additives and additives Can be added to the reaction resin before crosslinking For example, organic or inorganic fillers, fibers, Pigments, flow aids, reaction accelerators or Retarders, plasticizers or the like.

Embodiments of the invention are explained below. All percentages in the examples are by weight, the specification "Parts" refers to mass parts. The size distribution the SiO₂(Also called diameter distribution) In the examples as x ± y nm. X is thereby the Peak d_Max Of the distribution curve, y is half the half-width Of the distribution curve. Accordingly, the half-width is The distribution curve 2y.

example 1

A commercially available aqueous alkali metal silicate solution with a Water content of 47% and a ratio of SiO₂ to Na₂O Of 2.4 was diluted with demineralized water to a water content Of 97%. 100 parts of this dilute solution Were fed at a rate of 20 parts per hour through one with A commercially available acidic ion exchanger And then fed to a distillation sample, in The dilute deionized silicate solution at boiling temperature And the water distilling off from the Solution. After the end of the inflow, the Formed silica sol by further heating to 10 parts Narrowed The pH was adjusted to 10.5 to 11.

Examples 2 to 4

In each case, 100 parts of the sol prepared in Example 1 were obtained Mixed with 2,000 parts of isopropanol and the water passed through Atmospheric distillation down to one using the Karl Fischer method Specific content of less than 0.1%. Thereafter, 80 parts each of the following polyethers were added With stirring:<dl tsize="11" compact="compact"><dt>Example 2:</dt><dd>Polypropylene diol (PPG), molar mass (MM) 1000</dd><dt>Example 3:</dt><dd>Condensed with 15% polyethylene glycol (PEG) PPG, MM 4000</dd><dt>Example 4:</dt><dd>Polypropylene triol, MM 6000</dd></dl>

Subsequently, the volatile constituents were distillative At 50 ° C and a vacuum of up to 85 mbar.

The three samples obtained were water-clear. The particle size distribution Was measured by SANS and gave at all Three samples correspond to one another within the measuring accuracy Diameter distribution of 47 ± 11 nm.

Example 5

Example 1 was repeated, except that the water content Of the dilute alkali silicate solution to 98% As well as the feed rate to the distillation sample 15 parts per hour. After the concentration 9 parts of silica sol. The pH was adjusted to 10.5 to 11.

Examples 6 to 10

In each case, 100 parts of the sol prepared in Example 5 were obtained 2.5 parts of trimethylmethoxysilane were added and the mixture was stirred. To 2000 parts of isopropanol were added to these mixtures and The water by atmospheric distillation down to one Determined by the Karl Fischer method Than 0.1%. Thereafter, 80 parts each of the following Polyether with stirring:<dl tsize="12" compact="compact"><dt>Example 6:</dt><dd>PPG, MM 12000</dd><dt>Example 7:</dt><dd>PPG with 10% ethylene oxide is statistically Copolymerized, MM 3000</dd><dt>Example 8:</dt><dd>Polypropylene triol, MM 550</dd><dt>Example 9:</dt><dd>With 20% PEG end-capped polypropylenetriol, MM 2000</dd><dt>Example 10:</dt><dd>Polytetramethylene glycol, MM 650</dd></dl>

Subsequently, the volatile constituents were distillative At 50 ° C and a vacuum of up to 85 mbar.

The five samples obtained were water-clear. The particle size distribution Was measured by SANS and gave at all Samples correspond to one another within the measuring accuracy Diameter distribution of 30 ± 7 nm.

Example 11

Example 1 was repeated with the exception that the feed rate To the distillation sample 30 parts per Hour. After concentration, 15 parts of silica sol were added receive. The pH was adjusted to 10.5 to 11.

Example 12

100 parts of the sol prepared in Example 11 was added under Stirring with 3.9 parts of n-propyltrimethoxysilane and stirring Respectively. Thereafter, this mixture was converted into 620 parts of isopropanol Stirred and concentrated to 113 parts at 40 ° C. and 85 mbar. Subsequently, 110 parts of a hydroxyl-containing Polyacrylate ( 'Desmophen A 870 BA', Bayer AG) was added. The highly volatile constituents were then added At 40 ° C. and 58 mbar distillatively so carefully that The higher - boiling butyl acetate contained in the polyacrylate Of the dispersion. A water-clear dispersion was obtained With a diameter distribution determined by SANS Of 8 ± 2.5 nm.

Example 13

100 parts of the sol prepared in Example 11 were mixed with 5.9 parts of γ-glycidoxypropyldiethoxymethylsilane with stirring And then added to a solution of 60 parts of a Cycloaliphatic epoxy resin ( 'ERL 4221' from Union Carbide) In 620 parts of isopropanol. The volatile constituents Were then distilled at 50 ° C. and 85 mbar away. A water-clear dispersion was obtained A diameter distribution determined by SANS of 8 ± 2.5 nm.

Example 14

100 parts of the sol prepared in Example 11 was added under Stirring with 588 parts of isopropanol. Subsequently At 40 ° C. and 85 mbar to 147 parts. Thereafter 5.7 parts of γ-glycidoxypropyltrimethoxysilane with stirring And then added to a solution of 60 parts of a Cycloaliphatic epoxy resin ( 'ERL 4221' from Union Carbide) In 168 parts of isopropanol. The volatile constituents Were then distilled at 50 ° C. and 3 mbar away. A water-clear dispersion was obtained with one Determined by SANS, of 8 ± 2 Nm.

Example 15

Example 1 was repeated with the exception that the feed rate To the distillation chart 43 parts per Hour. After concentration, 8 parts of silica sol were added receive. The pH was adjusted to 10.5 to 11.

EXAMPLE 16

100 parts of the sol prepared in Example 15 were mixed with 5.6 parts of trimethoxyphenylsilane and stirred. After that This mixture was introduced into 610 parts of isopropanol and At 40 ° C. and 85 mbar to 118 parts. Subsequently Were added 225 parts of isopropylacetate and the mixture Again condented to 134 parts by distillation at 40 ° C. and 85 mbar. This mixture was then converted into 125 parts of a 50% solution of bisphenol A epoxy resin ( 'Epilox A 17-01', From Leuna Harze GmbH) in isopropylacetate and subsequently The volatile constituents at 50 ° C. and 3 mbar By distillation. A slightly opaque dispersion was obtained With a diameter distribution of 16 ± 5 nm.

Example 17

100 parts of the sol prepared in Example 15 were mixed with 2.8 parts of methoxytrimethylsilane and stirred. After that This mixture was introduced into 820 parts of isopropanol and At 40 ° C. and 85 mbar to 118 parts. Thereafter Mix this mixture with 423 parts of a 15% solution of Bisphenol F epoxy resin (&amp; quot; Epilox F 16-01 &amp; quot ;, Leuna Resin GmbH) in isopropylacetate and then the volatile Components are removed by distillation at 50 ° C. and 3 mbar. A slightly opaque dispersion was obtained with one by SANS Determined diameter distribution of 17 ± 5 nm.

Example 18

In each case, 100 parts of the sol prepared in Example 15 were obtained Treated with 5.3 parts of phenyltrimethoxysilane and stirred. To these mixtures were added 1000 parts of isopropanol And then to 120 parts each at 40 ° C. and 85 mbar Narrowed 220 parts of isopropylacetate were then added And the mixtures are again distilled at 40 ° C. and 85 mbar to 120 parts. Thereafter, Parts of a 50% isopropylacetate solution of the following Polyesterpolyols are added:<dl tsize="11" compact="compact"><dt>Example a:</dt><dd>Branched polyester polyol ( 'Desmophen 1100', Fa. Bayer AG)</dd><dt>Example b:</dt><dd>Polycarbonate-polyester polyol ( 'Desmophen C 200, Bayer AG)</dd><dt>Example c:</dt><dd>Polycaprolactone polyol ( 'TONE 2241', DOW Chemical)</dd></dl>

Subsequently, the volatile constituents were distillative At 50 ° C and a vacuum of up to 85 mbar. The Three samples obtained were water-clear. The particle size distribution Was measured by SANS and gave at all Three samples correspond to one another within the measuring accuracy Diameter distribution of 17 ± 5 nm.

Example 19

100 parts of the sol prepared in Example 15 were mixed with 4.5 parts of n-propyltrimethoxysilane and stirred. After that This mixture was dissolved in a solution of 80 parts Ε-caprolactam in 520 parts of n-propanol. The volatile Components were subsequently distilled at 60 ° C. And a vacuum of up to 85 mbar. One received one Water-clear dispersion, which at room temperature to a Colorless solid. It is obtained by melting at 70 ° C. But a watery dispersion with a throughput SANS determined the diameter distribution of 16 ± 7 nm.

Example 20

100 parts of the sol prepared in Example 15 were added under Stirring with 4.5 parts of propyltrimethoxysilane with stirring And then into a solution of 38 parts of a Plasticizer based on adipate ( 'Plasticiser 109', hanse Chemie GmbH) in 522 parts of isopropanol. The volatile Components were removed by distillation at 50 ° C. and 3 mbar. A yellow, water-clear dispersion was obtained with one Diameter distribution determined by SANS 18 ± 5 nm.

Example 21

100 parts of the sol prepared in Example 15 were mixed with 5.8 parts of phenyltrimethoxysilane and stirred. To To this mixture was added 1000 parts of isopropanol and then At 40 ° C. and 85 mbar to 122 parts. Subsequently Were added 225 parts of isopropylacetate and the mixture Again by distillation at 40 ° C. and 85 mbar to 110 parts Narrowed 100 parts PMMA molding compound granules ( 'Plexiglas 6N ', Röhm GmbH) were operated in a twin-screw degassing extruder ( 'ZSK 25', Werner &amp; Pfleiderer) were melted. Under a pressure of 42 bar, 100 parts of the above-prepared Isopropylacetate sols are added laterally, homogeneously And then the volatile constituents are dissolved in a Two-stage degassing process and blown under vacuum Degassed. By means of a post-sheeted granulator one obtained A water-clear colorless granulate with a SANS-determined Diameter distribution of 17 ± 7 nm.

From this granulate, Injection molding machine, the mechanical And thermal characteristic values ​​and with unmodified 'Plexiglass 6N'. The following were the results Values:<tables><table><tgroup cols="5"><tbody><row><entry namest="1" align="left">characteristic value</entry><entry namest="2" align="left">unit</entry><entry namest="3" align="left">standard</entry><entry namest="4" nameend="5" align="center">measured value</entry></row><row><entry align="center" /><entry align="center" /><entry align="center" /><entry align="center">unmodified</entry><entry align="center">modified</entry></row><row><entry align="left">Train E module</entry><entry align="left">MPa</entry><entry align="left">ISO 527</entry><entry align="right">3,200</entry><entry align="right">4.900</entry></row><row><entry align="left">breaking stress</entry><entry align="left">MPa</entry><entry align="left">ISO 527</entry><entry align="right">67</entry><entry align="right">103</entry></row><row><entry align="left">breaking elongation</entry><entry align="left">%</entry><entry align="left">ISO 527</entry><entry align="right">3</entry><entry align="right">3</entry></row><row><entry align="left">softening temperature</entry><entry align="left">° C</entry><entry align="left">ISO 306</entry><entry align="right">96</entry><entry align="right">115</entry></row><row><entry align="left">coefficient of elongation</entry><entry align="left">10^-6K^-1</entry><entry align="left">ASTM E 831</entry><entry align="right">80</entry><entry align="right">60</entry></row><row><entry align="left">Optical transmittance</entry><entry align="left">%</entry><entry align="left">DIN 5036</entry><entry align="right">92</entry><entry align="right">90</entry></row></tbody></tgroup></table></tables>

The example demonstrates the considerably improved mechanical properties And thermal characteristic values ​​of the plexiglass without The optical properties of which are markedly reduced by the addition of the Silica.

Example 22

100 parts of the sol prepared in Example 15 were added under Stirring with 588 parts of isopropanol. Subsequently At 40 ° C. and 85 mbar to 147 parts. Thereafter 5.7 parts of γ-glycidoxypropyltrimethoxysilane with stirring And then added to a solution of 60 parts of a Cycloaliphatic epoxy resin ( "ERL 4221" from Union Carbide) In 168 parts of isopropanol. The volatile constituents Were then distilled at 50 ° C. and 2 mbar away. A water-clear dispersion was obtained with one Diameter distribution determined by SANS 15 ± 4 nm.

Example 23

In this example, the rheological properties of Resins and polyetherpolyols which, on the one hand, are fused with pyrogenic Silica of the prior art and, on the other hand, according to the invention SiO₂Dispersions. AEROSIL® R8200 is a flame hydrolysis of silicon tetrachloride Produced fumed silica By Degussa.<tables><table><tgroup cols="4"><tbody><row><entry namest="1" nameend="4"><b>Viscosities SiO₂- filled resins and polyether polyols</b></entry></row><row><entry align="center">Resin / polyether polyol (manufacturer)</entry><entry align="center">SiO₂-Salary [%]</entry><entry align="center">Type of SiO₂articles</entry><entry align="center">Η (25 ° C) [mPa · s]</entry></row><row><entry align="center">ERL 4221 (Union Carbide)</entry><entry align="center">0</entry><entry align="center">-</entry><entry align="center">381</entry></row><row><entry align="center">ERL 4221 (Union Carbide)</entry><entry align="center">23</entry><entry align="center">Ex. 22</entry><entry align="center">422</entry></row><row><entry align="center">ERL 4221 (Union Carbide)</entry><entry align="center">40</entry><entry align="center">Ex. 22</entry><entry align="center">25810</entry></row><row><entry align="center">ERL 4221 (Union Carbide)</entry><entry align="center">5</entry><entry align="center">AEROSIL® R8200</entry><entry align="center">491</entry></row><row><entry align="center">ERL 4221 (Union Carbide)</entry><entry align="center">23</entry><entry align="center">AEROSIL® R8200</entry><entry align="center">pasty</entry></row><row><entry align="center">Baycoll BT 1380 (Bayer)</entry><entry align="center">0</entry><entry align="center">-</entry><entry align="center">595</entry></row><row><entry align="center">Baycoll BT 1380 (Bayer)</entry><entry align="center">20</entry><entry align="center">Ex. 8</entry><entry align="center">1030</entry></row><row><entry align="center">Baycoll BT 1380 (Bayer)</entry><entry align="center">50</entry><entry align="center">Ex. 8</entry><entry align="center">19800</entry></row><row><entry align="center">Baycoll BT 1380 (Bayer)</entry><entry align="center">5</entry><entry align="center">AEROSIL® R8200</entry><entry align="center">815</entry></row><row><entry align="center">Baycoll BT 1380 (Bayer)</entry><entry align="center">10</entry><entry align="center">AEROSIL® R8200</entry><entry align="center">1487</entry></row><row><entry align="center">Baycoll BT 1380 (Bayer)</entry><entry align="center">20</entry><entry align="center">AEROSIL® R8200</entry><entry align="center">pasty</entry></row><row><entry align="center">BisGMA / TEDMA</entry><entry align="center">0</entry><entry align="center">-</entry><entry align="center">1194</entry></row><row><entry align="center">BisGMA / TEDMA</entry><entry align="center">16</entry><entry align="center">Ex. 12</entry><entry align="center">2001</entry></row><row><entry align="center">BisGMA / TEDMA</entry><entry align="center">45</entry><entry align="center">Ex. 12</entry><entry align="center">42900</entry></row><row><entry align="center">BisGMA / TEDMA</entry><entry align="center">5</entry><entry align="center">AEROSIL® R8200</entry><entry align="center">1864</entry></row><row><entry align="center">BisGMA / TEDMA</entry><entry align="center">10</entry><entry align="center">AEROSIL® R8200</entry><entry align="center">3899</entry></row><row><entry align="center">BisGMA / TEDMA</entry><entry align="center">20</entry><entry align="center">AEROSIL® R8200</entry><entry align="center">pasty</entry></row></tbody></tgroup></table></tables>

It can be seen that, according to the invention, high SiO 2₂content Without excessively increasing the viscosity And hence the processability is made difficult or impossible power. On the other hand, an AEROSIL content of about 20% Regularly to a pasty consistency of the resin Or polyether polyol.

Example 24

The advantageous effect of SiO according to the invention₂dispersions On the mechanical properties of polymers is exemplified Of epoxy resins. In this example, the Epoxy resin ERL 4221 with the SiO₂Dispersion of Example 22 To the SiO indicated in Table 2₂Contents. For the UV curing (c to e), the samples were with 1% UV initiator ( "CYRACURE® UVI-6974" from Union Carbide) was added, Aluminum shells and 15 minutes at 60 ° C. and 1 mbar Long degassed. Subsequently, the samples were incubated for 10 minutes with A UV lamp (UVASPOT 400 H, from Dr. K. Hönle GmbH) in the Distance of 20 cm and irradiated for 1 hour at 160 ° C. For thermal curing (a and b), the epoxy equivalent weight was obtained According to the standard DIN 16 945 and 1 equivalent Of a cycloaliphatic anhydride ( "ALBIDUR HE 600", Hansechemie GmbH) was added. The samples are placed in aluminum shells And the mixture is heated at 60 ° C. and 1 mbar for 15 minutes Degassed. Curing takes place in 4 steps: 90 minutes at 90 ° C, 120 minutes at 120 ° C, 120 minutes at 140 ° C and 60 minutes At 160 ° C.

For the following fracture mechanics studies on the Determination of fracture toughness K_IC, The Bruchergie G_IC and Of the E-module E were made from the compact material CT standard test specimen With an edge length of 33 mm Of standard ASTM E 399-83 under quasi-static load Have been. Bending tests were carried out in three-point bending tests According to the standard DIN 53 452. <tables><table><tgroup cols="6"><tbody><row><entry namest="1" nameend="6"><b>Results of fracture mechanics</b></entry></row><row><entry align="right" /><entry align="center">SiO₂-Salary [%]</entry><entry align="center">Curing</entry><entry align="center">K_IC [MPa · m^1/2]</entry><entry align="center">G_IC [J / m²]</entry><entry align="center">E [MPa]</entry></row><row><entry align="center">a</entry><entry align="center">0</entry><entry align="center">HE600</entry><entry align="center">0.47 ± 0.05</entry><entry align="center">77.2 ± 22.0</entry><entry align="center">3053 ± 276</entry></row><row><entry align="center">b</entry><entry align="center">23</entry><entry align="center">HE600</entry><entry align="center">0.78 ± 0.02</entry><entry align="center">147.7 ± 7.9</entry><entry align="center">4146 ± 122</entry></row><row><entry align="center">c</entry><entry align="center">0</entry><entry align="center">UV</entry><entry align="center">0.28 ± 0.05</entry><entry align="center">26.2 ± 8.4</entry><entry align="center">3156 ± 81</entry></row><row><entry align="center">d</entry><entry align="center">23</entry><entry align="center">UV</entry><entry align="center">0.43 ± 0.04</entry><entry align="center">47.0 ± 6.1</entry><entry align="center">3893 ± 191</entry></row><row><entry align="center">e</entry><entry align="center">40</entry><entry align="center">UV</entry><entry align="center">0.51 ± 0.04</entry><entry align="center">45.7 ± 7.6</entry><entry align="center">5795 ± 276</entry></row></tbody></tgroup></table></tables>

The results of the tests show that, with the aid of the invention, SiO₂Dispersion fracture toughness, fracture energy and E modulus of the polymeric material can be significantly improved.