WO2011023266A1

WO2011023266A1 - Modified nanoparticles

Info

Publication number: WO2011023266A1
Application number: PCT/EP2010/004355
Authority: WO
Inventors: Helmut Steininger; Julien Courtois; Matthias Müller; Peter Deglmann; Vandana Kurkal-Siebert; Cornelia RÖGER
Original assignee: Basf Se
Priority date: 2009-08-28
Filing date: 2010-07-16
Publication date: 2011-03-03

Abstract

The present invention relates to modifiers for nanoparticles, to nanoparticles modified therewith, to nanocomposites comprising the modified nanoparticles, and to thermoplastic molding compositions, and also to processes for the production of the modifiers of the invention, of the modified nanoparticles, and of the nanocomposites and thermoplastic molding compositions, and to the use of said modified nanoparticles for addition to thermoplastic polymers.

Description

Modified nanoparticles

Technical field

The present invention relates to modifiers for nanoparticles, to nanoparticles modified therewith, and also to the use of said modified nanoparticles for addition to thermoplastic polymers.

Description of the prior art

Throughout the existence of the composite materials sector, it has been usual to use inorganic filler material particles of a few micrometers in size as additions for stabilizing or reinforcing polymer materials. Formulation of these conventional compositions has been focused on maximizing interaction between the filler material and the matrix of the corresponding polymer. A more detailed description of this is given in the document "Molecular Mechanisms of Failure in Polymer Nanocomposites, D. Gersappe, PRL 89(5), 58301 (2002)" and in corresponding reference documents cited therein. The general method used to achieve desired maximization of the interaction between the polymer matrix and the filler material is to select small particles of filler material, in order to increase the surface area available for interaction with the matrix. It can be shown that the performance potential of nanocomposites produced, for example, via a dispersion of nanoparticles in polymer melts is far superior to that of traditional compositions. This is revealed by way of example in Science 314 (2006) 1107 and in the work cited therein. Examples of possible improvements in properties in nanocomposite structures are viscosity reduction in the melt, less thermal degradation, greater mechanical damping, increased electrical conductivity, magnetic properties, and/or control of thermomechanical properties.

Viscosity reduction is particularly advantageous for injection molding. Reduced viscosity is associated with reduced injection times, or the corresponding process temperature can be reduced while dimensional stability remains the same or even increases. The materials developed are likely to satisfy future demands for high-quality injection molding of thin-walled products, with stringent demands placed upon dimensional stability. One of the thermomechanical properties which can be substantially influenced by nano-filler material in a polymer is glass transition temperature (Tg value) . This phenomenon is described in more detail in J. of Polymer Science, Part B: Polymer Physics 44 (2006) 2944-2950, and in the reference documents cited therein, where a possible change of up to +/- 30°C in the glass transition temperature of a polymer is reported to result from addition of a nano-filler material. This is of particular relevance because modulus of elasticity, hardness, conductivity, and various other physical properties can change by some orders of magnitude in the vicinity of the glass transition temperature. Accordingly, fine adjustment of the glass transition temperature of an appropriately designed nanocomposite structure can permit targeted control of the temperature range in which the same can be used. However, a point worth repeating here is that the physics underlying this behavior has not yet been understood, in particular because there is as yet no full understanding of the effects that particle/matrix interactions have on the behavior of the corresponding composition.

There is a rapidly increasing amount of literature describing the synthesis, modification, and dispersion of nanoparticles in polymer matrices.

EP 1 111 002 A2 discloses specific agents comprising organosilane and/or comprising organosiloxane, for modifying the surface of fillers, and discloses surface- modified fillers and their use for the production of filled compounded polyamide. Three different agents A, B, and C are described, where

A comprises at least one aminofunctional silicon compound

R-NH- (CH₂) 3"Si(CH₃) x (Z)₃-X,-

B comprises at least one aminofunctional silicon compound

H₂N- [(CHz)₂NHJy (CH₂) 3-Si(CH₃) x (Z)₃-X

and

at least one alkylfunctional silicon compound

or

at least one alkenylfunctional silicon compound

CH₂=CH- (CH₂) _n-Si (CH₃) x (Z) 3-x

or

at least one polyetherfunctional silicon compound

R- (0-CH₂-CHR' ) _n-0- (CH₂Jm-Si (CH₃) _x (Z) ₃__Xf in which n is a whole number from 5 to 20, and/or

comprises siloxanes;

C comprises at least one alkylfunctional silicon compound

R' -Si (CH₃) x (Z) 3-x

and

at least one alkenylfunctional silicon compound CH₂=CH- (CH₂) _n-Si (CH₃) _x (Z) ₃-_x

and/or

comprises siloxanes. Fillers mentioned in the description are glass fiber, glass beads, wollastonite, calcined kaolin, mica, talc, magnesium hydroxide, melamine cyanurate, montmorillonite, and "nanocomsites" . The examples use calcined kaolin. Incorporation of kaolin coated with 1% by weight of silane/siloxane into polyamide increases impact resistance and flowability of the compounded material.

EP 1 344 749 Al discloses a process for the production of nano-zinc-oxide dispersions stabilized via hydroxylated inorganic polymers. Here, zinc oxide nanoparticles are dispersed in a halogen-containing medium, the dispersion is added to a solution of hydroxylated inorganic polymers, and then the halogen-containing constituents are substantially removed. The hydroxylated inorganic polymers are produced via hydrolysis and condensation of monomeric and/or oligomeric alkoxysilanes and, respectively, organoalkoxysilanes, in a sol-gel process. Incorporation of the dispersions into polymeric materials is proposed, but no information is given about the effect thus achieved.

WO 2006/092442 Al discloses zinc oxide particles, the surface of which has been modified by alkoxyalkylsilanes. The particles are used as photocatalyst in heterogeneous catalysis .

WO 2007/043496 Al discloses transparent polymer nanocomposites which comprise finely dispersed nanocrystalline particles. Thiols having aromatic groups, and silanes having aromatic and hydrolyzable groups, are used to modify the surfaces of the particles. Benzyl mercaptan and phenyltrimethoxysilane are explicitly mentioned. The nanocrystalline particles are used to protect the polymer from UV radiation, without any adverse effect on the transparency of the polymer matrix.

WO 2007/0134712 Al discloses surface-modified nanoparticles which are obtainable via reaction, in an organic solvent, of precursors for the nanoparticles with a compound M₃-_X [C>₃-χSiRi_+x] , where x is a whole number from 0 to 2, M is H, Li, Na, or K, and all R respectively independently of one another are a hydrocarbon moiety which has from 1 to 28 carbon atoms and in which one or more carbon atoms can have been replaced by 0. The nanoparticles are used in polymers for protection from UV, in particular in polycarbonate (PC), polyethylene terephthalate (PET), polyimide (PI), polystyrene (PS) , polymethyl methacrylate (PMMA) , and in copolymers of said polymers.

WO 2007/059841 Al discloses a process for the production of zinc oxide nanoparticles by, in a step a) , reacting one or more precursors for the nanoparticles in an alcohol to give the nanoparticles, and, in a step b) when the critical absorption value has reached the desired value in the UV/VIS spectrum of the reaction solution, terminating the growth of the nanoparticles via addition of at least one modifier which is a precursor for silica, and, if appropriate, in a step c) , modifying the silica coating with at least one further surface modifier selected from the group consisting of organofunctional silanes, quaternary ammonium compounds, phosphonates, phosphonium compounds and sulfonium compounds, and mixtures thereof, and, if appropriate, in step d) , removing the alcohol from step a) and replacing it by another organic solvent. Surface modifiers proposed comprise adhesion promoters bearing two or more functional groups. One group of the adhesion promoter reacts chemically with the oxide surface of the nanoparticle; alkoxysilyl groups, halosilanes, and acidic groups of phosphoric esters and, respectively, phosphonic acids and phosphonic esters are proposed for this purpose. These have linkage by way of a spacer (C, Si)_nH_1n(N, 0,S)_x (n = 1-50, m = 2-100, x = 0-50) to a second functional group. The second functional group is acrylate, methacrylate, vinyl, amino, cyano, isocyanate, epoxy, carboxy, or hydroxy. The nanoparticles are used in polymers for protection from UV, in particular in polycarbonate (PC), polyethylene terephthalate (PET), poly- imide (PI) , polystyrene (PS) , polymethyl methacrylate (PMMA), and in copolymers of said polymers. Macromolecules 40 (2007) 1089-1100 discloses zinc oxide nanoparticles with surface-modification by tert- butylphosphonic acid, and composites of said surface- modified nanoparticles with PMMA. J. Phys. Chem. B 107 (2003) 4756-4762 discloses the production of zinc oxide nanoparticles via thermal decomposition of zinc acetate in the presence of tert- butylphosphonic acid. The particles are intended for use as optically active medium in light-emitting diodes.

Langmuir 17 (2001) 8362-8367 teaches that the growth rate of zinc oxide nanoparticles from homogeneous solution can be controlled via addition of 1-octanethiol or octadecylphosphonic acid. The particles are intended for use as nanostructured semiconductors.

However, the prior art provides no teaching as to how the interaction between the matrix of the corresponding polymer and the nanoparticles can be maximized in order to obtain nanocomposite structures with improved properties. Specific modifiers have now been found for nanoparticles, and these permit the production of modified nanoparticles which can be used for addition to thermoplastic polymers, for example polyamide, polymethyl methacrylate (PMMA), or styrene-acrylonitrile copolymers (SAN) , and permit the production of compounded polymer materials in which the interaction between polymer matrix and nanoparticles has been optimized. The particles can therefore be dispersed in the matrix without formation of agglomerates, and the interfacial energy between matrix and nanoparticles is smaller.

Summary of the invention

The invention provides modifiers for nanoparticles, complying with the formula Z- [O-CHR¹- (CH₂) _m] _n-0R² in which R¹ = H, CH₃, C₂H₅, phenyl, preferably CH₃;

R² = CH₃, C₂H₅, C₃H₇, C₄H₉ or C₅Hi_I-Ci₀H_2I, preferably CH₃; m = 1 or 2, preferably 1;

n = 1 to 4, preferably 3;

Z = (HO)₂P(O)-, (HO)₂P(O)-(CH₂)_X-, HO-SO₂-(CH₂)_K-,

(R³O) ₃-_yR⁴ _ySi- (CH₂) _X-,

in which x = 1 to 3; y = 1 to 3; and each of R³ and R⁴ independently of the other = CH₃, C₂H₅, C₃H₇, or C₄H₉, preferably (HO)₂P(O)- or (R³O)₃Si(CH₂J₃-, where

R³ = CH₃, C₂H₅.

The invention also provides nanoparticles modified by the modifiers of the invention. The invention further provides thermoplastic molding compositions and nanocomposites comprising the modified nanoparticles.

The invention also provides processes for the production of the modifiers of the invention, of the modified nanoparticles, and of the nanocomposites and, respectively, thermoplastic molding compositions.

Detailed description of the invention

For the purposes of this invention, the term "solvents" is also used to represent diluents. The dissolved compounds are present either in the form of solution at a molecular level or in the form of suspension, or dispersion, or emulsion in the solvent or in contact with the solvent. The term "solvents" also of course covers mixtures of solvents.

For the purposes of this application, "nanoparticles" are particles of size from 1 nm to 1000 nm.

"Liquid formulations" of the modified nanoparticles of the invention are solutions, dispersions, emulsions, or suspensions of the modified nanoparticles.

"Solid formulations" of the modified nanoparticles of the invention are solid-phase mixtures comprising modified nanoparticles, for example dispersions of the particles in a polymeric matrix, e.g. in polymers, in oligomeric olefins, in waxes, e.g. Luwax®, or in a masterbatch.

The "dispersion D" of the nanoparticles can for example also correspond to a suspension or to a solution, as a function of the concentration of the nanoparticles and of the nature of the solvent.

There are many different methods available to the person skilled in the art for determining the size of nanoparticles and of the modified particles, and these depend on the constitution of the particles and to some extent can differ in the particle-size results that they give. By way of example, particle size can be determined by measurements with the aid of a transmission electron microscope (TEM) , or by dynamic light scattering (DLS) , or UV absorption measurements. Measurements by means of dynamic light scattering (DLS) determine the secondary particle size. For the purposes of the present application, particle sizes are, if possible, determined with the aid of measurements from a transmission electron microscope (TEM) . Given an ideally spherical shape of the nanoparticles, particle size would correspond to particle diameter. It is, of course, possible that the size of any agglomerates produced from the initial primary particles as a consequence of accretion of nanoparticles is greater than 1000 nm. In one preferred embodiment, the primary particle size of the modified nanoparticles of the invention, measured by the TEM method, is from 1 nm to 100 nm, and in one particularly preferred embodiment it is from 1 nm to 50 nm, very particularly preferably from 1 nm to 30 nm.

"Modification" means that the nanoparticles interact with the modifier. As a function of the nature of the modifier and of the conditions, this can by way of example take the form of adsorption, of a coordinate bond, or of a chemical bond.

By way of example, the modification can take place via reaction of inorganic nanoparticles with the modifier where

(a) the inorganic nanoparticles are provided in a dispersion D, produced via reaction of compounds V in a solvent, and

(b) immediately after step (a) the modifier is added to the dispersion D.

Instead of the modifiers mentioned above, derivatives therof may also be used; for instance, derivatives wherein group Z comprises halogenides instead of hydroxyl or alkoxyl groups, i.e., Z = (HaI)₂P(O)-, (Hal) ₂P (0) - (CH₂) _x-, Hal-SO₂-(CH₂)χ- or (Hal) ₃__yR⁴ _ySi- (CH₂) _x-,

with x = 1 to 3; y = 1 to 3; each of R³ and R⁴ independently of the other = CH₃, C₂H₅, C₃H₇, or C₄Hg; and Hal = F, Cl, Br or I.

Furthermore, compounds may also be used which are precursors of the modifiers of the invention and comprise moieties which are transformed during the modification process into the groups Z defined above by suitable chemical reactions, for instance, oxidation or reduction.

The nanoparticles of the invention can be either crystalline or amorphous, or can have varying proportions of crystalline and amorphous structures. Detection uses TEM measurements or X-ray powder diffraction measurements.

As explained below, the stoichiometric or quantitative constitution of the modified nanoparticles of the invention can vary widely, for example as a function of the nature of the compounds V, or of the nature of the modifiers.

The compounds V from which the nanoparticles are formed are generally commercially available, or can be synthesized via processes well known to the person skilled in the art, from commercially available compounds. The compounds V that can be used are in principle any of the substances which are capable of forming inorganic nanoparticles via chemical reactions in a solvent. It is also possible to use a mixture of various compounds V. By way of example, compounds V that may be mentioned are those that form inorganic nanoparticles via a sequence of hydrolysis and condensation reactions (sol-gel process). Preferred compounds V used are those substances which lead to formation of inorganic nanoparticles comprising metal oxides or semimetal oxides, metal sulfides or semimetal sulfides, metal selenides or semimetal selenides, metal nitrides or semimetal nitrides, metal sulfates or semimetal sulfates, or metal carbonates or semimetal carbonates. Particular preference is given here to those compounds V which lead to formation of inorganic nanoparticles comprising metal oxides or comprising semimetal oxides, particularly preferably those leading to metal oxides. Compounds V of this type comprise, for example, the elements Si, Zn, Ti, Ce, Zr, Sn, Fe. Preference is given to Zn, Ti, Sn. In one embodiment, the compounds V are Ti(OH)₄, Ti(OEt)₄, titanium tetrapropoxide (Ti(OPr)₄), titanium tetraisoprop- oxide (Ti(OiPr)₄), Zn (acetate) ₂ (Zn(OAc)₂), Zn (methacrylate) 2, Zn (benzoate) ₂, ZnCl₂, ZnBr₂, Zn (NO₃) ₂, or SnCl₄. Preference is given to Zn(OAc)₂, Zn(NO₃J₂, Ti(OiPr)₄, or SnCl₄. The crystals of the compounds V can, if appropriate, comprise water of crystallization (e.g. Zn(OAc)₂ x 2 H₂O) .

In another embodiment of the particles of the invention, compounds V used for formation of the inorganic nanoparticles are other metal salts.

Preference is given here to use of the metal salts of mono- to pentavalent metal cations. It is particularly preferable to use the metal salts of di- to tetravalent metal cations. Examples of metal cations that can be used are alkali metal ions, alkaline earth metal ions, earth metal ions, or transition metal ions. Preferred metal cations are Zn(II), Ti(IV), Ce(I), Ce(III), Zr(II), Sn(II), Sn(IV), Fe(II), Fe(III). Particular preference is given to Zn(II), Ti(IV). The compounds V are preferably metal salts having acetate, formate, or benzoate anions. Acetate is particularly preferred.

As mentioned above, preference is also given to those compounds V which lead to formation of inorganic nanoparticles in a solvent and which comprise metal oxides or a mixture of these. Particular preference is given here to metal oxides of the form A_x0_y, where

x is a number in the range from 1 to 3, and

y is a number in the range from 1 to 5, and

A is a metal. Very particularly preferred metal oxides are ZnO, TiC>₂, ZrO₂, CeO₂, Ce₂Oa, SnO₂, SnO, Al₂O₃, SiO₂, or Fe₂O₃, in particular ZnO, TiO₂, ZrO₂, CeO₂, Ce₂O₃, SnO₂.

Preferred solvents used are water, methanol, ethanol, n- propanol, isopropanol, toluene, benzene, xylene, tetrahydrofuran, dioxane, dimethylformamide, benzyl alcohol, cyclopentanone, cyclohexanone, or a mixture of said solvents. It is very preferable that the solvent comprises water, ethanol, or toluene.

The modifiers of the invention interact with the inorganic nanoparticles based on the compounds V. It is preferable that said interaction takes place at the surface of the inorganic nanoparticles, the modified nanoparticles of the invention then being in essence surface-modified inorganic nanoparticles. The ratio by weight of modifier to nanoparticles can vary widely, and equally the structure of the modified nanoparticles of the invention can generally vary widely, for example as a function of the nature of the compound V. By way of example, the modifier can have been dispersed within the nanoparticle or its location can be at the surface of the particle. The distribution of the modifier in the particle can be homogeneous or heterogeneous. It is preferable that the location of the modifier is at or in essence at the surface of the particles. The covering of the surface of the nanoparticles by the modifier can be complete or partial, for example taking the form of individual islands. An example of a method for determining the distribution of the modifier in the particles determines the crystallinity of the particles with the aid of TEM measurements or X-ray diffraction. By way of example, distribution of the modifier in the particles generally disrupts the crystallinity of the particles more than distribution of the modifier in essence at the surface of the particles.

The size of the inorganic nanoparticles and of the modified nanoparticles of the invention is preferably from 1 nm to 1000 nm. The particle size is preferably from 1 nm to 100 nm. The particle size is particularly preferably from 1 nm to 50 nm, very particularly preferably from 1 nm to 30 nm, and in particular from 1 nm to 20 nm.

The type of interaction between modifier and nanoparticle can differ. By way of example, there can be covalent bonding between the modifier and the inorganic nanoparticle. Other possibilities are electrostatic (ionic) interaction, or interaction by way of dipole-dipole forces, or by way of hydrogen bonds. It is preferable that the modifier interacts covalently or electrostatically with the nanoparticles. It is also possible, of course, that the modifier interacts at a plurality of sites with the inorganic nanoparticle, for example forming a plurality of covalent bonds, or having not only covalent linkage but also other interactions with the nanoparticle, for example by way of hydrogen bonds.

The present invention also provides a process for making additions to thermoplastic polymers, where the modified nanoparticles of the invention are added to the polymers. One of the advantages of the modified nanoparticles of the invention is that there is very little tendency of the modifier toward migration in the polymer. In one preferred embodiment, the modified nanoparticles used for this purpose comprise those obtainable via reaction of compounds V which lead to formation of ZnO nanoparticles or which lead to TiO₂ nanoparticles, in a solvent, and immediate admixture of the modifier with the resultant dispersion.

In one embodiment, the reaction of the compounds V to give the inorganic nanoparticles takes place in a solvent and permits controlled production of a dispersion D of the nanoparticles in the solvent. Controlled production of the modified nanoparticles of the invention is achieved because the modifier is added to the dispersion immediately after the production of the dispersion D, without, for example, prior drying of the dispersion to give a powder. "Immediate" addition of the modifier to the dispersion means that the nanoparticles are not first isolated via removal of the solvent and then reacted in dry form or after redispersion. The precise juncture for addition of the modifier to the dispersion depends on the desired particle size or particle size distribution and can be determined by the person skilled in the art through preparatory experiments, for example by using light scattering. For controlled and reproducible production of the modified nanoparticles of the invention, it is important that the inorganic nanoparticles have a precisely defined initial condition in the dispersion D. The process minimizes the proportion of side reactions of the inorganic nanoparticles, e.g. through agglomeration. In one embodiment, the production of the modified nanoparticles of the invention comprises the following steps:

(A) provision of the compound V, optionally dissolved in a solvent,

(B) reaction of the compound V from (A) , optionally with addition of further substances, such as emulsifiers and/or catalysts, in a solvent to give inorganic nanoparticles with formation of a dispersion D,

(C) provision of the modifier, optionally dissolved in a solvent,

(D) addition of the modifier to the dispersion D from step (B) ,

(E) reaction of the modifier with the inorganic nanoparticles, optionally with increase of temperature and/or the use of further substances,

(F) optionally isolation of the modified nanoparticles,

(G) optionally purification and work-up of the modified nanoparticles,

(H) optional further modification of the modified nanoparticles,

(I) optionally redispersion of the modified nanoparticles .

In one preferred embodiment of the process for the production of the modified nanoparticles, in step (A) and/or step (C) , the compounds V and/or the modifier are dissolved in a solvent. It is particularly preferable that not only the compounds V but also the modifier has/have been dissolved in a solvent and are mixed in dissolved form, and in particular the compounds V and the modifier have been dissolved in the same solvent. Preference is further given in the process of the invention, in step (B) , to addition of further substances, such as initiators or catalysts, for the formation of the inorganic nanoparticles . By way of example, further substances used are bases, in particular EtONa, EtOK, EtOLi, PrONa, MeONa, NaOH, LiOH, KOH, trialkylamines, tetraalkylammonium hydroxides, or acids, in particular HCl, H₂SO₄, HNO₃, acetic acid, or salts, in particular tetraalkylammonium halides. In one embodiment of the process, in step (D) , mixtures of various modifiers can be used. The mixture of various modifiers can be provided prior to addition to the dispersion, or else can be produced in the dispersion via the respective addition of the various modifiers. Addition of the various modifiers in step (D) here can be simultaneous or non-simultaneous, overlapping or sequential, as long as one of the modifiers is added immediately after formation of the dispersion D. In one preferred embodiment, the production of the modified nanoparticles of the invention comprises the following steps: (A) Provision of Zn(OAc)₂ in ethanol. (B) Reaction of Zn(OAc)₂ in the presence of base, preferably NaOH or LiOH, to give ZnO nanoparticles. (C) Provision of the modifier in ethanol. (D) Addition of the dissolved substance M to the dispersion from step (B) . (E) Reaction of the modifier with ZnO nanoparticles. (F) Optional isolation of the modified nanoparticles. (G) Optional purification and work-up of the modified nanoparticles. (H) Optional further modification of the modified nanoparticles . (I) Optional redispersion of the modified nanoparticles.

In another preferred embodiment, the production of the modified nanoparticles of the invention comprises the following steps: (A) Provision of Ti(OiPr)₄ in hexane. (B) Addition of emulsifiers tetrabutylammonium bromide and reaction of Ti(OiPr)₄ in the presence of water to give Tiθ₂ nanoparticles. (C) Provision of the modifier in ethanol. (D) Addition of the modifier to the dispersion from (B) . (E) Reaction of the modifier with TiO₂ nanoparticles. (F) Optional isolation of the modified nanoparticles. (G) Optional purification and work-up of the modified nanoparticles. (H) Optional further modification of the modified nanoparticles. (I) Optional redispersion of the modified nanoparticles.

The pressure and temperature are generally of no great importance for the production of the modified nanoparticles of the invention. The selection of the temperature can have an effect on particle size, and naturally depends on the compounds V used. The reaction temperature is usually in the range from -5°C to 300⁰C, frequently in the range from 10 to 150⁰C. The reaction temperature is preferably in the range from 20 to 70⁰C. The reaction is usually carried out at atmospheric pressure or ambient pressure. However, it can also be carried out in the pressure range from atmospheric pressure up to 50 bar. Another advantage of the production process is that the particle size of the modified nanoparticles of the invention can be adjusted in a controlled manner. In particular, as mentioned above, it is possible to achieve targeted adjustment of the size of the modified nanoparticles by way of the reaction with the modifier, which takes place immediately after formation of the nanoparticles .

This variation of particle size can also be used to adjust the properties of the modified nanoparticles. According to the invention, for example, it is possible to vary the UV absorption properties of the modified nanoparticles, as a function of use. Examples of other properties which the person skilled in the art can adjust through routine experiments are the solubility properties of the modified nanoparticles and the transparency of the materials comprising the modified nanoparticles.

However, the modified nanoparticles of the invention can also be produced by using nanoparticles produced by other processes. Suitable nanoparticles can by way of example consist essentially of zinc oxide, silicon dioxide, aluminum oxide, titanium oxide, zirconium oxide, or cerium oxide, and can have been produced via precipitation from alcoholic or aqueous-alcoholic solutions of the corresponding salts through addition of alkalis, and the precipitation can have been carried out in the presence of the modifier, or the resultant suspension can have been treated with the modifier. A powder can be obtained from the suspension, by evaporating the solvent.

Examples of suitable alcohols are methanol, ethanol, n- propanol, and isopropanol. Examples of suitable alkalis are LiOH, NaOH, KOH, and NH₄OH.

By way of example, suitable nanoparticles can be produced as described in JP 04-357114. In an example, ZnO nanoparticles (0 < 50 nm) are produced via hydrolysis of a solution of a Zn salt (e.g. zinc chloride, zinc nitrate, zinc sulfate, or zinc acetate) . Examples of suitable solvents are alcohols, such as methanol, ethanol, n- propanol, or isopropanol, or a mixture of an alcohol and water. Operations here are carried out at a temperature ≥ 60⁰C and at a pH ≥ 9. The pH value is set via addition of an alkaline solution, for example of an aqueous solution of NaOH or KOH. If the reaction temperature is < 60⁰C or the pH is ≤ 9, the ZnO hydrosol is formed. The modification process can then be carried out in organic solvent. Suitable nanoparticles can also be produced as in JP 11- 279524. Accordingly, nanoparticulate ZnO (1 nm < 0 < 20 nm) is produced via mixing of an ethanolic solution of a Zn salt (such as zinc chloride, zinc nitrate, zinc stearate or zinc oleate) with an ethanolic solution of alkali (potassium hydroxide, sodium hydroxide, or ammonia) at pH ≤ 8, particularly preferably at pH ≤ 7.2. The mixing can be carried out continuously or batchwise. The modification process can then be carried out in organic solvent.

Suitable nanoparticles can also be produced as described in EP 1 157 064. In this process, a zinc oxide gel comprising ZnO nanoparticles (0 < 15 nm) is produced via basic hydrolysis of a Zn compound in alcohol or in an alcohol/water mixture. The hydrolysis process can be carried out in the presence of the modifier. The process is characterized in that the precipitate precipitated during the hydrolysis process is allowed to age until complete flocculation of the ZnO has taken place, and this is then compacted to give a gel and isolated from the supernatant phase (by-products) . Preferred zinc salt is zinc acetate, preferred base is KOH, and preferred alcohol is methanol. It is preferable to use a substoichiometric amount of the base .

Suitable nanoparticles can also be produced as described in DE 103 20 435, which describes 1.) the batchwise production of ZnO particles, by admixing a methanolic KOH solution with a methanolic zinc acetate solution, in a KOH/Zn ratio of from 1.7 to 1.8, with stirring, allowing the product to age at a temperature of from 40 to 65⁰C for a period of from 5 to 50 minutes, and then cooling it to a temperature ≤ 25⁰C. That document also describes 2.) the continuous production of ZnO particles by mixing a methanolic zinc acetate solution and a methanolic KOH solution in a KOH/Zn ratio of from 1.7 to 1.8 in a mixing element, aging the resultant precipitation suspension at a temperature of from 40 to 65°C for a period of from 5 to 50 minutes, and then cooling the mixture to a temperature ≤ 25⁰C.

Suitable nanoparticles can also be produced as described in US 2005/0260122. Here, oxidic nanoparticles (Al oxides, Ti oxides, Fe oxides, Cu oxides, Zr oxides, and other oxides, in particular ZnO) are produced via addition of an alcoholic solution of a metal salt to an alkaline alcoholic solution or, respectively, suspension. Suitable alcohols are methanol, ethanol, n-propanol and isopropanol. Suitable alkalis are LiOH, NaOH, KOH, NH₄OH. The process is characterized in that the metal salt solutions are added to the alkaline solutions and the pH is kept at pH > 7 during the entire reaction.

Suitable nanoparticles can also be produced as described in US 2006/0222586, which describes a process for the production of ZnO sol comprising crystalline ZnO nanoparticles (0 <15 nm) via a) hydrolysis of a Zn salt in an ethylene glycol solution at pH from 8 to 11, b) if appropriate, concentration of the precipitate to give Zn concentrations of from 0.3 to 3 mol/L, by allowing the mixture to settle and then removing the supernatant solvent, and c) aging of the precipitate at from 40 to 100⁰C for from 1 to 6 hours, until a transparent sol has formed .

The surface of the nanoparticles can additionally be coated. By way of example, ZnO particles or TiO₂ particles can be provided with a coating of SiO₂, in order to counteract the photocatalytic activity of said particles. This coating process can take place prior to the modification of the nanoparticles or simultaneously therewith.

The modification of the nanoparticles can be carried out in a manner known per se, e.g. corresponding to WO 2007/011980 A2. In one embodiment, the nanoparticles in powder form are brought into contact with the modifier. In another embodiment, the modifier is dissolved or dispersed in a solvent and in this form is brought into contact with the nanoparticles in dry form or in dispersed form. For the modification process, the metal oxide particles and the modifier are mixed in suitable mixing apparatuses, and preference is given here to the use of high shear forces.

In another embodiment, nanoparticles and modifier are brought into a contact by shaking or stirring. In one preferred embodiment, the solvents used in the modification process are good solvents. The dielectric constant of preferred solvents is greater than 5, preferably greater than 10. Particularly preferred polar solvents used are water, alcohols, in particular methanol, ethanol, 1-propanol, 2-propanol, ethers, in particular tetrahydrofuran, or a mixture of these. In one embodiment, the reaction can be carried out in the presence of a base (for example of an aqueous or alcoholic ammonia solution) , of an acid (such as hydrochloric acid) , or of at least one catalyst (such as organotitanium compounds, e.g. tetrabutyl titanate, or organotin compounds, e.g. dibutyltin dilaurate) which promote the hydrolysis or condensation of the modifier. The metal oxide particles can be modified with the modifier alone or with a mixture of the modifier in combination with further conventional surface functionalizing agents.

The amounts usually used of the modifier are, based on the nanoparticles, from 1 to 60% by weight, preferably from 2 to 30% by weight. The reaction with the nanoparticles preferably takes place at from 5 to 100⁰C, in particular from 40 to 70⁰C, within a period which is preferably from 6 minutes to 300 hours, in particular from 2 to 72 hours. The solvents and by-products can by way of example be removed by distillation, filtration (e.g. nanofiltration, ultrafiltration or Microcross filtration) , membrane processes, centrifugation, or decantation, or can be replaced by other solvents.

In another embodiment of the invention, the metal oxide particles also comprise an amorphous layer which comprises silicon and oxygen, aluminum and oxygen, or zirconium and oxygen, or they comprise a combination or mixture of these, and preferably comprise an amorphous SiO₂-, Al₂O₃-, or ZrO₂- containing layer or a mixture of these, applied prior to the reaction with the modifier.

The coatings can to some extent comprise hydrate groups or hydroxide groups. Coatings of this type are well known to the person skilled in the art (see, for example, US-A 2 885

366, DE-A 159 29 51, US-A 4 447 270, EP 449 888 Bl), and are obtainable by way of example via deposition of hydrolyzable Si-, Al- or Zr-containing precursors. Examples of materials used for this purpose are silicates, aluminates, or zirconates (e.g. sodium silicate, sodium aluminate or sodium zirconate) or a mixture of these. It is also possible to use acids (e.g. silicas, such as orthosilicic acid H₄SiO₄, or condensates of these, e.g. disilicic acid HgSi₂O₇, or polysilicic acids, for a coating comprising SiO₂; or to use metazirconic acid H₂ZrOa or orthozirconic acid H₄ZrO₄, for a coating comprising ZrO₂) , or to use hydroxides (e.g. Al(OH)₃). It is also possible to use organometallic precursors of Si, Al, or Zr, or a mixture of these, where these hydrolyze to produce SiO₂, AI₂O₃, or ZrO₂, or their hydrates or oxyhydroxides . Precursors of this type are known to the person skilled in the art. To produce an Si0₂-containing layer, for example, tetraalkoxysilanes (Si(OR)₄, e.g. tetramethoxysilane, tetraethoxysilane) are used. To produce an Al₂θ₃-containing layer, for example, Al alcoholates are used (e.g. aluminum isopropanolate, aluminum isobutanolate) . To produce a ZrO₂- containing layer, for example, Zr alcoholates are used (e.g. zirconium isopropanolate, zirconium n-butanolate, zirconium isobutanolate) .

The solids content of liquid formulations of the modified nanoparticles of the invention is generally in the range from 1 to 90% by weight and in particular in the range from 5 to 70% by weight, based on the total weight of the liquid formulation.

The liquid formulations of the modified nanoparticles of the invention can be used directly after dilution or as they stand. The liquid formulations can also comprise conventional additives, e.g. additives that alter viscosity (thickeners) , antifoams, bactericides, frost stabilizers, and/or surface-active substances. Among the surface-active substances are protective colloids and also low-molecular- weight emulsifiers (surfactants) , the latter generally differing from the protective colloids through a molar mass below 2000 g/mol, in particular below 1000 g/mol (weight average) . The protective colloids or emulsifiers can be of either anionic, nonionic, cationic, or zwitterionic type. The liquid formulations can also be formulated with conventional binders, for example with aqueous polymer dispersions, with water-soluble resins, or with waxes.

The modified nanoparticles of the invention are comprised within the liquid formulations and can be obtained in powder form from said liquid formulations (step (F) and (G) of the process of the invention) by removing the volatile constituents of the liquid phase. The form in which the modified nanoparticles of the invention are present in the powder can be either separate, agglomerated, or else to some extent that of a film. The powders here are obtainable by way of example through evaporation of the liquid phase, freeze drying, or spray drying. Liquid formulations of the invention are often obtainable via redispersion of the powders (step (I) of the process of the invention), for example in ethanol or toluene.

Solid formulations comprise, as a function of the application, a different concentration of the modified nanoparticles of the invention, which is generally in the range from 0.1 to 50% by weight and in particular in the range from 0.5 to 20% by weight, based on the total weight of the solid formulation.

By way of example, the solid formulations are a mixture of the modified nanoparticles of the invention in a carrier material, e.g. polyethylene waxes. To produce the solid formulation, the modified nanoparticles can, for example, be introduced into the molten matrix via dispersion at an elevated temperature, whereupon cooling produces the solid formulation. The solid formulation can, if appropriate, also comprise auxiliaries which improve the dispersion of the modified nanoparticles in the solid matrix (dispersing agents) . By way of example, waxes can be used for this purpose. The solid formulations can be used without dilution or after dilution to the concentration required for use. Examples of solid formulations are the formulations obtained after the removal of the volatile constituents from the liquid formulations described above. These are generally mixtures/dispersions of modified nanoparticles with/in poly- or oligomers (in a masterbatch or in waxes, e.g. Luwax^® from BASF SE), where these take the form of powders or waxes.

In one preferred embodiment, solid formulations are produced by dissolving or suspending a wax, such as a polyolefin wax, in particular a polyethylene wax such as Luwax^®, in a suitable solvent. Suitable solvents that can be used here are nonpolar organic solvents, preferably toluene, xylenes, or Solvesso. The dissolved or suspended wax is mixed with a liquid formulation of the modified nanoparticles, for example a dispersion of the modified nanoparticles, in an identical or different solvent. Suitable solvents for the liquid formulation are the abovementioned solvents. The mixing process is preferably continued until the mixture is homogeneous. The solvent or solvent mixture is then removed, for example via rotary evaporation or via distillation. After removal of the solvent, the product is preferably a homogeneous wax, which comprises the modified nanoparticles. The wax comprising the modified nanoparticles can be incorporated into thermoplastic polymers by the known processes. The solid or liquid formulations and the powders obtainable therefrom via removal of the liquid phase have the advantage that the modifier and also the inorganic constituents of the nanoparticles are held within the modified nanoparticles and, over a prolonged period, are not dissipated into the environment. The modifier and/or the inorganic nanoparticles are therefore present in a form which is particularly advantageous for their application. Furthermore, in the case of metal-containing inorganic nanoparticles, the metals are often inhibited from leaving the modified nanoparticles. This method can be used, for example, to control the action of the (cations of the) metals .

The modified nanoparticles of the invention in the form of their solid or liquid formulations or powders are preferably used for making additions to thermoplastic polymers. To this end, the particles can be incorporated into the organic polymers either in the form of solid or liquid formulation or else in the form of powders, by the usual methods. Mention may be made here by way of example of the mixing of the particles with the thermoplastic polymers prior to or during an extrusion step.

Thermoplastic polymers here are any desired thermoplastic and foils, fibers, or moldings of any design produced therefrom. These are also referred to by the simple term thermoplastic polymers for the purposes of this application. The thermoplastic polymers are preferably polyamides and copolymers of styrene or of methylstyrene with dienes and/or with acrylic derivatives, e.g. styrene- acrylonitrile copolymers (SAN) , acrylonitrile-butadiene- styrene copolymers (ABS) or acrylonitrile-styrene-acrylate copolymers (ASA) . Other examples of suitable thermoplastic polymers are polymethyl methacrylate (PMMA) , polycarbonate (PC) , polysulfone, polybutylene terephthalate (PBT) , and polyoxymethylene (POM). An example of a procedure for modifying a thermoplastic polymer first melts the polymer in an extruder, incorporates a particulate powder produced according to the invention into the polymer melt at a temperature of, for example, from 180 to 200⁰C, and produces pellets therefrom, from which it is then possible to produce foils, fibers, or moldings, by known processes.

The amount of modified nanoparticles which is sufficient in the polymer for the modification of the same can vary widely as a function of the modified nanoparticles or the intended use. It is preferable that the stabilized polymers comprise from 0.05 to 20% by volume of the modified nanoparticles, based on the total volume of the mixture. A very particularly preferred amount is from 0.1 to 10% by volume.

For the purposes of the use in the invention, it is, of course, also possible to use a mixture of various modified nanoparticles of the invention. The constitution and size distributions of the particles of said mixture can be identical or different.

For the use for addition to other materials, for example for the stabilization of thermoplastic polymers, the modified nanoparticles of the invention can also be used together with other additive systems, with the aim of improving overall effectiveness, for example with conventional emulsion concentrates, suspension concentrates, or suspoemulsion concentrates of polymer additives. Blending of the modified nanoparticles of the invention with conventional preparations of the abovementioned polymer additives achieves firstly a broadening of the activity profile, if the conventional preparation comprises polymer additives other than the particles of the invention, and secondly the advantages of the modified nanoparticles of the invention, in particular the improved migration resistance, are not lost through formulation with conventional polymer additive preparations. It is therefore possible to improve the performance characteristics of a conventional polymer additive preparation via formulation with modified nanoparticles of the invention.

In one preferred embodiment, the modified nanoparticles of the invention are used together with further stabilizers for the stabilization of polymers. Particular further stabilizers used for this purpose are UV absorbers, antioxidants, sterically hindered amines, nickel compounds, metal deactivators, phosphites, phosphonites, hydroxylamines, nitrones, amine oxides, benzofuranones, indolinones, thiosynergists, compounds that decompose peroxide, or basic costabilizers .

The amount of further stabilizers in the polymer can vary widely as a function of the stabilizer or the intended purpose. It is preferable that the stabilized polymers comprise from 0.01 to 2% by weight of the further stabilizers, very particularly from 0.05 to 1.0% by weight, based on the total weight of the mixture.

In one embodiment, the process for the incorporation of the modified nanoparticles of the invention into a polymer melt of a matrix polymer comprises the steps of (a) provision of modified nanoparticles in the form of a powder or in the form of a suspension;

(b) mixing of the modified nanoparticles with the matrix polymer itself and/or with a carrier polymer which has been dissolved in an organic solvent which is compatible with the matrix polymer,

(c) dispersion of the modified nanoparticles in the mixture of step (b) , where a stable dispersion of the modified nanoparticles is obtained,

(d) incorporation of the dispersion of step (c) into a melt of further matrix polymer in an extruder which has a plurality of compression zones, where the dispersion is brought into contact with the melt in a first compression zone at a pressure which is above the vapor pressure of the solvent of the dispersion at the temperature of the melt. In a step (b) , the modified nanoparticles are mixed with the matrix polymer itself and/or with a carrier polymer which has been dissolved in an organic solvent which is compatible with the matrix polymer. The modified manoparticles are then dispersed in the mixture (step (c) ) . This step is also termed "completion", and accordingly the polymer added is termed completion polymer. The completion polymer can be the matrix polymer or a carrier polymer which differs from the matrix polymer but is compatible therewith.

The selection of solvent is determined by the solution properties of the solvent for the respective polymer (carrier polymer or matrix polymer) and the boiling point, which must be neither too low nor too high relative to the processing temperature of the polymer. A result of excessively low boiling point is excessively rapid evaporation of the solvent at the injection nozzle during metering of the dispersion into the extruder, and thus blocking of the nozzle by the dispersion solidifying therein. A result of an excessively high boiling point, in particular above the processing temperature of the polymer in the extruder, is to inhibit complete extraction from the melt within the devolatilizing zones of the extruder. The boiling point of the solvent is generally at least 10⁰C below, preferably at least 60°C below, the processing temperature of the polymer melt in the extruder. The boiling point of the solvent is generally in the range from 80 to 210⁰C, preferably in the range from 100 to 160⁰C.

Preferred solvents are tetrahydrofuran, dimethylformamide, benzyl alcohol, cyclopentanone, cyclohexanone, toluene, xylene, N-methylpyrrolidone, methyl isobutyl ketone, and hexafluoroisopropanol .

If the matrix polymer is insoluble or is soluble only in solvents that cannot be used industrially, it is also possible to select a soluble carrier polymer for the completion process. Care has to be taken here to avoid any adverse effect of the carrier polymer on the properties of the end product, or any substantial expulsion of the carrier polymer out of the polymer melt, e.g. as a result of decomposition into low-molecular-weight components, during extrusion of the polymer melt.

In one embodiment, Ultramid 1C (PA 6/PA 66 copolymer) is added as carrier polymer when the intention is to incorporate the modified nanoparticles into nylon-6 (PA 6; poly-epsilon-caprolactam) as matrix polymer. This material is substantially degraded during processing in PA 6 at temperatures around 240⁰C.

In another embodiment, SANMA (styrene/acrylonitrile/maleic anhydride copolymer) is added as carrier polymer. During processing in the extruder, this reacts in the polymer melt with the terminal amino groups of nylon-6 or nylon-6, 6 as matrix polymer, and thus becomes chemically bonded to the matrix polymer. The energy that can be introduced by virtue of shear through the screws of the extruder is not sufficient to disperse very small, aggregated nanoparticles adequately without giving rise to any undesired phenomena. A further advantage of the modified nanoparticles of the invention is therefore that they have no tendency to form hard agglomerates.

The dispersion process can be carried out with stirring, e.g. using a dissolver disk, and, if appropriate, with heat. The temperature is typically, for example, from 60 °C to 80⁰C, when Ultramid 1 C (PA 6/ PA 66) is used as carrier polymer and benzyl alcohol is used as solvent. The completion polymer (carrier polymer or matrix polymer) here is preferably added in small portions. Further completion polymer is preferably added only when the preceding portion has dissolved completely. The ideal amount of completion polymer added in step (d) can be determined empirically. It is generally in the range from 5 to 30% by weight, based on the entire mixture.

The limiting polymer concentration in the dispersion can be determined by means of UV-VIS spectroscopy. Reaggregation processes which are a consequence of excessive polymer concentration lead to marked loss of transmittance in the wavelength region around 500 nm +/- 50 nm. An upper limit for polymer concentration is also set via the viscosity of the dispersion. The dispersion should not exceed the limits of good pumpability. The dispersion process for the mixture composed of nanoparticle dispersion and completion polymer (carrier polymer or matrix polymer) can also be carried out in a stirred ball mill, or any other type of ball mill, in a planetary gear mill, in a kneader, in a grinding tank, or in any other dispersion assembly. At low modifier concentrations, preference is given to the dispersion process in a mill or in a kneader, since otherwise it often becomes impossible to achieve homogeneous, aggregate-free dispersion of the nanoparticles in the mixture. The process here uses momentum transmission to break up the nanoparticle aggregates and separate the constituents from one another. Addition of a dispersing agent can be advantageous in order to inhibit rapid reaggregation of the nanoparticles while they are still within the mill, or during storage prior to further processing of the mixture in an extruder (step (e) ) .

In the simplest case, the dispersion assembly is a grinding tank, for example a steel container which has a charge of SAZ beads, where the mixture composed of nanoparticle dispersion and completion polymer is charged to said container. The mixture and SAZ beads are propelled by rotating perforated plates. The heat thus liberated is dissipated by a coolant. The grinding conditions (time, type, size, and amount of grinding material, rotation rate) are generally selected in such a way as to avoid damaging the primary particles and thus to avoid altering the particle size distribution disadvantageously . A step (d) incorporates the dispersion from step (c) into a melt of the matrix polymer, in an extruder.

Preferred matrix polymers are thermoplastics, such as SAN, ABS, ASA, nylon-6, or nylon-6,6. Other suitable thermo- plastics are PMMA, PC, polysulfones, PBT, and POM.

The extruder used for incorporating the nanoparticle dispersion is preferably a corotating, tightly intermeshing twin-screw extruder. The matrix polymer is fed at the ingoing end of the extruder, and completely plastified through a homogenizing zone suitable for the matrix polymer. Reverse-conveying screw elements then retard the melt and increase pressure. The extent of this back pressure depends on the solvent used in the nanodispersion. The temperature of the polymer melt is generally from 160 to 340⁰C, preferably from 200 to 300⁰C. The back pressure has to be above the vapor pressure of the solvent at the polymer melt temperature. The back pressure is generally from 1 to 30 bar, preferably from 5 to 15 bar.

The nanoparticle dispersion is injected into this zone of retardation (1st compression zone) . As a function of the viscosity of the nanoparticle dispersion, various pump systems are used to increase the pressure (gear pump, HPLC pump, piston-action diaphragm pump, excentric screw pump) . The pressure prevailing in the injection zone ensures that the dispersion remains liquid. Additional mixing elements within the injection zone mix the nanoparticle dispersion and the melt.

After the mixing process, the melt flows by way of the reverse-conveying screw elements into the 1st vacuum zone (2nd compression zone) . By virtue of the pressure drop, the solvent boils and is converted to the vapor phase. The resultant solvent vapor is removed by way of the vacuum system. In order to guarantee complete devolatilization of the resultant nanocomposite, a plurality of vacuum zones can be arranged in succession (2nd and further compression zones) . These zones are separated by reverse-conveying elements. The vacuum applied in the subsequent vacuum zone should be better than in the preceding zone.

The pressure in the 1st vacuum zone is generally from 1013 bar (ambient pressure) to 900 mbar (absolute) , preferably from 1013 bar to 950 mbar. The pressure in the 2nd vacuum zone is generally from 100 to 500 mbar, preferably from 100 to 200 mbar. The pressure in the 3rd vacuum zone is generally from 5 to 50 mbar, preferably from 5 to 10 mbar.

It is also possible to use an entrainer to promote the devolatilization process. The entrainer can be added between the devolatilization stages. The nature of this entrainer has to be such that the solvent used, derived from the nanodispersion, has high solubility in the entrainer. Suitable entrainers are generally low-boiling- point solvents, e.g. low-boiling-point alcohols, water, CO₂, and N₂. The content of finely dispersed modified nanoparticles in the resultant polymer melt is generally from 0.05 to 10% by volume, preferably from 0.1 to 3% by volume, based on the entirety of all of the components of the melt. The polymer melt comprising the finely dispersed modified nanoparticles is preferably further processed directly via extrusion to give foils or to give other semifinished products. Another possibility is the production of pellets. The pellets can be processed to give moldings in downstream processes, for example injection molding. These can be used by way of example as facade cladding, equipment casings, motor-vehicle add-on parts, structural elements, etc.

The invention also provides a polymer material which is composed of a matrix polymer and of modified nanoparticles finely dispersed therein, and which is obtainable by the process of the invention. In one embodiment of the invention, the content of nanoparticles is from 0.05 to 0.8% by volume, preferably from 0.1 to 0.5% by volume. In one embodiment of the invention, the matrix polymer is a styrene/acrylonitrile copolymer (SAN) . In another embodiment, the nanoparticles are zinc oxide nanoparticles, modified by a modifier of the invention. Inclusion of the finely dispersed nanoparticles into the matrix polymer leads to an improvement in the mechanical properties of the polymer material in relation to fracture. The examples below provide further explanation of the invention.

Examples

Synthesis of modifiers of the invention Example 1

Production of CH₃O[CH₂CH(CH₃)O]₃(CH₂)_BSi(OEt)₃

a) Production of the allyl alkoxylate

HO [CH₂CH (CH₃) 0] ₃CH₂CHCH₂

A mixture of allyl alcohol (174 g, 3.0 mol) and potassium tert-butanolate (4.18 g) was concentrated for 3 h at 100⁰C and from 3 to 4 mbar on a rotary evaporator. The mixture was then used as initial charge in a 2 1 pressurized autoclave from Mettler, and inertized three times with nitrogen at up to 5 bar, and the temperature was increased to 130°C. Propylene oxide (522 g, 9.0 mol) was then fed, and once the addition had ended stirring was continued overnight. This gave 700 g of allyl alcohol-3PO [¹H NMR(CDCl₃): δ= 5.88 (m, IH), 5.24 (m, 2H), 4.0-3.1 (m, HH) , 1.13 (m, 9H) ppm; polydispersity d = 1.10] b) Production of the methyl ether of the allyl alkoxylate CH₃O [CH₂CH (CH₃) 0] ₃CH₂CHCH₂

Allyl alcohol-3PO (483 g, 2.08 mol) was used as initial charge in a stirred apparatus, and 50% strength aqueous NaOH solution (957 g, 12.0 mol) was admixed with this dropwise at from 34 to 36°C. Dimethyl sulfate (349 ml, 3.68 mol) was then fed at 36°C within a period of 1 h. The reaction mixture was stirred overnight at 40⁰C and then, after addition of water (2080 g) , for 1 h at 95°C. The two phases were separated in a separating funnel and the organic phase was freed from the remaining water on a rotary evaporator. Ambosol (3% by weight) was then admixed with the compound, and the mixture was filtered and stabilized with 0.025% by weight of aqueous 33% strength sodium benzoate solution. This gave 419 g of product with >95% etherification level (¹H NMR after functionalization with trichloroacetyl isocyanate) . c) Hydrosilylation

The methyl ether of the allyl alkoxylate (199 g, 0.81 mol) was used as initial charge, and the apparatus was blanketed with argon. Triethoxysilane (150 ml, 1.0 mol) was then injected by way of a septum, and the reaction mixture was heated to from 80 to 90⁰C. Hexachloroplatinic acid (0.35 ml, 7.5% strength solution in isopropanol) was then added by way of a syringe and once the addition had ended stirring was continued for a further 15 min. This gave 305 g of CH₃O [CH₂CH (CH₃) O] ₃ (CH₂J₃Si (OEt)₃ with 80% silanization level (¹H NMR) .

Example 2a

Production of CH₃O[CH₂CH(CH₃)O]₃(PO) (OH)₂

a) Production of CH₃O[CH₂CH(CH₃)O]₃H

A mixture of methanol (128 g, 4.0 mol) and potassium tert-butanolate (4.95 g) was used as initial charge in a 2 1 pressure autoclave from Mettler and inertized with nitrogen at up to 5 bar, and the temperature was increased to 110⁰C. Propylene oxide (696 g, 12.0 mol) was then fed, and once the addition had ended stirring of the mixture was continued overnight. This gave 829 g of methanol-3P0 [¹H NMR (CDCl₃): δ = 3.92-3.20 (m, 12H), 1.13 (m, 9H) ppm; polydispersity d = 1.11]. b) Production of CH₃O[CH₂CH(CH₃)O]₃(PO) (OH)₂

Methanol-3P0 (250 g, 1.21 mol) and toluene (150 ml) were used as initial charge and heated to 120⁰C. Vacuum was applied and all of the volatile constituents were removed by distillation. A further 150 ml of toluene were added, and the reaction mixture was inertized with nitrogen and heated to 80⁰C. Polyphosphoric acid (140.7 g, 0.822 mol) in toluene was then added dropwise. The reaction mixture was heated to reflux and the progress of the reaction was followed by means of thin-layer chromatography (mobile phase: acetone/toluene/methanol 2:3:1). Once the reaction had ended, water and toluene were removed by distillation at reduced pressure (from 1050 to 519 mbar) , using a bath temperature of 120⁰C. The residue was extracted with n- pentane and methanol. Removal of the solvent from the n- pentane phase gave 71.2 g of liguid product.

Example 2b

Production of CH3[OCH2CH(CH3)]3(PO)(OH)2

a) Herstellung von CH₃[OCH₂CH(CH₃)]₃OTS

0.11 mol tosyl chloride and 0.11 mol DABCO are added to a stirred solution of 0.1 mol methanol-3PO in tetrahydro- furane (200 ml) . After six hours of stirring at room temperature, the salt that has formed is removed by filtration. The solvent is evaporated under reduced pressure, leaving CH₃[OCH₂CH(CH₃)]₃OTS (= methanol-3P0- TS) . b) Production of CH₃ [OCH₂CH (CH₃) ] ₃ (PO) (OEt) ₂

0.11 mol sodium diethylphosphite, dissolved in a small amount of tetrahydrofurane, are added to a stirred solution of 0.1 mol methanol-3PO-TS in tetrahydrofurane (100 ml) . After six hours of stirring at room temperature, the mixture is heated to reflux for four hours. After the mixture has cooled to room temperature, the sodium tosylate that has formed is removed by filtration. The solvent is evaporated under reduced pressure, leaving CH₃ [OCH₂CH (CH₃) ] ₃ (PO) (OEt) ₂. c) Production of CH₃ [OCH₂CH (CH₃) ] ₃ (PO) (OH) ₂

CH₃[OCH₂CH(CH₃J]₃(PO) (OEt)₂ is added to an excess of concentrated hydrochloric acid and heated to boiling for 10 minutes, thereby forming CH₃ [OCH₂CH (CH₃) ] ₃ (PO) (OH) ₂ by hydrolysis.

Production of modified nanoparticles of the invention

Example 3

Production of ZnO

73.6 g of zinc acetate dihydrate (Chemetall) were suspended in 2236 ml of 2-propanol in a 42 1 flask and heated to 75°C. In parallel with this, 32.8 g of potassium hydroxide were dissolved in 1168 ml of 2-propanol at 75°C. The KOH solution was then added to the zinc acetate suspension with vigorous stirring, and the resultant mixture was heated for 1 hour at 75°C, with stirring, and cooled to room temperature. The resultant white precipitate was allowed to settle overnight, the supernatant liquor was removed by suction, and the white residue was washed with 1000 ml of 2-propanol and allowed to settle. The supernatant liquor was again removed by suction, and the white residue was washed with 2-propanol and allowed to settle. 2-Propanol was then added to the ZnO so as to give a 2% by weight ZnO dispersion.

Example 4

Modification of ZnO with CH₃O [CH₂CH (CH₃) 0] ₃ (CH₂) ₃Si (OEt) ₃

A solution of 0.5 g of CH₃O [CH₂CH (CH₃) 0] ₃ (CH₂) ₃Si (OEt ) ₃ in 26 ml of 2-propanol was added dropwise, with vigorous stirring, to 100 g of the 2% by weight ZnO suspension from example 3 over a period of 30 minutes. The suspension was heated to 60⁰C, and the mixture was heated at reflux for 30 minutes. 1.7 g of a 25% by weight aqueous NH₃ solution were then added, and the resultant suspension was heated at 60⁰C for 12 hours, with stirring, whereupon the suspension became transparent. 2-Propanol and NH₃ were then removed in a rotary evaporator at 50⁰C, until the pressure was constant at below 10 mbar. The white residue was then dried for a further 30 minutes in vacuo at < 10 mbar (resultant N/Zn ratio < 0.2% by weight).

Example 5

Modification of ZnO with CH₃O[CH₂CH(CH₃)O]₃P(O) (OH)₂

214.1 g of a solution of CH₃O[CH₂CH(CH₃)O]₃P(O) (OH)₂

(8.58 g, 0.03 mol) in 2-propanol were added dropwise to

1515 g of the 2% by weight ZnO suspension from example 3 with vigorous stirring. The mixture was heated at reflux for 1 h, whereupon the suspension became transparent. 2- Propanol was then removed in a rotary evaporator at 70°C/75 mbar. The pale yellow residue was then slurried in 400 ml of petroleum ether in an ultrasound bath at room temperature, with stirring. The solid was allowed to settle, and the supernatant liquor was removed by suction. The residue was again slurried in 400 ml of petroleum ether, and the solid was allowed to settle and the supernatant liquor was removed by suction. The residue was dissolved in 202 g of benzyl alcohol and remaining petroleum ether was removed in a rotary evaporator at 64°C/300 mbar.

Production of nanocomposites of the invention

Example 6

Modified zinc oxide produced according to example 5 was incorporated into cyclohexanone, using a dissolver. This suspension comprised 9.3% by weight of ZnO with average diameter 25 nm in cyclohexanone. SAN having 23% acrylonitrile content (15% by weight) was then added to, and dissolved in, this dispersion.

Small amounts of polymer were then added to the clear "solution", with stirring by a dissolver disk, with heating (from 60⁰C to 80⁰C) . No further polymer was introduced until all the material had dissolved. For SAN having 23% acrylonitrile content, in an initial charge of ZnO-DMF solution, the empirically determined maximum amount of polymer is about 20% by weight. A suitable measurement method for determining the limiting concentration is UV-VIS spectroscopy, which within the wavelength region around 500 nm +/- 50 nm reacts sensitively to reaggregation processes in the mixture, with a loss of transmittance. The viscosity of the mixture can also place an upper limit on polymer concentration. The mixture has to remain pumpable. The completion polymer is generally identical with the matrix polymer in which the nanoparticles are to be homogeneously dispersed in the extruder.

The extruder used was a ZSK 30 (corotating twin-screw extruder, diameter 30 mm) from Coperion Werner & Pfleiderer. The length/diameter ratio of the screw was 41. The rotation rate of the extruder was 250 rpm at a temperature of 230⁰C.

1.5 kg/h of SAN having 23% acrylonitrile content were added at the ingoing end of the extruder. The abovementioned nanodispersion was fed at 1.1 kg/h by way of a gear pump in the injection zone. The pressure in the 1st vacuum zone was ambient pressure, that in the 2nd vacuum zone was 200 mbar absolute, and that in the 3rd vacuum zone 50 mbar absolute. The nanocompound was discharged in the form of a strand by way of a pelletizing die (diameter 4 mm) and pelletized, or else extruded in the form of a foil.

Figures 1 and 2 show the resultant dispersion of the ZnO nanoparticles in the polymer in TEM images at 2 different magnifications. The ZnO particles are clearly seen to be separate and not agglomerated. Dispersion within the matrix polymer is very uniform. Example 7

Modified zinc oxide produced according to example 4 was incorporated into cyclohexanone, using a dissolver. This suspension comprised 9.3% by weight of ZnO with average diameter 25 nm in cyclohexanone. An amount corresponding to 15% by weight of PMMA (Lucryl^® G66, BASF SE) was then added to, and dissolved in, this dispersion.

1.5 kg/h of PMMA were added at the ingoing end of the extruder. The abovementioned nanodispersion was fed at 1.1 kg/h by way of a gear pump in the injection zone. The pressure in the 1st vacuum zone was ambient pressure, that in the 2nd vacuum zone was 200 mbar absolute, and that in the 3rd vacuum zone 50 mbar absolute. The nanocompound was discharged in the form of a strand by way of a pelletizing die (diameter 4 mm) and pelletized, or else extruded in the form of a foil.

Figures 3 and 4 show the resultant dispersion of the ZnO nanoparticles in the polymer in TEM images at 2 different magnifications. The ZnO particles are clearly seen to be separate and not agglomerated. Dispersion within the matrix polymer is very uniform. Example 8

If the intention is to incorporate the nanodispersion into a polymer which is not soluble in the solvents that can be used, the carrier-polymer method can be used. Instead of the insoluble base polymer, a compatible, soluble polymer is added to the dispersion. An example of this is the use of soluble Ultramid 1C in insoluble Ultramid B27 (PA6) .

Modified zinc oxide produced according to example 4 was incorporated into cyclohexanone, using a dissolver. This disperision comprised 9.3% by weight of ZnO with average diameter 19 nm in cyclohexanone. PA 6/6,6 copolymer (15% by weight) was added to this dispersion, and was dissolved with heating of the dispersion to from 60 to 80⁰C. The extruder used was a ZSK 30 (corotating twin-screw extruder, diameter 30 mm) from Coperion Werner & Pfleiderer. The length/diameter ratio of the screw was 41. The rotation rate of the extruder was 250 rpm at a temperature of 260⁰C.

1.5 kg/h of PA 6 were added at the ingoing end of the extruder. The abovementioned nanodispersion was fed at 1.1 kg/h by way of a gear pump in the injection zone. The pressure in the 1st vacuum zone was ambient pressure, that in the 2nd vacuum zone was 200 mbar absolute, and that in the 3rd vacuum zone 50 mbar absolute. The nanocompound was discharged in the form of a strand by way of a pelletizing die (diameter 4 mm) and pelletized, or else extruded in the form of a foil (thickness ~ 6 mm) .

Figures 5 and 6 show the resultant dispersion of the ZnO nanoparticles in the polymer in TEM images at 2 different magnifications. The ZnO particles are clearly seen to be separate and not agglomerated. Dispersion within the matrix polymer is very uniform.

Example 9

Example 8 was repeated, but modified zinc oxide produced according to example 5 was used instead of the modified zinc oxide produced according to example 4.

Figures 7 and 8 show the resultant dispersion of the ZnO nanoparticles in the polymer in TEM images at 2 different magnifications. The ZnO particles are clearly seen to be separate and not agglomerated. Dispersion within the matrix polymer is very uniform.

Example 10 (comparison)

Example 8 was repeated, but a zinc oxide modified with trioxadecanoic acid was used instead of the modified zinc oxide produced according to example 4.

Figures 9 and 10 show the resultant dispersion of the ZnO nanoparticles in the polymer, in images from an optical microscope (dark field) at 2 different magnifications. The dispersion of the ZnO particles in the matrix polymer is seen to be non-uniform and the particles are seen to form agglomerates with diameters in the micrometer range.

Claims

1. A modifier for nanoparticles, complying with the formula

Z- [O-CHR¹- (CH₂ ) _m] _n-OR²

in which

R¹ = H, CH₃, C₂H₅, phenyl;

R = CH₃, C₂H₅, C₃H₇, C₄H₉, or C₅Hn-Ci_OH_2I;

m = 1 or 2;

n = 1 to 4;

Z = (HO)₂P(O)-, (HO)₂P(O)-(CH₂)_X-, HO-SO₂- (CH₂) _x-,

(R³O) ₃__yR⁴ _ySi- (CH₂) _x-, (HaI)₂P(O)-, (Hal) ₂P (0) - (CH₂) _x-, HaI-SO₂- (CH₂) _x-_f (Hal) ₃-_yR⁴ _ySi- (CH₂) _x-,

in which x = 1 to 3; y = 1 to 3; each of R³ and R⁴ independently of the other = CH₃, C₂H₅, C₃H₇, or C₄H₉; and Hal = F, Cl, Br, or I.

2. The modifier according to claim 1, complying with the formula

Z- [O-CHR¹- (CH₂) _m] _n-0R²

in which

R¹ = H, CH₃, C₂H₅;

R² = CH₃, C₂H₅, C₃H₇, or C₄H₉;

m = 1 or 2;

n = 1 to 4;

Z = (HO)₂P(O)-, (HO)₂P(O)-(CH₂J_x-, HO-SO₂- (CH₂) _x-,

(R³O) ₃-_yR⁴ _ySi- (CH₂J_x-,

in which x = 1 to 3; y = 1 to 3; and each of R³ and R⁴ independently of the other = CH₃, C₂H₅, C₃H₇, or C₄H₉.

3. The modifier according to claim 1 or 2, complying with the formula

Z- [0-CH₂-CH₂] 2-OCH3.

4. The modifier according to claim 1 or 2, complying with the formula

Z- [O-CH (CH₃) -CH₂] ₃-OCH₃.

5. The modifier according to claim 1 or 2, complying with the formula

Z- [0-CH₂-CH₂-CH₂] -OCH₃.

6. The modifier according to any of claims 1 to 5, in which Z is (HO)₂P(O)- or (C₂H₅O) ₃Si- (CH₂) ₃- .

7. The modifier according to any of claims 1 to 5, in which Z is (HO) ₂P (0) - (CH₂)_X-.

8. A modified nanoparticle, obtainable via the reaction of inorganic nanoparticles with modifiers according to any of claims 1 to 7.

9. The modified nanoparticle according to claim 8, wherein the inorganic nanoparticles comprise metal oxides.

10. The modified nanoparticle according to claim 9, wherein the metal oxides are ZnO, TiO₂, ZrO₂, CeO₂, Ce₂O₃, SnO₂, SnO, Al₂O₃, SiO₂ or Fe₂O₃, or a mixture of said metal oxides.

11. A process for the production of modified nanoparticles according to any of claims 8 to 10, comprising the following steps:

(A) provision of a compound V, from which inorganic nanoparticles can be produced, optionally dissolved in a solvent,

(B) reaction of the compound V from (A) , optionally with addition of further substances in a solvent to give inorganic nanoparticles with formation of a dispersion D,

(C) provision of at least one modifier according to any of claims 1 to 7, optionally dissolved in a solvent,

(D) addition of the modifier to the dispersion D from step (B),

(F) optionally isolation of the modified nanoparticles, (G) optionally purification and work-up of the modified nanoparticles,

(H) optional further modification of the modified nanoparticles,

(I) optionally redispersion of the modified nanoparticles.

12. The process according to claim 11, wherein further substances added in step (B) comprise initiators or catalysts for the formation of the inorganic nanoparticles.

13. The process according to claim 11 or 12, wherein further substances added in step (E) comprise initiators or catalysts for the formation of the modified nanoparticles.

14. A nanocomposite, comprising a thermoplastic polymer and modified nanoparticles according to any of claims 8 to

10.

15. The nanocomposite according to claim 14, in which the thermoplastic polymer is a polyamide.

16. The nanocomposite according to claim 14, in which the thermoplastic polymer is a styrene-acrylonitrile copolymer.

17. The nanocomposite according to claim 14, in which the thermoplastic polymer is a polymethyl methacrylate.

18. A thermoplastic molding composition, comprising a thermoplastic polymer and modified nanoparticles according to any of claims 8 to 10.

19. The thermoplastic molding composition according to claim 18, in which the thermoplastic polymer is a polyamide .

20. The thermoplastic molding composition according to claim 18, in which the thermoplastic polymer is a styrene- acrylonitrile copolymer.

21. The thermoplastic molding composition according to claim 18, in which the thermoplastic polymer is a polymethyl methacrylate.

22. A process for the production of a nanocomposite according to any of claims 14 to 17 or of a thermoplastic molding composition according to any of claims 18 to 21, comprising the steps of

(a) provision of modified nanoparticles according to any of claims 8 to 10 in the form of a powder or in the form of a suspension;

(c) dispersion of the modified nanoparticles in the mixture of step (b) , where a stable dispersion of the nanoparticles is obtained,

(d) incorporation of the dispersion of step (c) into a melt of further matrix polymer in an extruder which has a plurality of compression zones, where the dispersion is brought into contact with the melt in a first compression zone at a pressure which is above the vapor pressure of the solvent of the dispersion at the temperature of the melt.

23. The process according to claim 22, in which the matrix polymer is a polyamide.

24. The process according to claim 22, in which the matrix polymer is a styrene-acrylonitrile copolymer.

25. The process according to claim 22, in which the matrix polymer is a polymethyl methacrylate.

26. The use of modifiers according to any of claims 1 to 7 for the modification of inorganic nanoparticles.

27. The use of modified nanoparticles according to any of claims 8 to 10 for addition to thermoplastic polymers.