EP1163291A1

EP1163291A1 - Plastic composites containing metal oxides

Info

Publication number: EP1163291A1
Application number: EP00912473A
Authority: EP
Inventors: Juan Conzalez-Blanco; Jochen Mahrenholtz; Cliff Scherer; Stefanie KLINGELHÖFER; Werner Hoheisel; Jens Sicking; Lars KRÜGER; Ingo Steffens; Ulrike Pitzer; Gregor Kaschel
Original assignee: Bayer AG; Wolff Walsrode AG
Current assignee: Bayer AG; Dow Produktions und Vertriebs GmbH and Co OHG
Priority date: 1999-02-23
Filing date: 2000-02-17
Publication date: 2001-12-19
Also published as: WO2000050504A1; AU3423100A; JP2002537463A

Abstract

The invention relates to plastic composites based on fine-particulate filling materials or filling materials which contain oxidic metal compounds. The invention also relates to a method for producing the plastic composites.

Description

Plastic composites containing metal oxides

The invention relates to UV-absorbing plastic composites based on fine particulate fillers, which contain oxidic metal compounds, and to processes for their production. Plastic foils made of polyamide and (thermoplastic) polyurethane are particularly preferred, which enable the products packaged therein, such as foodstuffs, to have improved UV protection and still retain their transparency.

Commercial molecular-based UN absorbers such as Tinuvine from Ciba cannot be used in polymer films for food packaging for toxicological reasons. When using particulate UV protection agents such as titanium dioxide, cerium dioxide, when incorporating commercial powders, the films become very cloudy and have specks due to agglomeration of the powders, which does not lead to the desired product properties.

Therefore, the task was to produce plastic composites with particulate UV protection agents, which, in addition to the desired UV protection of the plastics and the packaging, have a speck-free plastic surface.

Fillers are used in plastics to improve mechanical properties (e.g. modulus of elasticity, impact strength, tensile strength), to increase heat stability, thermal and electrical conductivity, to improve UV stability or for coloring properties. They are usually added in a mass fraction of up to 60% by weight. Examples of such fillers are: talc, mica, kaolin, glass fibers, oxides, carbon black, starch.

Most fillers are only used after a surface treatment.

A surface treatment (or surface modification) is carried out, for example, with Polymers to achieve a good compatibility of the fillers in the plastic matrix.

Methods have already become known from DD-A-0 279 681, by means of which fine particulate suspensions of oxidic particles can be provided as fillers for plastics by wet comminution (wet grinding). Particles with a grain size> 1 μm are obtained after the wet grinding process.

From DD-A-0 284 684 a wet grinding process for the production of layered silicates (kaolinite) has become known, according to the last line of the

Summary of this document the impression could arise that particle diameters of 0.05 to 0.3 μm, that is down to 0.05 μm (corresponding to 50 nm), could be obtained. This is obviously a typographical error because on page 2 of the document it is said in the section "Statement of the nature of the invention", line 8, that the grinding suspension is 0.05 to 0.3

Mass fractions in% of the kaolin to be ground should be added to cationic dispersing agents.

The production of suspensions with an average particle diameter of less than 100 nm has not previously been described using this method. (M. Pahl: shredding technology, Verlag TUN Rheinland; K. Höffl: shredding and classifying machines, Springer Verlag). M. Pahl and K. Höffel mention the particle range of the wet comminuted suspensions to particle sizes smaller than 10 μm without explicitly specifying a lower limit or to provide a teaching on how suspensions of such small particles could be produced. From the range of services offered by the IKTS (Fraunhofer Institute for Ceramic Technologies and Sintered Materials) in Dresden, ceramic high-performance grinding balls are available for the size reduction range between 0J - 200 μm. The Νass reduction range is defined down to 0.1 μm. Widespread fine particulate fillers for plastics with primary particle sizes <100 nm are, for example, silicon dioxide (Aerosil ^® ) and carbon black: Aerosil ^® (Degussa AG; Pigments series: Hydrophobic Aerosil ^® , production, properties and applications) has primary particles from 5 to 50 nm in diameter; Carbon black (Degussa AG; Pigments series: Degussa carbon black pigments and pigment black preparations for plastics) with primary particle diameters from 10 to 100 nm. However, both products themselves consist of agglomerates of primary particles. These so-called secondary particles have diameters in the range of several hundred nm.

Fine particulate powders with a primary particle diameter <100 nm tend to agglomerate due to the high van der Waal forces; the stronger capillary forces also have an effect on pastes, so that it is not possible to take advantage of these powders (Nanostructured Materials 8 (4), 399 (1997)). When these fine particulate powders are aggregated, for example by sintering, partial melting or surface reactions, sinter bridges are formed which no longer allow redispersion (Nanostructured Materials, ibid.).

Other fine particulate fillers for plastics are, for example, colloidal SiO 2 suspensions with primary particle diameters between 5 - 150 nm (DD-A-

0 232 288) and BaSO 4 with an average particle diameter smaller than 200 nm (EP-A-0 354 609).

From DE-A-19 540 623 it is known that with agglomerate-free incorporation of fine particulate particles in organic or organically modified inorganic particles in polymer matrices, a previously unknown qualitative leap into e.g. the mechanical and thermodynamic properties that can sustainably improve the performance properties of such composite materials. It is crucial that the fillers are not in the form of a stabilized, (essentially) agglomerate-free suspension in the form of an agglomerated powder

Matrix phase integrated and (if necessary by a suitable surface fication of the particles) the agglomerate-free state remains even in the final composite material. From the same publication it is known that surface modifiers with a molecular weight <500 are added to commercially available colloidal suspensions or freshly precipitated suspensions consisting of inorganic particles in the fine particle range (<200 nm), which agglomerate the

Prevent particles in the plastic matrix.

Processes known to date, e.g. from DE-A-19 540 623 describe the use of commercial colloidal suspensions, which are mostly obtained from precipitation reactions, consisting of inorganic particles in the finely particulate range with particle sizes smaller than 200 nm. These suspensions were dispersants (surface modifiers) with a molecular weight less than 500 added to prevent agglomeration of the particles in the plastic matrix.

However, this method has the disadvantage that colloidal suspensions are usually precipitated in water. Furthermore, in this process the mostly aqueous phase has to be replaced by organic solvents and / or reactive monomers; this is associated with a high economic outlay. Another disadvantage of this process is that it can lead to agglomeration of the primary particles.

Surprisingly, it was found that UV-absorbing plastic composites based on finely particulate fillers, which contain oxidic metal compounds, can be produced by the process described below, the transparency of the moldings being retained. Plastic foils made of polyamide and (thermoplastic) polyurethane are particularly preferred, in particular they should enable the products packaged therein, such as food, to have improved UV protection. The primary particle size of the oxidic metal compounds used for spherical particles is between 0.5-50 nm. For needle-shaped (or ellipsoidal) particles, the longest axis has a value less than 300 nm. According to the invention, these particles, agglomerates or aggregates are wet comminuted.

Surprisingly, according to the present invention, finely particulate oxidic metal compounds by means of wet grinding could be used to produce concentrated suspensions with an average particle diameter of less than 100 nm. The suspensions were prepared in the solvents or reactive monomers as they are required for the subsequent polymerization to give the corresponding plastic composites.

The suspensions were then polymerized to a plastic composite, optionally after further dilution with monomers.

The wet comminution in the stirred ball mill was carried out at defined pH values in the presence of pH regulators at pH values from pH = 3 to pH = 5. The suspensions produced in this way show a high stability in agglomeration and sedimentation.

The potential to absorb UV light can already be determined on the suspensions containing TiO ₂ . It can be seen that acicular particles even have a higher absorption efficiency than spherical particles. This effect enables even more effective UV protection when installing needle-shaped particles in a plastic composite than when using the same mass of spherical particles. The following table compares the absorption coefficient (as a function of the wavelength) of a suspension consisting of acicular primary particles with a length of approx. 80 nm and a thickness of approx. 10 nm that of spherical primary particles (diameter approx. 10 nm).

The mean particle diameter of the suspensions is defined as the d ₀ value using the ultracentrifuge method (mass distribution). d ₅₀ means that 50% of the particles (based on the mass) are smaller than the specified size.

An important point in the UV protection of many polymeric materials is that the UV absorber is optically neutral. In the case of transparent plastics in particular, the UV absorber should not make a significant contribution to light scattering and thus to clouding the composite. Since the efficiency for light scattering increases in proportion to the volume of a particle, breaking the needles into smaller units is advantageous in order to keep clouding of the plastic composite to a minimum.

It is therefore particularly advantageous that, in the process presented here, the particles with an acicular morphology could be broken or that the particles were comminuted.

Insulated primary particles of acicular morphology, which are compared with the starting particle size by the process, are preferably incorporated into the plastic films. wet crushing to about half of the initial size of the longest axis of the primary particles. Due to the genuinely comminuted needle-shaped primary particles in the plastic films, it was possible to achieve a lower turbidity of the composite compared to the genuinely comminuted primary particles of acicular morphology.

Polymer composites based on polyamide and on (thermoplastic) polyurethane with titanium dioxide and cerium dioxide as fillers are preferred. Polyamide films and (thermoplastic) polyurethane films with a plastic thickness of less than 200 μm are particularly preferred.

Plastic composites that contain magnetic oxides such as magnetite or maghemite as fillers show magnetic properties.

The application relates to the use of the plastic composites according to the invention for the production of moldings.

The invention also relates to moldings produced from plastic composites according to the invention and the processes described in the claims.

The application also relates to plastic composites according to the invention, characterized in that the oxidic compound is present as primary particles, agglomerate, aggregate and / or as a mixture thereof, the agglomerates and aggregates having an average particle size of less than 100 nm.

The application relates to plastic composites containing at least one finely dispersed oxidic compound (component a) with an average particle size of less than 100 nm, which is an oxide of the elements Ti, Zn, Sn, W, Mo, Ni, Wi, Ce , In, Hf, Fe, whereby of these oxides individual or mixtures of oxides from this group can be used and / or

Reaction products of oxides of the metals of the fourth, fifth and sixth Sub-group (IVb, Vb, VIb) of the PSE with hydroxides and / or carbonates of the metals of the first and second main groups (I, II) of the PSE.

Another subject matter are plastic composites according to the invention, characterized in that the plastic matrix made of polyamide films with a thickness of less than

200 mm and the titanium dioxide particles in the composite have an ellipsoidal morphology and the longest axis is less than 50 nm, preferably less than 40 nm.

The application also relates to plastic composites according to the invention, characterized in that the plastic matrix consists of polyamide foils with a thickness of less than 200 μm, wherein the polyamide foil can also be part of a composite foil.

The invention relates to plastic composites containing at least one oxide

Elements Ti, Zn, Sn, W, Mo, Ni, Wi, Ce, In, Hf, Fe, whereby individual but also mixtures of oxides from this group can be used and / or reaction products of oxides of the metals of the fourth, fifth and sixth subgroup (IVb, Vb, VIb) of the periodic table (PSE) with hydroxides and / or carbonates of the metals of the first and second main group (I, II) of

PSE such as, for example, BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , BaZrO ₃ , CaZrO ₃ , SrZrO ₃ , with a spherical morphology and an average primary particle size of less than 50 nm, preferably less than 30 nm and particularly preferably less than 15 nm and / or an acicular or ellipsoidal morphology, the longest axis being less than 100 nm.

The invention further relates to the production of these plastic composites based on suspensions obtained by wet grinding and containing compounds of component a). (b) optionally a pH regulator

(c) optionally water and / or an organic solvent

(d) one or more monomers

(e) optionally further auxiliaries which are customary per se, such as, for example, surfactants and polymers, preferably surfactants.

Subsequently, the suspensions according to the invention - if appropriate a further proportion - of component (d) and any polymerization initiators which may be required are added. The polymerization is then carried out in a manner known per se to the person skilled in the art, e.g. through an increase in temperature.

Component a)

The compounds of component a) include at least one oxide of the elements Ti, Zn, Sn, W, Mo, Ni, Wi, Ce, In, Hf, Fe, with individual but also mixtures of oxides from this group being used can and / or reaction products of oxides of metals of the fourth, fifth and sixth subgroup (IVb, Vb, VIb) of the Periodic Table (PSE) with hydroxides and / or

Carbonates of the metals of the first and second main groups (I, II) of the PSE, preferably BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , BaZrO ₃ , CaZrO ₃ , SrZrO ₃ , with a spherical morphology and an average primary particle size of less than 50 nm, are preferred less than 30 nm and particularly preferably less than 15 nm and / or a needle-shaped or ellipsoidal morphology, the longest axis being less than

300 nm, preferably less than 200 nm, particularly preferably less than 100 nm. is.

The oxides to be used according to the invention can be produced, for example, using the following processes: flame hydrolysis, flame pyrolysis, plasma processes, sol-gel processes, controlled nucleation and growth processes and

Emulsion and microemulsion processes. The morphology and average particle size of the primary particles of the powders and pastes of the oxides can be determined with the aid of electron micrographs.

It is preferably less than 50 nm, more preferably less than 30 nm and particularly preferably less than 15 nm. The primary particles of the oxides can have a spherical shape. They can also be in the form of their agglomerates or aggregates, these having an average particle size of less than 100 nm.

The primary articles can also be acicular or ellipsoidal morphology. The longest axis should be less than 300 nm, preferably less than 200 nm and particularly preferably less than 100 nm.

Particularly preferred compounds of component a) are titanium dioxide and cerium dioxide.

Another particularly preferred component (a) is also BaTiO ₃ .

Iron oxides (hematite, maghemite, goethite, magnetite) are also preferred.

The preferred oxides also include oxides with a finite magnetization, for example ferrites, in particular maghemite and magnetite.

The compounds of component (a) contained in the plastic composites according to the invention can be present either in the form of their primary particles, agglomerates or aggregates of primary particles or mixtures of the two. Agglomerates or aggregates are understood to be particles in which several primary particles interact with one another via van der Waals forces, or in which the Primäφartikel are connected by surface reaction or "sintering" during the manufacturing process.

The primary particles can optionally additionally have a coating with at least one further inorganic oxide, preference being given to silicon dioxide, zirconium dioxide and aluminum oxide.

Component (a) is preferably used in an amount of 5 to 30% by weight, in particular 10 to 30% by weight, particularly preferably 15 to 30% by weight, based on the total preparation, the amounts given on the

Suspension are related.

Component b)

As component b) pH regulators are to be understood. These include inorganic mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, perchloric acid and organic acids such as benzenesulfonic acid, 1-naphthalenesulfonic acid, chloroacetic acid, terephthalic acid, trichloroacetic acid. Benzene sulfonic acid is particularly preferred.

Component (b) is preferably used in an amount of 0.001 to 5% by weight, based on the total preparation, the amounts given being based on the suspension.

Component c) Suitable solvents (c) are, for example: water, aliphatic C 1 -C alcohols, such as methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol or tert-butanol, aliphatic ketones, such as acetone, methyl ethyl ketone, Methyl isobutyl ketone or diacetone alcohol, polyols, such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, polyethylene glycol with an average molecular weight of 100 to 4000, preferably 400 to 1500 g / mol or

Glycerol, monohydroxyether, preferably monohydroxyalkylether, particularly vorzugt mono-Cι-C -alkylglykolether as Ethylenglykolmonoalkyl-, -monomethyl-, -diethylenglykolmonomethylether or diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monoethyl ether, thiodiglycol, triethylene glycol monomethyl ether or monoethyl ether, also 2-pyrrolidone, N-methyl-2-pyrrolidone, N -Ethyl-pyrrolidone, N-vinyl-pyrrolidone, 1,3-dimethyl-imidazolidone, dimethylacetamide and dimethylformamide.

Mixtures of solvents in component (c) are also suitable.

Component (c) is preferably used in an amount of 19 to 12% by weight, in particular 18 to 12.5% by weight, particularly preferably 16.9 to 12.5% by weight, based on the total preparation , is used, the amounts given being based on the suspension.

Component d)

Suitable monomers d) are, for example:

Caprolactams, in particular ε-caprolactam; Dicarboxylic acids, especially adipic acid; Diamines, especially hexamethylenediamine; Polyols-polyethers; Polyols-polyester; Diisocyanates, especially toluene diisocyanate, hexamethylene diisocyanate, 4,4 'methylene di (phenyl isocyanate), 4,4' methylene di (cyclohexyl isocyanate).

Component (d) is preferably used in an amount of 75.9 to 48% by weight, in particular 71.9 to 50% by weight, particularly preferably 68 to 50% by weight, based on the total preparation , the quantities being based on the suspension.

Component e)

Suitable auxiliaries such as surfactants or polymers are to be regarded as component e). Compounds which are listed in the “Surfactants Europe, A. Directory of Surface Acitive Agents available in Europe” (Edited by Gordon L. Hollis, Royal Socity of Chemistry, Cambridge (1995)) are to be regarded as surfactants.

Component (e) is preferably used in an amount of 0.05 to 5% by weight, in particular 0.05 to 2.5% by weight, based on the total preparation, the amounts given being based on the suspension .

Process: The plastic composites according to the invention are produced from suspensions of components (a), (b), (c), (d) and optionally (e).

To prepare the suspensions, component (a) is generally in powder form or in the form of the water-moist presscake together with part of the pH regulator b) optionally the solvent (c) and with the monomers d) to give a homogeneous grinding suspension, for example by means of an agitator chute, Dissolvers and similar aggregates, if necessary after pre-shredding, struck (ie introduced and homogenized).

The wet comminution of component (a) includes both the pre-comminution and the fine grinding. The solids concentration of component (a) of the suspension is preferably above the desired concentration of the finished suspension. The desired final concentration is preferably set after the pre-comminution. After the pre-crushing, grinding is carried out to the desired particle size distribution. Come for this grind

Units such as kneaders, roller mills, kneading screws, ball mills, rotor-stator mills, dissolvers, corundum disc mills, vibrating mills and in particular high-speed, continuously or discontinuously charged agitator ball mills with grinding media with a diameter of 0J to 5 mm are possible. The grinding media can be made of glass, ceramic or metal, e.g. Be steel. The

Grinding temperature is preferably in the range of 0 to 250 ° C, but usually at room temperature, especially below the cloud point of the surfactant used (component e).

In a likewise preferred procedure, the grinding can be carried out partially or completely in a high-pressure homogenizer or in a so-called jet disperser (known from DE-A-19 536 845), as a result of which the grinding body abrasion content in the suspension or Release of soluble substances from the grinding media, can be reduced to a minimum or completely avoided.

In a particularly preferred procedure, the wet comminution of ellipsoidal or needle-shaped primary particles in an agitator ball mill at agitator speeds of at least 3000 revolutions per minute and comminution bodies made of zirconium dioxide with a grain size between 0.3 and 0.4 mm leads to real comminution, i.e. for breaking the ellipsoidal primary particles into smaller units.

In order to avoid the abrasion of the mill into the suspension as far as possible and to prevent the resulting colored suspensions, an agitator ball mill with an inner lining made of silicon carbide and with a ceramic disk stirrer made of silicon carbide is used.

In a dilution step, the suspension obtained is mixed in the desired monomers of component (d) and possibly with further pH regulators of component b) and homogenized, and adjusted to the desired final concentration.

It is also possible to remove readily volatile solvents (for example using a rotary evaporator) after wet comminution in the stirred ball mill and, if necessary, to add further monomers of component (d) to carry out the polymerization. It is also possible to filter the suspension after wet comminution in an agitator ball mill (for example with a filter press). Subsequently, the paste obtained in this way is polymerized after possibly adding further monomers of component d) and possibly pH regulators of component b).

Before further use of the suspensions, these are optionally finely filtered, for example using 0.5 to 5 μm membrane or glass filters.

The plastic composites according to the invention are produced on the basis of the suspensions of components (a), (b), (c), (d) and optionally (e).

The suspensions produced according to the invention are polymerized.

The necessary polymerization initiators must also be added.

The suspensions prepared according to the invention can also be dried after being dispersed in a stirred ball mill. Drying temperatures of 20 to 150.degree. C., in particular 50 to 120.degree. C., are preferably used, with the application of a vacuum also being advantageous.

Drying is generally carried out using the usual drying apparatus such as paddle dryers, drying cupboards, spray dryers, fluidized bed dryers, freeze drying etc. The residual water content after drying is preferably less than 2% by weight, based on the solids content.

The thus dried and modified oxidic compound (or additive) can be incorporated (compounded) with granules of thermoplastic materials, for example in an extruder, into the plastic matrix.

The plastic composites thus produced according to the invention preferably consist of

Polyamide or (thermoplastic) polyurethane. The plastic composites thus produced according to the invention particularly preferably consist of polyamide and / or (thermoplastic) polyurethane.

The invention relates to preparations of suspensions of the following composition: Component (a) is preferably present in an amount of 5 to 30% by weight, in particular 10 to 30% by weight, particularly preferably 15 to 30% by weight, based on the total preparation used, the quantities being based on the suspension.

Subsequently, the suspensions according to the invention, if appropriate a further portion, component (d) and any required poly- merization initiators too. The polymerization is then carried out in a manner known per se to the person skilled in the art, for example by increasing the temperature.

Plastic composites according to the invention are preferably characterized in that the plastic matrix consists of polyamide films with a thickness of less than 200 μm, the polyamide film also possibly being part of a composite film.

The finished polymer composite according to the invention contains 0.01-30% by weight of component a), preferably 0.05-10% by weight, particularly preferably 0.5-5% by weight.

Examples

Example 1;

1600 g of ε-caprolactam are dissolved in small quantities in succession in 400 mL deionized water with intensive mixing by a laboratory stirrer. 400 g of TiO ₂ (Hombitec RM 300, from Sachtleben) are added to this solution and homogenized using an Ultra-Turrax stirring system. Subsequently, benzenesulfonic acid is added in small amounts and homogenized using the Ultra-Turrax stirring system until the pH of the system has a value between pH = 3 and pH = 4.

This suspension is wet-crushed in a stirred ball mill, Drais-PML-V / H, using grinding balls made of zirconium oxide with a size of 0.3 to 0.4 mm, crushing body filling degree 70%, stirrer speed 4000 rpm over a period of 360 minutes. The agitator and the inner material consist of silicon carbide.

The particle characterization was carried out using the ultracentrifuge (mass distribution) method. The following values were determined for the mass distribution:

Here (for particle sizes of the homogenized suspension before wet comminution) dio means that 10% of all particles are not larger than 44 nm, d50 means that 50% of all particles are not larger than 65 nm, and d90 means that 90% of all particles are not larger than 102 nm. In this context, particles are to be understood as primary particles as well as aggregates or agglomerates.

Here (for the particle sizes after wet comminution) dio means that 10% of all particles are not larger than 21 nm, d50 means that 50% of all particles are not larger than 33 nm and d <} 0 means that 90% of all particles are not larger than 51 nm. In this context, particles are to be understood as primary particles as well as aggregates or agglomerates.

60 g of the wet-crushed suspension are added to 940 g of a ε-caprolactam melt at 90 ° C. in a cylindrical, double-walled glass apparatus with a heated drain, a filling volume of approx. 1 liter and a metal spiral stirrer. After triple N compensation, the mixture is heated to 200 ° C. with stirring. After one hour at 200 ° C, the temperature is raised to 270 ° C and held for 4 hours. The melt is then spun off and the strand obtained is granulated. After 10 hours of extraction with water in the Soxhlet apparatus, the granules are dried in a water jet vacuum for 48 hours.

The dry material is used on a conventional flat film line

Single screw extruder processed into a monoflat film with a width of 300mm and a thickness of 50μm at a melt temperature of 270 ° C and a chill roll temperature of 90 ° C. In detail, the system (type Kühne) consists of the following units:

Screw diameter: 37 mm

Screw length: 24 D.

Degassing: no

Feed bush: smooth

Nozzle: 300 mm, flexible lip

Lip gap: 0.8 mm

Chill roll trigger: Somatec

Casting roller, chrome-plated The film has a thickness of 50 μm and contains 1% by weight of TiO. It appears transparent and has no specks on the surface. Their UV protection properties are shown in the following table, in which the light transmission values are plotted in comparison to a pure, unfilled polyamide film.

Example 2 (comparison):

In 400 mL deionized water, 1600 g ε-

Caprolactam dissolved with intensive mixing by a laboratory stirrer. 400 g of TiO (Hombitec RM 300, from Sachtleben) are added to this solution and homogenized using an Ultra-Turrax stirring system.

In a cylindrical, double-walled glass apparatus with a heated drain, one

Filling volume of approx. 1 liter and metal spiral stirrer are added to 940 g of a ε-caprolactam melt at 90 ° C. 60 g of the suspension. After triple N ₂ compensation, the mixture is heated to 200 ° C. with stirring. After one hour at 200 ° C, the temperature is raised to 270 ° C and held for 4 hours. Subsequently the melt is spun off and the strand obtained is granulated. After 10 hours of extraction with water in the Soxhlet apparatus, the granules are dried in a water jet vacuum for 48 hours.

The dry material is processed on a conventional flat film line with a single screw extruder to a mono flat film with a width of 300mm and a thickness of 50μm at a melt temperature of 270 ° C and a chill roll temperature of 90 ° C. In detail, the system (type Kühne) consists of the following units:

Screw diameter: 37 mm

Screw length: 24 D.

Degassing: no

Feed bush: smooth

Nozzle: 300 mm, flexible lip

Lip gap: 0.8 mm

Chill roll trigger: Somatec

Casting roller, chrome-plated

The film has a thickness of 50 μm and contains 1% by weight of TiO. It appears transparent and has specks on the surface. It also has a higher one

Scattering effect for light on than the film in example 1. The comparison is shown in the following table:

Example 3:

500 g of hematite (Sicotrans L2816 ^® BASF, primary article size: length approx. 100 nm, width approx. 10 nm with agglomerate sizes of up to several μm, determined by means of transmission electron microscopy) are dissolved in 2000 g of a solution of ε-caprolactam in deionized water (80 wt .Tln. Ε-caprolactam and 20 parts by weight of water) with intensive mixing with a laboratory stirrer and the pH is adjusted to pH 2.5 with a benzenesulfonic acid solution.

This suspension is in a stirred ball mill, Drais-PML-V / H, using grinding balls made of zirconium oxide with a size of 0.3 to 0.4 mm, crushing fill level 70%, stirrer speed 4000 rpm for 30 minutes at a pH - Value of 2.5 to 3 wet crushed. The agitator and the inner material of the mill are made of silicon carbide. The particle characterization was carried out using the ultracentrifuge (mass distribution) method. The following values were determined for the mass distribution:

Here, dio means that 10% of all particles are not larger than 19 nm, dso means that 50% of all particles are not larger than 29 nm, and d90 means that 90% of all particles are not larger than 46 nm. In this context, particles are to be understood as primary particles as well as aggregates or agglomerates.

No particles with a particle size above 100 nm were found.

Example 4:

890 g of maghemite press cake (Bayer AG, primary particle diameter 10 nm with agglomerate sizes of up to several μm, determined by means of transmission electron microscopy, solids content is 45% by weight) are dissolved in 1610 g of a solution of ε-caprolactam in water (80 parts by weight ε -Caprolactam and 20 parts by weight of water) with intensive mixing with an Ultraturrax and the pH is adjusted to pH 2.5 with a benzenesulfonic acid solution.

This suspension is in a stirred ball mill, Drais-PML-V / H, using grinding balls made of zirconium oxide with a size of 0.3 to 0.4 mm, crushing degree of filling 70%, stirrer speed 4000 rpm over a period of 60 minutes wet crushed at a pH of 2.5 to 3. The agitator and the inner material of the mill are made of silicon carbide. The suspension is then filtered under pressure through a filter sieve with a mesh size of 5 μm. The particle characterization was carried out using the ultracentrifuge (mass distribution) method. The following values were determined for the mass distribution:

Here, dio means that 10% of all particles are not larger than 23 nm, dso means that 50% of all particles are not larger than 40 nm, and d90 means that 90% of all particles are not larger than 107 nm. In this context, particles are to be understood as primary particles as well as aggregates or agglomerates.

Example 5:

250 g of a suspension prepared according to Example 3, containing hematite (Sicotrans

L2816 ^® , BASF), were homogenized in 750 g of a mixture of ε-caprolactam / water (80 parts by weight of ε-caprolactam and 20 parts by weight of water) using an Ultra-Turrax stirrer for 10 minutes. The homogenized suspension was then poured into a cylindrical, double-walled glass apparatus with a heated drain, a filling volume of approx. 1 liter and a metal spiral stirrer. After triple N ₂ -

Compensation was heated to 200 ° C. with stirring. After one hour at 200 ° C, the temperature is raised to 270 ° C and held there for 4 hours. The melt was then spun off and the strand obtained was granulated. After 10 hours of extraction with water in the Soxhlet apparatus, the granules were dried in a water jet vacuum for 48 hours.

To characterize the composite, thin sections of the strand were made and evaluated using electron microscopic images. Composites with a complete primary particle distribution of the hematite particles resulted in the polymer matrix. No agglomerates were identified in the electron micrographs identified.

Example 6:

312 g of a suspension prepared according to Example 4, containing maghemite (Bayer AG), was in 688 g of a mixture of ε-caprolactam / water (80 parts by weight of ε-caprolactam and 20 parts by weight of water) for 10 minutes homogenized with an Ultra-Turrax stirrer. The homogenized suspension is then poured into a cylindrical, double-walled glass apparatus with a heated drain, a filling volume of approx. 1 liter and a metal spiral stirrer. After 3 times ^ compensation, the mixture is heated to 200 ° C. with stirring. After one hour at 200 ° C, the temperature is raised to 27 _, 0 ° C and held for 4 hours. The melt is then spun off and the strand obtained is granulated. After 10 hours of extraction with water in the Soxhlet apparatus, the granules are in for 48 hours

Water jet vacuum dried.

To characterize the composite, thin sections of the strand are made and evaluated using electron microscopic images. This resulted in composites with a high proportion of primary particles and agglomerates or aggregates of primary particles. 90% of the agglomerates or aggregates have an average particle diameter of less than 100 nm.

Claims

1. Plastic composites containing at least one finely dispersed oxidic compound (component a) with an average particle size of less than 100 nm, which is an oxide of the elements Ti, Zn, Sn, W,

Mo, Ni, Wi, Ce, In, Hf, Fe, it being possible to use individual or mixtures of oxides from this group and / or reaction products of oxides of the metals of the fourth, fifth and sixth subgroup (IVb, Vb, VIb) of the PSE with hydroxides and / or carbonates of the metals of the first and second main groups (I, II) of the PSE.

2. Plastic composite according to claim 1, characterized in that the plastic matrix consists of polyamide and polyurethane.

3. Plastic composite according to claims 1 to 2, characterized in that the plastic matrix consists of polyamide.

4. Plastic composite according to claims 1 to 3, characterized in that the plastic matrix consists of polyamide films with a thickness of less than 200 microns, wherein the polyamide film can also be part of a composite film.

5. Plastic composites according to claim 4, wherein the proportion of component a) according to claim 1 is 0.01-30 wt .-%.

6. Plastic composites according to claims 1 to 5, characterized in that the oxidic compound has a spherical morphology with an average particle size of less than 50 nm, preferably less than 30 nm and particularly preferably less than 15 nm.

7. Plastic composites according to claims 1 to 6, characterized in that the oxidic compound has a needle-shaped or ellipsoidal morphology, the longest axis being shorter than 300 nm, preferably shorter than 200 nm and particularly preferably shorter than 100 nm.

8. Plastic composites according to claims 1 to 7, characterized in that the oxidic compound is present as a primary article, agglomerate, aggregate and / or as a mixture thereof, the agglomerates and aggregates having an average particle size of less than 100 nm.

9. Plastic composites according to claims 1 to 8, characterized in that the plastic matrix consists of polyamide films with a thickness of less than 200 μm and the titanium dioxide particles have an ellipsoidal morphology and the longest axis is less than 50 nm, preferably less than 40 nm.

10. Plastic composite according to claims 1 to 9, characterized in that the oxidic compound of component (a) is a reaction product of oxides of the metals of the fourth, fifth and sixth subgroup (IVb, Vb, VIb) of the periodic table (PSE) with hydroxides and / or carbonates of the metals of the first and second main groups (I, II) of the PSE.

11. Plastic composite according to claim 10, characterized in that the oxidic compound of component (a) is BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , BaZrO ₃ , CaZrO ₃ , and / or SrZrO ₃ .

12. Plastic composites according to claims 1 to 11, characterized in that the oxidic compound of component (a) is titanium dioxide.

13. Plastic composite according to claims 1 to 11, characterized in that the oxidic compound of component (a) is cerium dioxide.

14. Plastic composite according to claims 1 to 11, characterized in that the oxidic compound of component (a) is BaTiO ₃ .

15. Plastic composite according to claims 1 to 11, characterized in that the oxidic compound of component (a) is iron oxide.

16. A method for producing plastic composites according to claim 1, characterized in that a suspension of the fine particulate oxidic compound of component (a) by wet comminution at defined pH

Values, preferably between pH = 3 and pH = 5, is produced and this is then polymerized to plastic composites.

17. A process for the production of plastic composites according to claim 1 and claim 16, characterized in that in the wet comminution of ellipsoidal particles, a real comminution of the primary particles to at least half of the initial size, i.e. Axis length is done.

18. A process for the production of plastic composites according to claim 1, characterized in that a suspension of the finely particulate oxidic compound of component (a) is produced by wet comminution and then dried and the oxide or additive thus dried and modified with granules of thermoplastic materials in the plastic matrix is incorporated.

19. Use of the plastic composites according to claims 1 to 18 for the production of molded bodies.

20. Molded body produced according to claim 19.

21. Films produced according to claim 19.