EP1326928A1

EP1326928A1 - Composite particles

Info

Publication number: EP1326928A1
Application number: EP01969777A
Authority: EP
Inventors: Daniel-Gordon Duff; Werner Hoheisel; Kai BÜTJE
Original assignee: Bayer AG; Bayer MaterialScience AG
Current assignee: Bayer Intellectual Property GmbH
Priority date: 2000-10-09
Filing date: 2001-09-26
Publication date: 2003-07-16
Also published as: KR100773221B1; KR20030041154A; WO2002031060A1; US20020071948A1; AU2001289927A1; US6565973B2; CN1468289A; HK1061041A1; DE10049803A1; TWI316952B; CN1262610C; JP2004511612A

Abstract

The invention relates to improved modifications of inorganic and organic pigments. Depending on the pigment material, said pigments can be used as IR light absorbers or as colorants and cause negligible opacifying of the matrix.

Description

composite

The present invention relates to composite particles which represent significantly improved modifications of inorganic and organic pigments and which, depending on the pigment material, act as absorbers for visible and / or infrared light and can therefore be used as colorants and or as infrared (IR) light absorbers and cause negligible clouding of the matrix.

The composite particles according to the invention can be used in media in which high transparency, that is to say a low turbidity, is important, such as, for. B. in

Clear varnishes, paints, plastics, glass or coatings made from these materials. They can also be used to match color tones in non-transparent media.

It is known that inorganic pigments, which are used in transparent systems, may have a size of less than 10 nm or only a few 10 nm in order not to cause additional cloudiness. Because of their generally lower refractive index, this limit is found for organic pigments with somewhat larger particle sizes, but here too too large pigments cause turbidity. In addition, these small particles - they are also called "nanoparticles"

- be very well dispersed and stabilized in the matrix, since agglomeration of these particles, i.e. the formation of secondary particles, in turn leads to clouding and often also to a color change.

A disadvantage of the known technical solutions to this problem is the high time and cost-intensive effort involved in incorporating the nanoparticles into the matrix in the required degree of dispersion. The particles, which are usually in the form of powders or pastes, are subjected to intensive shear forces (e.g. by grinding) in order to break up the agglomerates present in such small units that the scattering of light by these units and thus also the clouding of the matrix

(e.g. paint binder) becomes negligible. The breaking up of agglomerated nanoparticles into isolated primary particles usually requires a much higher effort than z. B. in agglomerates consisting of larger primary particles (> 100 nm) is the case. However, since the almost complete deagglomeration of the nanoparticles is absolutely necessary for transparent coloring, the poor dispersibility of conventional, transparent pigments becomes a very important disadvantage for their use.

In order to ensure transparency of the matrix when using UV light-absorbing pigments in cosmetics, the distribution of the UV-absorbing inorganic particles in or on approximately 300 nm large dielectric particles is reported, which in turn are then introduced into the matrix as carriers ( WO 95/09895). The material of the large dielectric particles is selected in accordance with the matrix used in such a way that the refractive index of the compound particle consisting of dielectric particles and pigment differs only slightly from the refractive index of the surrounding matrix, thus maximizing transmission in the entire visible part of the light spectrum , However, this literature only discloses UV-absorbing particles such. B. TiO ₂ or ZnO. The aim was to achieve the highest possible optical transmission in the range of wavelengths above 400 nm, which inevitably precludes transparent color pigments and solar IR absorbers.

Most attempts to improve the transparency and incorporation of transparent pigments aim at the dispersibility of the pigments. For example, it was reported that improved dispersibility of fine hematite particles could be achieved by organic (JP-A 07 126 018) or inorganic (JP-A 05 208 829) treatment of the pigments or coating of the pigment particle surface. By improving the compatibility of the particle surfaces with the matrix or by shielding the adhesive forces between the pigment particles, the effort required for dispersion can be somewhat reduced. In all of these proposed approaches, however, a very complex dispersion, almost up to the primary particle size, is still necessary in order to achieve a transparent, intensive coloring. In the aftertreatment of iron oxide hematite particles with, inter alia, silicon dioxide (EP-A 0 997 500), an SiO ₂ content greater than 20% is expressly considered to be nonsensical because the two desired effects of aging resistance or improved dispersibility should be achieved with significantly less post-treatment material.

The production of supported particles, which can also be colored, is reported in connection with their use as heterogeneous catalysts (Catal.

Today (1997), 34, 281-305). Iron oxide haematite, which is applied to silicon dioxide, is also described for use as a heterogeneous catalyst (React. Kinet. Catal. Lett. (1999), 66, 183-18). However, a possible use as a transparent pigment is not discussed, and the transfer of catalyst properties to optical properties of pigments in a plastic or lacquer matrix is in no way obvious.

In order to synthetically recreate a mineral, "Thiviers Earth", a press cake of iron oxide particles of the goethite crystal modification was incorporated into a silicon dioxide dispersion (EP-A 0 947 564). However, the aim of this work was a composite in which the particle size of the Iron oxide preferably takes a value between 0.1 and 1 μm. In this case, no transparent color was produced, but - as is directly apparent to the person skilled in the art - a scatter color. These pigments would therefore be unsuitable for the transparent coloring of organic matrices.

The present invention was therefore based on the object of providing specially modified, highly transparent composite particles which absorb visible and / or infrared light and do not have the disadvantages known in the prior art. Infrared (IR) light is understood here to mean light which is in the solar radiation beyond the visibility limit, ie. H. is contained in the wavelength range between approx. 700 nm and approx. 2500 nm.

This object is achieved according to the invention by such composite particles which contain inorganic and / or organic pigment particles with a primary particle size of 1 nm to 100 nm, preferably between 1 nm and 50 nm, which are based on solid inorganic or organic colorless carrier particles of a primary particle size of 1 nm to 200 nm adhere, wherein either the pigment primary particles are essentially not agglomerated with other pigment primary particles and also generally are at a certain minimum distance from one another or that any agglomerates of these pigment primary particles which are formed are less than 100 nm, preferably less than 50 nm, and these are then at a certain minimum distance from one another. Said minimum distance should generally be at least a quarter of the particle or agglomerate diameter. Here and below, pigment should be understood to mean those particles which absorb visible and / or infrared light.

It was found that the combination of the individual pigment particles with a primary particle size of 1 nm to 100 nm and a carrier consisting of agglomerates of semiconductor oxide, metal oxide or polymer particles, with a primary particle size of 1 nm to 10 μm, preferably 2 nm to 500 nm, is advantageous. To avoid cloudiness, these composite particles consisting of supported pigments only have to be dispersed very roughly and therefore with little effort, since moderate agglomerate formation of these carrier pigments of up to a few μm in size does not cloud the matrix and is therefore tolerated can. A matrix is understood to be a dielectric material such as B. a clear coat, paint, plastic, glass or a coating material. Here, as in the following, the primary particle size is defined so that it corresponds to the diameter of a sphere with the same volume.

It has also been found that coating individual pigment particles with a primary particle size of 1 nm to 100 nm with other primary particles or coating particles consisting of semiconductor oxides, metal oxides or polymers with a total layer thickness of 1 nm to 10 μm is advantageous. To avoid turbidity, these pigments coated with other particles only have to be dispersed very roughly and therefore with little effort, since moderate agglomerate formation of these coated pigments of up to a few μm in size does not lead to clouding of the matrix and can therefore be tolerated , A matrix is understood to be a dielectric material such as B. a clear coat, paint, plastic, glass or a coating material. The carrier particles or the shells around the pigment particles thus act as spacers for the optically active pigment cores, which are up to a few tens of nanometers in size, in order to decouple them electromagnetically. With such a decoupling, no substantial light scattering is caused by an agglomeration of the carrier particles or the coated particles. A further prerequisite for reducing the light scattering from the supported or coated pigments is that the material of the support or the casing has a refractive index similar to that of the surrounding matrix. In most material combinations between carrier or shell and pigment, the material of the carrier should be an even lower and in a few cases a slightly higher one

Have refractive index as the surrounding matrix. In all cases there is an average refractive index for the supported or coated pigment, which has only a slight difference to the refractive index of the surrounding matrix, which further minimizes light scattering.

The invention therefore relates to composite particles which contain inorganic and or organic pigment particles with an average primary particle size of 1 nm to 100 nm, preferably between 1 nm and 50 nm, which are based on solid inorganic or organic colorless carrier particles with an average particle size of 1 nm to 200 nm stick, characterized in that the pigment primary particles are not substantially agglomerated with other pigment primary particles and are generally at a certain minimum distance from one another, this distance should generally be a quarter of the pigment primary particle diameter.

The invention further relates to composite particles which contain pigment particles with an average primary particle size of 1 nm to 100 nm, preferably 1 nm to 50 nm, which are coated with other primary particles, also called coating particles, or with a solid inorganic or organic layer, the Layer thickness of the shell should generally be at least one eighth of the pigment primary particle diameter. The invention furthermore relates to composite particles which contain agglomerates of inorganic and / or organic pigment particles with an average primary particle size of 1 nm to 100 nm, preferably between 1 nm and 50 nm. Said agglomerates adhere to solid inorganic or organic colorless carrier particles with an average primary particle size of 1 nm to 200 nm and are characterized in that they are on average less than 100 nm, preferably less than 50 nm, and usually at a certain minimum distance stand to each other, this distance should generally be a quarter of the agglomerate diameter.

The invention furthermore relates to composite particles which contain agglomerates of inorganic and / or organic pigment particles with a primary particle size of on average 1 nm to 100 nm, preferably between 1 nm and 50 nm. Said agglomerates are on average less than 100 nm, preferably less than 50 nm, which are coated with a solid or particulate, inorganic or organic layer, the total layer thickness of the shell generally being at least one eighth of the agglomerate diameter.

The invention further relates to compostite particles, as described above, but which contain combinations of different types of pigment particles, carrier particles and / or coating particles.

In addition, objects of the invention are transparent coloring and / or transparent IR-absorbing coating materials consisting of the composite particles, which are coated in a clear lacquer (for example polyester, acrylic, alkyd resin, chlorinated rubber, epoxy resin, acrylic resin, oil -, nitro, polyester, polyurethane and combination paints based on cellulose nitrate and alkyd resin), plastic or glass are incorporated.

In addition, objects of the invention are transparently colored and / or transparent IR-absorbing materials consisting of a plastic (for example polycarbonate, polyamide, polyethylene, polypropylene, polymethyl acrylate, polymethyl methacrylate, Polyurethane, polyethylene terephthalate, polystyrene, styrene acrylonitrile) or glass, in which the composite particles according to the invention are incorporated.

The term inorganic pigments includes metals such as B. Cu, Ag, Au, Pt, Pd, Co or alloys of these elements, semiconductors such. B. Si and all oxides,

Nitrides, phosphides and sulfides of metals and semiconductors as well as other substances such as Aluminates, especially iron oxides and oxide hydroxides, chromium oxides, cadmium sulfide, cadmium selenide, cadmium sulfoselenide, bismuth vanadate, chromate pigments, ultramarine pigments, iron blue pigments and mixed phase pigments, e.g. doped rutile pigments. The term inorganic pigments also includes doped materials such as B. tin-doped indium oxide, aluminum-doped zinc oxide, antimony-doped tin oxide, fluorine-doped tin oxide or metal-doped silicon oxide.

Materials which are suitable as inorganic pigment in the sense of the invention are also inorganic materials whose crystal lattice (host material) is doped with such foreign ions, so that the material fluoresces. These include in particular all materials and material classes that are used as so-called phosphors in fluorescent screens or fluorescent lamps and as described in Ullmann's Encyclopedia of Industrial Chemistry, WILEY-VCH, 6 * edition, 1999 Electronic Release, chapter

“Luminescent Materials: 1. Inorganic Phosphors” are mentioned. Materials suitable for the purposes of the invention as inorganic pigment are therefore materials of the type XY: A, where X is a cation from one or more elements of the main groups la, 2a, 3a, 4a, the subgroups 2b, 3b, 4b, 5b, 6b, 7b or the lanthanides of the periodic table, Y is either a polyatomic anion from one or more element (s) of the main groups 3a, 4a, 5a, the subgroups 3b, 4b , 5b, 6b, 7b and or 8b and element (s) of main groups 6a and / or 7 or a monatomic anion from main group 5a, 6a or 7a of the periodic table and A is the doping material from anions from one or more elements of the lanthanides and / or elements of the main groups la, 2a and or AI, Cr, Tl, Mn,

Ag, Cu, As, Nb, Nd, Ni, Ti, In, Sb, Ga, Si, Pb, Bi, Zn, Co. The concentration of the doping material in the host lattice is between 10 ^"5 mol% and 50 mol%, before increases between 0.01 mol% and 30 mol%, particularly preferably between 0.1 mol% and 20 mol%.

Among the material class of the fluorescent pigment particles, preference is given to sulfides, selenides, sulfoselenides, oxysulfides, borates, aluminates, gallates, silicates,

Germanates, phosphates, halophosphates, oxides, arsenates, nanadates, obiobates, tantalates, sulfates, tungstates, molybdates, alkali halides and other halides or nitrides are used as host materials for the fluorescent pigment particles. Examples of these material classes are given together with the corresponding doping in the following list (materials of type B: A with B =

Host material and A = doping material):

Li Eu; Na TI; Cs Tl; Cs Na; LiF: Mg; LiF: Mg, Ti; LiF: Mg, Na; KMgF ₃ : Mn;

Al ₂ O ₃ : Eu; BaFCkEu; BaFCkSm; BaFBπEu; BaFCl _0, ₀ ₅ Br, _5: Sm; BaY ₂ F ₈ : A (A = Pr, Tm, Er, Ce); BaSi ₂ O ₅ : Pb; BaMg2Al 6θ27: Eu;! BaMgAl! 4θ2 ₃ : Eu; BaM- GAIι ₀ Oι ₇ : Eu; BaMgAl ₂ O ₃ : Eu; Ba ₂ P2θγ: Ti; (Ba, Zn, Mg) ₃ Si ₂ O ₇ : Pb;

Ce (Mg, Ba) Alι ιOi9 _; Ce _0; 65 ^τ 0.35 ^M g ^A1 ll ° 19: Ce, Tb; ^M § ^A1 1 lOi9: Ce, Tb; MgF ₂ : Mn; MgS: Eu; MgS: Ce; MgS: Sm; MgS: (Sm, Ce); (Mg, Ca) S: Eu; MgSiO ₃ : Mn; 3.5MgO-0.5MgF ₂ -GeO ₂ : Mn; MgWO ₄ : Sm; MgWO: Pb; 6MgO-As ₂ O ₅ : Mn; (Zn, Mg) F2: Mn; (Zn4Be) Sθ4: Mn; Z ^ SiO ^ Mn; Zn2Siθ4: Mn, As; ZnO: Zn;

ZnO: Zn, Si, Ga; Zn ₃ (PO ₄ ) ₂ : Mn; ZnS: A (A = Ag, Al, Cu); (Zn, Cd) S: A (A = Cu, Al, Ag, Ni); CdB04: Mn; CaF ₂ : Mn; CaF ₂ : Dy; CaS: AA = lanthanide, Bi); (Ca, Sr) S: Bi; CaW04: Pb; CaWθ4: Sm; CaSO: A (A = Mn, lanthanide);

3Ca ₃ (P04) ₂ -Ca (F, Cl) ₂ : Sb, M _n ; CaSiO ₃ : Mn, Pb; Ca ₂ Al ₂ Si ₂ O ₇ : Ce; (Ca, Mg) SiO ₃ : Ce; (Ca, Mg) SiO ₃ : Ti; 2SrO-6 (B ₂ O ₃ ) -SrF ₂ : Eu; 3Sr ₃ (P04) 2-CaCl ₂ : Eu; A ₃ (PO ₄ ) 2-ACl ₂ : Eu

(A = Sr, Ca, Ba); (Sr, Mg) ₂ P2θ7: Eu; (Sr, Mg) 3 (PO) ₂ : Sn; SrS: Ce; SrS: Sm, Ce;

SrS: Sm; SrS: Eu; SrS: Eu, Sm; SrS: Cu, Ag; Sr ₂ P2θ7: Sn; Sr ₂ P2θ7: Eu;

Sr4Ali4θ25: Eu; SrGa ₂ S ₄ : A (A = lanthanide, Pb); SrGa ₂ S ₄ : Pb;

Sr ₃ Gd ₂ Si ₆ O ₁₈ : Pb, Mn; YF ₃ : Yb, Er; YF ₃ : Ln (Ln = lanthanide); YLiF ₄ : Ln (Ln = lanthanide); Y3Al ₅ O ₁₂ : Ln (Ln = lanthanide); YAl ₃ (BO ₄ ) ₃ : Nd, Yb; (Y, Ga) BO ₃ : Eu; (Y, Gd) BO ₃ : Eu; Y ₂ Al ₃ Ga ₂ O ₁₂ : Tb; Y ₂ SiO ₅ : Ln (Ln = lanthanide); Y ₂ O ₃ : Ln (Ln =

Lanthanides); Y2θ2S: Ln (Ln = lanthanide); YNO4.-A (A = lanthanide, In);

Y (PN) O ₄ : Eu; YTaO ₄ : Νb; YAlO ₃ : A (A = Pr, Tm, Er, Ce); YOCl: Yb, Er;

LnPO ₄ : Ce, Tb (Ln = lanthanides or mixtures of lanthanides); LuVO: Eu; GdVO ₄ : Eu; Gd ₂ O ₂ S: Tb; GdMgB ₅ O ₁₀ : Ce, Tb; LaOBr: Tb; La ₂ O ₂ S: Tb; LaF ₃ : Nd, Ce;

BaYb ₂ F ₈ : Eu; NaYF ₄ : Yb, Er; NaGdF ₄ : Yb, Er; NaLaF ₄ : Yb, Er; LaF ₃ : Yb, Er, Tm; BaYF ₅ : Yb, Er; Ga ₂ O ₃ : Dy; GaN: A (A = Pr, Eu, Er, Tm); Bi ₄ Ge ₃ O ₁₂ ; LiNbO ₃ : Nd, Yb; LiNbO ₃ : He; LiCaAlF ₆ : Ce; LiSrAlF ₆ : Ce; LiLuF ₄ : A (A = Pr, Tm, Er, Ce); Li ₂ BO ₇ : Mn, SiO _x : Er, Al (0 <x <2).

As materials for the carrier or the encapsulation particles come such oxides, fluorides, chlorides of metals and semiconductors and e.g. Aluminosilicates or polymers in question, which are essentially transparent in the visible spectral range.

The term volume concentration refers to the proportion of the pigment volume in the total volume of the solid phase of the composite particles. The total volume is the volume of the pigment plus that of the carrier material but without any empty spaces in the composite.

In a preferred embodiment, non-metallic pigments are present in a volume concentration of 1% - 60% and metallic pigments at 1% - 40% based on the pigment / carrier composite or pigment / carrier composite. In a particularly preferred embodiment, non-metallic pigments are present in a volume concentration of 10% - 50% and metallic pigments at 5% - 20%, based on the pigment / carrier composite.

In a preferred embodiment, non-metallic pigments are present in a volume concentration of 1% - 60% and metallic pigments at 1% - 40%, based on the shell pigment composite. In a particularly preferred embodiment, non-metallic pigments are present in a volume concentration of 10% - 50%) and metallic pigments are 5% - 20% based on the shell pigment composite. In a further preferred embodiment, the carrier particles or the shell material have a real refractive index in the visible spectral range, which is between 1.3 and 1.9. For example, the use of silicon dioxide as carrier material or shell material is particularly advantageous.

In the ideal case, the refractive index of the composite of pigment and carrier particles is equal to that of the matrix in which the composite particles are incorporated for the purpose of coloring. In this particularly preferred embodiment, the volume concentration of the pigment is based on the pigment / carrier

Composite approximately a value that can be derived from the following mathematical relationship:

C _vo . = (N _m a ~ N _tr ) / (N _pi -Nt _r )

C _v ι is the volume concentration of the pigment based on the pigment / carrier composite, N _ma the refractive index of the matrix in which the composite is embedded, N _tr the refractive index of the carrier material and N _p -, the refractive index of the pigment. Refractive index is understood here to mean the real part of the same.

However, the refractive index of the composite may differ slightly, preferably not more than 0.3 units, from that of the surrounding matrix.

In a further preferred embodiment, the permissible agglomerates are

Carrier-pigment composites or pigment / coating particle composite less than 50 μm, particularly preferably less than 10 μm, very particularly preferably less than 2 μm, in order to avoid specks visible to the naked eye and to ensure a homogeneous color impression or infrared absorption.

In a further possible embodiment, the composite can be modified on the surface by means of inorganic or organic aftertreatment, so that the dispersibility of the composite in the matrix is improved. Examples:

example 1

In order to demonstrate the advantageous effect of the composite particles according to the invention, iron oxide nanoparticles (hematite) with a size of approximately 10 nm, which have been applied to silicon dioxide particles, were used. This particle size was determined on the basis of electron microscopic examinations.

Production of the carrier pigments:

To produce an iron oxide sol, 2.7 g of iron (III) chloride (FeCl ₃ .6H ₂ O) was dissolved in 50 ml of distilled water. A further volume of 450 ml of distilled water was heated to the boil and the fresh iron (III) chloride solution was added dropwise (less than 2 ml / min) with very intensive stirring. The solution was then kept boiling for a further 10 minutes and then cooled. Nanoparticles of iron (III) oxide in the crystal form of hematite are dispersed in water. For applying this iron oxide particles on silica support 200 ml of distilled water were charged and 3.2 g silica (Aerosil ^® 200, Degussa, DE) dispersed therein. In order to improve the state of dispersion, the predispersion was treated with an ultrasound finger (200 W, 5 min). The iron oxide sol was then added to the silicon dioxide dispersion with stirring, sodium hydroxide solution was added until the pH reached 3.5 and the mixture was stirred for a further 5 minutes. The solid was separated off by centrifugation and then dried at 80 ° C. in a vacuum drying cabinet for several hours.

Testing the color properties of the composite particles:

A lacquer layer was produced in the following way. The base paint consisted of a mixture of 3500.0 g of alkyd resin ^® Alkydal F 48 (55% dry residue was in 38: 7 Spirit: xylene; Bayer AG, DE), 385.0 g of solvent naphtha 100, 28.8 g

2-butanone oxime, 55% in white spirit and 96.3 g of ethyl glycol acetate. A shaker (Olbrich paint mixer rm 5000) was used for the dispersion. A 100 ml wide-mouth glass bottle (round) was used as the grinding set. There were 50.0 g Ai2θ ₃ balls with d = 1.6 mm - 2.5 mm used. 40.0 g of the above-mentioned basic paint mixture (approx. 48% dry residue), the dry substances, 0.38 g Octa-Soligen lead with 24% Pb; 0.10 g of Octa-Soligen cobalt with 6% Co (all Borchers GmbH, Monheim, DE) and a lot of composite particles were added to the grinding set (100 ml wide-mouth glass bottle, round), so that a concentration of

Hematite was adjusted to 1% by weight based on the dry paint. The mixture was then dispersed for 3 hours. The drying agents were added immediately before the dispersion.

The fully dispersed lacquers were filtered through disposable sieves with a mesh size of approx. 280 μm. To assess the pigments, the dispersed varnishes were applied to black and white tiles (opal glass tiles) using a paint bar (gap height depending on requirements). Drying takes place for one day at room temperature and then for 1 h at 65 ° C in a drying cabinet. Diffuse reflection spectra in the ultraviolet and visible spectral range were recorded.

Figures 1 and 2 demonstrate the advantageous properties of the paint described above based on the composite particles according to the invention. The illustrations show the diffuse reflection of the paint spreads on the black and white surface as a function of the wavelength.

The reflection from this varnish on the black surface (Fig. 1) is almost independent of the wavelength and only varies between 0.6% and 1.8% in the range between 400 nm and 800 nm. On the white surface (Fig. 2 ) the reflection increases from less than 1% at a wavelength of 400 nm to more than 75%

760 nm. This shows the low scattering and high absorption capacity of the lacquer which contains the composite particles according to the invention

The composite consisting of carrier pigment is in a poorly dispersed state in this lacquer layer. Electron micrographs

(Fig. 3) show that agglomerates in the size range of up to a few micrometers are present. In the case of unsupported pigments, such agglomerates inevitably lead to an undesirable cloudiness (see comparative example). The advantageous color impression of the supported pigments, even in the case of poor dispersion, is made clear on the basis of CIELAB values, which were measured with the Lambda 900 color measuring device from Perkin Elmer (see table).

Example 2

In order to demonstrate the advantageous effect of the composite particles according to the invention, iron oxide nanoparticles (hematite) with a size of approximately 10 nm, which have been applied to silicon dioxide particles, were used. This particle size could be confirmed by means of electron microscopic examinations.

Production of the composites:

The iron oxide dispersion was prepared as described in Example 1.

For applying this iron oxide particles on silica support 190 ml of distilled water were charged and a dispersion of 10.7 g of a dispersion of silicon dioxide (Levasil ^® 300/30 (Bayer AG, Leverkusen, DE)) was mixed.

The iron oxide sol was then added to the silicon dioxide dispersion with stirring, sodium hydroxide solution was added until the pH reached 3.5 and the mixture was stirred for a further 5 minutes. The solid was separated by centrifugation and then dried at 80 ° C. in a vacuum drying cabinet. The test specimen of the color properties of the pigment was carried out as already described in Example 1.

Figures 4 and 5 demonstrate the advantageous properties of the lacquer described above based on the composite particle according to the invention. The images show the diffuse reflection of the paint spreads on the black and white surface as a function of the wavelength.

The reflection from this varnish on the black surface (Fig. 4) is independent of the wavelength and is less than 1% in the range between 400 nm and 800 nm. On the white surface (Fig. 5) the reflection increases by less than 1% at a wavelength of 400 nm to over 75% at 720 nm. This shows the low scattering and high absorption capacity of the lacquer based on composite particles that contain iron oxide pigment.

The composite particles containing the supported pigment are present in this lacquer layer even in a poorly dispersed state. Electron microscope images (Fig. 6) show that agglomerates in the size range of up to a few micrometers are present. In the case of unsupported pigment, such agglomerates inevitably lead to an undesirable cloudiness (see comparative example).

The advantageous color impression of the supported pigments is made clear on the basis of CIELAB values, which were measured with the Lambda 900 color measuring device from Perkin Elmer (see table).

Example 3

40 g of the cationically adjusted Levasil® 200S silicon oxide dispersion (Bayer AG, DE) were introduced. To this was added 75 g of a dispersion of Pigmentnanoparti- no, Bayscript Magenta VPSP ^® 20015 (Bayer AG, DE) with a pigment content of 4 wt .-%, with stirring added rapidly. The solid was then filtered off, washed and dried at 80 ° C. The magenta-silica composite powder thus obtained was then subjected to dry grinding. A Pulverisette ^® 2 (Fritsch GmbH, Idar-Oberstein, DE) was used. The mill works on the principle of a mortar mill. The grinding set, grater bowl and pestle are made of agate. The pestle is loaded with the highest pressure by moving the weight on the lever arm. The weight and lever arm are flush. The speed of the friction cup was 70 min ^"1 (at 50 Hz mains frequency). The friction cup has an inner diameter of 150 mm. The pestle has a diameter of 70 mm

Mill manufacturer adjusted so that the ground material was pushed from the wall under the pestle. 2.0 g of pigment were weighed out. The milling time was 30 minutes.

Testing the color properties of the composite particles:

It has a varnish layer in the following manner: The base paint consisted of a mixture of 3500.0 g of alkyd resin ^® Alkydal F 48 (55% dry residue in 38: 7 TestbenzimXylol; Bayer AG, DE), 385.0 g of solvent naphtha 100, 28.8 g of 2-butanone oxime, 55% by weight in white spirit, and 96.3 g of l-methoxy-2-propyl acetate. The dispersion was carried out in a ball mill (PM 4 planetary high-speed mill

(Retsch GmbH & Co. KG, Haan, DE). The movement sequence of the mill can be described as follows: Up to four grinding vessels (planets) rotate around a common center. The radius of the circular path to the center of the grinding bowl is approx. 15 cm. In addition, the grinding containers (planets) rotate in the opposite direction of rotation with each revolution around the center (sun) about 1.2 times around their own vertical axis. The speed of the mill is 250 min ^"1. 10 agate balls with d = 15 mm and 80 agate balls with d = 10 mm were used. 100.0 g of the above-mentioned basic lacquer mixture (approx. 48% dry residue) Trok- kenstoffe (0.94 g-octa-soligen lead with 24% Pb; 0.25 g-octa-soligen cobalt with 6% Co (Borchers GmbH, Monheim, DE) and a lot of composite particles were in the grinding set (250 ml agate grinding container) added so that a concentration of composite particles corresponding to 13% by weight based on the dry paint was set. The whole was then dispersed for 4 hours. The dry substances were added immediately before the dispersion. "The finished dispersed paints were mixed with disposable sieves 400 μm mesh size filtered.

To assess the composite particles, the dispersed paint was spread with a paint dumbbell on a non-absorbent black and white cardboard (wet layer thickness = 120 μm). The lacquered cardboard (spread) was then dried for at least 12 h at room temperature.

Figures 7 and 8 demonstrate the advantageous properties of the paint described above based on the composite particles according to the invention. It shows the diffuse reflection of the paint spreads on the black and white surface as a function of the wavelength.

The reflection from this varnish on the black surface (Fig. 7) is slightly dependent on the wavelength and is below 3.2% in the range between

400 nm and 800 nm. On the white background (Fig. 8) the reflection increases from approx. 1% at a wavelength of 560 nm to approx. 12% at 420 nm and to over 90% at 750 nm. These results show this Low scatter and high absorption capacity of the highly transparent lacquer based on the composite particles, which consist of supported organic magenta pigment.

Example 4

FeSO ₄ solution was converted according to the prior art (DE-A 2 508 932, US-A

2 558 304) by precipitation with sodium hydroxide solution in the presence of glycolic acid and subsequent oxidation with air, a transparent, yellow iron oxide pigment of the α-FeOOH modification with a BET specific surface area of approx. 110 m ² / g manufactured. The pigment was filtered off, washed free of salt and the filter cake was diluted to 28.2 g FeOOH / l with deionized (NE) water. The suspension had a pH of 3.5.

Levasil 300 silica sol, approx. 30% by weight SiO ₂ (commercial product from Bayer AG, DE), was diluted to 31.5 g SiO / l with non-ferrous water. The dispersion had a pH of 10.3.

100 ml of demineralized water were placed in a beaker and 15 g each of FeOOH and SiO in the form of the diluted dispersions mentioned were added within one hour

Room temperature metered in simultaneously with two peristaltic pumps while stirring. After stirring for 30 minutes, the pH was 6.4.

The composite was filtered through a membrane filter (0.45 μm pore size) and washed with demineralized water until the conductivity of the filtrate was <100 μS / cm.

After drying at 75 ° C. and deagglomeration in a powder mill (Starmix), 21 g of a light brown powder were obtained, with an FeOOH content of 63.5% by weight determined by redox titration.

The color properties of the composite particles produced in this way were tested as described in Example 3, with the exception, however, that the duration of the dispersion in the planetary high-speed mill this time was only 60 minutes, and that the amount weighed in was chosen such that the pigmentation level was 5 % FeOOH based on the total FeOOH + lacquer was.

Figures 9 and 10 demonstrate the advantageous properties of the paint described above based on the composite particles according to the invention. The images show the diffuse reflection of the paint spreads on the black and white surface as a function of the wavelength.

The reflection from this varnish on the black surface (Fig. 9) is slightly dependent on the wavelength and is less than 2.5% in the range between 400 nm and 800 nm. The reflection on the white surface (Fig. 10) increases from approx. 1% at a wavelength of 400 nm to approx. 77% at 750 nm. These results show the low scattering and high absorption capacity of the highly transparent lacquer based on the composite particles that contain supported iron oxide (goethite) pigments.

The advantageous color impression of the composite particles is made clear on the basis of CIELAB values, which were measured with the Lambda 900 color measuring device from Perkin Elmer (see table).

Example 5

An aqueous dispersion of nanoparticles made of tin-doped indium oxide (ITO), (Nanogate GmbH, Saarbrücken, DE) contains 20% by weight of ITO dispersed in ethanol.

4 g of the pyrogenic silicon oxide Aerosil ^® 200 (Degussa AG, DE) were in 100 g

Dispersed water and added 5 g of the ITO dispersion with vigorous stirring.

The solid was separated by centrifugation and then at 80 ° C. in

Vacuum drying cabinet dried within several hours. The ITO silicon dioxide composite powder obtained in this way was then subjected to dry grinding.

The Pulverisette ^® 2 mill described in Example 3 was used under the conditions described there. Testing the color properties of the pigment:

It has a varnish layer in the following manner: The base paint consisted of a mixture of 3500.0 g of alkyd resin ^® Alkydal F 48 (55% dry residue in 38: 7 TestbenzimXylol; Bayer AG, DE), 28.7 g 2-butanone oxime , 55% by weight in white spirit, 47.8 g Octa Solingen Calcium 4 basic (Borchers GmbH, Monheim,

DE), 8.1 g Octa Solingen Kobalt 6 B (Borchers GmbH, Monheim; DE), 32.0 g Octa Solingen Zirkonium 6 (Borchers GmbH, Monheim, DE) and 57.7 g glycolic acid n-butyl ester.

A plate paint rubbing machine (Muller), as described in DIN EN ISO 8780-5 (April 1995), was used to incorporate the composite particles into the paint. (JEL 25/53, J. Engelsmann AG, Ludwigshafen, DE). The effective plate diameter was 24 cm. The speed of the lower plate was approximately 75 min ^"1. By hanging a 2.5 kg load weight on the load bracket, the force between the plates was set to approximately 0.5 kN. 300 mg of composite particles and 2.00 g of lacquer were obtained dispersed in a step of 100 revolutions according to the method described in DIN EN ISO 8780-5 (April 1995), section 8.1 The muller was opened and the lacquer was quickly collected on the lower plate outside the center point, followed by a further 2.00 g of lacquer added and the plates folded in. After two steps, each 50 revolutions without load weight, the preparation was finished. The lacquer filled with composite particles was spread with a film applicator on a non-absorbent black and white cardboard (wet layer thickness = 120 μm) Cardboard (spread) was then dried for 12 hours at room temperature, and diffuse reflection spectra were found in the ultraviolet, visible and near infrared spectra ral area added.

Figures 11 and 12 demonstrate the advantageous properties of the paint described above based on the composite particles according to the invention. The illustrations show the diffuse reflection of the paint spreads on the black and white surface as a function of the wavelength.

The reflection of light through this lacquer on the black base (Fig. 11) is almost independent of the wavelength and is less than 3% in the range between see 400 nm and 800 nm. On the white background (Fig. 12) the reflection drops from 90% at a wavelength of 650 nm to 10% at a wavelength of 1800 nm. This shows the low scattering and high infrared absorption capacity of the highly transparent lacquers based on the composite particles that contain worn indium tin oxide.

Example 6

Composite particles consisting of iron oxide-silicon dioxide composite were produced as explained in Example 2. The powder obtained in this way was then subjected to dry grinding. The Pulverisette ^® 2 mill described in Example 3 was used under the conditions described there.

A plastic plate colored with the composite particles was then produced. As plastic, an additive-free, unstabilised polycarbonate served (Makrolon ^® 2808 from Bayer AG, Leverkusen) with an average molecular weight of about 28,000 (Mw by GPC), solution viscosity: η = l, 28 (5 g / 1 methylene chloride). 1 g of the composite particles was added to 199 g of granules of the polcarbonate to obtain a 0.5% by weight mixture. This was placed in a kneader (Brabender kneader) and kneaded at 230 ° C. for 10 minutes at a speed of 30 rpm. The subsequently cooled material was then in a heated press (Weber, type PW-20) at 250 ° C for 7 min. long melted and then pressed with a pressure of 200 kN to small plates (90 mm x 60 mm x 2 mm). In this way, polycarbonate sheets were obtained, the 0.5 wt% composite particles consisting of approx. 20

% By weight of hematite and approximately 80% by weight of silicon oxide. This ratio of the hematite and silicon oxide proportions is optimized for incorporation into polycarbonate in accordance with the relationship C _vo ι ~ (Nma - Nt _r ) (N _P i - N _tr ) given in the description. This sample is referred to below as sample (a).

To assess the color and transparency, the color value (according to CIELAB with illuminant D65, 10 ° observer) and the haze (haze according to ASTM D 1003) of the po- lycarbonate plate measured. The haze value was 9%. The color value is: L * = 56.2; a * = 28.7; b * = 63.3.

For comparison, composite particles were produced analogously to Example 2, in which the weight ratios between hematite and silicon oxide (b) approx. 50% by weight / 50% by weight, (c) approx. 33% by weight / 67% by weight and (d) approx. 10 These composite particles were then incorporated into polycarbonate according to the method given above in this example. In order to ensure that the coloring hematite content is contained in the polycarbonate sample in a similar amount, the content of carrier pigment in the polycarbonate was ( b) about 0.2% by weight, (c) about 0.3% by weight and (d) about 1% by weight.

The results for color value (according to CIELAB with illuminant D65, 10 ° observer, Perkin bucket, Lambda 900) and the haze (Haze according to ASTM D 1003) of the polycarbonate plate are as follows:

This table shows that the scattering effect of sample (a) is the lowest in which the relative ratio of hematite and silicon oxide in the composite particles for the matrix material polycarbonate is optimal according to the above mathematical relationship.

Example 7

An aqueous dispersion of nanoparticles made of tin-doped indium oxide (ITO), (Nanogate GmbH, Saarbrücken, DE) contains 20% by weight of ITO dispersed in ethanol. 4 of the fumed silica Aerosil ^® 200 g (Degussa AG, DE) was dispersed in 100 g water and 20 g of the ITO dispersion was added with vigorous stirring. The solid was separated by centrifugation and then dried at 80 ° C. in a vacuum drying cabinet over a period of several hours. The ITO silicon dioxide composite powder obtained in this way was then subjected to dry grinding.

The Pulverisette 2 mill described in Example 3 was used under the conditions described there.

A plastic plate was then produced which contained the composite particles produced in this way. As the plastic additive-free, unsta- bilisiertes polycarbonate served (Makrolon ^® 2808 from Bayer AG, Leverkusen) with an average molecular weight of about 28,000 (Mw by GPC), solution viscosity: η = l, 28 (5 g / 1 methylene chloride). 3.2 g of the composite particles were added to 196.8 g of granules of the polycarbonate to obtain a 1.6% by weight mixture. This was placed in a kneader (Brabender kneader) and at 230 ° C for 10 min with a

Speed of 30 rpm kneaded. The subsequently cooled material was then in a heated press (Weber, type PW-20) at 250 ° C for 7 min. long melted and then pressed with a pressure of 200 kN to small plates (90 mm x 60 mm x 2 mm). In this way, polycarbonate sheets were obtained which contained 1.6% by weight of composite particles consisting of approximately 50% by weight of ITO and approximately 50% by weight of silicon oxide. This ratio of the proportions of hematite and silicon oxide is optimized for incorporation into polycarbonate according to the relationship C _vo ι ~ (N _ma - N _tr ) / (N _P i - N _tr ) given in the description.

To assess the transparency and the IR absorption capacity, the

Transmission and the haze (Haze according to ASTM D 1003) of the polycarbonate plate measured. The haze value was 10%. The transmission of the plate is shown in Figure 13. The transmission increases from the UV range to over 70% at a wavelength of 630 nm and drops to below 3.5% at 1200 nm. This demonstrates the high transparency of the polycarbonate lens in the visible

Spectral range and the high absorption capacity in the near IR range. Such a pane is therefore well suited for use as a heat protection pane. Example 8

2.25 g of iron (II) oxalate dihydrate was dissolved in 29.3 g of water. 4 g of Aerosil ^® 200 (Degussa-Hüls AG, DE) were placed in the oven and the iron oxalate solution was added.

The solid was dried at 100 ° C for 12 hours and then heated in air for 10 hours at 500 ° C, resulting in decomposition of the iron oxalate and formation of iron oxide particles. The iron oxide-silica composite powder thus obtained was then subjected to dry grinding. The Pulverisette 2 mill described in Example 3 was used under the conditions described there.

The color properties of the pigment were tested as described in Example 5.

Figures 14 and 15 demonstrate the advantageous properties of the paint described above based on the composite particles according to the invention. The images show the diffuse reflection of the paint spreads on the black and white surface as a function of the wavelength.

The reflection from this varnish on the black surface (Fig. 14) shows only a slight dependence on the wavelength and is below 14% in the range between 400 nm and 800 nm. The reflection on the white surface (Fig. 15) increases from less than 2% at a wavelength of 400 nm to over 75% at 720 nm. This shows the low scattering and high absorption capacity of the transparent lacquer based on the iron oxide pigment.

Example 9

For comparison with the composites made by mixing dispersions or the system made by decomposing iron oxalate in the presence of silica particles, an iron oxide / Silicon dioxide-containing solid produced, in the synthesis of which both substances are formed by reaction from precursors.

The method of preparation is described in the literature (G. Concas, G. Ennas, D. Gatteschi, A. Musinu, G. Piccaluga, C. Sangregorio, G. Spano, J.L. Stanger,

D. Zedda, Chem. Mater. 1998, 10, 495). 5.7 g of iron nitrate nonahydrate was dissolved in 18.4 g of water. 20.8 g of tetraethoxysilane (TEOS) was dissolved in 17.7 g of ethanol. The iron nitrate solution was introduced and the TEOS solution was added with stirring. After stirring for one hour, the pH was 0.9. The transparent, yellow sol was poured into a plastic beaker and stored in the air for 9 days.

The solid gel thus formed was then successively dried at 60 ° C for two days, at 80 ° C for two days and then at 100 ° C for two days. The sample was then calcined at 800 ° C. overnight (air-annealed).

The iron oxide-silicon dioxide composite obtained in this way was then subjected to dry grinding. The Puverisette ^® 2 described in Example 3 was used under the conditions described there. Here too, the grinding time was 30 minutes.

The color properties of the composite particles were tested as described in Example 3.

Figures 16 and 17 demonstrate the advantageous properties of the paint described above based on the composite particles according to the invention. The images show the diffuse reflection of the paint spreads on the black and white surface as a function of the wavelength.

The reflection from this varnish on the black surface (Fig. 16) is almost independent of the wavelength and is less than 2.5% in the range between 400 nm and 800 nm. The reflection on the white surface (Fig. 17) increases from under

10% at a wavelength from 400 nm to over 90% at 800 nm. This shows the low scattering and high absorption capacity of the highly transparent lacquer based on the composite particles that contain carrier iron oxide pigment. Comparative Example:

To demonstrate the effectiveness of the composite particles according to the invention, a lacquer based on the iron oxide pigment was produced analogously to Examples 1 and 2, but without the pigment particles being applied to carrier particles.

The iron oxide dispersion was prepared as described in Example 1.

This incorporation of the non-supported pigment into the lacquer gives a cloudy layer and a dull color. Figures 18 and 19 show the reflection of such a lacquer layer on a black or white background. The measurement curves shown for comparison show a higher reflection of the paint on the black surface (Fig. 18), which is caused by the increased scattering effect of the agglomerated pigments. In contrast, the reflection of the varnish from the white surface is significantly lower, which is equivalent to a duller shade (Fig. 19). The measurement curves demonstrate the clear advantage with regard to the color properties for the lacquer which contains the composite particles according to the invention. The following table shows a comparison of the CIELAB values which were measured using the Perkin Elmer Lambda 900 color measuring device.

Claims

claims:

1. Composite particles, the inorganic and / or organic pigment particles

Contain primary particle size of on average 1 nm to 100 nm, preferably between 1 nm and 50 nm, which adhere to solid inorganic or organic colorless carrier particles with a primary particle size of on average 1 nm to 200 nm, characterized in that the pigment primary particles essentially are not agglomerated with other pigment particles and are essentially at a certain minimum distance from one another, which distance should generally be at least a quarter of the particle diameter.

2. Composite particles which contain inorganic and or organic pigment particles with a primary particle size of on average 1 nm to 100 nm, preferably between 1 nm and 50 nm, which are coated with a particulate or solid, inorganic or organic layer, the layer thickness of the shell in usually at least one eighth of the pigment primary particle diameter.

3. Composite particles, the agglomerates of inorganic and / or organic pigment particles with a primary particle size of on average 1 nm to

Contain 100 nm, preferably between 1 nm and 50 nm, these agglomerates adhering to solid inorganic or organic colorless carrier particles with a primary particle size of on average 1 nm to 200 nm, characterized in that the agglomerates of the pigment particles are essentially less than 100 together nm, preferably less than 50 nm, and are usually at a certain minimum distance from one another, which is usually a quarter of the agglomerate diameter.

4. Composite particles which contain agglomerates of inorganic and / or organic pigment particles with a primary particle size of on average 1 nm to 100 nm, preferably between 1 nm and 50 nm, these agglomerates being smaller than 100 nm on average and with a particulate or solid - Organic or organic layer are encased, which generally has a total layer thickness of at least one eighth of the agglomerate diameter.

5. Composite material, characterized in that it contains combinations of composite particles according to claims 1 to 4 of different inorganic and organic types of pigment particles with a primary particle size of on average 1 nm to 100 nm.

Composite material, characterized in that it contains combinations of composite particles according to claims 1 and 3 of different inorganic or organic, colorless types of carrier particle materials with a primary particle size of on average 1 nm to 200 nm.

7. Composite material, characterized in that it contains combinations of composite particles according to claims 2 and 4 of different inorganic or organic, colorless materials for the coating particles.

8. Composite material according to claims 1 to 7, characterized in that it contains inorganic pigments from the group of oxides, nitrides, phosphides and sulfides of metals and semiconductors, aluminates, iron oxides and - oxide hydroxides, chromium oxides, cadmium sulfide, cadmium selenide, cadmium sulfoselenide, Bismuth vanadate, chromate pigments, ultramarine pigments, iron blue pigments and mixed phase pigments.

, Composite material according to claims 1 to 7, characterized in that it contains primary particles which absorb infrared radiation from the near or solar infrared region.

10. Composite material according to claims 1 to 7, characterized in that it contains inorganic pigments from the group of doped materials.

11. Composite material according to claims 1 to 10, characterized in that the carrier or cladding materials have a real refractive index in the visible spectral range between 1.3 and 1.9.

12. Use of the composite material according to claims 1 to 10 for the purpose of transparent coloring or light absorption, characterized in that the matrix into which the composite material is introduced has a refractive index which is less than 0.3 units from that of the composite. posit material differs.

13. Surface coatings containing composite material according to claims 1 to 11.

14. Plastics containing composite material according to claims 1 to 11.

15. Substrates coated with coatings according to claim 13.