WO2003059834A1

WO2003059834A1 - Glass-ceramic composite containing nanoparticles

Info

Publication number: WO2003059834A1
Application number: PCT/EP2002/014043
Authority: WO
Inventors: José ZIMMER; Jörg Hinrich FECHNER
Original assignee: Schott Glas; Carl-Zeiss-Stiftung Trading As Schott Glas; Carl-Zeiss-Stiftung
Priority date: 2002-01-18
Filing date: 2002-12-11
Publication date: 2003-07-24
Also published as: JP2005532972A; AU2002352237A1; DE10201747C1

Abstract

The invention relates to a composite material which comprises a glass phase or glass-ceramic phase. The invention is characterized in that the inorganic composite material comprises nanoparticles and that the glass phase or glass-ceramic phase is charged with nanoparticles on or in the surface.

Description

GLASS-CERAMIC COMPOSITE CONTAINING NANOPARTICLES

The invention relates to an inorganic glass-ceramic composite material comprising a glass or glass ceramic phase and nanoparticles. The composite material is characterized in particular by its antimicrobial, anti-inflammatory, wound-healing and light-absorbing and light-scattering properties.

Glasses with bioactive and sometimes also antimicrobial effects are available from L.L. Hensch, J. Wilson, An Introduction to Bioceramics, World Scientific Publ., 1993, as Bioglas. Such bioglass is characterized by the formation of hydroxylappatite layers in aqueous media. Heavy metal-free alkali-alkaline earth silicate glasses with antimicrobial properties are described in the applications WO 01/04252 and WO 01/03650.

DE 19647 368 A1 shows composite materials containing a substrate and a nanocomposite that is in functional contact therewith. The substrate can consist of glass material and be in the form of powders. The nanocomposite can completely or partially cover the substrate as a coating.

A glass powder has become known from US Pat. No. 5,676,720 which comprises 40-60% by weight of SiO ₂ , 5-30% by weight of Na ₂ 0, 10-35% by weight of CaO, 0-12% by weight of P ₂ 0 ₅ , a glass ceramic made from a glass of such a composition has also become known.

No. 5,981,412 describes a bioactive bioceramic for medical applications with the crystalline phase Na ₂ O 2 CaO 3 SiO ₂ . The crystallite size is 13 μm. The ceramization takes place with tempering steps for nucleation and crystallization. The focus is on the mechanical properties such as K _1c . The proportion of crystal phases is between 34 and 60% by volume. Nanoparticles such as Ti0 ₂ or ZnO are used with particle sizes of approx. 20 - 100 nm for UV blocking in cosmetic and other products. UV blocking is based on absorption, reflection and scattering of the radiation by these nanoparticles. UVB (290 - 320 nm) UVA (320 - 400 nm) radiation is scattered more than the radiation in the visible range. Thus, the skin in sun protection products can be protected from sunburn.

However, TiO ₂ , in particular in the crystalline form anatase, is also photocatalytically active. The absorption of photons creates electron-hole pairs that can react with molecules on the TiO ₂ particle surface or environment. Among other things, radicals can develop here, which can have damaging effects on living organisms. In order to avoid such negative effects, TiO ₂ nanoparticles are currently coated with SiO ₂ or Al ₂ O ₃ , especially for cosmetic applications.

In particular, TiO ₂ nanoparticles, if they get into human cells, can lead to DNA damage. The skin is not a barrier for nanoparticles, since they can also penetrate through the skin. To minimize the damaging effect of the nanoparticles, according to WO 99/60994 Ti0 ₂ -

Nanoparticles are provided with capture ions which prevent the formation of radicals on the nanoparticle surface by electron hole interception.

The object of the invention is to avoid the disadvantages of the prior art and to provide an inorganic material which, in addition to antimicrobial, anti-inflammatory and skin-regenerating properties, also absorbs, reflects and scatters light, in particular UV radiation, but also radiation in the visible range , radical formation under UV radiation should be avoided and migration of the nanoparticles in the body tissue can be prevented. The object is achieved by using the ceramic-glass composite according to claim 1.

The ceramic-glass composite consists of different phases. These are a glass or glass ceramic phase as well as nanocrystals. The nanocrystals are located on or in the surface of the larger glass or glass ceramic particles.

The nanopowders have particle sizes with d50 values <500 nm, preferably <200 nm, more preferably <100 nm, most preferably <50 nm. However, the primary particle size can be significantly lower.

The glass or glass ceramic phases which contain these nanoparticles on or in the surface are preferably in powder form with particle sizes with d50 <100 μm, preferably <50 μm, more preferably <10 μm.

The particle sizes of the glass powders are even more preferably <5 μm, preferably <2 μm, in special cases <1 μm.

If a glass ceramic powder is present, the crystals of the glass ceramic have crystallite sizes (d50) <10 μm, preferably <1 μm, particularly preferably <500 nm, preferably <100 nm, in special cases <50 nm.

The ceramic-glass composite material of the invention is characterized in that the nanoparticles firmly on the surface of larger glass particles. The nanoparticles can be coated with a glassy layer that prevents or suppresses a slight reaction of the nanoparticles with the environment.

The chemical resistance of the glass or of the glass ceramic is preferably so high that the glass does not completely dissolve in cosmetic formulations and the nanoparticles coated with glass thus remain coated. The chemical composition of the glass has antimicrobial, anti-inflammatory and skin-care properties.

Furthermore, the material can have a biocidal, in any case a biostatic effect against bacteria, fungi and viruses, but can be skin-friendly and toxicologically harmless in contact with humans.

For certain applications, special requirements are placed on the purity of the powder, so that the toxicological harmlessness of the glass powder is guaranteed.

The exposure to heavy metals should be as low as possible. Desirable maximum concentrations in the area of cosmetic products are, for example, Pb <20 ppm, Cd <5 ppm, As <5 ppm, Sb <10 ppm, Hg <1 ppm, Ni <10 ppm.

The glass or the starting glass of the glass ceramic preferably have the following components:

SiO ₂ as a network builder between 30-70% by weight. At low concentrations, the spontaneous tendency to crystallize increases sharply and the chemical resistance strongly decreases. At higher SiO ₂ values, the crystallization stability can decrease and the processing temperature is increased significantly, so that the hot forming properties deteriorate. Si0 ₂ is also a component of the crystalline phases formed during a ceramization.

Na ₂ O is used as a flux when melting the glass. At concentrations <5%, the melting behavior is negatively affected. Sodium is part of the phases that form during ceramization. Sodium is released from the powder, inter alia, by ion exchange in aqueous media. K ₂ O acts as a flux when melting the glass. In addition, potassium is released in aqueous systems inter alia by ion exchange.

The chemical resistance of the glass and thus the release of ions in aqueous media is adjusted via the P ₂ 0 ₅ content. The P ₂ 0 ₅ content is between 0 and 10% by weight. At higher P ₂ O ₅ values, the hydrolytic resistance of the glass ceramic becomes too low.

To improve the meltability, the glass can contain up to 5% by weight of B ₂ O ₃ .

The amount of Al ₂ O ₃ should be <15% by weight in order to ensure sufficient crystallization stability of the glass for production. For glasses of glass ceramics with reinforcing antimicrobial and anti-inflammatory skin-care properties, Al ₂ O _{3 should be} <5% by weight, preferably <2% by weight, particularly preferably <1% by weight. -% his.

To increase the antibacterial properties of the glass ceramic, antibacterial ions such as e.g. Ag, Au, 1, Ce, Cu, Zn can be contained in concentrations of <5% by weight. The concentration of these ions is <5% by weight, in particular <2% by weight in total.

Ions such as Ag, Cu, Au, Li can also be included as additives to adjust the high-temperature conductivity of the melt and thus to improve the meltability with HF melting processes.

Coloring ions such as Fe, Co, V, Cu, Cr can be added individually or in combination in a total concentration of <1% by weight. By introducing oxides such as TiO ₂ and CeO, which also have an absorbing effect in the UV range, into the base glass, effective blocking of the UV radiation can be achieved, the UV edge being able to be set in a defined manner by adding different contents. The total concentration of these oxides is <5% by weight, preferably <2% by weight, more preferably <1% by weight.

The glass can contain ions such as Ce, Mn, Ag, Au, Cu, Zn, Fe, which can act as electron scavengers. In this way, radical formation can be suppressed by the electron-hole pairs generated by Ti0 ₂ under UV radiation.

Certain ions can therefore have a dual function. On the one hand, they reinforce the antimicrobial effect synergistically and can also trap free electrons through redox reactions, which could lead to radical formation. The concentration of the elements is <2% by weight, in particular <1% by weight, particularly preferably <0.1% by weight

The glass is melted using conventional melting technologies or high-frequency processes and shaped into block glass or so-called “ribbons”. In a preferred embodiment, the glass or the starting glass of the glass ceramic can be ground to powder. The particle size of these powders is preferably <100 μm, particularly preferred <50 μm, in particular <10 μm, in particular <5 μm, in particular <1 μm. Both dry and “wet” grinding technology can be used for this. In the case of "wet" grinding, the powders can then be dried.

In a second step, the glass powders can be mixed with the nanopowders. This can be done dry or the nanopowders are added as a dispersion to the dry or "wet" glass powders. An alternative production route is to add the nanoparticles to the glass during the first grinding process. After the mixing process, the nanoparticles are on the surface of the glass powder. If the nanopowders have been added in dispersion form, drying may be necessary. The mixture is sintered in the oven. The nanopowders combine with the glass powders. Surface diffusion processes coat the nanoparticles with glass during sintering. As a result, the nanoparticles are encapsulated from the environment. The chemical resistance of this glass encapsulation is so high that a surface reaction of the Ti0 ₂ with the environment is suppressed in cosmetic formulations.

The sintering temperatures for viscous sintering are above T _{g of} the starting glass, preferably

more than 0 ° C to 500 ° C above T _g , particularly preferably more than 20 ° C to 200 ° C above T _g , particularly preferably more than 50 ° C to 100 ° C above T _g .

In addition, the sintering can also take place below T _g , this is referred to as so-called diffusion-controlled solid-state sintering. The temperatures here are preferably 200 ° C. to 0 ° C. below T _g , in particular 100 ° C. to 10 ° C. below T _g . With this low-temperature sintering, the meal and energy consumption can be reduced by reduced sintering together.

Depending on the type of glass, the glass is ceramized at sufficiently high temperatures. The main phases here include Alkali-alkaline earth silicates such as sodium calcium silicates, alkaline earth silicates such as calcium silicate are formed.

The sintering can also be carried out in a multi-stage temperature-time program, for example in order to specifically fuse the Nanoparticles with the glass and, if possible, controlled to carry out a ceramicization of the glass.

Depending on the temperature control, a different degree of fusion and degree of encapsulation of the nanoparticles with the glass surface can be achieved.

After the sintering process, the powders are ground again to adjust the final particle size.

The sintering process can be carried out in such a way that the glass phase can be ceramized. The additional scattering or reflection effects can be set by ceramizing the base glass with a defined crystallite size. The effects can be controlled by process parameters such as the temperature-time profile of the process, but also by the amount of crystal former added.

The composite material is usually used as a powder, particle sizes of <100 μm being obtained by a final grinding process. Particle sizes of <50 μm or <20 μm have proven to be expedient. Particle sizes <10 μm and smaller than 5 μm are particularly suitable. Particle sizes <1 μm have been found to be particularly suitable. The grinding process can be carried out dry as well as with aqueous and non-aqueous grinding media.

The total amount of nanoparticles in the composite material is <20% by weight, preferably <10% by weight, more preferably <5% by weight.

The light-influencing effects are achieved on the one hand by the nanoparticles, which lead intrinsically to the absorption and scattering of the light, on the other hand by the surface morphology of the glass or glass-ceramic particles, which lead to scattering of the light, and by bulk characteristics of the glass or glass-ceramic particles , The sintered nanoparticles can simultaneously act as heterogeneous nuclei for the crystallization of the glass phase. The crystallization with the nanoparticles can thus be influenced.

The combination of the nanoparticles with biologically active glass leads to a UV blocker with positive skin properties. The disadvantages of nanoparticles cannot be compensated for, but overcompensated.

Furthermore, the coating of the glass particles with nanopowders leads to additional light-scattering effects which are not observed in the pure glass or glass ceramic powders and which can be attributed to the changed surface morphology.

The powders are ideally suited to be used in the field of cosmetic products. This can include Products in the field of color cosmetics or UV protection products.

Further fields of application are, for example, in the area of light protection, in the field of paints and varnishes, as well as in medical products and in the field of polymers.

The invention will be described below by way of example using the exemplary embodiments and the figures.

Show it:

Fig. 1 wide-angle X-ray diagram of a sample with a base glass according to

Embodiment 1 and TiO ₂ (rutile) nanoparticles sintered thereon

Fig. 2 SEM image of a base glass according to embodiment 1 without sintered TiO ₂ nanoparticles 3 - 5 SEM images of a basic glass according to embodiment 1 with 5% by weight of TiO ₂ nanoparticles sintered at 560 ° C. for one

Hour Fig. 6 TEM image of a base glass according to embodiment 1 with

5% by weight of TiO ₂ nanoparticles sintered at 560 ° C for one

hour

First, a base glass is melted from the raw materials specified in Table 1, which was then formed into glass ribbons, which are also referred to as ribbons. These ribbons were further processed into powder with a particle size d50 = 4 μm by means of dry grinding.

Table 1: Compositions in% by weight of the base glasses

The 4 μm glass powder of type 1 was dry-mixed in a drum mill with 5% by weight of TiO ₂ nanopowder with a secondary particle size of approximately 100 nm.

The powder mixture was then sintered in a chamber furnace at 580 ° C. for 2 hours. The sintered powder was then briefly ground again in a drum mill, so that a particle size of approximately 5 μm was set.

Under these sintering conditions, no crystalline secondary phases with a significant phase fraction can be detected using an X-ray diffraction diagram.

The nanopowders are firmly sintered into the surface of the glass powder and largely completely coated with a glassy phase. This could be demonstrated using SEM and TEM.

The antimicrobial effect of the powder was according to Europ. Pharamkopoe (3rd edition) tested and is shown in Table 2.

Table 2: Antimicrobial effect

Skin tolerance tests of a DAC cream formulation with 5% by weight and 10% by weight were carried out. No skin irritation was observed.

1 shows an X-ray diagram of a base glass according to embodiment 1 with sintered TiO ₂ on (rutile) nanoparticles. Sintering took place at 560 ° C for one hour. The x-ray diagram clearly shows the amorphous structure of the base glass and the crystalline structure of the sintered Ti0 ₂ particles. The X-ray reflections of the sintered TiO ₂ particles are given the reference number 1.

2 shows an SEM image of a base glass according to embodiment 1 without sintered nanoparticles. The glass powder was sintered at 560 ° C for one hour. A smooth surface without sintered nanoparticles can be seen.

FIGS. 3-5 show a base glass according to embodiment 1 with 5% by weight of TiO ₂ nanoparticles (rutile). This composition, like the comparative sample whose surface is shown in FIG. 2, was sintered at 560 ° C. for one hour. In contrast to the comparison sample shown in FIG. 2, the surface is no longer smooth. The solid bond between the individual nanoparticles, in this case the rutile and the base glass powder, can be clearly seen in FIG. 3. The solid bond between the nanoparticles and the base glass powder can also be clearly seen in FIGS. 4 and 5. The sample composition is the same sample as in the SEM image according to FIG. 3.

6 shows a transmission electron microscopy TEM image of a base glass according to embodiment 1 with 5% by weight of TiO ₂ nanoparticles sintered at 560 ° C. for one hour. It can be seen on this TEM image that the Ti0 ₂ (rutile) nanoparticles designated by the reference number 10 is surrounded by a glassy phase which is given the reference number 20.

The antimicrobial anti-inflammatory UV-radiation-reducing glass-ceramic composite materials can preferably be used in powder form as an additive in the cosmetic industry, for example in sun protection creams and day creams and creams against skin aging.

For the first time, the invention provides a material in which different properties are combined in one material. Protection of the radical formation is achieved by coating the TiO ₂ with an antimicrobial, anti-inflammatory and skin-regenerating layer. This happens in particular because the nanoparticles are bound to glass and thus no skin penetration can occur. In powder form, the material has special light-scattering, absorbing, reflective properties due to surface modification.

Claims

claims

1. Composite material comprising a glass or glass ceramic phase, characterized in that the inorganic composite material comprises nanoparticles and the glass or glass ceramic phase is coated on or in the surface with nanoparticles.

2. Composite material comprising a glass or glass ceramic phase, the

Glass or the starting gias of glass ceramics

Si0 ₂ 30 - 80% by weight

Na ₂ O 5 -40% by weight κ ₂ o 0-40% by weight

Li ₂ 0 0-40 wt%

CaO 5 -40% by weight

MgO 0-40% by weight

AI ₂ O ₃ 0-15% by weight ₂ O ₅ 0-20% by weight

B ₂ 0 ₃ 0-20% by weight

Ti0 ₂ 0-5% by weight

ZnO 0-5% by weight, characterized in that the inorganic composite material

Includes nanoparticles and the glass or glass ceramic phase is covered on and / or in the surface with nanoparticles.

3. Composite material according to claim 2, characterized in that the glass or initial glass of the glass ceramic comprises: TiO ₂ 0.1-5% by weight

4. Composite material comprising a glass or glass ceramic phase, the glass or the starting glass of the glass ceramic Si0 ₂ 30 - 80% by weight

Na ₂ O 5 -40% by weight

K ₂ 0 0-40% by weight

Li ₂ 0 0-40 wt%

CaO 5 -40% by weight

MgO 0-40 wt%.

AI ₂ O ₃ 0-15% by weight

P ₂ 0 ₅ 2 -20% by weight

B ₂ 0 ₃ 0-20% by weight

Ti0 ₂ 0-5 wt.%, Characterized in that the inorganic composite material

5. Composite material comprising a glass or glass ceramic phase according to claim 4, wherein the glass or the starting glass of the glass ceramic phase Si0 ₂ 35 -60 wt.%

Na ₂ O 5-30% by weight

K ₂ 0 0-20% by weight

CaO 5-30% by weight

MgO 0-10% by weight

AI ₂ O ₃ 0-5% by weight

P ₂ 0 ₅ 2 -10% by weight

B ₂ 0 ₃ 0-5% by weight, characterized in that the inorganic composite material comprises nanoparticles and the glass or glass ceramic phase is coated on and / or in the surface with nanoparticles.

6. Composite material according to one of claims 1 to 5, characterized in that the nanoparticles are titanium oxide nanoparticles.

7. Composite material according to one of claims 1 to 5, characterized in that the nanoparticles are zinc oxide nanoparticles.

8. Composite material according to one of claims 1 to 7, characterized in that the proportion of nanoparticles is <20% by weight, preferably <10% by weight, particularly preferably <5% by weight.

9. Composite material according to one of claims 1 to 8, characterized in that the nanoparticles are coated with a glass or glass ceramic phase.

10. Composite material according to one of claims 1 to 9, characterized in that the glass or glass ceramic phases electron-hole scavenger ions, in particular Ce, Fe, Mn, Ag, Au with a concentration <5 wt.%, In particular, 1% by weight, particularly preferably <0.1% by weight.

11. Composite material according to one of claims 1-10, characterized in that the composite material antibacterial ions such as Ag, Au, I, Ce, Cu, Zn in mass fractions <5% by weight, in particular <2% by weight, are particularly preferred Contains <1% by weight.

12. Composite material according to one of claims 1 to 11, wherein the glass or the starting glass of the glass ceramic is in powder form and the particle size of the powder is <100 microns.

13. Composite material according to one of claims 1 to 11, wherein the glass or the starting glass of the glass ceramic is in powder form and the particle size of the powder is <10 microns.

14. Composite material according to one of claims 1 to 11, wherein the glass or the starting glass of the glass ceramic is in powder form and the particle size of the powder is <1 μm.

5 15. A method for producing a composite material according to claims 1 to 14 with the following steps:

15.1 the glass or the starting glass of the glass ceramic is ground to a powder

15.2 the powder obtained according to step 15.1 is mixed with the nanoparticles I.

15.3 the mixture obtained according to step 15.1 is sintered into an inorganic composite material according to one of claims 1 to 14.

16. A method for producing a composite material according to claims 1 i to 14 with the following steps:

16.1 the glass or the starting glass of the glass ceramic is ground to a powder and the powder is mixed with nanoparticles in the same process step

16.2 the mixture obtained according to step 16.1 is sintered into an inorganic composite material according to one of claims 1 to 14.

17. The method according to any one of claims 15 to 16, characterized in that the sintering temperature is 20 ° C to 500 ° C, preferably 50 ° C to 200 ° C, particularly preferably 50 ° C to 100 ° C above the glass transition temperature of the starting glass.

18. Use of a composite material according to one of claims 1 to 14 to protect the skin from harmful UV radiation in cosmetic products.

19. Use of a composite material with antimicrobial, anti-inflammatory and wound-healing, skin-care effect according to one of claims 1 to 14 for use in cosmetic products.

20. Use of a composite material with antimicrobial and UV-protective effect according to one of claims 1 to 14 for use in paints and varnishes.

21. Use of a composite material with antimicrobial, anti-inflammatory, wound-healing, skin-care and UV-blocking effect according to one of claims 1 to 14 for use in medical products and preparations.

22. Use of a composite material with antimicrobial, anti-inflammatory, wound-healing and UV-blocking action according to one of claims 1 to 14 for use in plastics and polymers.