DE19746885A1 - Production of nano-structured mouldings and coatings - Google Patents

Abstract

A process for the production of nano-structured mouldings and coatings comprises (a) preparation of a free-flowing material containing nano-scale inorganic solid particles (I) with polymerisable and/or polycondensable organic surface groups, (b1) pouring the material into a mould or (b2) coating it onto a substrate, and (c) polymerisation and/or polycondensation of the surface groups to give a hardened moulding or coating. Also claimed are (i) nano-structured mouldings obtained by this process, (ii) a process for the production of highly scratch- resistant coatings on plastic substrates, and (iii) substrates coated with a nano-structured layer made by process (ii).

Description

The present invention relates to nanostructured moldings and layers as well Process for their production. In particular, the present invention relates nanostructured moldings and layers that are made with the help of a wet chemical Process are produced.

Nanostructured materials have been known for a long time. You will be in generally produced by having nanoscale particles with diameters in the compacted lower nanometer range by a suitable method (see e.g. H. Glider, Nanocrystalline Materials, Pergamon Press, Oxford, 1989). this happens mostly under high pressure. Here one uses the high diffusion rates in the Outskirts of the nanoscale particles, under the action of pressure (and possibly simultaneous exposure to elevated temperatures) Compression to dense bodies takes place. Corresponding wet chemical processes, such as the sol-gel process, usually lead to porous gels because due to the high surface activity of the particles they bind takes place, however, the particles are closely lined up and filled in Gusset has not occurred. Materials produced by such processes are uniform, d. H. they have interface phases, their composition does not differ (significantly) from that of the particle phase (le only the gas phase of the environment must also be present).

It has now surprisingly been found that when the nanoscale Particles with polymerizable and / or polycondensable organic Surface groups are provided and these surface groups polymerized and / or be polycondensed, nanostructured by the wet chemical method Material systems are accessible that were previously manufactured in a dry way Systems are equal or even superior. In particular are on this Highly transparent materials are also accessible, because of the low Distances of the particles to each other (one to a few nm) are the correlation lengths for the Raleigh scatter cannot be achieved.  

The present invention thus relates to a process for the production of nanostructured moldings and layers, which comprises the following stages:

• a) Providing a nanoscale inorganic solid particle with polymerizable and / or polycondensable organic Flowable mass containing surface groups;
• b1) inserting the mass from step a) into a mold; or
• b2) applying the mass from step a) to a substrate;
• c) polymerization and / or polycondensation of the organic Surface groups of the inorganic solid particles to form a hardened molded body or a hardened layer.

In many cases, it can be advantageous if one of the above step c) thermal aftertreatment, preferably at a temperature in the range of 60 up to 150 ° C, in particular 80 to 130 ° C, of the hardened molded body or hardened layer connects.

Alternatively or additionally, a (further) thermal compression of the Molded body or the layer at a temperature of at least 250 ° C, preferably at least 400 ° C, and in particular at least 500 ° C. in the In the case of a layer on a substrate, this thermal compaction can can of course only be carried out if the substrate material is such can withstand high temperatures without impairment, as z. B. at Glass and many metals or metal alloys (but also some plastics) the case is.

In some cases it may also be advisable to use a (further) thermal Compression at temperatures in the range of 800 to 1500 ° C, preferably 1000 up to 1400 ° C.

In the present description and the appended claims are intended to "Nanoscale inorganic solid particles" those with a medium  Particle size (an average particle diameter) of not more than 200 nm, preferably not more than 100 nm, and in particular not more than 70 nm be meant. A particularly preferred particle size range is 5 to 50 nm.

The nanoscale inorganic solid particles can consist of any materials, but they preferably consist of metals and in particular of metal compounds such as (optionally hydrated) oxides such as ZnO, CdO, SiO ₂ , TiO ₂ , ZrO ₂ , CeO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , La ₂ O ₃ , Fe ₂ O ₃ , Cu ₂ O, Ta ₂ O ₅ , Nb ₂ O ₅ , V ₂ O ₅ , MoO ₃ or WO ₃ ; Chalcogenides such as sulfides (e.g. CdS, ZnS, PbS and Ag ₂ S), selenides (e.g. GaSe, CdSe and ZnSe) and tellurides (e.g. ZnTe or CdTe), halides such as AgCl, AgBr, AgI, CuCl, CuBr, CdI ₂ and PbI ₂ ; Carbides such as CdC ₂ or SiC; Arsenides such as AlAs, GaAs and GeAs; Antimonides such as InSb; Nitrides such as BN, AlN, Si ₃ N ₄ and Ti ₃ N ₄ ; Phosphides such as GaP, InP, Zn ₃ P ₂ and Cd ₃ P ₂ ; Phosphates, silicates, zirconates, aluminates, stannates and the corresponding mixed oxides (e.g. those with a perovskite structure such as BaTiO ₃ and PbTiO ₃ ).

The nanoscale inorganic solid particles used in stage a) of the process according to the invention are preferably those of oxides, sulfides, selenides and tellurides of metals and mixtures thereof. According to the invention, particular preference is given to nanoscale particles of SiO ₂ , TiO ₂ , ZrO ₂ , ZnO, Ta ₂ O ₅ , SnO ₂ and Al ₂ O ₃ and mixtures thereof.

Since the nanoscale particles that can be used according to the invention have a wide range of refractive indices can be selected by suitable selection of these nanoscale Particles the refractive index of a molded body or a layer in a convenient manner the desired value can be set.

The production of the nanoscale solid particles used according to the invention can be done in the usual way, e.g. B. by flame pyrolysis, plasma processes, Gas phase condensation processes, colloid techniques, precipitation processes, Sol-Gel-Pro processes, controlled nucleation and growth processes, MOCVD processes  and (micro) emulsion processes. These procedures are in the literature described in detail. In particular, e.g. B. metals (for example according to the Reduction of precipitation processes), ceramic oxidic systems (through Precipitation from solution), but also salt-like or multi-component systems be used. The salt-like or multi-component systems include also semiconductor systems.

The production of the polymerizable and / or polycondensable organic surface groups provided nanoscale inorganic Solid particles that are used according to the invention can in principle be divided into two can be carried out in various ways, namely on the one hand Surface modification of already produced nanoscale inorganic Solid particles and the other by producing these inorganic nanoscale solid particles using one or more Compounds that have such polymerizable and / or polycondensable Groupings. These two paths are discussed below and in the Examples explained in more detail.

In the case of the organic polymerizable and / or polycondensable Surface groups can be any groups known to the person skilled in the art act which is a radical, cationic or anionic, thermal or photochemical polymerization or thermal or photochemical Polycondensation (if appropriate in the presence of a suitable initiator or Catalyst) are accessible. Are preferred according to the invention Surface groups that have a (meth) acrylic, allyl, vinyl or epoxy group have, with (meth) acrylic and epoxy groups being particularly preferred. At the groups capable of polycondensation would be, above all, hydroxyl, carboxy and To name amino groups, with the help of ether, ester and amide bonds can be obtained between the nanoscale particles.

According to the invention it is also preferred that the on the surfaces of the nanoscale particles present organic groupings that the comprise polymerizable and / or polycondensable groups, a relative  have low molecular weight. In particular, the molecular weight the (purely organic) groupings 300 and preferably 200, especially preferably 150, do not exceed. Of course, this clearly includes higher molecular weight of the compounds comprising these groupings (Molecules) not out.

As already mentioned above, the polymerizable / polycondensable surface groups can in principle be provided in two ways. If a surface modification of nanoscale particles that have already been produced is carried out, all (preferably low molecular weight) compounds are suitable for this purpose which, on the one hand, have one or more groups which have (functional) groups (such as, for example, OH groups) on the surface of the nanoscale solid particles in the case of oxides) can react or at least interact, and on the other hand have at least one polymerizable / polycondensable group. Thus, the corresponding connections z. B. form both covalent and ionic (salt-like) or coordinative (complex) bonds to the surface of the nanoscale solid particles, while dipole-dipole interactions, hydrogen bonds and van der Waals interactions should be mentioned among the pure interactions. The formation of covalent and / or coordinative bonds is preferred. Specific examples of organic compounds that can be used to modify the surface of the nanoscale inorganic solid particles are, for example, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, β-dicarbonyl compounds (e.g. β-diketones or β-carbonylcarboxylic acids) with polymerizable double bonds, ethylenically unsaturated alcohols and amines, epoxides and the same. According to the invention, particularly preferred as such compounds are - in particular in the case of oxidic particles - hydrolytically condensable silanes with at least (and preferably) one non-hydrolyzable radical which has a polymerizable carbon-carbon double bond or an epoxy ring. Such silanes preferably have the general formula (I):

XR ¹ -SiR ² ₃ (I)

where X is CH ₂ = CR ³ -COO, CH ₂ = CH or glycidyloxy, R ^{3 is} hydrogen or methyl, R ^{1 is} a divalent hydrocarbon radical with 1 to 10, preferably 1 to 6 carbon atoms, which optionally has one or more heteroatom groups ( e.g. O, S, NH), which separate adjacent carbon atoms from one another, and the radicals R ² , identical or different from one another, from alkoxy, aryloxy, acyloxy and alkylcarbonyl groups and halogen atoms (in particular F, Cl and / or Br) are selected.

The groups R ² are preferably identical and selected from halogen atoms C _1-4 alkoxy groups (e.g. methoxy, ethoxy, n-propoxy, i-propoxy and butoxy), C _6-10 aryloxy groups (e.g. phenoxy ), C _1-4 acyloxy groups (e.g. acetoxy and propionyloxy) and C _2-10 alkylcarbonyl groups (e.g. acetyl).

Particularly preferred radicals R ² are C _1-4 alkoxy groups and in particular methoxy and ethoxy.

The radical R ¹ is preferably an alkylene group, in particular one with 1 to 6 carbon atoms, such as. B. ethylene, propylene, butylene and hexylene. When X is CH ₂ = CH, R ^{1 is} preferably methylene and in this case can also be a mere bond.

X preferably represents CH ₂ = CR ³ -COO (where R ^{3 is} preferably CH ₃ ) or glycidyloxy. Accordingly, particularly preferred silanes of the general formula (I) are (meth) acryloyloxyalkyltrialkoxysilanes such as, for. B. 3-Me thacryloyloxypropyltri (m) ethoxysilane and glycidyloxyalkyltrialkoxysilanes such as 3-glycidyloxypropyltri (m) ethoxysilane.

The nanoscale inorganic solid particles are already being produced using one or more connections that over polymerizable / polycondensable groups can have one subsequent surface modification are disregarded (although this is of course possible as an additional measure).  

The in situ production of nanoscale inorganic solid particles with polymerizable / polycondensable surface groups is explained below using the example of SiO ₂ particles. For this purpose, the SiO ₂ particles z. B. by the sol-gel process using at least one hydrolytically polycondensable silane with at least one polymerizable / poly condensable group. Suitable silanes of this type are, for example, the silanes of the general formula (I) already described above. These silanes are preferably used either alone or in combination with a suitable silane of the general formula (II)

SiR ² ₄ (II)

wherein R ^{2 has} the meaning given above, used. Preferred silanes of the general formula (II) above are tetramethoxysilane and tetraethoxysilane.

Of course, it is also possible to use, in addition or as an alternative to the silanes of the general formula (II), other silanes, e.g. B. those that have a (non-hydrolyzable) hydrocarbon group without any functional group, such as methyl or phenyltrialkoxysilanes. In particular, if an easy-to-clean (easy to clean) surface of the shaped body or the layer is desired, it may be advisable to add a certain amount (for example the addition of the silanes of the general formula (I) and optionally the general formula (II) B. up to 60 and in particular up to 50 mole percent on the basis of all silanes used) silanes with fluorine-containing (non-hydrolyzable) residues, especially hydrocarbon residues. Silanes of the above formula (I) in which R ^{2 is} as defined above, R ^{1 represents} an ethylene group and X represents a perfluoroalkyl group having 2 to 12, preferably 4 to 8, carbon atoms are particularly preferred. Other silanes that can be used for this purpose are e.g. B. those with (per) fluorinated aryl (especially phenyl) groups. Of course, such fluorinated silanes can also be used for the surface modification of already finished nanoscale inorganic solid particles.

The material used in stage a) of the process according to the invention is in the form of a still flowable mass (suspension). The liquid constituent of this mass is composed, for example, of water and / or (preferably water-miscible) organic solvents and / or compounds which were used or produced in the course of the production of the nanoscale particles or their surface modification (e.g. alcohols in the case of of alkoxysilanes), together. Suitable organic solvents optionally used are, for example, alcohols, ethers, ketones, esters, amides and the like. An (additional) constituent of the flowable composition can, for example, also be at least one monomeric or oligomeric species which has at least one group which can react (polymerize or polycondense) with the polymerizable / polycondensable groups present on the surface of the nanoscale particles. As such species, for. B. monomers with a polymerizable double bond such as acrylic acid esters, methacrylic acid esters, styrene, vinyl acetate and vinyl chloride. As (preferably used) monomeric compounds with more than one polymerizable bond, those of the general formula (III) may be mentioned in particular:

(CH ₂ = CR ³ -COZ-) _n -A (III)

wherein
n = 2, 3 or 4, preferably 2 or 3 and in particular 2;
Z = O or NH, preferably O;
R ³ = H, CH ₃ ;
A = n-valent hydrocarbon radical having 2 to 30, in particular 2 to 20, carbon atoms, which may have one or more heteroatom groups which are each located between two adjacent carbon atoms (examples of such heteroatom groups are O, S, NH, NR (R = hydrocarbon radical ), preferably O).

The hydrocarbon radical A can also carry one or more substituents which are preferably selected from halogen (in particular F, Cl and / or Br), alkoxy (in particular C _1-4 alkoxy), hydroxy, optionally substituted amino, NO ₂ , OCOR ⁵ , COR ⁵ (R ⁵ = C _1-6 alkyl or phenyl). However, the radical A is preferably unsubstituted or substituted with halogen and / or hydroxy.

In a particularly preferred embodiment of the present invention, A of an aliphatic diol, an alkylene glycol, a polyalkylene glycol or an optionally alkoxylated (e.g. ethoxylated) bisphenol (e.g. bisphenol A) derived. In this context, preferred alkylene glycols are ethylene glycol, Propylene glycol and butylene glycol, especially ethylene glycol. Preferred Polyalkylene glycols are diethylene glycol, triethylene glycol, tetraethylene glycol and the like.

Other usable compounds with more than one double bond are for Example allyl (meth) acrylate, divinylbenzene and diallyl phthalate. Likewise, for Example a compound with 2 or more epoxy groups can be used (in the case the use of epoxy-containing surface groups), e.g. B. Bisphenol A-di glycidyl ether or an (oligomeric) precondensate of an epoxy group containing hydrolyzable silane (e.g. glycidoxypropyltrimethoxysilane).

If additional monomeric compounds with polymerizable / poly condensable groups are used, their proportion preferably does not more than 20% by weight, in particular not more than 15 and particularly preferred not more than 10% by weight of the total solids content of the flowable mass from stage a).

In stage b) of the process according to the invention, the flowable mass from stage a) either placed in a suitable mold to produce a shaped body, or applied to a desired substrate to make up all or part of the substrate to coat. The coating methods suitable for this purpose are conventional and known to those skilled in the art. Examples include diving Spraying, knife coating, brushing, spinning, etc.

Before being introduced into the mold or applied to the substrate, the flowable mass, for example by adding solvent or evaporation of volatile constituents (especially existing solvent) a suitable viscosity can be set.  

For coating with the flowable mass of stage a) des The method according to the invention is suitable for substrates made of any materials, especially made of plastics, metal and glass. These substrate materials can if applicable, one before applying the flowable mass Undergo surface treatment (e.g. degreasing, roughening, corona Discharge, treatment with a primer etc.). Especially in the case of Coating plastic substrates can provide suitable adhesion by adding a suitable monomeric polymerizable compound and / or according to the Preferred embodiment described below are provided.

Examples include the metal substrates that can be coated according to the invention Metals such as aluminum, copper, zinc, nickel and chrome and Metal alloys such as (stainless) steel, brass and bronze called. Suitable Plastic substrates are, for example, those made of polycarbonate, polyesters, Polyamides, polystyrene, poly (meth) acrylates (e.g. polymethyl methacrylate) and PVC.

In stage c) of the process according to the invention, a polymerization and / or Polycondensation of the polymerizable / polycondensable surface groups the nanoscale organic solid particles (and possibly the polymerizable / polycondensable groups of the additionally used monomeric or oligomeric species) carried out. This polymerization / poly Condensation can be carried out in the manner familiar to the person skilled in the art become. Such a polymerization / polycondensation preferably takes place in Presence of a suitable catalyst or starter (initiator) that the flowable mass of stage a) at the latest immediately before its introduction into the Form or application is added to the substrate.

All common and known to the expert come as starter / starter systems Starter / starting systems in question, including radical photo starters, radical ones Thermal starter, cationic photo starter, cationic thermal starter and any Combinations of the same.  

Specific examples of radical photo starters that can be used are Irgacure® 184 (1-hydroxy cyclohexylphenyl ketone), Irgacure® 500 (1-hydroxycyclohexylphenyl ketone, Benzophenone) and other photoinitiators available from Ciba-Geigy of the Irgacure® type; Darocur® 1173, 1116, 1398, 1174 and 1020 (available from Merck); Benzophenone, 2-chlorothioxanthone, 2-methylthioxanthone, 2- Isoprnpylthioxanthone, benzoin, 4,4'-dimethoxybenzoin, benzoin ethyl ether, Benzoin isopropyl ether, benzil dimethyl ketal, 1,1,1-trichloroacetophenone, Diethoxyacetophenone and dibenzosuberone.

Examples of radical thermal starters are u. a. organic peroxides in the form of Diacyl peroxides, peroxydicarbonates, alkyl peresters, alkyl peroxides, perketals Ketone peroxides and alkyl hydroperoxides as well as azo compounds. As concrete Examples would be in particular dibenzoyl peroxide, tert-butyl perbenzoate and To call azobisisobutyronitrile.

An example of a cationic photo starter is Cyrncure® UVI-6974, while a preferred cationic thermal starter is 1-methylimidazole.

These starters are in the usual amounts known to those skilled in the art (preferably 0.01-1% by weight, in particular 0.1-0.5% by weight, based on the Total solids content of the flowable mass from stage a)) used.

The polymerization / polycondensation of stage c) of the invention The method is preferably carried out thermally or by irradiation (in particular with UV light). A photochemical is particularly preferred Polymerization / polycondensation or a combination of thermal and photochemical polymerization / polycondensation.

The polymerization / polycondensation can be preceded by a removal of another volatile, non-polymerizable / non-polycondensable compound dungen from the mass in the mold or on the substrate. This Removal of volatile constituents can also or additionally on the Polymerization / polycondensation stage or thereafter.  

The following is a typical method according to the invention that is to be transparent Shaped bodies can be exemplified, the specified ones Value ranges and procedures independent of the specific ones used Materials have general validity.

Nanoscale particles of, for example, SiO ₂ , TiO ₂ , ZrO ₂ or other oxidic or sulfidic materials (particle size 30 to 100 nm, preferably 40 to 70 nm) are in a solvent (for example in a lower alcohol such as methanol, ethanol, propanol) in one Concentration of 1 to 20 wt .-%, preferably 5 to 15 wt .-%, dispersed and with a surface modifier with polymerizable / polycondensable groups in an amount of preferably 2 to 25 wt .-%, in particular 4 to 15 wt .-% % (based on the total solids content). If, for example, silanes are used, the surface modification can be carried out by stirring for several hours at room temperature. If appropriate, a monomeric or oligomeric material with polymerizable / polycondensable groups, which is compatible with the surface modifier or the surface groups, can then be added in an amount of, for example, up to 20% by weight, preferably 4 to 15% by weight, based on the total solids content) are added. After adding one or more suitable starters (each in an amount of, for example, 0.01 to 1% by weight, preferably 0.1 to 0.5% by weight, based on the total solids content), the solvent is partially removed ( preferably 50 to 98, in particular 75 to 95%). The still flowable mass is then given the desired shape, which is followed by the removal of the remaining solvent. A first hardening is then carried out. A photopolymerization is preferably used to reduce the reaction times; any light sources, in particular UV light-emitting sources, can be used (e.g. mercury vapor lamps, xenon lamps, laser light, etc.). The curing with laser light allows an application for the so-called "rapid prototyping". After thermal post-curing for further densification of the structure (e.g. 0.5-4 hours at 70 to 150 ° C, preferably 1-2 hours at 80 to 100 ° C), a green body is obtained. This green body can e.g. B. within 2 to 10 hours, preferably 3 to 5 hours, to a temperature of z. B. heated to 500 ° C and kept for example 2 to 10 hours (preferably 3-5 hours) at this temperature. In most cases, this step leads to the complete loss of the organic (carbon-containing) groupings in the shaped body. For final compression, the molded body can then within z. B. heated for 2 to 10 hours (preferably 3-5 hours) to a temperature of, for example, 1400 ° C and for example 1 to 5 hours (preferably 2-3 hours) at this temperature. A colorless, transparent, purely inorganic molded body can be obtained in this way.

For layer production, for example, one can proceed in such a way that hydrolyzable silanes with polymerizable / polycondensable groups in one Concentration of preferably not more than 100% by weight, especially not more than 75% by weight (based on nanoparticles), for example with brines oxidic or sulfidic nanoparticles are given. After Viscosity adjustment by adding or removing solvent (e.g. Alcohol) and after adding a photoinitiator (e.g. at a concentration of 5 % By weight based on the silane used) leads to hardening of the layer the selected substrate with preferably UV light to transparent, crack-free and homogeneous layers. A thermal aftertreatment at 60 to for example 100 ° C usually leads to a significant improvement in Layer properties, however, is not essential. The layers produced in this way have good abrasion resistance. Since the thermal Aftertreatment can be carried out at relatively low temperatures, too Substrates with low thermal stability can be used without any problems. How already mentioned above, consists of varying the amount and type of used Silane and by the addition of an additional organic monomer (Methacrylates, acrylates, etc.) in low concentrations (for example <5% by weight) the possibility of adapting the adhesive properties of the layer to the substrate, so that z. B. glass and plastics can be coated equally. Further leads to the use of the above-mentioned fluorinated silanes in the Surface modification to easy-to-clean layers on the corresponding  Substrates or a lowering of the surface energy during the addition from Z. B. surfactants can increase the surface energy.

In particular for the coating of plastic substrates, the procedure according to a preferred embodiment of the present invention is that metal oxide nanoparticles (in particular those of AlOOH, ZrO ₂ , TiO ₂ and the like) are used in a relatively high concentration (usually at least 15 and preferably at least 20 % By weight or at least 7 or 10% by volume, with preferred upper limits at 80% by weight, in particular 60% by weight or 40% by volume, in particular 25% by volume) in a liquid system dispersed, which comprises at least one hydrolyzable silane with a polymerizable / poly-condensable group (z. B. one of the above general formula (I)) as an essential component, and then carries out a (usual) pre-hydrolysis of the silane. In addition to the silane with a polymerizable / polycondensable group, other hydrolyzable components may also be present, in particular other (optionally fluorinated) silanes (e.g. those of the general formula (II) above) and / or hydrolyzable compounds (e.g. alkoxides, halides) ) of main and subgroup metals (e.g. Al, Ti, Zr). After the pre-hydrolysis, further species with more than one (preferably two) copolymerizable / copolycodable groups (in particular those of the general formula (III) above, preferably in amounts of up to 80, in particular up to 70 and particularly preferably up to 50 mol. %) are added. (Meth) acrylate groups are particularly preferred as polymerizable groups. Before applying to a plastic substrate, a solvent (e.g. an alcohol) can be added to this system to adjust the viscosity, as well as conventional paint additives. Surprisingly, although the resulting lacquer can be cured thermally (preferably after adding an appropriate thermostarter), when using a photoinitiator (preferably in the usual amounts indicated above), (sole) photochemical curing (preferably with UV light) also increases a highly scratch-resistant, transparent layer that also adheres well to most plastic substrates without pretreating their surfaces (e.g. in the case of polycarbonates, polystyrene, poly (meth) acrylate, etc.).

Of course, the appropriate coating composition dyes, matting agents, etc. are also added if a colored or non-transparent layer is desired.

An additional advantage of the procedure just described is that that, since it is preferably carried out without separately added solvent (except for the purpose of adjusting the viscosity after the pre-hydrolysis), one in the booth Solvent exchange often described in technology prior to application is not is required.

The following examples serve to further illustrate the present invention.

Example 1: Production of a transparent organic-free SiO ₂ molded body

SiO ₂ particles (OX-50, primary particle size 40 nm) are dispersed in a concentration of 10% by weight with stirring and ultrasound in isopropanol for about 30 minutes. 3-Methacryloxypropyltrimethoxysilane (MPTS) in an amount of 6% by weight, based on the SiO ₂ content, is slowly added with stirring. The SiO ₂ particles are silanized by stirring at 50 ° C. for 3 hours. 6% by weight (based on the total solids content) of tetraethylene glycol dimethacrylate (TEGDMA) are then added and the mixture is stirred for a further 15 minutes. Finally, 2 mol% Irgacure® 184 (Ciba-Geigy) per mole of double bond are added as a photo starter for the UV polymerization. The solvent is then partially distilled off under vacuum (complete distillation of the alcohol leads to gel formation, so that a free-flowing or pourable suspension can no longer be obtained). The suspension obtained in this way can be used directly for the production of bulk materials by photopolymerization.

For this purpose, the SiO ₂ / MPTS / TEGDMA system is poured into a molded polyethylene body. For degassing, the viscous sol is again treated under vacuum (100 mbar) at 25 ° C. for hours. A UV / IR combination dryer (Beltron company) is used to crosslink the organic portion. The mercury vapor lamps each have an output of 400 mW / m ² . The complete photopolymerization of a bulk of 5 mm thickness is achieved by an irradiation amount of 240 J / cm ² . After the photopolymerization, a dimensionally stable body is obtained. By oven treatment at 80 ° C, wet-free drying of the photopolymerized bulk is carried out within one hour. This gives a solvent-free and binder-containing molded SiO ₂ body, which corresponds to a ceramic green body. In order to burn out the remaining organic fraction, the temperature of the furnace is increased from 80 ° C to 500 ° C within 3 hours, after which the latter temperature is maintained for a further 3 hours. This gives a porous SiO ₂ bulk which, as can be concluded from IR spectroscopic studies, is free of organic groups. Finally, the temperature is increased from 500 ° C to 1400 ° C within 3 hours and the latter temperature is then held for 2 hours. In this way, a transparent molded body is finally obtained.

Example 2: Production of an organic-free, transparent ZrO ₂ molded body

Nanoscale zirconium oxide particles ("TOSOH-Zirconia TZ-8Y" with a primary particle size of 90 nm) are dispersed in isopropanol with stirring and ultrasound. To modify the surface, 3.2% by weight (based on the ZrO ₂ content) of MPTS is added to the suspension with stirring. After stirring for 3 hours at 50 ° C., the ZrO ₂ particles have been silanized. 3.2% by weight (based on the ZrO ₂ content) of TEGDMA are then added and the mixture is stirred at 20 ° C. for a further 15 minutes. Then 3 mol% Irgacure® 184 per mol double bond are added as a photo starter. This is followed by partial removal of the solvent under vacuum. The still flowable suspension thus obtained is used directly for the production of bulk materials by photopolymerization. In order to obtain a shaped body with a thickness of 5 mm, an output of 350 J / cm ^{2 is} used.

By oven treatment of the photopolymerized molded body at 80 ° C., crack-free drying of the photopolymerized bulk is achieved within 30 minutes. This results in a solvent-free and binder-containing ZrO ₂ bulk, which corresponds to a ceramic green body. In order to burn out the remaining carbon, the temperature of the furnace is increased from 80 ° C to 450 ° C within 3 hours and kept at the latter temperature for 3 hours. This gives a porous ZrO ₂ bulk which is free of organic groups. Finally, the temperature is increased from 450 ° C to 1400 ° C within 3 hours and held at the latter value for 4 hours. The sintered shaped body thus obtained is translucent to opaque.

Example 3: Synthesis of a sol to produce layers with high Refractive index

86.861 g of TiO ₂ sol (3.5% by weight of TiO ₂ in isopropanol; particle size: 5 nm) are mixed with 1.989 g of tributyl phosphoric acid and stirred for 1 hour. A solution of 1.2 g of distilled γ-glycidyl oxypropyltrimethoxysilane (GPTS) in 100 g of 2-isopropoxyethanol is then added dropwise to the sol at 100 ° C. After stirring for 1 hour, the mixture is cooled to room temperature and 0.8775 g of hydrolyzed GPTS (prepared by adding 23.63 g of distilled GPTS with 2.70 g of 0.1 N HCl and stirring for 24 hours and then distilling off) low molecular weight reaction products at 3 mbar) added. After stirring for 15 minutes, the mixture is distilled under vacuum (3 mbar) and then diluted with 120 g of 2-isopropoxyethanol. In this way a transparent, agglomerate-free sol is obtained.

Example 4: Synthesis of a sol to produce low layer layers Refractive index

A mixture of 23.63 g GPTS (distilled) and 12.45 g tetraethoxysilane (TEOS) 2.88 g of 0.1 N HCl are added for the purpose of hydrolysis and condensation. The the resulting reaction mixture is then stirred at 20 ° C. for 24 hours and then vacuum distillation (at 3 mbar) for removal subjected to low molecular weight constituents. Finally, the remaining Reaction product diluted with 50 g isopropoxyethanol as a solvent.  

Example 5: Synthesis of a sol to produce low layer layers Refractive index and additional easy-to-clean function

There are 26.63 g of distilled GPTS with 8.30 g TEOS and 0.11 g of 1H, 1H, 2H, 2H-Per mixed fluoroctyltriethoxysilane (FTS) for 15 minutes with stirring. The resulting sol is stirred at 20 ° C for 4 hours with 4.5 g of 0.1 N HCl hydrolyzed and condensed. Then 52.10 g of isopropoxyethanol and 0.53 g Phosphoric acid is added and the mixture is stirred at 20 ° C. for a further 2 hours.

Example 6: Production of a layer with the sol from example 3 on glass

The sol from Example 3 is mixed with 0.08 g of Cyracure® UVI-6974 (Ciba-Geigy) and 0.02 g 1-methylimidazole added. After intensive stirring, the mixture is filtered and is can then be used as a coating varnish. Glass panes (10 cm × 10 cm × 2 mm) are cleaned with 2-propanol and dried in air before coating.

The coating varnish is defined by spin coating onto the substrate upset. The layer thickness is determined by the speed of rotation of the substrate controlled.

A UV / IR combination dryer (from Beltron) is used to harden the layer. The device used has two mercury vapor lamps for irradiation with UV light, an IR emitter, the output of which can be used to regulate the surface temperature, and a treadmill on which the substrates can be guided under the UV / IR emitter at a defined speed. The power of the mercury vapor lamps is 400 mW / cm ² each.

The IR emitter is set to 120 ° C, the belt speed is 2.6 m / min. and the coated substrates are used three times in total Settings passed.

The final stage of curing consists of a 15 minute thermal Aftertreatment at 120 ° C in a circulating air dryer.  

Example 7: Production of a layer with the sol from Example 3 Polycarbonate (PC)

Polycarbonate panes (10th cm x 10 cm x 2 mm; Pretreatment as in Example 6) according to the method of Example 6 coated and cured. Differences: the IR radiator is at 100 ° C set and the final stage of curing consists of a 30-minute thermal aftertreatment at 100 ° C in a circulating air dryer.

Example 8: Production of a layer with the sol from Example 3 Polymethyl methacrylate (PMMA)

Using the coating material from Example 3, polymethyl methacrylate Disks (10 cm × 10 cm × 2 mm; pretreatment as in Example 6) after the Method of Example 6 coated and cured: Differences: no IR-Be radiation and the final stage of curing consists of a 60 minute thermal aftertreatment at 80 ° C in a circulating air dryer.

Example 9: Production of a layer with the sol from example 4 on a PC

The coating material from Example 4 is mixed with 0.72 g of Cyracure® UVI-6974, 0.36 g of 1-methylimidazole and 10 g of a 0.02 weight percent aluminum tributoxyethanolate solution in 2-isopropoxyethanol and mixed intensively. The necessary dilution is achieved by adding 50 g of 2-isopropoxyethanol reached. With this coating material, polycarbonate panes (see Example 7) coated and cured by the method of Example 7. Differences: the substrates are four times at a tape speed of 2 m / min. passed and the final stage of curing consists of a 60- minute after-treatment at 100 ° C in a circulating air dryer.  

Example 10: Production of a layer with the sol from example 4 on PMMA

The procedure is as in Example 9, but without using the IR radiator. The final stage of curing consists of a 60 minute thermal After-treatment at 70 ° C in a circulating air dryer.

Example 11: Production of a layer with the sol from example 5 on a PC

The coating material according to Example 5 is according to Example 8 with initiators provided and cured by the method described in Example 8.

Properties of the layers produced in Examples 6 to 11 Examination methods

Refractive index: ellipsometric
Transmission (550 nm): spectroscopic (one-sided coating of the substrates)
Reflection (550 nm): spectroscopic (blackened uncoated back of the substrates)
Adhesion (layer on substrate): cross cut and adhesive tape test according to DIN 53151 and DIN 58196
The values thus obtained are summarized in the following table.

Example 12: Coating of plastic substrates

248.8 g (1 mol) of MPTS are introduced and, with stirring, 136.84 g (20% by volume) AlOOH nanopowder (Sol P3, 15 nm, Degussa) added. The hydrolysis takes place through slowly add 36 g (2 mol) of deionized water and boil for 2.5 h 100 ° C. After cooling, the pre-hydrolyzate is mixed with 282 g of 1-butanol Solids content of 45% diluted with 3.5 g (0.5% by weight) Byk®-306 as Leveling agent added. 5.46 g (3 mol%) are used for UV polymerization Benzophenone added as a photo starter. The application of the coating systems on various plastics is done by means of spin coating. The The layer is cured by UV radiation for 2 minutes Mercury lamp.

The coating shows good adhesion (GT / TT = 0/0) without substrate pretreatment, e.g. B. on PMMA. The scratch-resistant coating has an abrasion hardness of 11% after 1000 Cycles (Taber Abraser, CS-10F, 500 g / roll).

Example 13: Coating of plastic substrates

The procedure of Example 12 is repeated, except that in addition to Benzophenone 1.05 g (1 mol%) diethanolamine can be used as a starter.

The coating shows good adhesion (GT / TT = 0/0) without substrate pretreatment, e.g. B. on PMMA. The scratch-resistant coating has an abrasion hardness of 9% after 1000 Cycles (Taber Abraser, CS-10F, 500 g / roll).

Example 14: Coating of plastic substrates

248.8 g (1 mol) of MPTS are introduced and, with stirring, 99.52 g (17% by volume) AlOOH nanopowder (Sol P3, 15 nm, Degussa) added. The hydrolysis takes place through slowly add 36 g (2 mol) of deionized water and boil for 2.5 h 100 ° C. After cooling, the pre-hydrolyzate with 49.5 g (15 mol%) of TEGDMA and 3.9 g (0.5% by weight) of Byk®-306 as leveling agent and mixed with 343 g of 1-butanol  diluted to a solids content of 45%. For UV polymerization, 0.6 g (0.25 mol%) benzophenone added as a photo starter. The application of the Coating system on various plastics is done using a centrifuge coating. The layer is cured by UV radiation for 2 minutes using a mercury lamp.

The coating shows good adhesion (GT / TT = 0/0) without substrate pretreatment e.g. B. PMMA. The scratch-resistant coating has an abrasion hardness of 15% after 1000 Cycles (Taber Abraser, CS-10F, 500 g / roll). Due to the dimethacrylate Flexibility and the water stability of the coating increased. (Storage at 65 ° C in deionized water <14 days, without dimethyl acrylate 7 days.)

Claims (23)

1. A process for the production of nanostructured moldings and layers comprising the following stages:

• a) Provision of a nanoscale inorganic solid particles with flowable mass containing polymerizable and / or polycondensable organic surface groups;
• b1) placing the mass from stage a) in a mold; or
• b2) applying the mass from step a) to a substrate; and
• c) Polymerization and / or polycondensation of the surface groups of the solid particles to form a hardened shaped body or a hardened layer.

2. The method according to claim 1, characterized in that it as an additional Stage a thermal aftertreatment, preferably at a temperature in the Range of 60 to 150 ° C, the shaped body or the layer of step c) includes. 3. The method according to any one of claims 1 and 2, characterized in that that there is a thermal compression of the molded body as an additional stage or the layer at a temperature of at least 250 ° C, preferably at least 400 ° C. 4. The method according to any one of claims 1 to 3, characterized in that that the nanoscale particles from those of metal compounds, especially oxides, sulfides, selenides and tellurides of metals and Mixtures of the same are selected. 5. The method according to any one of claims 1 to 4, characterized in that the nanoscale particles are selected from those of SiO ₂ , TiO ₂ , ZrO ₂ , ZnO, Ta ₂ O ₅ , SnO ₂ and Al ₂ O ₃ and mixtures thereof. 6. The method according to any one of claims 1 to 5, characterized in that that the polymerizable and / or polycondensable surface groups are selected from organic residues, which have a (meth) acrylic, vinyl, Allyl or epoxy group. 7. The method according to any one of claims 1 to 6, characterized that the solid particles used in stage a) through surfaces modification of nanoscale solid particles with the corresponding Surface groups were produced. 8. The method according to any one of claims 1 to 6, characterized in that that using the solid particles used in step a) at least one compound with corresponding polymerizable / poly condensable groups are produced. 9. The method according to any one of claims 1 to 8, characterized in that that the production of the inorganic solid particles after the sol-gel Ver driving takes place. 10. The method according to any one of claims 1 to 9, characterized in that the inorganic solid particles from step a) additionally fluorinated surface groups, preferably those of the formula R _f CH ₂ -CH ₂ - wherein R _{f represents} a perfluoroalkyl radical having 2 to 12 carbon atoms, exhibit. 11. The method according to any one of claims 1 to 10, characterized in that that step c) in the presence of those not bound to the solid particles polymerizable and / or polycondensable monomers or oligomers Species is carried out. 12. The method according to any one of claims 1 to 11, characterized in that that stage c) in the presence of a thermal starter and / or photo starter is carried out.   13. The method according to any one of claims 1 to 12, characterized in that that step c) a photochemical polymerization / polycondensation includes. 14. The method according to any one of claims 1 to 13, characterized in that that the substrate of stage b2) is made of plastic, Metal or glass. 15. Nanostructured moldings, obtainable by the process according to any of claims 1 to 14. 16. A method for producing highly scratch-resistant nanostructured layers on plastic substrates according to claim 1, comprising the following steps:

• a) providing a dispersion of nanoscale metal oxide particles in a system comprising at least one hydrolyzable silane with a polymerizable / polycondensable group in a concentration of at least 15% by weight and subsequent prehydrolysis of the silane;
• b) applying the mass from step a) to a plastic substrate; and
• c) photochemical curing of the layer applied to the plastic substrate.

17. The method according to claim 16, characterized in that the metal oxide particles are those of Al ₂ O ₃ , TiO ₂ and / or ZrO ₂ . 18. The method according to any one of claims 16 and 17, characterized in records that the silane via a meth (acrylic) group, vinyl group or Allyl group has. 19. The method according to any one of claims 16 to 18, characterized in records that in step a) the metal oxide particles in a concentration of at least 20% by weight, preferably at least 30% by weight become.   20. The method according to any one of claims 16 to 19, characterized in records that the pre-hydrolysis of step a) in the absence of separately added organic solvent is carried out. 21. The method according to any one of claims 16 to 20, characterized records that a photoinitiator is added before performing step b). 22. The method according to any one of claims 16 to 21, characterized in records that the plastic substrate is one made of poly (meth) acrylates, Is polycarbonates or polystyrene. 23. Substrate provided with a nanostructured layer, obtainable after A method according to any one of claims 1 to 14 and 16 to 22.