EP1248685B1 - Method for producing a microstructured surface relief by embossing thixotropic layers and microstructured surface relief - Google Patents

Abstract

A method is described for producing a microstructured surface relief by applying to a substrate a coating composition which is thixotropic or which acquires thixotropic properties by pretreatment on the substrate, embossing the surface relief into the applied thixotropic coating composition with an embossing device, and curing the coating composition following removal of the embossing device. The substrates obtainable by this method, provided with a microstructured surface relief, are particularly suitable for optical, electronic, micromechanical and/or dirt repellency applications.

Description

The present invention relates to a method for producing microstructured Surface reliefs in which the surface relief is embossed with an embossing device embossed thixotropic coating composition applied to a substrate is provided with this microstructured surface relief substrates as well as the Use of these substrates.

Surface relief structures are used for various fields of application. In the foreground are decorative applications, for example on metal, plastic, cardboard or stone. In addition, applications for the production of non-slip floor coverings, shoe soles, refined textiles, structured soundproofing panels or electrical cables are mentioned. In addition to screen printing processes, printing processes with structured rollers or casting processes are used to create relief structures with dimensions in the mm range. For technical reasons, thixotropic, structurally or highly viscous lacquers are used, additives known from the prior art being used for thixotroping. These can also be fine-scale inorganic powders such as SiO ₂ or CaCO ₃ . Thixotropic lacquer and binder systems can also be used to produce stochastic surface relief structures using spray processes with the addition of relatively coarse-grained particles that determine the structural geometry.

Roll embossing processes ("embossing") play an important role. One differentiates hot stamping, stamping thixotropic lacquers and reactive stamping. At the The embossing roller is hot stamped into a thermoplastic substrate which is over the Glass transition point is heated, pressed. Then the structure is through rapid cooling fixed after the roller was pulled out. In an analogous way This process also uses small, rigid stamps Production of very fine structures in the µm and 100 nm range for electronic Applications examined. Disadvantages here are inaccuracies that are caused are used by the high thermal expansion coefficient thermoplastic polymers and the high restoring forces as a result are very small Radii of curvature that also round off edges when cooling rapidly to lead. Other disadvantages are the long process times and the principle Not suitable for the so-called "stepping", in which a sequence of embossments on neighboring surface units with a small, gradually offset Stamp large areas to be structured. When embossing thixotropic paints remains the relief due to the thixotropic rheology of the varnish, at least for one largely preserved in the period of fixation by hardening or Drying can be done. So far, however, this method has only been used for production of relatively coarse structures with dimensions in the mm range.

For structures with dimensions in the µm to nm range for optical or microelectronic applications place very high demands on the Abformtreue. For optical and microelectronic µm or nm structures is therefore "Near-net shaping" with a defined slope is required.

For surface relief structures with dimensions in the µm to nm range is next to only the reactive stamping was used for hot stamping. When reactive embossing is imperative that the structured coating film under the plan stamp used by thermal treatment or UV radiation is cured before the indented stamp is removed from the coating film can be. This also applies if another, downstream Heat treatment a further compression takes place. A. Gombert et al., Thin Solid Films, 351 (1,2) 1999, 73-78, assume that even when the Reactive embossing on the roller technology the curing under the embossing tool must be done. It is believed that this is necessary in order to prevent the surface forces, which are particularly high at small radii of curvature the non-hardened layer to round the microstructure and thus to Loss of impression accuracy would result if you try a thixotropic embossing would. From a technological point of view, hardening after removal of the Roller particularly interesting as this is due to the creation of surface reliefs large areas, e.g. B. as a moth eye anti-reflective structure for display applications, in the rolling process with shorter process times and higher process reliability than with Would allow hardening under the roller.

WO-A-95/31413 describes a process for the production of structured inorganic layers where a coating composition that is available is by hydrolysis and polycondensation of hydrolyzable silanes and optionally adding fine-scale fillers, applied to a substrate and e.g. is structured with an embossing stamp. The coating composition is structured while the die is in the coating composition located. Thixotropic coating compositions will not described.

WO-A-93/06508 discloses optical elements with an embossed surface structure, where the embossed surface is made of a transparent composite material consists. The structuring can also be done here by means of an embossing stamp and the composition is cured before removing the stamp. Thixotropic coatings are also not mentioned.

The invention has for its object a method for producing To provide microstructures with dimensions in the lower µm to nm range, that on the one hand the high demands on impression accuracy, which are in this dimension range are necessary, guaranteed and on the other hand shorter manufacturing times allows.

The object of the invention is surprisingly achieved by a method for Production of a microstructured surface relief solved, in which one Substrate applies a coating composition that is thixotropic or that obtained thixotropic properties with a Embossing device the surface relief in the applied thixotropic coating composition embosses and the coating composition Removing the embossing device hardens.

With the method according to the invention, a true-to-shape impression is very high accuracy and steepness also possible in the microstructure area is far above the state of the art. In addition, the manufacturing times be shortened significantly, which is particularly true for the microstructuring of large areas is important.

The coating composition can be applied in any conventional manner become. All common wet chemical coating processes can be used be used. Examples are spin coating, (electro) dip coating, Knife coating, spraying, spraying, pouring, brushing, flood coating, film casting, Knife casting, slot coating, meniscus coating, curtain coating, roller application or Common printing processes, such as screen printing or flexoprint. Are preferred continuous coating processes such as flat spraying, flexoprinting, Roller application or wet chemical film coating techniques. The amount of applied coating composition is chosen so that the desired layer thickness is achieved. For example, it works in such a way that the embossing process layer thicknesses in the range of 0.5 to 50 microns, preferably 0.8 to 10 microns, particularly preferably 1 to 5 microns can be obtained.

The coating composition can be thixotropic even before application or after application to the substrate it is pretreated to be thixotropic Attained properties. A coating composition is preferably used which only after application to the substrate by appropriate Pretreatment becomes thixotropic. The thixotropy is one Property of certain viscous compositions whose viscosity Action of mechanical forces (shear stress, shear stress, etc.) decreases. In the context of the present application, the terms "Thixotropy" and "thixotropic" are used in the sense that they are also pseudoplastic Include systems. Thixotropic systems in the narrower sense differ of pseudoplastic systems in that the change in viscosity with them there is a certain time delay (hysteresis). Because of this are Thixotropic systems according to the invention preferred, although also pseudoplastic Systems with good results can be used and therefore by the here terms used "thixotropy" and "thixotropic" are included.

Thixotropic compositions are familiar to the person skilled in the art. It is him too Measures such as the addition of thixotropic agents or viscosity regulators, known, which lead to thixotropic compositions.

If the coating composition is not yet thixotropic before application, the applied coating composition is pretreated so that sets the thixotropic behavior. Of course, one can also be done before Application Thixotropic coating composition pretreated after application e.g. to reinforce the thixotropic behavior. Just as naturally a non-thixotropic coating composition must be selected so that it can acquire the thixotropic property through pretreatment.

Pretreatment here is in particular a thermal treatment or Understood radiation treatment of the applied coating composition, which can also be used in combination. If necessary but also a simple evaporation of the solvent (flashing off) are sufficient to achieve a thixotropic behavior. The ventilation can also be one precede the above pretreatments. Examples of usable Radiation types are IR radiation, UV radiation, electron radiation and / or Laser radiation. The pretreatment preferably consists of a thermal one Treatment. For this the coated substrate, e.g. in an oven, over one warmed up for a certain period of time.

Naturally, the temperature ranges used or the intensity of the Radiation and the pretreatment time from each other and especially from the Coating composition, e.g. the type of coating composition, the additives used and the type and amount of the used Solvent, from. Through the resulting processes, such as evaporation of the solvent or condensation processes, the applied Coating compositions thixotropic. It is important to ensure that still there is no curing of the coating composition. The corresponding Parameters are known to the person skilled in the art, or he can easily use them determine routine attempts.

The parameters of the pretreatment, e.g. the temperature, preferably so chosen that the solvent residues present in the layer largely be driven out, but that it is not yet to harden the coating composition, e.g. about cross-linking reactions. This is especially in The presence of thermostars is important. With thermal treatment it will coated substrate e.g. at temperatures in the range of 60 to 180 ° C, preferred 80 to 120 ° C over a period of e.g. Warmed for 30 s to 10 min. Especially the pretreatment is preferably carried out so that for the applied Coating composition a viscosity of 30 Pa s to 30,000 Pa s, preferably 30 Pa s to 1000 Pa s, particularly preferably 30 Pa s - 100 Pa s, achieved becomes. This also applies to non-pretreated coating compositions preferred areas. The pretreated layer may e.g. both Organic coating compositions listed below modified inorganic polycondensates or precursors thereof to form a gel act.

The microstructured surface relief is embossed using a conventional one Embosser. It can e.g. around a stamp or a roller act, the use of rollers is preferred. For special cases, e.g. Rigid stamps are also suitable. The roller can e.g. a hand roller or one machine embossing roller. The negative is on the embossing device Image (negative master) of the microstructure to be embossed a positive master is won. The structure of the master can be flexible or be rigid.

Typical contact pressures are in the range of 0.1 to 100 MPa, depending on, for example, the structural geometry and the degree of crosslinking of the coating film. Typical roller speeds are in the range from 0.6 m / min to 60 m / min. This underlines the great advantage of the method according to the invention over the reactive embossing used according to the prior art, in which it takes about 10 minutes to produce a microstructured surface relief of an area of 1 cm ² in discontinuous operation.

In contrast to reactive embossing, in which curing takes place as long as the Embossing device located in the coating composition is according to the invention only hardened when the embossing device consists of the coating composition was removed. Naturally, this does not mean that the Embossing device, such as in the rolling process, not in another place for another or continuous embossing process can be used. It is essential that the section of the embossed surface relief, that of the hardening is no longer in contact with the embossing device.

The hardening becomes the usual in coating technology Hardening processes understood that lead to essentially none (Permanent) deformation of the hardened layer is more possible. Here you will find in Depending on the type of coating composition e.g. a Crosslinking, compaction or glazing, condensation or drying instead of. The hardening or fixation of the embossed surface relief should be within 1 minute, better within 30 s and preferably within 3 s Demoulding, that is to say after the embossing device has been removed. If necessary, the hardened layer can also be subjected to thermal aftertreatment be glazed in the organic components leaving a pure inorganic matrix are burned out.

The hardening is in particular in the form of a thermal hardening, a hardening by radiation or a combination thereof. To be favoured known radiation curing methods used. Examples of usable Radiation types have been listed above for pretreatment. Prefers radiation curing takes place by means of UV radiation or electron beams. In each The fixation should be for maximum possible networking, densification or Condensation of the coating.

The surface relief structure is independent of any existing one random surface roughness a defined pattern of surveys and Indentations in the surface layer. The pattern formed can be stochastic or periodic, but it can also be a certain desired pattern represent. A microstructured surface profile has dimensions in the µ mouth / or nm range, with dimensions being the dimensions of the Depressions or increases (amplitude height) or the distances (period) between them is understood. However, additional ones can also be Superstructures are integrated, e.g. save special information can. Examples of this are light-directing or holographic structures and optical data storage. There are also micro-structured reliefs, e.g. if There are depressions in the µm and / or nm range, while the distances between the wells are not in this area, and vice versa. Of course, in addition to the structures in the µmund / or larger structures may also be present in the nm range. The Microstructured surface reliefs generally have structures Dimensions below 800 µm, preferably below 500 µm, particularly preferably below 200 µm. Even with even smaller dimensions under 30 µm and even in Nanometer range below 1 µm and even below 100 nm will give good results achieved.

The coating composition used according to the invention can be applied to any any substrate can be applied. Examples of this are metal, glass, ceramics, Paper, plastic, textiles or natural materials such as Wood. As examples for metal substrates e.g. Called copper, aluminum, brass, iron and zinc. Examples of plastic substrates are polycarbonate, polymethyl methacrylate, Polyacrylates, polyethylene terephthalate. The substrate can be in any form e.g. as a plate or foil. Of course, surface-treated ones are also suitable Substrates for the production of microstructured surfaces, e.g. painted or metallized surfaces.

The coating compositions can be chosen so that opaque or transparent, electrically conductive, photoconductive or insulating coatings can be obtained. Are preferred, especially for optical applications, transparent coatings. The coatings can also be colored. The coating compositions can e.g. are in the form of gels, sols, dispersions or solutions.

In a preferred embodiment, the applied one Coating composition before the embossing process as a gel. Preferably the coating composition is applied as a sol to the substrate and converted into the gel by the pretreatment, the thixotropic behavior is obtained. The gel formation comes e.g. by solvent withdrawal and / or Condensation processes.

Coating compositions can be conventional Coating systems based on organic polymers or glass or ceramic-forming compounds as binders or matrix-forming components act if the coating compositions are thixotropic or by pretreatment can achieve thixotropic behavior. Can as a binder the organic polymers known to the person skilled in the art are used. Prefers the organic polymers used still contain functional groups that networking is possible. The coating compositions further contain with organic polymers as binders, preferably still nanoscale inorganic solid particles so that coatings are formed from a polymer layer compounded with nanoparticles. As polymers are any known plastics such. B. polyacrylic acid, polymethacrylic acid, Polyacrylates, polymethacrylates, polyolefins, polystyrene, polyamides, polyimides, Polyvinyl compounds, such as polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, Polyvinyl acetate and corresponding copolymers, e.g. B. poly (ethylene vinyl acetate), Polyester, e.g. B. polyethylene terephthalate or polydiallyl phthalate, polyarylates, Polycarbonates, polyethers, e.g. B. polyoxymethylene, polyethylene oxide or Polyphenylene oxide, polyether ketones, polysulfones, polyepoxides and fluoropolymers, e.g. B. polytetrafluoroethylene.

Coating compositions based on glass- or ceramic-forming compounds can be coating compositions based on inorganic solid particles, preferably nanoscale inorganic solid particles, or hydrolyzable starting compounds, in particular metal alkoxides or alkoxysilanes. Examples of nanoscale inorganic solid particles and of hydrolyzable starting compounds are given below.
Particularly good results are obtained with coating compositions based on organically modified inorganic polycondensates (ormocers, nanomers, etc.), for example polyorganosiloxanes, or their precursors. Accordingly, the use of such coating compositions is particularly preferred. A further improvement can be achieved if the organically modified inorganic polycondensates or precursors thereof contain organic radicals with functional groups via which crosslinking is possible and / or if they are in the form of so-called inorganic-organic nanocomposite materials. Coating compositions based on organically modified inorganic polycondensates which are suitable for the present invention are described, for example, in DE 19613645, WO 92/21729 and WO 98/51747, to which reference is made. These components are explained in detail below.

The production of the organically modified inorganic polycondensates or Precursors of this take place in particular by hydrolysis and condensation of hydrolyzable starting compounds according to the prior art known sol-gel process. Prehydrolyzates in particular are among precursors and / or pre-condensates with a lower degree of condensation Roger that. The hydrolyzable starting compounds are Element compounds with hydrolyzable groups, at least a part these compounds also include non-hydrolyzable groups, or oligomers from that. Preferably contain at least 50 mol%, particularly preferably at least 80 mol% and very particularly preferably 100 mol% of those used hydrolyzable starting compounds at least one non-hydrolyzable Group.

In addition, mixtures of organic monomers, oligomers and / or polymers of the usual type can be used with the organic polymers.

In the case of the production of the organically modified inorganic polycondensates or their precursors used hydrolyzable starting compounds it is in particular connections of at least one element M from the Main groups III to V and / or the subgroups II to IV of the periodic table of the elements. They are preferably hydrolyzable compounds of Si, Al, B, Sn, Ti, Zr, V or Zn, in particular those of Si, Al, Ti or Zr, or Mixtures of two or more of these elements. It should be noted that of course, other hydrolyzable compounds can also be used can, especially those of elements of main groups I and II of Periodic table (e.g. Na, K, Ca and Mg) and the subgroups V to VIII of the Periodic table (e.g. Mn, Cr, Fe and Ni). Also hydrolyzable compounds of Lanthanides can be used. Preferably they just do it but no more than 40 and in particular no more than 20 of the compounds mentioned Mol% of the total hydrolyzable monomeric compounds used. When using highly reactive hydrolyzable compounds (e.g. aluminum compounds) it is advisable to use complexing agents that have a spontaneous precipitation of the corresponding hydrolysates after adding water prevent. Suitable complexing agents are mentioned in WO 92/21729 reactive hydrolyzable compounds can be used.

As a hydrolyzable starting compound, the at least one non-hydrolyzable Group, are preferably hydrolyzable organosilanes or oligomers of it used. Accordingly, organosilanes that can be used in the following explained in more detail. Corresponding hydrolyzable starting compounds of others The above-mentioned elements are derived analogously from those listed below hydrolyzable and non-hydrolyzable residues, where appropriate the different valence of the elements must be taken into account. This too In addition to the hydrolyzable groups, compounds preferably contain only one non-hydrolyzable group.

A preferred coating composition accordingly preferably comprises a polycondensate or precursors obtainable, for example, by the sol-gel process, based on one or more silanes of the general formula R _a -Si-X _(4-a) (I), in which the radicals R are identical or are different and represent non-hydrolyzable groups, the radicals X are identical or different and mean hydrolyzable groups or hydroxyl groups and a is 1, 2 or 3, or an oligomer derived therefrom. The value a is preferably 1.

In the general formula (I) the hydrolyzable groups X, which can be identical or different, are, for example, hydrogen or halogen (F, Cl, Br or I), alkoxy (preferably C _1-6 alkoxy, such as methoxy, ethoxy) , n-propoxy, i-propoxy and butoxy), aryloxy (preferably C _6-10 aryloxy such as phenoxy), acyloxy (preferably C _1-6 acyloxy such as acetoxy or propionyloxy), alkylcarbonyl (preferably C _{2- 7-} alkylcarbonyl, such as acetyl), amino, monoalkylamino or dialkylamino, preferably having 1 to 12, in particular 1 to 6, carbon atoms. Preferred hydrolyzable radicals are halogen, alkoxy groups and acyloxy groups. Particularly preferred hydrolyzable radicals are C _1-4 alkoxy groups, especially methoxy and ethoxy.

With the non-hydrolyzable radicals R, the same or different can be non-hydrolyzable radicals R with a functional Group via which crosslinking is possible or non-hydrolyzable residues R act without a functional group.

The non-hydrolyzable radical R without a functional group is, for example, alkyl (preferably C _1-8 -alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl and t-butyl, pentyl, hexyl, octyl or cyclohexyl ), Aryl (preferably C _6-10 aryl, such as phenyl and naphthyl) and corresponding alkylaryls and arylalkyls. The radicals R and X may optionally have one or more customary substituents, such as halogen or alkoxy.

Specific examples of functional groups via which crosslinking is possible are, for example, the epoxy, hydroxy, ether, amino, monoalkylamino, dialkylamino, optionally substituted anilino, amide, carboxy, vinyl, allyl, alkynyl -, acrylic, acryloxy, methacrylic, methacryloxy, mercapto, cyano, alkoxy, isocyanato, aldehyde, alkylcarbonyl, acid anhydride and phosphoric acid groups. These functional groups are bonded to the silicon atom via alkylene, alkenylene or arylene bridge groups, which can be interrupted by oxygen or -NH groups. Examples of non-hydrolyzable radicals R with vinyl or alkynyl group are C _2-6 alkenyl, such as vinyl, 1-propenyl, 2-propenyl and butenyl and C _2-6 alkynyl, such as acetylenyl and propargyl. The bridging groups mentioned and any substituents present, such as in the case of the alkylamino groups, are derived, for example, from the alkyl, alkenyl or aryl radicals mentioned above. Of course, the radical R can also have more than one functional group.

Specific examples of non-hydrolyzable radicals R with functional groups via which crosslinking is possible are a glycidyl or a glycidyloxy (C _1-20 ) alkylene radical, such as β-glycidytoxyethyl, γ-glycidyloxypropyl, δ-glycidyloxybutyl, ε-glycidyloxypentyl, ω-glycidyloxyhexyl, and 2- (3,4-epoxycyclohexyl) ethyl, a (meth) acryloxy (C _1-6 ) alkylene radical, where (C _1-6 ) alkylene, for example for methylene, Ethylene, propylene or butylene, and a 3-isocyanatopropyl radical.

Specific examples of corresponding silanes are γ-glycidyloxypropyltrimethoxysilane (GPTS), γ-glycidyloxypropyltriethoxysilane (GPTES), 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropyldimethylchlorosilane, 3-aminopropyltrimethoxysilane (APTS), 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminoproyltrimethoxysilane, N- [N '- (2'-aminoethyl) -2-aminoethyl] -3-aminopropyltrimethoxysilane, hydroxymethyltriethoxysilane, Bis- (hydroxyethyl) -3-aminopropyltriethoxysilane, N-hydroxyethyl-N-methylaminopropyltriethoxysilane, 3- (meth) acryloxypropyl triethoxysilane and 3- (meth) acryloxypropyltrimethoxysilane. Further examples of usable according to the invention hydrolyzable silanes can e.g. can also be found in EP-A-195493.

In the case of the functional groups mentioned above, via which crosslinking is possible is, it is in particular polymerizable and / or polycondensable Groups, under polycondensation reactions also polyaddition reactions be understood. If used, the functional groups are preferred selected so that via optionally catalyzed polymerization, addition or cross-linking reactions can be carried out.

Functional group can be chosen, which with itself the above can perform the reactions mentioned. Examples of such functional Groups are epoxy-containing groups and reactive carbon-carbon multiple bonds (especially double bonds). Concrete and preferred Examples of such functional groups are glycidoxy and above (Meth) acryloxy radicals. It can also be a functional group, which can enter into corresponding reactions with other functional groups (so-called corresponding functional groups). Then there will be hydrolyzable starting compounds are used, both functional groups contain or mixtures that the respective corresponding functional Groups included. Is only one in the polycondensate or in the preliminary stage contain functional group, the corresponding corresponding functional group in the crosslinking agent which may then be used are located. Examples of corresponding functional group pairs are vinyl / SH, Epoxy / amine, epoxy / alcohol, epoxy / carboxylic acid derivatives, methacryloxy / amine, Allyl / amine, amine / carboxylic acid, amine / isocyanate, isocyanate / alcohol or Isocyanate / phenol. When using isocyanates, these are preferred in Form of blocked isocyanates used.

In a preferred embodiment, organically modified inorganic Polycondensates or precursors thereof based on hydrolyzable starting compounds used, at least a part of the used hydrolyzable compounds are the hydrolyzable compounds discussed above Compounds with at least one non-hydrolyzable residue with a functional group through which networking is possible. Prefers contain at least 50 mol%, particularly preferably at least 80 mol% and very particularly preferably 100 mol% of the hydrolyzable used Starting compounds with at least one non-hydrolyzable residue functional group through which crosslinking is possible. For this, γ-glycidyloxypropyltrimethoxysilane (GPTS), γ-glycidyloxypropyltriethoxysilane are particularly preferred (GPTES), 3- (meth) acryloxypropyl triethooysilane and 3- (meth) acryloxypropyltrimethoxysilane used.

In addition, organically modified inorganic polycondensates or precursors thereof can be used which at least partially have organic radicals which are substituted with fluorine. For this purpose, additionally or alone, for example, hydrolyzable silicon compounds can be used with at least one non-hydrolyzable radical which has 2 to 30 fluorine atoms bonded to carbon atoms, which are preferably separated from Si by at least two atoms. As hydrolyzable groups z. B. those are used as indicated in formula (I) for X. Specific examples of fluorosilanes are C ₂ F ₅ -CH ₂ CH ₂ -SiZ ₃ , nC ₆ F ₁₃ -CH ₂ CH ₂ -SiZ ₃ , nC ₈ F ₁₇ -CH ₂ CH ₂ -SiZ ₃ , nC ₁₀ F ₂₁ -CH ₂ CH ₂ -SiZ ₃ with (Z = OCH ₃ , OC ₂ H ₅ or Cl); iC ₃ F ₇ O-CH ₂ CH ₂ CH ₂ -SiCl ₂ (CH ₃ ), nC ₆ F ₁₃ -CH ₂ CH ₂ -SiCl ₂ (CH ₃ ) and nC ₆ F ₁₃ -CH ₂ CH ₂ -SiCl (CH ₃ ) ₂ . The use of such a fluorinated silane results in the corresponding coating being additionally given hydrophobic and oleophobic properties. Such silanes are described in detail in DE 4118184. These fluorinated silanes are preferably used when rigid punches are used. The proportion of fluorinated silanes is preferably 0.5 to 2% by weight, based on the total organically modified inorganic polycondensate used.

As already mentioned above can be used to produce the organically modified inorganic condensates also partially hydrolyzable starting compounds are used which have no non-hydrolyzable groups. For the usable hydrolyzable groups and the usable elements M is based on referenced above. Are particularly preferred for this Alkoxides of Si, Zr and Ti used. Such coating compositions based on hydrolyzable compounds with non-hydrolyzable groups and hydrolyzable compounds without non-hydrolyzable groups are e.g. in WO 95/31413 (DE 4417405) to which reference is hereby made. With these coating compositions, the surface relief can thermal aftertreatment to a glass-like or ceramic microstructure be compressed.

Specific examples are listed below.
Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (On- or iC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) ₄ , SiCl ₄ , HSiCl ₃ , Si (OOCC ₃ H) ₄ , Al (OCH ₃ ) ₃ , Al (OC ₂ H ₅ ) ₃ , Al (OnC ₃ H ₇ ) ₃ , Al (OiC ₃ H ₇ ) ₃ , Al (OC ₄ H ₉ ) ₃ , Al (OiC ₄ H ₉ ) ₃ , Al (O-sek-C ₄ H ₉ ) ₃ , AlCl ₃ , AlCl (OH) ₂ , Al (OC ₂ H ₄ OC ₄ H ₉ ) ₃ , TiCl ₄ , Ti (OC ₂ H ₅ ) ₄ , Ti (OC ₃ H ₇ ) ₄ , Ti (OiC ₃ H ₇ ) ₄ , Ti (OC ₄ H _{9) 4 '} Ti (2-ethylhexoxy) ₄ ; ZrCl ₄ , Zr (OC ₂ H ₅ ) ₄ , Zr (OC ₃ H ₇ ) ₄ , Zr (OiC ₃ H ₇ ) ₄ , Zr (OC ₄ H ₉ ) ₄ , ZrOCl ₂ , Zr (2-ethylhexoxy) ₄ , and Zr compounds which have complexing residues, such as, for example, β-diketone and methacrylic residues, BCl ₃ , B (OCH ₃ ) ₃ , B (OC ₂ H ₅ ) ₃ , SnCl ₄ , Sn (OCH ₃ ) ₄ , Sn (OC ₂ H ₅ ) ₄ , VOCl ₃ and VO (OCH ₃ ) ₃ .

The results are greatly improved if coating compositions based on inorganic-organic nanocomposites are used. These are, in particular, composites based on the hydrolyzable starting compounds listed above, at least some of which have non-hydrolyzable groups, and nanoscale inorganic solid particles or composites based on nanoscale inorganic solid particles modified with organic surface groups. These inorganic-organic nanocomposites of the former case can be obtained by simply mixing the organically modified inorganic polycondensates or precursors obtained from the hydrolyzable starting compounds with the nanoscale inorganic solid particles. The hydrolysis and condensation of the hydrolyzable starting compounds can, however, also preferably take place in the presence of the solid particles. In another embodiment, nanocomposites are produced by compounding soluble organic polymers with the nanoscale particles.
The nanoscale inorganic solid particles can consist of any inorganic materials, but in particular they consist of metals or 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, Agl, CuCl, CuBr, Cdl ₂ and Pbl ₂ ; Carbides such as CdC ₂ or SiC; Arsenides such as AlAs, GaAs and GeAs; Antimonides such as InSb; Nitrides such as BN, AIN, 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. metal-tin oxides, such as indium-tin oxide (ITO), antimony-tin oxide (ATO), fluorine-doped tin oxide (FTO), Zn- doped Al ₂ O ₃ , luminescent pigments with Y- or Eu-containing compounds, or mixed oxides with a perovskite structure such as BaTiO ₃ and PbTiO ₃ ). A type of nanoscale inorganic solid particles or a mixture of different nanoscale inorganic solid particles can be used.

The nanoscale inorganic solid particles are preferably an oxide, hydrated oxide, nitride or carbide of Si, Al, B, Zn, Cd, Ti, Zr, Ce, Sn, In, La, Fe, Cu, Ta, Nb, V, Mo or W, particularly preferably of Si, Al, B, Ti and Zr.

Oxides or oxide hydrates are particularly preferably used. Preferred nanoscale inorganic solid particles are SiO ₂ , Al ₂ O ₃ , ITO, ATO, AlOOH, ZrO ₂ and TiO ₂ , such as boehmite and colloidal SiO ₂ . Particularly preferred nanoscale SiO ₂ particles are commercially available silica products, for example silica sols such as the Levasile®, silica sols from Bayer AG, or pyrogenic silicas, for example the Aerosil products from Degussa.

The nanoscale inorganic solid particles. generally have a particle size in the range from 1 to 300 nm or 1 to 100 nm, preferably 2 to 50 nm and particularly preferably 5 to 20 nm. This material can be used in the form of a powder, but is preferably in the form of a, in particular acidic or alkaline, stabilized sols are used.
The nanoscale inorganic solid particles can be used in an amount of up to 50% by weight, based on the solid components of the coating composition. In general, the content of nanoscale inorganic solid particles is in the range from 1 to 40, preferably 1 to 30, particularly preferably 1 to 15% by weight.

The inorganic-organic nanocomposites can be composites Basis of nanoscale modified with organic surface groups act inorganic solid particles. When modifying the surface of nanoscale solid particles are known in the art Methods as e.g. is described in WO 93/21127 (DE 4212633). Nanoscale inorganic solid particles are preferably used here, those with polymerizable and / or polycondensable organic surface groups or such surface groups are provided that one of the matrix have a similar chemical structure or polarity. Such polymerizable and / or polycondensable nanoparticles and their production are e.g. in the WO 98/51747 (DE 19746885).

The production of the polymerizable and / or polycondensable organic surface groups provided nanoscale inorganic Solid particles can, in principle, be carried out in two different ways become, namely on the one hand by surface modification of already produced nanoscale inorganic solid particles and on the other Production of these inorganic nanoscale solid particles using of one or more compounds which are polymerizable via such and / or polycondensable groupings. These two ways will be explained in more detail in the above-mentioned patent application.

In the case of the organic polymerizable and / or polycondensable surface groups can be any groups known to the person skilled in the art which a polymerization or polycondensation are accessible. It is here in particular to the functional groups already mentioned above, via which networking is possible. 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 polycondensing groups would e.g. Isocyanate, alkoxy, hydroxy, To name carboxy and amino groups, with the help of urethane, ether, ester and Amide bonds between the nanoscale particles can be obtained. According to the invention, it is also preferred that the surfaces of the nanoscale particles present organic groupings that the polymerizable and / or polycondensable groups include a relative have low molecular weight. In particular, the molecular weight the (purely organic) groupings 500 and preferably 300, especially preferably 200, do not exceed. Of course, this clearly includes higher molecular weight of the compounds comprising these groupings (Molecules) not made (e.g. 1000 and more).

As already mentioned above, the polymerizable / polycondensable In principle, surface groups are provided in two ways. Will one Surface modification of already produced nanoscale particles, all (preferably low molecular weight) compounds are suitable for this purpose, which on the one hand have one or more groups that are on the surface of the nanoscale solid particles present (functional) groups (such as for example OH groups in the case of oxides) react or at least can interact, and on the other hand at least one polymerizable / polycondensable Have group. Thus the corresponding connections e.g. both covalent and ionic (salt-like) or coordinative (complex or Form chelate bonds to the surface of the nanoscale solid particles, while among the pure interactions exemplary dipole-dipole interactions, Hydrogen bonds and van der Waals interactions should be mentioned. The formation of covalent is preferred and / or coordinative bonds. Specific examples of Surface modification of the nanoscale inorganic solid particles organic compounds that can be used are, for example, unsaturated ones 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, epoxies and the like. According to the invention, particular preference as such compounds are especially in the case of oxidic particles - hydrolytically condensable silanes with at least (and preferably) a non-hydrolyzable residue via which crosslinking is possible.

For examples of these hydrolyzable silanes with a functional group, by means of which crosslinking is possible, reference is made to the above statements on formula (I) with regard to the hydrolyzable starting compounds. Preferred examples are silanes of the general formula (II): YR ¹ -SiR ² ₃ wherein Y represents CH ₂ = CR ³ -COO, CH ₂ = CH, glycidyloxy, an amine or acid anhydride group, R ^{3 represents} hydrogen or methyl, R ^{1 is} a divalent hydrocarbon radical having 1 to 10, preferably 1 to 6 carbon atoms, which optionally contains one or more heteroatom groups (for example O, S, NH) which separate adjacent carbon atoms 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 (eg methoxy, ethoxy, n-propoxy, i-propoxy and butoxy), C _6-10 aryloxy groups (eg 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 having 1 to 6 carbon atoms, such as 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.

Y is preferably CH ₂ = CR ³ -COO (where R ^{3 is} preferably CH ₃ ) or glycidyloxy. Accordingly, particularly preferred silanes of the general formula (II) are (meth) acryloyloxyalkyltrialkoxysilanes such as, for example, 3-methacryloyloxypropyltri (m) ethoxysilane and glycidyloxyalkyltrialkoxysilanes such as for example 3-glycidyloxypropyltri (m) ethoxysilane.

For the in situ production of nanoscale inorganic solid particles with polymerizable / polycondensable surface groups is on WO 98/51747 (DE 19746885).

Surprisingly, the organically modified inorganic polycondensates or their precursors and especially the inorganic-organic Nanocomposites that exist as gel layers before the embossing process, which mainly through condensation of the silanol groups involved and solvent removal arise, such a strong thixotropic character that the true to form Impression with very small structural dimensions, also in the microstructure area leads to a very high accuracy and steepness that goes far beyond the state of the art. Due to the inorganic-organic hybrid character the gels are much more flexible than pure ones made from metal alkoxides inorganic gels, but more stable than solvent-free organic monomer / oligomer layers. This also applies to inorganic-organic composites without nanoparticles, however, the thixotropic character is due to the composition with inorganic Nanoparticles promoted.

In a particularly preferred embodiment, the coating composition is before the embossing process as a thixotropic gel Solvent removal and largely complete condensation of the existing Inorganically condensable groups were obtained, so that the degree of condensation the inorganic matrix is very high or substantially complete. The subsequent hardening then causes organic crosslinking of the gel existing organic residues with functional groups via which one Crosslinking is possible (polymerization and / or polycondensation).

The coating composition may optionally contain spacers. Spacers are understood to mean organic compounds which preferably contain at least two functional groups which, with the components of the coating composition, in particular with the functional groups of the polycondensates, via which crosslinking is possible, or the polymerizable and / or polycondensable groups of the nanoscale inorganic solid particles, can interact and thereby, for example, bring about a flexibilization of the layer. The spacers preferably have at least 4 CH ₂ groups in front of the organofunctional group, calculated from the group attached to the surface; a CH ₂ group can also be replaced by an -O-, -NH or -CONH group.

Organic compounds, such as phenols, can be used in the Coating composition as spacer or as connecting bridges be introduced. The most commonly used connections for this purpose are bisphenol A, (4-hydroxyphenyl) adamantane, hexafluorobisphenol A, 2,2-bis (4-hydroxyphenyl) perfluoropropane, 9,9-bis (4-hydroxyphenyl) fluorenone, 1,2-bis-3- (hydroxyphenoxy) ethane, 4,4'-hydroxy-octafluorobiphenyl and tetraphenolethane.

Examples of in the case of coating compositions based on (meth) acrylate Components that can be used as spacers are bisphenol A bisacrylate, bisphenol A-bis methacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, neopentylglycol dimethacrylate, Neopentyl glycol diacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, Triethylene glycol diacrylate, diethylene glycol dimethacrylate, Tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol diacrylate, Polyethylene glycol dimethacrylate, 2,2,3,3-tetrafluoro-1,4-butanediol diacrylate and dimethacrylate, 1,1,5,5-tetrahydroperfluoropentyl-1,5-diacrylate and dimethacrylate, Hexafluorobisphenol A diacrylate and dimethacrylate, octafluorohexanediol 1,6-diacrylate and dimethacrylate, 1,3-bis (3-methacryloxypropyl) tetrakis (trimethylsiloxy) disiloxane, 1,3-bis (3-acryloxypropyl) tetrakis (trimethylsiloxy) disiloxane, 1,3-bis (3-methacryloxypropyl) tetramethyldisiloxane and 1,3-bis (3-acryloxypropyl) tetramethyldisiloxane.

Polar spacers can also be used, including organic ones Compounds with at least two functional groups (epoxy, (meth) acrylic, Mercapto, vinyl, etc.) at the ends of the molecules, which are due to the Incorporation of aromatic or heteroaromatic groups (such as phenyl, benzyl, etc.) and heteroatoms (such as O, S, N, etc.) have polar properties and a Interaction with the components of the coating composition can enter into.

a) auf Epoxidbasis: Poly(phenylglycidylether)-co-formaldehyd, Adipinsäure-bis-(3,4-epoxycyclohexylmethylester), 3-[Bis-(2,3-epoxypropoxymethyl)methoxy]-1,2-propandiol, 4,4-Methylen-bis-(N,N-diglycidylanilin), Bisphenol A-diglycidylether, N,N-Bis-(2,3-epoxypropyl)-4-(2,3-epoxypropoxy)anilin, 3,4-Epoxycyclohexancarbonsäure(3,4-epoxycyclohexylmethylester), Glycerinpropoxylattriglycidylether, Hexahydrophthalsäurediglycidylester, Isocyanursäuretris-(2,3-epoxypropyl)-ester, Poly(propylenglycol)-bis-(2,3-epoxypropylether), 4,4'-Bis(2,3-epoxypropoxy)biphenyl.

b) auf Methacryl- und Acryl-Basis: Bisphenol A-dimethacrylat, Tetraethylenglycoldimethacrylat, 1,3-Diisopropenylbenzol, Divinylbenzol, Diallylphthalat, Triallyl 1,3,5-Benzoltricarboxylat, 4,4'-Isopropylidendiphenoldimethacrylat, 2,4,6-Triallyloxy-1,3,5-Triazin, 1,3-Diallylurea, N,N'-Methylenbisacrylamid, N,N'-Ethylenbisacrylamid, N,N'-(1,2-Dihydroxyethylen)-bisacrylamid, (+)-N,N'-Diallyltartardiamid, Methacrylanhydrid, Tetraethylenglycoldiacrylat, Pentaerythritoltriacrylat, Diethyldiallylmalonat, Ethylendiacrylat, Tripropylenglycoldiacrylat, Ethylenglycoldimethacrylat, Triethylenglycoldimethacrylat, 1,4-Butandioldimethacrylat, 1,6-Hexandioldiacrylat, 2-Ethyl-2-(hydroxymethyl)-1,3-propandioltrimethacrylat, Allylmethacrylat, Diallylcarbonat, Diallylsuccinat, Diallylpyrocarbonat.

Examples of the polar spacers mentioned above are:

a) on an epoxy basis: poly (phenylglycidyl ether) -co-formaldehyde, adipic acid bis- (3,4-epoxycyclohexylmethyl ester), 3- [bis- (2,3-epoxypropoxymethyl) methoxy] -1,2-propanediol, 4,4 -Methylene-bis- (N, N-diglycidylaniline), bisphenol A-diglycidyl ether, N, N-bis- (2,3-epoxypropyl) -4- (2,3-epoxypropoxy) aniline, 3,4-epoxycyclohexane carboxylic acid (3rd , 4-epoxycyclohexylmethyl ester), glycerol propoxylate triglycidyl ether, hexahydrophthalic acid diglycidyl ester, tris (2,3-epoxypropyl) isocyanurate, poly (propylene glycol) bis (2,3-epoxypropyl ether), 4,4'-bis (2,3-epoxypropoxy) biphenyl.

b) on a methacrylic and acrylic basis: bisphenol A dimethacrylate, tetraethylene glycol dimethacrylate, 1,3-diisopropenylbenzene, divinylbenzene, diallyl phthalate, triallyl 1,3,5-benzene tricarboxylate, 4,4'-isopropylidenediphenol dimethacrylate, 2,4,6-triallyloxy -1,3,5-triazine, 1,3-diallylurea, N, N'-methylene bisacrylamide, N, N'-ethylene bisacrylamide, N, N '- (1,2-dihydroxyethylene) bisacrylamide, (+) - N, N'-diallyltartardiamide, methacrylic anhydride, tetraethylene glycol diacrylate, pentaerythritol triacrylate, diethyldiallylmalonate, ethylene diacrylate, tripropylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol methacrylate, 1,6-ethanediol methacrylate, 1,6-butanedioldimethyl methacrylate, 1,4-butanedioldimyl methacrylate, 1,4-butanedioldimyl methacrylate, 1,4-butanedioldimyl methacrylate, 1,4-butanedioldimyl methacrylate, 1,4-butanediol dimethyl methacrylate, 1,4-butanediol dimethyl methacrylate, 1,4-butanediethyl dimethyl acrylate, 1,4-butanediol methacrylate, 1,4-butanediol dimethyl methacrylate, 1,4-butanediol dimethyl methacrylate, 1,4-butanediol dimethyl methacrylate, 1,4-butanediol dimethyl acrylate, 1,4-butanediol methacrylate, 1-dimethyl acrylate, 1,6-butanediol, , Diallyl carbonate, diallyl succinate, diallyl pyrocarbonate.

The inorganic-organic nanocomposites can optionally also contain organic polymers, which may have functional groups Have networking. Examples include the examples given above Coating composition based on organic polymers.

The coating composition may contain further additives which are described in the technology usually added depending on the purpose and desired properties become. Specific examples are thixotropic agents, crosslinking agents, solvents, e.g. high-boiling solvents, organic and inorganic color pigments, also in the nanoscale range, metal colloids, e.g. as a carrier more optical Functions, dyes, UV absorbers, lubricants, leveling agents, wetting agents, adhesion promoters and starter.

The starter can be used for thermally or photochemically induced crosslinking. For example, it can be a thermally activated radical starter, such as a peroxide or an azo compound thermal polymerization, e.g. of methacryloxy groups initiated. Another possibility is that the organic crosslinking over actinic radiation, e.g. B. UV or laser light or electron beams. For example, the crosslinking of double bonds is usually carried out under UV radiation.

All common starters / starter systems known to the person skilled in the art come as starters in question, including radical photo starters, radical thermal starters, cationic photo starter, cationic thermal starter and any combination the same.

Specific examples of radical photo starters that can be used are Irgacure® 184 (1-hydroxycyclohexylphenyl 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-isopropylthioxanthone, Benzoin, 4,4'-dimethoxybenzoin, benzoin ethyl ether, benzoin isopropyl ether, Benzil dimethyl ketal, 1,1,1-trichloroacetophenone, diethoxyacetophenone and dibenzosuberon.

Examples of radical thermal starters include organic peroxides in the form of diacyl peroxides, peroxydicarbonates, alkyl peresters, alkyl peroxides, perketals, ketone peroxides and alkyl hydroperoxides and azo compounds. Dibenzoyl peroxide, tert-butyl perbenzoate and azobisisobutyronitrile should be mentioned as specific examples.
An example of a cationic photo starter is Cyracure® UVI-6974, while a preferred cationic thermal starter is 1-methylimidazole.

These starters are preferred in the usual amounts known to the person skilled in the art 0.01 - 5 wt .-%, in particular 0.1 - 2 wt .-%, based on the total solids content the coating composition used. Of course Under certain circumstances, the starter can be dispensed with entirely, e.g. in the case of electron beam or laser curing.

Crosslinking agents which can be used are those which are conventional in the prior art Compounds with at least two functional groups are used. Of course, the functional groups should be chosen so that one Crosslinking of the coating composition can take place.

The substrates obtainable by the process according to the invention with Microstructured surface relief can be advantageous for the production of optical or electronic microstructures are used. examples for Areas of application are optical components such as microlenses and microlens arrays, Fresnel lenses, microfresnel lenses and arrays, light control systems, optical Waveguides and waveguide components, optical gratings, diffraction gratings, Holograms, data storage, digital, optically readable storage, anti-reflective structures (Moth eyes), light traps for photovoltaic applications, labeling, embossed Antiglare layers, microreactors, microtiter plates, relief structures on aero and hydrodynamic surfaces and surfaces with a special feel, transparent, electrically conductive relief structures, optical reliefs on PC or PMMA sheets, security marks, reflective layers for Traffic signs, stochastic microstructures with fractal substructures (Lotus leaf structures) and embossed resist structures for structuring semiconductor materials.

The following examples illustrate the invention without restricting it.

example 1 Preparation of a coating composition

a) Preparation of the hydrolyzate 131.1 g of boehmite were placed in a 1 liter three-necked flask with an intensive reflux condenser (Disperal Sol P3) and 327.8 g of 3-methacryloxypropyltrimethoxysilane (MPTS) offset. The mixture was heated to 80 ° C. with stirring and under for 10 min Reflux cooked. Then 47.5 g of water (bidist.) Were stirred added and the mixture further heated to 100 ° C. Noticed after about 10 min strong foaming of the reaction mixture. After that, the approach boiled under reflux for a further 2.5 h. Eventually the hydrolyzate was on Cooled to room temperature and filtered (pressure filtration: 1. glass fiber pre-filter; 2. Fine filter 1 µm).

b) Preparation of the final formulation 60 g of hydrolyzate were mixed with 9 g of amine-modified epoxy acrylate (UCB Chemical) Spacer, 0.6 g Byk® 306 leveling agent, 48 g 1-butanol and 0.62 g (3 mol% with respect to the Double bond amount) Benzophenone mixed as a photoinitiator.

Production of micro-structured surface reliefs

a) Digitale Struktur: Herstellung der Walze: Aufkleben einer Negativ-Ni-Master-Struktur (120 - 160 nm Amplitudenhöhe) auf einen Eisenzylinder (Durchmesser 400 mm, Länge 400 mm).Die Struktur des verwendeten Positiv-Masters zur Abformung einer digitalen Struktur im nm-Bereich (AFM-Tiefenprofil) ist in Figur 1 gezeigt. Man erkennt tiefliegende Strukturen mit hoher Flankensteilheit und mit einer Amplitude von ca. 160 nm und einer Periode von 2,5 µm.Figur 2 zeigt die Struktur der mit dem Negativ-Master abgeformten digitalen Struktur (Master aus Figur 1) (AFM-Tiefenprofil). Man erkennt auch hier tiefliegende Gräben (Tiefe ca. 180 nm) mit hoher Flankensteilheit, was die hohe Abformgenauigkeit des erfindungsgemäßen Verfahrens mit dem verwendeten Nanokompositgel unterstreicht.

b) µm-Reliefstruktur: Es wurde eine Al-Walze (Länge 100 mm, Durchmesser 40 mm) mit unregelmäßiger "Pyramiden"-Struktur eingesetzt. Figur 3 zeigt eine profilometrische Aufnahme der pyramidalen µm-Reliefstruktur (Struktur des Positiv-Masters). Man erkennt eine lateral makroskopische Reliefstruktur mit Strukturhöhen zwischen 20 und 35 µm. Die Oberflächenrauhigkeit liegt bei etwa 4 µm.

The above coating composition was applied to PC and PMMA plates by flood coating and to PET film using doctor blades (wet film thickness 25-50 μm). The coating was then predried in the drying cabinet at 90 ° C. for 4 minutes. The following rollers were used for structuring:

a) Digital structure: production of the roller: sticking a negative Ni master structure (120 - 160 nm amplitude height) onto an iron cylinder (diameter 400 mm, length 400 mm). The structure of the positive master used for the impression of a digital structure in the nm range (AFM depth profile) is shown in FIG. 1. Deep structures with high slope and with an amplitude of approx. 160 nm and a period of 2.5 µm can be seen. FIG. 2 shows the structure of the digital structure molded with the negative master (master from FIG. 1) (AFM depth profile) , Deep trenches (depth approx. 180 nm) with high steepness can also be seen here, which underlines the high molding accuracy of the method according to the invention with the nanocomposite gel used.

b) µm relief structure: An Al roller (length 100 mm, diameter 40 mm) with an irregular "pyramid" structure was used. FIG. 3 shows a profilometric image of the pyramidal μm relief structure (structure of the positive master). A lateral macroscopic relief structure with structural heights between 20 and 35 µm can be seen. The surface roughness is around 4 µm.

In Figure 4, the corresponding structure molded with the negative master is closed see. A lateral macroscopic, pyramidal structure can also be seen here Structural heights of approx. 20 - 30 µm. The slightly lower structure height in the case The molded structure is at different positions in the master or in the replica due. The surface roughness is also about 4 microns, so that too a high level of impression accuracy has been demonstrated for the µm range.

Example 2 Preparation of a coating composition

a) Preparation of the hydrolyzate 20.24 g of zirconium (IV) -n-propoxide with 4.3 g of methacrylic acid were placed in a 500 ml flask mixed and stirred for 30 min (solution A). In parallel, in one additional flask to 37.2 g methacryloxytrimethoxysilane 3.5 g water and 0.62 g 0.1 N HCl added dropwise and also stirred for 30 min (solution B). Then solution B cooled to about 5 ° C. in an ice bath and solution A was added dropwise. After a another stirring time of approx. 60 min and warming to room temperature were added Coating sol still added 1.1 g of triethoxytridecafluorooctylsilane.

b) Preparation of the final formulation 0.37 g of Irgacure was added to the coating composition prior to coating 187 (Union Carbide) as photoinitiator.

Production of micro-structured surface reliefs

a) Hologramm-Struktur: Nickelprägefolie mit Hologrammstruktur (200-500 nm Amplitudenhöhe) aufgeklebt auf den Eisenzylinder einer Laborprägeanlage.

b) Digitale Struktur: Nickelfolie mit auslesbarer binärer Struktur (150 nm Amplitudenhöhe) aufgeklebt auf den Eisenzylinder einer Laborprägeanlage.

c) Prägeprozeß: Die thermisch getrockneten Substrate wurden mit Hilfe einer Laborprägeanlage strukturiert. Nach dem Prägevorgang erfolgte eine Fixierung der Struktur durch UV-Härtung mit einem Hg-Strahter.

The coating material obtained was applied to 20 cm × 20 cm PMMA plates by flood coating (wet film thickness 25-50 μm) and knife coating (wet film thickness 20 μm). The coating was then predried in the drying cabinet at 80 ° C. for 10 minutes. The following rollers were used for structuring:

a) Hologram structure: nickel stamping foil with hologram structure (200-500 nm amplitude height) glued to the iron cylinder of a laboratory stamping system.

b) Digital structure: Nickel foil with readable binary structure (150 nm amplitude height) glued onto the iron cylinder of a laboratory stamping machine.

c) Embossing process: The thermally dried substrates were structured using a laboratory embossing system. After the embossing process, the structure was fixed by UV curing with an Hg emitter.

Claims (13)

1. A method of producing a microstructured surface relief by applying to a substrate a coating composition which is thixotropic or which acquires thixotropic properties by pretreatment on the substrate, embossing the surface relief into the applied thixotropic coating composition with an embossing device, and curing the coating composition after removal of the embossing device.
2. The method of producing a microstructured surface relief of claim 1, characterized in that the applied coating composition is rendered thixotropic by thermal treatment at 60 to 180°C and/or irradiation.
3. The method of producing a microstructured surface relief of claim 1 or 2, characterized in that after the embossing operation the coating composition is cured or densified by thermal treatment and/or irradiation.
4. The method of producing a microstructured surface relief of any of the preceding claims, characterized in that the coating composition gives rise to a transparent coating.
5. The method of producing a microstructured surface relief of any of the preceding claims, characterized in that a surface relief structure having dimensions in the range below 800 µm is obtained.
6. The method of producing a microstructured surface relief of any of claims 1 to 5, characterized in that a coating composition is used which comprises an organically modified inorganic polycondensate or precursors thereof and, where appropriate, nanoscale inorganic particulate solids.
7. The method of producing a microstructured surface relief of claim 6, characterized in that the organically modified inorganic polycondensate or its precursor comprises a polyorganosiloxane or precursors thereof.
8. The method of producing a microstructured surface relief of any of claims 1 to 7, characterized in that a coating composition is used which has been obtained by compounding a soluble organic polymer with nanoscale inorganic particulate solids.
9. The method of producing a microstructured surface relief of any of claims 6 to 8, characterized in that the organic polymer or organically modified inorganic polycondensate or its precursor comprises organic radicals containing functional groups by way of which crosslinking is possible.
10. The method of producing a microstructured surface relief of any of claims 6 to 9, characterized in that the organic polymer or organically modified inorganic polycondensate or its precursor comprises fluorine-substituted organic radicals.
11. The method of producing a microstructured surface relief of any of claims 1 to 10, characterized in that a coating composition is used which comprises nanoscale inorganic particulate solids containing polymerizable and/or polycondensable organic surface groups.
12. A substrate provided with a microstructured surface relief, characterized in that said microstructured surface relief is obtainable by a method according to claim 10 or 11.
13. The use of a substrate with a microstructured surface relief of claim 12 for optical, electronic, micromechanical and/or dirt repellency applications.

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