EP1633805A1

EP1633805A1 - Method for producing scratch-resistant coating systems devoid of condensation

Info

Publication number: EP1633805A1
Application number: EP04734514A
Authority: EP
Inventors: Peter Bier; Peter Capellen
Original assignee: Bayer MaterialScience AG
Current assignee: Covestro Deutschland AG
Priority date: 2003-06-05
Filing date: 2004-05-24
Publication date: 2006-03-15
Also published as: JP2006526494A; IL172099A0; CA2528063A1; WO2004108801A1; CN1798797A; US20040247899A1; TW200512237A; KR20060015336A; DE10325436A1

Abstract

The invention relates to a method for producing coating systems comprising a substrate (S), one or more scratch-resistant coatings (K) and a topcoat (D) that is devoid of condensation. The invention also relates to coating systems that are produced according to said method and to the use of said systems.

Description

Process for the production of anti-fog scratch-resistant coating systems

The present invention relates to a method for producing layer systems containing a substrate (S), one or more scratch-resistant layers (K) and a fog-free top layer (D), and to layer systems produced by the method and their use.

With the help of the sol-gel process, it is possible to produce inorganic-organic hybrid materials by targeted hydrolysis and condensation of alkoxides, mainly silicon, aluminum, titanium and zircon.

This process creates an inorganic network. Via correspondingly derivatized silicic acid esters, additional organic groups can be incorporated, which can be used on the one hand for functionalization and on the other hand for the formation of defined organic polymer systems. Due to the large number of possible combinations of both organic and inorganic components as well as the fact that product properties can be greatly influenced by the manufacturing process, this material system offers a very wide range of variation. This means that coating systems in particular can be maintained and tailored to a wide variety of requirement profiles.

Such coating systems are preferably used to make plastics and glass scratch-resistant. Coating agents of this type are described in more detail in the chapter “Production of the scratch-resistant layers”.

All of these coatings are not fog-free. For the purposes of the invention, freedom from fogging means that the coated moldings do not become cloudy in the steam at 90 ° C. within 10 minutes due to condensing moisture. In addition, water drops applied to it must wet the molded body, the water contact angle being less than 40 degrees, preferably less than 20 degrees.

DE 199 52 040 A1 discloses substrates with a particularly abrasion-resistant diffusion barrier layer system, the diffusion barrier layer system comprising a hard base layer based on hydrolyzable epoxysilanes and a cover layer arranged above it. The top layer is obtained by applying and curing a coating sol based on tetraethoxysilane.

From US 4,842,941 a plasma coating method is known in which a siloxane lacquer is applied to a substrate, the substrate coated in this way is introduced into a vacuum chamber and the

Surface of the coated substrate is activated in a vacuum with oxygen plasma. After

Activation takes place in a dry chemical or physical overcoating with a silane in a high vacuum according to the CVD (Chemical Vapor Deposition). This forms a highly scratch-resistant layer of silicon oxide on the substrate.

Although in both cases the top cover layers consist essentially of silicon oxide, they are not fogging-free.

According to the prior art it is known to mold plastic bodies by coating with a coating agent based on silica sols as described in EP-A 149 182, EP-A 378 855, EP-A 374 516, JP-A 51-6193, JP-A 51 -81877, US 4,994,318, JP-A 07 053747, JP-A 03 050288, JP-A 60-245685, JP-A 60-096682 and JP-A 58-029832 or based on organic hydrophilic polymers listed in EP -A O l li 8646, DE-A 0 312 9262, JP-A 200 3-01 2966 to be fitted with no fogging.

The parts equipped with it are fog-free, but their scratch resistance and the durability of the anti-fog properties under extreme conditions such as boiling steam water or aggressive chemicals are limited.

The present invention is therefore based on the object of providing a method for producing a fog-free scratch-resistant layer system comprising a substrate (S), one or more scratch-resistant layers (K) and a fog-free top layer (D), which has optimum adhesion properties between the scratch-resistant layer (K ) and cover layer (D) and is also suitable for the uniform coating of three-dimensional substrates (S). The method is also intended to decouple the production of the scratch-resistant layer (K) and the top layer (D) and to ensure that a scratch-resistant layer (K) which has been produced once is coated with the top layer (D) without any problems and even after a storage period of a few weeks or months can be.

According to the invention, this object is achieved by a method for producing a layer system comprising a substrate (S), one or more scratch-resistant layers (K) and a fog-free top layer (D)

a) applying one or more coating agents to a substrate (S), the coating agent or agents comprising polycondensates based on at least one silane produced by the sol-gel process and at least partially curing them to form scratch-resistant layers (K);

b) surface treatment of the upper scratch-resistant layer (K) by flame treatment, with simultaneous production of the fog-free cover layer (D), which essentially consists of an oxidic compound of silicon, aluminum, titanium, indium, zirconium, tin and / or cerium, by adding silicon, aluminum, titanium, zirconium, tin and / or cerium compounds in the fuel gas-air mixture.

After application of the scratch-resistant layer (K), the layer systems can also be temporarily stored and then surface-treated at any time initially in accordance with step (b) and overcoated with the top layer (D). The manufacturing method according to the invention can be carried out simply and inexpensively.

According to a preferred embodiment of the invention, the surface treatment of the upper scratch-resistant layer (K) with simultaneous production of the fog-free cover layer (D) in step (b) by flame treatment with the addition of silicon, aluminum, titanium, zirconium, tin and / or cerium compounds in the fuel gas / air mixture.

The metering of the additives for producing the fog-free top layer (D) works according to the principle of metered admixture of an organic precursor or an aerosol into the air stream. The dosing is carried out by process-controlled evaporation or by spray mist. Suitable devices include the burner SMB22 in combination with the control units of the FTS series from Arcogas GmbH Rötweg 24 in Mönsheim, Germany. Easily evaporable organometallic compounds, in particular alcoholates or acetates of the above metals, are suitable as organic precursors. Silicon tetraalkoxides have proven to be particularly favorable.

Aqueous dispersions of metal oxide nanoparticles, which are injected into the air stream and deposited, are particularly suitable for the production of aerosols.

In comparison to the plasma process described in US Pat. No. 5,008,148, the application of the metal oxide layers claimed here is considerably easier and less expensive. No. 5,008,148 describes the coating of polycarbonate or polyphenylene sulfide articles with metal oxide layers using a low-pressure plasma process for UV protection. The articles manufactured according to US 5,008,148 are not fogging-free.

During flame treatment, an open flame, preferably its oxidizing part, acts on the surface of the molded plastic body. An exposure time of approx. 0.2 s is usually sufficient. depending on the shape and mass of the molded part to be activated.

Experience shows that a mixture setting with an air fraction slightly above the stoichiometric mixture (slightly lean mixture) is usually the best

Successful treatment results. For the oxidizing effect of the flame, both the Combustion process from the outside world used oxygen, and especially the oxygen contained in the supplied air-gas mixture of importance.

The air-gas mixture supplied also has a strong influence on the characteristics of the flame, for example a flame operated with a "rich" mixture (high gas content) is just as unstable as a flame operated with a "lean" mixture (low gas content).

The standard air / gas ratios for mixture setting are:

Air to methane (natural gas)> 8: 1

Air to propane (LPG)> 25: 1

Air to butane> 32: 1

In addition to the mixture setting, the burner setting and the burner spacing are crucial for effective flame treatment. The burner output influences the entire flame characteristic (temperature, ion distribution, size of the active zone). When the burner output changes, the flame length changes, which in turn results in the distance from the burner to the product.

The burner output, usually expressed in kW, is directly proportional to the amount of gas currently flowing (liters per minute). Too little power leads to poor treatment, i.e. the surface energy is not increased sufficiently. With higher power, the ion concentration increases and the treatment is intensified. Too high an output leads to a high material temperature and thus to the melting of the surface. This can be seen from the fact that the surface is shiny or matt after flame treatment.

The working speed and thus the possible contact time is usually specified by the user, which results in the requirement for the burner output. The working speed and the burner output should always be optimally coordinated with one another in tests.

It has turned out to be particularly advantageous if the flame treatment is carried out in a continuous flame treatment system at a continuous speed of 1 to 20 m / min, in particular 2 to 10 m / min.

The surface treatment increases the adhesion energy of the scratch-resistant layer (K), resulting in very good adhesion of the fog-free top layer (D). The fog-free cover layer (D) preferably has a water contact angle below 40 degrees below 20 degrees and the polar portion of the surface tension of the cover layer (D) is above 20%, preferably above 30%.

It is also advantageous if the surface treatment is carried out after the scratch-resistant layer (K) has completely hardened.

Production of the scratch-resistant layer (K)

The scratch-resistant layer (K) is produced in step (a) by applying a coating agent to a substrate (S), the coating agent comprising a polycondensate based on at least one silane, which is produced by the sol-gel method, and at least partially curing thereof. The production of such scratch-resistant layers (K) on a substrate (S) is fundamentally known to the person skilled in the art.

The choice of substrate materials (S) for coating is not restricted. The coating compositions are preferably suitable for coating wood, textiles, paper, stone goods, metals, glass, ceramics and plastics, and in particular are particularly suitable for coating thermoplastics, as described in Becker / Braun, Plastic Pocket Book, Carl Hanser Verlag, Munich, Vienna 1992 , The coating compositions are particularly suitable for coating transparent thermoplastics and preferably polycarbonates. Spectacle lenses, optical lenses, automobile lenses and plates in particular can be coated with the compositions obtained according to the invention.

The scratch-resistant layer (K) is preferably formed in a thickness of 0.5 to 30 μm. A primer layer (P) can also be formed between the substrate (S) and the scratch-resistant layer (K).

Any silane-based polycondensates produced by the sol-gel process can be used as the coating agent for the scratch-resistant layer (K). Particularly suitable coating agents for the scratch-resistant layer (K) are in particular

(1) methyl silane systems,

(2) silica sol-modified methylsilane systems,

(3) silica sol-modified silyl acrylate systems,

(4) with other nanoparticle-modified silyl acrylate systems (in particular boehmite),

(5) cyclic organosiloxane systems and (6) nanoparticle-modified epoxysilane systems.

The abovementioned coating compositions for the scratch-resistant layer (K) are described in more detail below:

(1) Methyl silane systems

Known polycondensates based on methylsilane, for example, can be used as coating agents for the scratch-resistant layer (K). Polycondensates based on methyltrialkoxysilanes are preferably used. The substrate (S) can be coated, for example, by applying a mixture of at least one methyltrialkoxysilane, a water-containing organic solvent and an acid, evaporating the solvent and curing the silane to form a highly crosslinked polysiloxane under the influence of heat. The solution of the methyltrialkoxysilane preferably consists of 60 to 80% by weight of the silane. Methyltrialkoxysilanes which hydrolyze rapidly are particularly suitable, which is particularly the case when the alkoxy group contains no more than four carbon atoms. Strong inorganic acids such as sulfuric acid and perchloric acid are particularly suitable as catalysts for the condensation reaction of the silanol groups formed by hydrolysis of the alkoxy groups of methyltrialkoxysilane. The concentration of the acidic catalyst is preferably about 0.15% by weight, based on the silane. Alcohols such as methanol, ethanol and isopropanol or ether alcohols such as ethyl glycol are particularly suitable as inorganic solvents for the system consisting of methyltrialkoxysilane, water and acid. The mixture preferably contains 0.5 to 1 mole of water per mole of silane. The production, application and curing of such coating compositions are known to the person skilled in the art and are described, for example, in the publications DE-A 2136001, DE-A 2113734 and US 3 707 397, to which reference is expressly made.

(2) Silica-modified methylsilane systems

Polycondensates based on methylsilane and silica sol can also be used as the coating agent for the scratch-resistant layer (K). Particularly suitable coating compositions of this type are polycondensates prepared by the sol-gel process, consisting essentially of 10 to 70% by weight of silica sol and 30 to 90% by weight of a partially condensed organoalkoxysilane in an aqueous / organic solvent mixture. Particularly suitable coating compositions are the thermosetting, primer-free silicone hard coating compositions described in US Pat. No. 5,503,935, which, based on the weight: (A) 100 parts of resin solids in the form of a silicone dispersion in aqueous / organic solvent with 10 to 50% by weight of solids and consisting essentially of 10 to 70% by weight of colloidal silicon dioxide and 30 to 90% by weight of a partial condensate an organoalkoxysilane and

(B) 1 to 15 parts of an adhesion promoter selected from

(i) an acrylated polyurethane adhesion promoter with an M _n of 400 to 1,500 and selected from an acrylated polyurethane and a methacrylated polyurethane and

(ii) an acrylic polymer with reactive or interactive sites and an M _n of at least 1,000.

include.

Organoalkoxysilanes which can be used in the preparation of the dispersion of the thermosetting, hardness-free silicone hard coating compositions in aqueous / organic solvent preferably fall under the formula

(R) _a Si (OR ¹ ) _4-a ,

where R is a monovalent Cι. ₆ -hydrocarbon radical, in particular a Cι _-4 -ATkylrest, R ^{1 is} an R or a hydrogen radical and a is an integer from 0 to 2 inclusive. The organoalkoxysilane of the aforementioned formula is preferably methyltrimethoxysilane, methyltrihydroxysilane or a mixture thereof which can form a partial condensate.

The production, properties and curing of such heat-curable, hardness-free silicone hard coating compositions are known to the person skilled in the art and are described in detail, for example, in US Pat. No. 5,503,935, the content of which is expressly incorporated by reference here.

Polycondensates based on methylsilanes and silica sol with a solids content of 10 to 50% by weight dispersed in a water / alcohol mixture can also be used as the coating agent for the scratch-resistant layer (K). The solids dispersed in the mixture comprise silica sol, in particular in an amount of 10 to 70% by weight, and a partial condensate derived from organotrialkoxysilanes, preferably in an amount of 30 to 90% by weight, the partial condensate preferably having the formula R ' Si (OR) ₃ , wherein R 'is selected from the Grappe, consisting of alkyl radicals having 1 to 3 carbon atoms and Aryl residues with 6 to 13 carbon atoms, and R is selected from the group consisting of alkyl residues with 1 to 8 carbon atoms and aryl residues with 6 to 20 carbon atoms. The coating composition preferably has an alkaline pH, in particular a pH of 7.1 to about 7.8, which is achieved by a base which is volatile at the curing temperature of the coating composition. The production, properties and curing of such coating compositions are fundamentally known to the person skilled in the art and are described, for example, in US Pat. No. 4,624,870, the content of which is expressly incorporated by reference here.

The coating agents mentioned above and described in US Pat. No. 4,624,870 are mostly used in combination with a suitable primer, the primer forming an intermediate layer between the substrate (S) and the scratch-resistant layer (K). Suitable primer compositions are, for example, polyacrylate primers. Suitable polyacrylate primers are those based on polyacrylic acid, polyacrylic esters and copolymers of monomers with the general formula

O

CH ₂ CYCOR

where Y is H, methyl or ethyl and R is an .ia-alkyl group. The polyacrylate resin can be thermoplastic or thermosetting and is preferably dissolved in a solvent. For example, a solution of polymethyltriethacrylate (PMMA) in a solvent mixture of a rapidly evaporating solvent such as propylene glycol methyl ether and a slower evaporating solvent such as diacetone alcohol can be used as the acrylate resin solution. Particularly suitable acrylate primer solutions are thermoplastic primer compositions containing

(A) polyacrylic resin and

(B) 90 to 99 parts by weight of an organic solvent mixture containing

(i) 5 to 25% by weight of a solvent with a boiling point of 150 to 200 ° C. under normal conditions, in which (A) is freely soluble and

(ii) 75 to 95% by weight of a weaker solvent with a boiling point of

90 to 150 ° C under normal conditions, in which (A) is soluble.

The preparation, properties and drying of the latter thermoplastic primer compositions are known to the person skilled in the art and are described, for example, in US 5 041 313, the content of which is expressly incorporated by reference. As already mentioned at the beginning, the primer layer is arranged between the substrate (S) and the scratch-resistant layer (K) and serves to promote adhesion between the two layers.

Further coating compositions for the scratch-resistant layer (K) based on methylsilane and silica sol are described, for example, in the publications EP 0 570 165 A2, US 4,278,804, US 4,495,360, US 4,624,870, US 4,419,405, US 4,374,674 and No. 4,525,426, the content of which is expressly incorporated herein by reference.

(3) silica sol-modified silyl acrylate systems,

Polycondensates based on silyl acrylate can also be used as the coating agent for the scratch-resistant layer (K). In addition to silyl acrylate, these coating compositions preferably contain colloidal silica (silica sol). Particularly suitable silyl acrylates are acryloxy-functional silanes of the general formula

in which R ³ and R ^{4 are} identical or different monovalent hydrocarbon radicals, R ^{5 is} a divalent hydrocarbon radical with 2 to 8 carbon atoms, R ^{6 is} hydrogen or a monovalent hydrocarbon radical, the index b is an integer with a value from 1 to 3, the index c is an integer with a value of 0 to 2, and the index d is an integer with a value of (4-bc), or

glycidoxy-functional silanes of the general formula

where R ⁷ and R ^{8 are} the same or different monovalent hydrocarbon radicals, R ^{9 is} a divalent hydrocarbon radical with 2 to 8 coblene atoms, the index e is an integer with a value from 1 to 3, the index f is an integer with a value of 0 to 2, and the index g is an integer with a value of (4-ef), and mixtures thereof. The production and properties of these acryloxy-functional silanes and glycidoxy Functional silanes are known in principle to the person skilled in the art and are described, for example, in DE 31 26 662 A1, to which reference is expressly made here. Particularly suitable acryloxy-functional silanes are, for example, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethonxysilane, 2-methacryloxyethytrimethoxysilane, 2-acryloxyethyltrimethoxysilane, 3-methacryloxypropyltriethoxy-silane, 3-acryloxypropyltriethoxysiloxysilane-methoxy-siloxysilane-3-methoxy-siloxysilane-3-methoxysiloxysilane. Particularly suitable glycidoxy-functional silanes are, for example, 3-glycidoxypropyltrimethoxysilane, 2-glycidoxyethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane and 2-glycidoxyethyltriethoxysilane. These compounds are also described in DE 31 26 662 AI. As a further constituent, these coating compositions can contain further acrylate compounds, in particular hydroxyacrylates. Other acrylate compounds that can be used are, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxy-3-methacryloxypropyl acrylate, 2-hydroxy-3-acryloxypropyl acrylate, 2-hydroxy-3-methacryloxypropyl methacrylate, diethyl acrylate , Triethylene glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, tetrahydrofurfuryl methacrylate and 1,6-hexanediol diacrylate. Particularly preferred coating compositions of this type are those which contain 100 parts by weight of colloidal silica, 5 to 500 parts by weight of silyl acrylate and 10 to 500 parts by weight of further acrylate. In combination with a catalytic amount of a photoinitiator, such coating compositions can be cured after application to a substrate (S) by UV radiation to form a scratch-resistant layer (K), as described in DE 31 26 662 A1. The coating compositions can also contain conventional additives. Particularly suitable are the radiation-curable scratch-resistant coatings described in US Pat. No. 5,990,188, which, in addition to the aforementioned components, also contain a UV absorber such as triazine or dibenzylresorcinol derivatives. Further coating compositions based on silyl acrylates and silica sol are described in the printed publications US Pat. No. 5,468,789, US Pat. No. 5,466,491, US Pat. No. 5,318,850, US Pat. No. 5,242,719 and US Pat. No. 4,455,205, the contents of which are expressly incorporated by reference.

(4) With other nanoparticle-modified silyl acrylate systems

Polycondensates based on silyl acrylates which contain nanoscale A10 (OH) particles, in particular nanoscale boehmite particles, as a further constituent can also be used as coating agents. Coating agents of this type are described, for example, in the printed publications WO 98/51747 AI, WO 00/14149 AI, DE-A 197 46 885, US 5 716 697 and WO 98/04604 AI, the content of which is expressly incorporated by reference here. By adding photoinitiators, these coating compositions can be hardened after application to a substrate (S) by UV rays, with the formation of a scratch-resistant layer (K). (5) Cyclic organosiloxane systems

Polycondensates based on multifunctional cyclic organosiloxanes can also be used as coating agents for the scratch-resistant layer (K). Such multifunctional, cyclic organosiloxanes include, in particular, those of the following formula

SiX _a R ₃ -a

(CH ₂ ) _n

Si -O

R m

with m = 3 to 6, preferably 3 to 4, n = 2 to 10, preferably 2 to 5, particularly preferably 2, R = Ci to C ₈ alkyl and / or C ₆ to C ₄ aryl, preferably to C ₂ Alkyl into consideration, where n and R within the molecule can be the same or different, preferably the same, and the further radicals have the following meaning:

(A) for X = halogen, ie Cl, Br, I and F, preferably Cl with a = 1 to 3 or X = OR ', OH with a = 1 to 2, with R' = Q to C ₈ alkyl, preferably to C ₂ alkyl, or

(B) for X = (OSiR ₂ ) _p [(CH ₂ ) _n SiY _a R _3-a ] with a = 1 to 3, where a can be identical or different, preferably identical, within the molecule,

p = 0 to 10, preferably p = 0 and

Y = halogen, OR ', OH, preferably Cl, OR', OH with R '= to C ₈ -alkyl, preferably to C ₂ -alkyl, or

(C) X = (OSiR ₂ ) p [(CH2) “SiR3. _a [(CH2) _n SiYaR3-a] a] with a = 1 to 3, where a can be the same or different, preferably the same, within the molecule,

p = 0 to 10, preferably p = 0 and

Y = halogen, OR *, OH, preferably Cl, OR ', OH with R' = d to C ₈ alkyl, preferably to C ₂ alkyl, are used. Compounds with n = 2, m = 4, R = methyl and X = OH, OR 'with R' = methyl, ethyl and a = 1 are particularly suitable. The production and properties of such multifunctional cyclic organosiloxanes and their use in scratch-resistant coating compositions are accordingly Generally known to a person skilled in the art and described, for example, in Drackschrift DE 196 03 241 Cl, the content of which is expressly incorporated by reference here. Further coating compositions based on cyclic organosiloxanes are described, for example, in the publications WO 98/52992, DE 197 11 650, WO 98/25274 and WO 98/38251, the content of which is also expressly referred to here.

(6) Nanoparticle-modified epoxysilane systems

Polycondensates based on hydrolyzable silanes with epoxy groups are also suitable as coating agents for the scratch-resistant layer (K). Preferred scratch-resistant layers (K) are those which are obtainable by curing a coating composition comprising a polycondensate based on at least one silane which has been prepared by the sol-gel process and which has an epoxide group on a non-hydrolyzable substituent and optionally a curing catalyst selected from Lewis Bases and alcoholates from titanium, zircon or aluminum. The production and properties of such scratch-resistant layers (K) are described for example in DE 43 38 361 AI.

Preferred coating compositions for scratch-resistant layers based on expoxylilanes and nanoparticles are those which

has a silicon compound (A) with at least one hydrolytically non-releasable radical which is bonded directly to Si and contains an epoxy group,

particulate materials (B),

a hydrolyzable compound (C) of Si, Ti, Zr, B, Sn or V and preferably additionally

a hydrolyzable compound (D) of Ti, Zr or Al,

contain.

Such coating compositions result in highly scratch-resistant coatings that adhere particularly well to the material. The compounds (A) to (D) are explained in more detail below. The compounds (A) to (D) can be contained not only in the composition for the scratch-resistant layer (K), but also as an additional component (s) in the composition for the cover layer (D).

Silicon compound (A)

The silicon compound (A) is a silicon compound which has 2 or 3, preferably 3, hydrolyzable radicals and one or 2, preferably one, non-hydrolyzable radical. The only or at least one of the two non-hydrolyzable residues has an epoxy group.

Examples of the hydrolyzable radicals are halogen (F, Cl, Br and I, in particular Cl and Br), alkoxy (in particular. -Alkoxy such as, for example, methoxy, ethoxy, n-propoxy, i-propoxy and n-butoxy, i -butoxy, sec-butoxy and tert-butoxy), aryloxy (especially C ₆ -ιo-aryloxy e.g. phenoxy), acyloxy (especially Cι. -acyloxy such as acetoxy and propionyloxy) and alkylcarbonyl (e.g. acetyl) , Particularly preferred hydrolyzable residues are alkoxy groups, especially methoxy and ethoxy.

Examples of non-hydrolyzable radicals without an epoxy group are hydrogen, alkyl, in particular C _1-4 -alkyl (such as methyl, ethyl, propyl and butyl), alkenyl (in particular C ₂ -alkenyl such as vinyl, 1-propenyl, 2-propenyl and butenyl), alkynyl (especially C ₂ -. ₄ alkynyl such as acetylenyl and propargyl), and aryl, in particular .ι ₀ aryl such. As phenyl and naphthyl), the groups just mentioned optionally one or more substituents such. B. may have halogen and alkoxy. Methacrylic and methacryloxypropyl residues can also be mentioned in this connection.

Examples of non-hydrolyzable radicals with an epoxy group are, in particular, those which have a glycidyl or glycidyloxy group.

Concrete examples of silicon compounds (A) which can be used according to the invention can, for. B. pages 8 and 9 of EP-A-195493.

I '

Silicon compounds (A) which are particularly preferred according to the invention are those of the general formula

R ₃ Si '

in which the radicals R are the same or different (preferably identical) and represent a hydrolyzable grappa (preferably C 1 -C alkoxy and special methoxy and ethoxy) and R 'represents a glycidyl or glycidyloxy (C 2 O 2) alkylene radical , especially ß-glycidyl oxyethyl-, γ-glycidyloxypropyl, δ-glycidyl-oxybutyl-, ε-glycidyloxylpentyl-, ω-glycidyl-oxyhexyl-, ω-glycidyloxyoctyl-, ω-glycidyl-oxynonyl-, ω-glycidyloxydylidyl-, 2- (3,4-epoxycyclohexyl) ethyl.

Because of its easy accessibility, γ-glycidyloxypropyltrimethoxysilane (hereinafter abbreviated as GPTS) is particularly preferably used according to the invention.

Particulate materials (B)

The particulate materials (B) are an oxide, hydrated oxide, nitride or carbide of Si, Al and B and of transition metals, preferably Ti, Zr and Ce, with a particle size in the range from 1 to 100, preferably 2 to 50 nm and particularly preferably 5 to 20 nm and mixtures thereof. These materials can be used in the form of a powder, but are preferably used in the form of a (in particular acid-stabilized) sol. Preferred particulate materials are boehmite, Si0 ₂ , Ce0 ₂ , ZnO, rn ₂ 0 ₃ and Ti0 ₂ . Nanoscale boehmite particles are particularly preferred. The particulate materials are commercially available in the form of powders and the production of (acid stabilized) sols therefrom is also known in the art. In addition, reference can be made to the manufacturing examples given below. The principle of stabilizing nanoscale titanium nitride using guanidine propionic acid is e.g. B. described in German patent application DE-A 43 34639.

Boehmite sol with a pH in the range from 2.5 to 3.5, preferably 2.8 to 3.2, which can be obtained, for example, by suspending boehmite powder in dilute HCl is particularly preferably used.

The variation of the nanoscale particles is usually accompanied by a variation in the refractive index of the corresponding materials. For example, the replacement of boehmite particles by Ce0 ₂ , Zr0 ₂ or Ti0 ₂ particles to give materials with higher refractive indices, the refractive index according to the Lorentz-Lorenz equation being additive from the volume of the high refractive index component and the matrix.

As mentioned, cerium dioxide can be used as the particulate material. This preferably has a particle size in the range from 1 to 100, 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 used in the form of a (in particular acid-stabilized) sol. Particulate cerium oxide is commercially available in the form of sols and powders, and the production of (acid-stabilized) sols therefrom is also known in the art. Compound (B) is preferably used in the composition for the scratch-resistant layer (K) in an amount of 3 to 60% by weight, based on the solids content of the coating agent for the scratch-resistant layer (K).

Hydrolyzable Compounds (C)

In addition to the silicon compounds (A), other hydrolyzable compounds of elements from the group consisting of Si, Ti, Zr, Al, B, Sn and V are also used to produce the scratch-resistant coating composition, and preferably with the silicon compound (s) (A) hydrolyzed.

The compound (C) is a compound of Si, Ti, Zr, B, Sn and V of the general formula

R _X XM ⁺⁴ R ' ₄ . _X or

R _X M ⁺³ R ' _3-X

where M a) Si ⁺⁴ , Ti ⁺⁴ , Zr ⁺⁴ , Sn * ⁴ , or b) Al ⁺³ , B ⁺³ or (VO) ⁺³ , R represents a hydrolyzable radical, R 'represents a non-hydrolyzable radical represents and x in the case of tetravalent metal atoms M (case a)) 1 to 4 and in the case of trivalent metal atoms M (case b)) 1 to 3. If several radicals R and / or R 'are present in a compound (C), these can in each case be the same or different. X is preferably greater than 1. That is, the compound (C) has at least one, preferably a plurality of hydrolyzable radicals.

Examples of the hydrolyzable radicals are halogen (F, Cl, Br and 1, in particular and Br), alkoxy (in particular such as methoxy, ethoxy, n-propoxy, i-propoxy and n-butoxy, i-butoxy, sec-butoxy or tert-butoxy), aryloxy (in particular C ₆ .0 ₀ -aryloxy, e.g. phenoxy), acyloxy (in particular ^ -acyloxy such as acetoxy and propionyloxy) and alkylcarbonyl (e.g. acetyl). Particularly preferred hydrolyzable residues are alkoxy groups, especially methoxy and ethoxy.

Examples of non-hydrolyzable radicals are hydrogen, alkyl, in particular C ₄ alkyl (such as methyl, ethyl, propyl and n-butyl, i-butyl, sec-butyl and tert-butyl),

Alkenyl (in particular C ₂ -alkenyl such as, for example, vinyl, 1-propenyl, 2-propenyl and butenyl), alkynyl (in particular C 1 -C -alkynyl such as, for example, acetylenyl and propargyl) and

Aryl, especially C ₆ ιo-aryl, such as phenyl and naphthyl), wherein the above-mentioned groups optionally have one or up more substituents such as halogen and alkoxy, can point. Methacrylic and methacryloxypropyl residues can also be mentioned in this connection.

In addition to the examples of the compounds of the formula I contained in the top layer composition, the following preferred examples of compound (C) can be mentioned:

CH ₃ -SiCl ₃ , CH ₃ -Si (0C ₂ H ₅ ) ₃ , C ₂ H ₅ -SiCl ₃ , C ₂ H ₅ -Si (OC ₂ H ₅ ) 3,

C ₃ H ₇ -Si (OCH ₃ ) ₃ , C ₆ H ₅ -Si (OCH ₃ ) ₃ , C ₆ H ₅ -Si (OC ₂ H ₅ ) ₃ ,

(CH ₃ 0) ₃ -Si-C ₃ H ₆ -Cl,

(CH ₃ ) ₂ SiCl ₂ , (CH ₃ ) ₂ Si (OCH ₃ ) ₂ , (CH ₃ ) ₂ Si (OC ₂ H ₅ ) ₂ ,

(CH ₃ ) ₂ Si (OH) ₂ , (C6H ₅ ) 2SiCl2, (C ₆ H ₅ ) ₂ Si (OCH ₃ ) ₂ ,

(C ₆ H ₅ ) ₂ Si (OC ₂ H ₅ ) ₂ , (iC ₃ H ₇ ) ₃ SiOH,

CH ₂ = CH-Si (OOCCH ₃ ) ₃ ,

CH ₂ = CH-SiCl ₃ , CH ₂ = CH-Si (OCH ₃ ) ₃ , CH ₂ = CH-Si (OC ₂ H ₅ ) ₃ ,

CH ₂ = CH-Si (OC ₂ H ₄ OCH ₃ ) ₃ , CH ₂ = CH-CH ₂ -Si (OCH3) 3,

CH ₂ = CH-CH ₂ -Si (OC ₂ H ₅ ) _3ϊ

CH ₂ = CH-CH ₂ -Si (OOCCH ₃ ) ₃ ,

CH ₂ = C (CH ₃ ) -COO-C ₃ H ₇ -Si (OCH3) 3,

CH ₂ = C (CH ₃ ) -COO-C ₃ H ₇ -Si (OC ₂ Hs) 3,

Compounds of type S1R are particularly preferably used, where the radicals R can be the same or different and stand for a hydrolyzable group, preferably for an alkoxy group with 1 to 4 carbon atoms, in particular for methoxy, ethoxy, n-propoxy, i-propoxy, n -Butoxy, i-butoxy, sec-butoxy or tert-butoxy.

As can be seen, these compounds (C) (in particular the silicon compounds) can also have non-hydrolyzable radicals which have a CC double or triple bond. If such compounds are used together with (or even instead of) the silicon compounds (A), the composition can also contain (preferably epoxy or hydroxyl group-containing) monomers such as, for. B. meth (acrylates) are incorporated (self- Of course, these monomers can also have two or more functional groups of the same type, such as. B. poly (meth) acrylates of organic polyols; the use of organic polyepoxides is also possible). When the corresponding composition is thermally or photochemically induced, the organic species is polymerized in addition to the structure of the organically modified inorganic matrix, as a result of which the crosslinking density and thus also the hardness of the corresponding coatings and moldings increase.

In the composition for the scratch-resistant layer (K), compound (C) is preferably used in an amount of 0.2 to 1.2 mol, based on 1 mol of silicon compound (A).

Hydrolyzable compound (D)

The hydrolyzable compound (D) is a compound of Ti, Zr or Al of the following general formula

M (R "') _m

where M stands for Ti, Zr or Al and the radicals R '"can be identical or different and stand for a hydrolyzable group and n is 4 (M = Ti, Zr) or 3 (M = AI).

Examples of the hydrolyzable groups are halogen (F, Cl, Br and I, in particular Cl and Br), alkoxy (in particular C ₆ alkoxy such as methoxy, ethoxy, n-propoxy, i-propoxy and n-butoxy , i-butoxy, sec-butoxy or tert-butoxy, n-pentyloxy, n-hexyloxy), aryloxy (especially C ₆ -o-aryloxy e.g. phenoxy), acyloxy (especially ^ -acyloxy such as acetoxy and propionyloxy) and alkylcarbonyl (e.g., acetyl) or Cι _-6 alkoxyC _2-3 -alkylgrappe, ie one of Cι. ₆ -Alkylethylenglykol or -propylenglykol derived group, wherein alkoxy has the same meaning as mentioned above.

M is particularly preferred aluminum and R '"ethanolate, sec-butanolate, n-propanolate or n-butoxyethanolate.

In the composition for the scratch-resistant layer (K), compound (D) is preferably used in an amount of 0.23 to 0.68 mol, based on 1 mol of silicon compound (A).

To achieve a more hydrophilic character of the scratch-resistant coating agent, a Lewis base (E) can optionally also be used as a catalyst.

Furthermore, a hydrolyzable silicon compound (F) with at least one non-hydrolyzable radical which has 5 to 30 directly on carbon atoms can optionally be used has bound fluorine atoms, these carbon atoms being separated from Si by at least 2 atoms. The use of such a fluorinated silane means that the corresponding coating is additionally given hydrophobic and dirt-repellent properties.

The compositions for the scratch-resistant layer (K) can be produced by the process described in more detail below, in which a sol of the material (B) has a pH in the range from 2.0 to 6.5, preferably 2.5 to 4.0 , is reacted with a mixture of the other components.

They are even more preferably produced by a process which is also defined below, in which the sol as defined above is added in two portions to the mixture of (A) and (C), with certain temperatures preferably being maintained, and the addition of (D. ) between the two portions of (B), also preferably at a certain temperature.

The hydrolyzable silicon compound (A) can optionally be prehydrolyzed together with the compound (C) using an acidic catalyst (preferably at room temperature) in aqueous solution, preferably using about 1/2 mole of water per mole of hydrolyzable group. Hydrochloric acid is preferably used as the catalyst for the pre-hydrolysis.

The particulate materials (B) are preferably suspended in water and the pH is adjusted to 2.0 to 6.5, preferably to 2.5 to 4.0. Acidification is preferred

Hydrochloric acid used. When boehmite is used as the particulate material (B), a clear sol is formed under these conditions.

The compound (C) is mixed with the compound (A). The first portion of the particulate material (B) suspended as described above is then added. The amount is preferably selected so that the water contained therein is sufficient for the semi-stoichiometric hydrolysis of the compounds (A) and (C). It is 10 to 70% by weight of the total amount, preferably 20 to 50% by weight.

The reaction is slightly exothermic. After the first exothermic reaction has subsided, the temperature is adjusted to about 28 to 35 ° C., preferably about 30 to 32 ° C. by tempering, until the reaction starts and an internal temperature is reached which is higher than 25 ° C., preferably higher than 30 ° C and more preferably higher than 35 ° C. After the end of the addition of the first portion of the material (B), the temperature is maintained for 0.5 to 3 hours, preferably 1.5 to 2.5 Hours and then cools down to approx. 0 ° C. The remaining material (B) is preferably added slowly at a temperature of 0 ° C. Then the compound (D) and, if appropriate, the Lewis base (E) are also preferably added slowly after the addition of the first portion of the material (B) at about 0 ° C. The temperature is then kept at about 0 ° C. for 0.5 to 3 hours, preferably for 1.5 to 2.5 hours, before adding the second portion of the material (B). Then the remaining material (B) is slowly added at a temperature of approx. 0 ° C. The added dropwise solution is preferably pre-cooled to approximately 10 ° C. immediately before being added to the reactor.

After the slow addition of the second portion of the compound (B) at about 0 ° C., the cooling is preferably removed so that the reaction mixture is warmed up to a temperature of more than 15 ° C. (to room temperature) slowly without additional temperature control.

In order to adjust the theological properties of the scratch-resistant layer compositions, inert solvents or solvent mixtures can optionally be added at any stage of the preparation. These solvents are preferably the solvents described for the top layer composition.

The scratch-resistant layer compositions can contain the usual additives described for the top layer composition.

The application and hardening of the scratch-resistant layer composition takes place after drying, preferably thermally at 50 to 200 ° C., preferably 70 to 180 ° C. and in particular 110 to 130 ° C. Under these conditions, the curing time should be less than 120, preferably less than 90, in particular less than 60 minutes.

The layer thickness of the hardened scratch-resistant layer (K) should be 0.5 to 30 μm, preferably 1 to 20 μm and in particular 2 to 10 μm.

Production of a further highly scratch-resistant layer (SK) as an intermediate layer between the scratch-resistant layer (K) and the fog-free top view (D)

If desired, a highly scratch-resistant layer (SK) is produced by applying a solvent-based coating agent based on a silane to the surface-treated scratch-resistant layer (K) and curing it.

The coating compositions for the highly scratch-resistant layer (SK) can be, for example, the coating sols made of tetraethoxysilane (TEOS) and known in DE 19952040 A1 Act glycidyloxypropyltrimethoxysilane (GPTS). The coating sol is prepared by prehydrolyzing and condensing TEOS with ethanol as the solvent in HCL acidic aqueous solution. GPTS is then stirred into the thus pre-hydrolyzed TEOS and the sol is stirred for some time with heating. Other variants are described in DE 10245 729, DE 10245 725 and DE 102 52421.

example 1

354.5 g (3.0 mol) of n-butoxyethanol were added dropwise to 246.3 g (1.0 mol) of aluminum tri-sec-butanolate with stirring, the temperature rising to about 45 ° C. After cooling, the aluminate solution must be kept closed.

1239 g 0.1N HC1 were submitted. With stirring, 123.9 g (1.92 mol) of boehmite were added (Disperal® Sol P3 ^®, Condea). The mixture was then stirred at room temperature for 1 hour. The solution was filtered through a depth filter to remove solid contaminants.

787.8 g (3.33 mol) of GPTS (γ-glycidyloxypropyltrimethoxysilane) and 608.3 g of TEOS (tetraethoxysilane) (2.92 mol) were mixed and stirred for 10 minutes. 214.6 g of the boehmite sol were added to this mixture within about 2 minutes. A few minutes after the addition, the sol warmed to about 28 to 30 ° C. and was clear even after about 20 minutes. The mixture was then stirred at 35 ° C. for about 2 hours and then cooled to about 0 ° C.

At 0 ° C. ± 2 ° C., 600.8 g of the Al (OEtOBu) ₃ solution prepared as described above in sec-butanol, containing 1.0 mol of Al (OEtOBu) _{3, were then} added. After the addition had ended, the mixture was stirred for a further 2 hours at approx. 0 ° C. and then the remaining boehmite sol was also added at 0 ° C. ± 2 ° C. The reaction mixture obtained was then warmed to room temperature in about 3 hours without temperature control. Byk ^® 306 from Byk was added as a leveling agent. The mixture was filtered and the paint obtained was stored at + 4 ° C.

Example 2

GPTS and TEOS are submitted and mixed. The amount of boehmite dispersion required for semi-stoichiometric prehydrolysis of the silanes (prepared analogously to Example 1) is slowly poured in with stirring. The reaction mixture is then stirred at room temperature for 2 hours. The solution is then cooled to 0 ° C using a cryostat. Aluminum tributoxyethanolate is then added dropwise via a dropping funnel. After the addition of the aluminate, the mixture is stirred at 0 ° C. for 1 hour. The rest of the boehmite dispersion is then added with cryostat cooling. After stirring for 15 minutes at room temperature, the cerium dioxide dispersion and BYK ^® 306 are added as leveling agents. batch quantities

Example 3 (primer)

The primer solution is prepared by dissolving 6 g of Araldit PZ 3962 and 1.3 g of Araldit PZ 3980 in 139.88 g of diacetone alcohol at room temperature in accordance with patent application EP-A 1282 673.

Example 4

203 g of methyltrimethoxysilane were mixed with 1.25 g of glacial acetic acid. 125.5 g of Ludox ^® AS (ammonium stabilized colloidal silica sol from DuPont, 40% Si0 ₂ with a silicate particle diameter of about 22 nm and a pH of 9.2) were diluted with 41.5 g of deionized water to the content of Si0 _{2 set} to 30 wt .-%. This material was added to the acidified methyltrimethoxysilane with stirring. The solution was stirred for a further 16 to 18 hours at room temperature and then added to a mixed solvent of isopropanol / n-butanol in a weight ratio of 1: 1. Finally, 32 g of the UV absorber 4- [γ- (tri- (methoxy / ethoxy) silyl) propoxy] -2-hydroxybenzophenone was added. The mixture was stirred at room temperature for two weeks. The composition had a solids content of 20% by weight and contained 11% by weight of the UV absorber, based on the solids. The coating composition had a viscosity of about 5 cSt at room temperature.

To accelerate the polycondensation reaction, 0.2% by weight of tetrabutylammonium acetate was mixed in homogeneously before the application.

Example 5 (primer)

3.0 parts of polymethyl methacrylate (Elvacite ^® 2041 from DuPont) was blended with 15 parts diacetone alcohol and 85 parts of propylene glycol monomethyl ether and two hours stirred at 70 ° C until completely dissolved. Then 0.5 part of the UV absorber Uvinol N 539 (cyanoacrylate) from BASF, Ludwigshafen was added to the solution.

Example 6

0.4% by weight of a silicone leveling agent and 0.3% by weight of an acrylate polyol, namely Joncryl 587 (M _n 4300) from SC Johnson Wax Company in Racine, Wisconsin, were stirred into the coating sol prepared according to Example 4. To accelerate the polycondensation reaction, 0.2% by weight of tetra-n-butylammonium acetate were mixed in homogeneously, as in Example 4 before the application.

Specimen production

Sheets measuring 100 * 150 * 3.2 mm were injection molded from polycarbonate (Makrolon 3103 ^® and Makrolon AL 2647 ^® from Bayer AG) on the FH160 injection molding machine from Klöckner. The polycarbonate granules were dried for twelve hours at 120 ° C. in a circulating air drying cabinet to a residual moisture below 0.01% before processing. The melt temperature was 300 ° C. The tool was tempered to 90 ° C. The closing pressure was 770 and the after-pressure 700 bar. The total cycle time of the injection molding process was 48.5 seconds.

Makrolon 3103 is a UV-stabilized bisphenol A polycarbonate with an average molecular weight M _w (weight average) of approx. 31000 g / mol. Makrolon AL 2647, also a bisphenol A polycarbonate, contains an additive package consisting of UV stabilizer, mold release agent and thermal stabilizer. Its average molecular weight M _w is approximately 26500 g / mol.

Coating the polycarbonate sheets with scratch-resistant coating systems

Test pieces were produced with the coating compositions obtained as follows:

The injection molded polycarbonate sheets were cleaned with isopropanol and, if necessary, primed by flooding with a primer solution.

The primer solution was dried and, in the case of the primer of Example 3, then additionally subjected to a heat treatment at 130 ° C. for half an hour.

The primed polycarbonate sheets were then flooded with the scratch-resistant coating agent (Examples 1, 2, 4). The primer rank is omitted for the scratch-resistant coating agent of Example 6. The air drying time for dust drying is 30 minutes at 23 ° C and 53% relative Humidity. The dust-dry plates were heated in an oven at 130 ° C for 30 to 60 minutes and then cooled to room temperature.

Apply the fog-free top layer

After curing, the coated plates were stored at room temperature for two days. The fog-free top layer is then applied by flaming with the FTS 401 device from Arcotec, Mönsheim, Germany. The belt speed was 20 m / min, the amount of air 120 and the amount of gas 5.5 1 min. The device combination FTS 201D / 99900017 was used for the silicate coating.

Examination of the coated panels

After two days of storage at room temperature, the following surface properties were determined on these plates:

Surface tension and water contact angle according to DUST EN 828

Polar component of the surface tension according to equation (8) in "Some aspects of wetting theory and its applications in the study of the change in the surface properties of polymers" in paint and varnish, 77th year, No. 10, 1971,

P. 997 ff.

Model greenhouse test

vapor test

Model greenhouse test

The coated polycarbonate sheets were attached at an angle of 60 ° with the coated side down on the ceiling of a model greenhouse, so that the water-spreading effect could be compared by observing the formation of droplets. In the model greenhouse, water was evaporated with a heating source, so that a temperature of 50 ° C and a humidity of 100% was established.

The plates were left under these conditions for 6 hours and then heated in a dry heating cabinet at 40 ° C. for 4 hours. The procedure was then repeated alternately in the model greenhouse and in the heating cabinet until the water-spreading effect disappeared (evident from the droplet formation on the plate). As a criterion for the Durability of the fog-free layer was given the number of cycles before droplet formation occurs.

Steam test (100 ° C)

The steam test was carried out as a further test. The coated polycarbonate sheets were exposed to a closed water vapor atmosphere at 100 ° C. It was observed when the water-spreading effect disappeared and the first drop formation occurred.

All fog-free layers produced according to the invention were still functional even after 3 hours.

The evaluation results are shown in Table 1.

Table 1

Claims

claims

1. A method for producing a layer system comprising a substrate (S), one or more scratch-resistant layers (K) and a fog-free cover layer (D), characterized by

b) surface treatment of the upper scratch-resistant layer (K) by flame treatment, while at the same time producing the fog-free cover layer (D), which essentially consists of an oxidic connection of silicon, aluminum, titanium, indium, zirconium, tin and / or cerium, by addition of silicon, aluminum, titanium, zirconium, tin and / or cerium compounds in the fuel gas-air mixture.

2. The method according to claim 1, characterized in that the coating agent for one of the scratch-resistant layers (K) is a polycondensate based on methylsilane.

3. The method according to claim 1, characterized in that the coating agent for one of the scratch-resistant layers (K) is a polycondensate prepared by the sol-gel process from essentially 10 to 70 wt .-% silica sol and 30 to 90 wt .-% of a partially condensed organoalkoxysilane in an aqueous / organic

Includes solvent mixture.

4. The method according to claim 1, characterized in that the coating agent for one of the scratch-resistant layers (K) a polycondensate based on at least one silane, which has an epoxy group on a non-hydrolyzable substituent and optionally particles and one

Curing catalyst selected from Lewis bases and alcoholates of titanium, zirconium or aluminum.

5. The method according to claim 1, characterized in that the coating agent for one of the scratch-resistant layers (K) is a polycondensate based on at least one silyl acrylate.

6. The method according to claim 1, characterized in that the coating agent for one of the scratch-resistant layers (K) comprises methacryloxypropyltrimethoxysilane and AIO (OH) nanoparticles.

7. The method according to claim 1, characterized in that the coating agent for one of the scratch-resistant layers (K) is a polycondensate based on at least one multifunctional cyclic organosiloxane.

8. The method according to claim 1, characterized in that the coating agent for one of the scratch-resistant layers (K) is a polycondensate based on a silane with four hydrolyzable groups.

9. The method according to any one of the preceding claims, characterized in that the

Surface treatment to prevent fogging after the scratch-resistant layer (K) has completely hardened.

10. The method according to any one of the preceding claims, characterized in that the surface treatment is carried out in a flame treatment system.

11. The method according to any one of the preceding claims, characterized in that the

Surface treatment is carried out in a continuous flame treatment system at a throughput speed of 1 to 20 m / min.

12. The method according to any one of the preceding claims, characterized in that the substrate (S) consists of plastic.

13. The method according to any one of the preceding claims, characterized in that the scratch-resistant layers (K) are formed in a thickness of 0.1 to 30 microns.

14. The method according to any one of the preceding claims, characterized in that the fog-free upper cover layer (D) is formed in a thickness of less than 1 μm.

15. The method according to any one of the preceding claims, characterized in that a primer layer (P) is formed between the substrate (S) and scratch-resistant layer (K).

16. The method according to any one of the preceding claims, characterized in that the scratch-resistant layers (K) are thermally and / or radiation dried after application at a temperature> 20 ° C.

17. The method according to any one of the preceding claims, characterized in that the coating agent for the fog-free top layer (D) consists essentially of an organic compound of silicon and / or aluminum, titanium, zirconium, tin, cerium, indium.

18. The method according to any one of the preceding claims, characterized in that particularly easily evaporable organic compounds or aerosols are used to produce the fog-free cover layer (D).

19. The method according to any one of the preceding claims, characterized in that silicon compounds, in particular tetraalkoxysilanes, are preferably used to produce the fog-free cover layer (D).

20. The method according to any one of the preceding claims, characterized in that the fog-free cover layer (D) has a water contact angle below 40 degrees and a polar portion of the surface tension over 20, preferably over 30%.

21. Layer system obtainable by a process according to one of claims 1 to 20.

22. Use of the layer system according to spoke 21 for the production of transparent, fog-free coatings on molded articles made of glass.

23. Use of the layer system according to claim 21 for the production of non-fogging

Coatings on molded articles made of thermoplastic materials.

24. Use according to spoke 23, characterized in that the molded body is transparent.

25. Use according to claim 23, characterized in that the shaped body consists of polymethyl methacrylate, polystyrene, polyvinyl chloride, polyurethane or polycarbonate.

26. Use according to claim 23, characterized in that the molded body consists of polycarbonate.

7. Use of the shaped bodies according to spoke 22 to 26 as a component of automobiles, greenhouses, swimming pools, stadiums, train stations, factory halls, roof covers, walls, lamp covers, architectural glazing, domelights, visors, glasses, graphics, billboards, displays, packaging or of panes for Transportation of all kinds.