DE10036434A1 - Preparation of a barrier layer useful for packaging of foodstuffs or materials sensitive to moisture and aromatics, comprises reacting a silane mixture with an acidic silica sol - Google Patents

Abstract

A barrier layer with low permeability on one surface is prepared by reacting a silane mixture condensable to siloxane with an acidic silica sol to give a pre-condensate, and deposition of the precondensate containing at least the main constituent as a coating solution onto the surface in a crosslinked thin layer. Preparation of a barrier layer with low permeability on one surface by reacting a silane mixture condensable to siloxane, containing alkoxy groups and organic crosslinkable functional groups bonded to silicon, with an acidic silica sol to give a pre-condensate, deposition of the precondensate containing at least the main constituent as a coating solution onto the surface in a thin layer, with crosslinking of the thin layer with the aid of organic polymerizable functional groups either by heating and radiation. An Independent claim is included for an object with a barrier layer obtained as above having low surface permeability towards at least one of the materials: water, oxygen, oils, fats, and aromatics.

Description

The invention relates to a method for producing as Barrier layers usable siloxane layers as well as with Objects provided with barrier layers.

Barrier layers can be placed directly on sensitive objects who are upset to these against all kinds of external input protect rivers, especially against exposure of moisture, solvents, or other liquid or gaseous, organic or inorganic substances.

Applications find barrier layers, for example, in the Microelectronics, being oxidic or generally inorganic Barrier layers (for example oxides or nitrides from Alumi nium or silicon) a semiconductor or a semiconductor Protect the circuit especially against moisture. The bar Riereschicht can be applied directly to the semiconductor circuit brought be a sub-layer of the semiconductor circuit or be a layer of packaging. Bars are also known barrier layers made from organic paints, in particular from Epoxides.

Barrier layers are another application especially outer sublayers of materials made by little or no protection against exposure of vapors or liquids, or the a very high permeability for gases, vapors or liquids have features. Barrier layers are therefore used especially as coatings for packaging materials lines such as paper, cardboard or cardboard as well as textiles, sern or general tissues, on the one hand both the be coated materials against the effects mentioned protect and on the other hand the materials coated with it  to protect objects, in particular using the coated materials as Verpac kung material. It is especially for the latter use desirable to find barrier layers as thin as possible, the rest of the properties of the coated Ma little or at least not adversely affect materials.

Known barrier layers exist for example on the Ba sis of organically modified siloxanes. Such as ORMOCER known organic-inorganic hybrid polymers can through condensation of condensable and with suitable ten organic groups substituted silanes become. For further modification, the siloxanes can be put together men with other organic and cocondensation Ver bonds are condensed to further increase the properties influence. Even with a number of fillers, Si loxanes can be modified. Another way to modes Specification of siloxanes consists of one or more of the condensed compounds with polymerizable groups substitute and this after the condensation to the siloxane crosslink by polymerization.

From US 5,618,628 as oxygen barrier layers usable sol-gel layers known by hydrolysis tion of tetrafunctional alkoxy silanes in aqueous acidic Solution in the presence of an acid or metal catalyst be condensed. The sol-gel polymers obtained can di are spread directly onto objects to be protected and are already as a bar after drying without further hardening barrier layers effective.

EP 0 062 899 B1 discloses a curable coating agent the basis of olefinically unsaturated polysiloxanes known, wel che especially for the production of scratch-resistant coatings are suitable on plastics. To do this, use olefinic unsaturated groups substituted alkoxysilanes with sown saturated alkoxysilanes and optionally containing epoxy groups  Silanes in aqueous or aqueous / alcoholic solution in an presence of an acid catalyst implemented. After the order The coatings can be applied to the desired surfaces more ionizing radiation, for example with an electron beam len or UV light can be cured by polymerization.

Composite materials suitable for packaging using ORMOCER layers are, for example, from the DE 196 50 286 A1 known. Such composite systems are based on a carrier material, for example a film and at least at least two layers, one of which is an inorganic contains organic hybrid polymer, which by hydrolyti cal polycondensation of an organofunctional silane and subsequent crosslinking of the organic groups obtained becomes. The barrier function, especially against moisture and gases will interact with another layer achieved, especially a vapor-deposited sili ziumoxidschicht.

This two-layer barrier layer has good properties have low permeability Gases and water vapor, however, is a double layer with two to produce different layers only with great effort.

The object of the present invention is therefore to unite fold method for producing a barrier layer give to liquids, gases and water vapor ne has a high barrier effect and with the thin film such materials as well as compact bodies in simpler Way can be provided.

According to the invention, this object is achieved by a method Claim 1 solved. Advantageous embodiments of the invention and provide one with the barrier layer according to the invention Further subject matter can be found in the subject matter.  

With the method according to the invention one becomes a barrier layer creates a suitable siloxane layer, which in addition to the anor ganic siloxane backbone additionally by reaction orga nofunctional groups is organically networked. In a he Most stage, a precondensate is first generated by a Organic and alkoxy groups, bonded to silicon their crosslinkable silane mixture carrying functional groups is reacted with an acidic silica sol. With these condens tion, in which a siloxane is formed, remains the organi get polymerizable functional groups.

The pre-condensate is an aqueous sol, which remains stable at room temperature for at least 3 months. A coating solution containing this sol is now applied in a thin layer to a surface to be coated and then crosslinked thermally or under the action of ionizing radiation. A barrier layer is obtained which has an extremely low permeability to moisture, vapors and gases. With a 1 to 10 µm thick barrier layer, a water vapor permeability (according to DIN 53122-3) of less than 100 g / m ² d (d = day) is obtained. The water vapor permeability can be further improved by suitable adjustment of the organic group, so that permeability of less than 30 g / m ² d can be achieved for exemplary embodiments. The oxygen permeability (according to ASTM-D 3985-1 ) can also be set to a low value of less than 100 (cm) ³ / m ² d.bar. The best exemplary embodiments achieve oxygen permeabilities of less than 3 (cm) ³ / m ² d.bar.

The barrier layers are resistant to water and solder solvents, especially against alkanes, chlorinated carbon Hydrogen oils, alcohols, ketones, esters, aromatic Solvents and against some acids and bases. except they are impervious to oils and fats and work well against gaseous aromas as a barrier.  

The siloxane layer can be used as a barrier layer on any Substrates (surfaces) are applied, in particular on Paper, cardboard and cardboard, on textile fibers or fabrics and on plastic films. The adhesion on these surfaces is very good, so that there is also a high abrasion resistance. Since the barrier effect already in thin layers of 1 to 10 µm is reached, the other properties of the coated materials remain largely unchanged. According to the invention, this provides a barrier layer ne sheet materials in particular for use as Ver packaging material suitable. The barrier effect is in particular This is always advantageous when a counter to be packed stood against external influences (liquids, gases, fragrances or flavors) is to be protected when the packaged item for example, is a food with packaging must prevent loss of moisture or aroma and au also if the packaging is against a food or soak out of other items to be packaged or greasing must be protected.

The silane mixture for producing the precondensate contains at least one silane of the formula 1:

R _a ¹ R _b ² Si (OR) _c 1

where R ^{1 is} a group bonded to silicon via an Si-C bond with at least one crosslinkable, organic functional group selected from carbon-carbon double bond, carbon-carbon triple bond or epoxy group. R ² is an optionally substituted, saturated aliphatic or aromatic hydrocarbon group, while R represents an alkyl radical. The parameters a, b and c add up to the value 4, where a can take the values 1 or 2 , b stands for 0 or 1 and c can be 2 or 3. The alkyl radical R preferably has up to 4 carbon atoms and is in particular a methyl or ethyl group.

The silane mixture can also be different from the general ones Formula 1 contain corresponding silanes. Through a variation the silanes in parameters a, b and c can crosslink density can be set in the later barrier layer.

In addition to the indispensable silane containing the organic crosslinkable functional group, the silane mixture can additionally also contain at least one further silane of the general formula 2:

R _d ² R _e ³ Si (OR) _f 2

where R and R ^{2 are} as defined above. The radical R ³ can be defined as R ² , but is independent of R ² and can be different from this. The parameters d, e and f add up to 4 again, where d can take the values 1 or 2 and e is 0 or 1. This further silane serves, without lowering the crosslinking density of the inorganic siloxane skeleton, to introduce a further group R ² in order to influence the polar or non-polar properties of the later barrier layer. Longer alkyl radicals, aromatic radicals or other non-polar groups as radical R ² lower the polarity of the barrier layer.

The polymerization of the organic functional group contained in silane 1 can be carried out in the presence of a copolymerizable further substance. If the functional crosslinkable group R ^{1 is} an olefinically unsaturated group, copolymerization is preferably carried out using olefinically unsaturated but preferably di- and more functional, that is to say di- and polyunsaturated compounds, in particular (meth) acrylates. If the functional crosslinkable group R ^{1 is} an epoxy group, then di- and polyepoxides as well as di- and polyols can be used for copolymerization with the silane mixture or with the precondensate.

An essential part of the method according to the invention is the silica sol. Below that is a stabilized dispersion on of silicon oxide particles in usually aqueous or understood aqueous / alcoholic solution, usually can contain up to 40 wt .-% particles. According to the invention the silica sol is acidic, that is, its pH is 7 or fewer. Although the natural pH value of silica re is acidic, the silica sol according to the invention can be used Using organic or inorganic acid (e.g. HCl or Es acetic acid) to a lower pH. The Silica sol and its pH is essential for the condensate tion reaction of the silane mixture since the silica sol the dispersed silicon oxide particles crystalli sation nuclei for the polycondensation of the silane represent the silane mixture. The pH value determines there at the size of the pores in the sol, with a lower pH leads to smaller pores. Smaller pores also mean a lower permeability. The pH of the silica sol is also decisive for the stability of the precondensate, which only in acidic medium the high stability of at least 3 months naten owns. A preferred pH for the silica sol is in the range from 3 to 6. Such silica sols are in the Trade available and are for example under the brands Levasil, Lefasol, Köstrosol, Bindziel, Aerosil or Sipernat distributed. However, other silica sols are also in accordance with the invention used.

With the silica sol used according to the invention, the condensation reaction of the silanes or the silane mixture starts automatically. However, it is also possible to add a condensation catalyst, in particular an organic or inorganic proton-containing acid, a Lewis acid or a metal chelate complex. Due to the acidic silica sol, condensation catalysts based on bases such as amines, sodium hydroxide and others are less suitable. Alternatively, it is also possible to add an organometallic compound of the general formula 3 to the siloxane mixture:

M (OR) _g 3

in which R is defined as in formulas 1 and 2. M stands for germanium, silicon, titanium, zirconium or aluminum. The index g is 3 in the case of aluminum and is otherwise 4. The compound 3 is capable of co-condensation with the siloxane and leads to the incorporation of the central atom M into the siloxane framework. This allows the inorganic content in the sol and thus in the barrier layer to be increased.

As already mentioned, the condensation can be carried out without a catalyst and takes place at room temperature. However, the condensation is preferably supported by increasing the temperature, heating to values of 20 to 80 ° C. being suitable. If the condensation is carried out at room temperature, the condensable groups are already condensed after about 3 hours of stirring. The condensation can be carried out without further solvents, and the precondensate obtained is also stable in storage “in bulk”. For later processing for the coating solution or for coating the surface to be provided with a barrier layer, the precondensate can be diluted with up to 20% solvent, alcohols (for example isopropanol and ethanol) and water or mixtures thereof being preferred. Accordingly, a coating solution used in accordance with the invention, including any additional additives, may have the following composition, expressed in percent by weight:

• 1. A 10 to 60%, preferably 15 to 35% silanes of the general my Formula 1
• 2. B 0 to 50% alkoxysilane of the general formula 2, wherein up to 3 different silanes of formula 2 and in particular  1 to 2 different alkylsilanes can be included can
• 3. C 0 to 20% of a compound of general formula 3, where with up to 2 different organometallic compounds can be used
• 4. D 10 to 55% silica sol, preferably 20 to 45%
• 5. E 0.2 to 0.8 mol of bifunctional or multifunctional substance which can be copolymerized with the epoxide group in the silane 1 per mol of epoxy group used, it being possible for up to 2 different substances to be added to the precondensate (only applies if the silane 1 contains an epoxy group)
• 6. F up to 20% solvent, preferably alcohol and / or water

If necessary, the coating solution can also have one or several fillers for further modification of the properties ten can be added. As fillers are polymers and oli gomeric compounds that are reactive either in that Precondensate or during crosslinking into the siloxane or the barrier layer can be integrated. Possible it is, however, only the filler mechanically as particles to be integrated into the siloxane matrix. These fillers, too up to a proportion of an additional 10% by weight in the coating solution may not interfere with condensation the final crosslinking to the siloxane precondensate.

Suitable fillers are polymers or dispersions for example, the under the following trade names D. E. R., Pa raloid, Saxofloc, Cerafac, Aquacer, Acrosol, Acronal, Mowi lith, Vinnapas, Contraqua, Glaswachs, Vinnol, or among the Designations poly (bisphenol A) co-epichlorohydrin, polysty ren, polyvinyl alcohol, polyvinylene fluoride, polyme thyl (meth) acrylate available fabrics.

In addition to the components mentioned, the precon densat thermal and / or photochemical initiators added be set, the thermal or photochemical polymerization  supported. For a number of different silanes Mixtures do not require initiators for crosslinking. The initiators are preferably used in an amount of 0 to 3% by weight (based on the total coating solution) set. It is also possible to use a comm Combination of a photochemical with a thermal step perform.

As mentioned, the crosslinking can be done by ionizing radiation (in particular by UV radiation) and / or thermally be performed. Thermal curing is at 100 to 160 ° C, preferably at 120 to 140 ° C. At a Combined curing is first photoche triggered by mixing and thermally hardened.

With the invention, mono- or composite materials can be used Barrier layers and thus with barrier properties against about liquids, gases, flavors and water vapor will see. Such properties are common in applications the packaging and construction industry for sealing building materials fen advantageous. The excellent locking effect and the loading resistance to water, solvents and a number of acids and bases is achieved with a barrier layer, which are applied in a thin layer on a carrier material becomes. Mono-carrier materials such as paper and card are suitable clay, cardboard, foil and composite materials such as bonded Cardboard boxes, tiles, felt and textiles. The barrier layer can be a superficial layer, but can also be part of one Composite material in which the barrier layer is one of several layers and possibly also an intermediate layer between first and second layers, for example between two layers of paper. In this application you can the barrier layer or the coating solution also as Ka Schier adhesive for laminating paper, cardboard and cardboard as Substrate with other materials, such as foils or papers serve.  

Hollow bodies or porous materials with internal ones can also be used Surfaces are coated with the barrier layer.

The properties of the barrier layers and thus the properties of the surfaces provided with barrier layers are determined according to the invention by the crosslinking density and the radicals R ² bound to silicon. The groups R ² in the silanes of the general formulas 1 and 2 are preferably, in particular, unsubstituted alkyl groups, those with 1 to 8 carbon atoms being preferred. Suitable radicals R ² for the silanes of the silane mixture are the groups methyl, ethyl, propyl, butyl, cyclohexylmethyl, cyclooctyl, cyclopentyl, decyl, dodecyl, eicosyl, hexyl, octyl, phenyl, phenylmethyl and their derivatives.

In silane 1 and 2 , the group R preferably has 1 to 4 carbon atoms and is therefore, for example, methyl, ethyl, n- or i-propyl, but preferably methyl or ethyl. The group R ¹ is or preferably carries a group such as vinyl, allyl, 2-methylpropenyl, 1,7-octadienyl, 7-octenyl, 2,4-pentadienyl, phenylethenyl, phenylethynyl, ethynyl, 3-cyclohexenyl, O- (methacryloxyethyl) -N- (triethoxysilyl) propyl, methacryloxypropyl, methacryloxymethyl, epoxycyclohexylethyl, epoxypropyloxypropyl, epoxyhexyl.

For the silane of the general formula 2, the groups R ^{2 can} also be fluoroalkyl groups, in particular those having 2 to 14 carbon atoms and at least 3 fluorine atoms. Examples of such fluoroalkyl groups are tridecafluoro-1,1,2,2-tetrahydrooctyl and heptaldecafluoro-1,1,2,2-tetrahydrodecyl. Fluorinated aromatic groups can also serve as radicals R ² , for example pentafluorophenyl, as further fluorinated groups.

The following substances are particularly suitable as photochemical and / or thermal initiators: melamine, dicyandia mid, histidine, N-methylimidazole, uric acid, maleic anhydride, succinic anhydride, phthalic anhydride, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-on, bis (2, 6 -dimethoxybenzoyl) -2,4-trimethylpentylphosphine oxide, bis (2, 4, 6 -dimethylbenzoyl) - 2,4,4- trimethylpentylphosphine oxide), 1-hydroxycyclohexylphenyl ketone, 1- [4- ( 2- hydroxyethoxy) phenyl] - 2-hydroxy-2-methyl-1-propan-1-one, azoisobutyronitrile, hydrogen peroxide-urea adduct, ammonium persulfate, dilauroyl peroxide, dicyclichexylate, Cumylperoxyneodeca noat, dibenzoyl peroxide, didecanoyl peroxide, di (3,5,5-trimethylheyanoyl) peroxide, disuccinoyl peroxide, tert-butyl peroxybenzoate, di (tert-butyl) peroxide, 2,2-di (tert-butylperoxy) butane, 1,1-di ( tertbutylperoxy) cyclohexane, cyclohexanone peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, tert-amyl hydroperoxide and their mixtures. Azo compounds, azides and peroxides in particular serve as thermal initiators.

If silanes of the general structure formula 1 are used which contain epoxy groups, the crosslinking of the epoxy groups is optionally supported by the bis- or polyfunctional substances mentioned. Such can be selected, for example, from 4,4 '- (phenylenediisopropylidene) bisphenol [2167-51-3], for example 4,4' - (1,3-phenylenediisopropylidene) bisphenol [13595-5-0], 4, 4'-cyclohexylidenebisphenol [843-55-0], bis (4-hydroxyphenyl) methane [620-92-8], 4,4'Sulfonyldiphenol [80-09-1], bis (4-hydroxyphenyl) propane [80- 05-7], 2,2-bis (4-hydroxy-3-methylphenyl) propane [79-97-0], bis (hydroxymethyl) tricyclo ( 5.2.1.0 ^2.6 ) decane [26896-48-0], 4 , 4'-isopropylidenebis (dimethylphenol) [5613-46-7] and their mixtures. The corresponding CAS number is given in brackets.

In the following the invention is based on exemplary embodiments play and explained the associated figures.  

Figs. 1 to 3 are schematic cross-sections through the invention, provided with barrier layers objects.

1. Preparation of a first coating solution (precondensation sat)

As silane 1 , γ-glycidyloxypropyltrimethoxysilane is used. 3.1 g of silane are mixed with 5.3 g of silica sol with a pH of less than or equal to 7 (for example Köstrosol 0815 BS) and stirred for 3 hours at room temperature. A precondensation is obtained which is stable in storage for 3 months. In a variant, 1 g of 0.1 n-HCl can be added before the condensation.

2. Preparation of a second coating solution (precondensation sat)

Before the condensation, 6.34 g of alkylsilane 2 (for example octyltriethoxysilane) are additionally added to the composition of Example 1. The mixture is stirred for 3 hours at room temperature or heated to 40 to 70 ° C for half an hour and then stirred for another 2 hours at room temperature. The composition is then fully condensed and the precondensate can be stored for at least 3 months.

3. Preparation of a modified coating solution

Bisphenol A is added to the starting materials of the second exemplary embodiment as a coadditive (bisfunctional starting material), 0.4 mol of bisfunctional starting material being added per epoxy group present. The condensation can be carried out as in embodiment 2 at room temperature or at a slightly elevated temperature.

4th embodiment

The exemplary embodiments (precondensates) 1 to 3 are Thermal and / or UV initiators in a proportion of up to 3 wt. % added. This does not affect the ability to condense influenced. The finished coating solution remains despite set initiators stable over 3 months and does not gel.

5th embodiment

For this purpose, the embodiments 1 and 2 are repeated with the difference that instead of the Si lan containing epoxide groups, an olefinic silane 1 is now used, namely 2.1 g of methacrylopropyltrimethoxysilane. Here, too, the precondensation can be carried out under mild conditions without the addition of additional condensation catalysts. The coating solutions obtained (precondensation) are stable even for a long time (several months) with added thermal / photochemical initiators and do not gel.

6th embodiment

The exemplary embodiments 1 to 5 are repeated with the difference that in addition to the precondensate, 10% filler, for example a wax (for example Cerafac 127 ), is added before or after the condensation reaction. Even if the filler is added to the starting components before the condensation, the condensation reaction is not impaired by this and can be carried out under the mild conditions mentioned.

7. Carrying out a coating

Depending on the desired thickness of the barrier layer to be produced, different application methods can be used to coat a surface. Continuous barrier layers on objects with predominantly flat surfaces, in particular on sheet-like materials, are applied, for example, by doctoring, rolling, spraying or spraying. If necessary, the coating compositions can be adjusted to an appropriate viscosity for the chosen application method by adding solvents (alcohol, for example isopropanol) or water. For coating smooth surfaces, the coating composition is e.g. B. applied in an amount of 3 to 20 g / m ² , which is sufficient to produce a dense barrier layer.

8. Networking of the applied layers

The networking of the coating solutions or the thin layers according to the invention is thermally at 110 to 150 ° C, with a reaction time of 3 to 5 Mi grooves is sufficient. This is particularly the case with the Be layering of thermally sensitive materials or surfaces chen an advantage. Alternatively, networking through Be radiation with UV light, but for what usually coating solution with UV initiators required are. It is also possible to network through a start short-term UV radiation and by a thermi complete after-treatment at 110 to 150 ° C.

Fig. 1 shows a schematic cross section through a he inventively coated substrate 2. The substrate is preferably a thin film-like material, for example paper or plastic film, and has a smooth surface 4 . The barrier layer 1 applied thereon has a sufficient barrier effect for moisture and gases already in a thickness of 1 to 10 μm. The surface 4 can also be an inner surface of a hollow body or a pore.

Fig. 2 on the basis of a schematic cross section of a further possibility, an object of the present invention with a barrier layer is to be provided. In the exemplary embodiment, the coating solution is applied to the surface of a first layer 2 of paper, plastic, cardboard or cardboard as layer 5 . A further material layer 3 is then applied to the still uncrosslinked layer, which surface consists of the same or, preferably, different material of the selection mentioned for the first layer 2 . Adequate contact between the two layers 2 and 3 can be produced, for example, by lamination, where the two material webs 2 and 3 with the layer 5 of the coating solution arranged in between are carried out under pressure between two rollers. Only then is the coating composition crosslinked. Thermal crosslinking is preferred for this purpose. If one of the two materials 2 or 3 is a transparent material for UV radiation, UV crosslinking can also be carried out for this exemplary embodiment. The crosslinking creates an intimate connection between the two material webs 2 and 3 , the crosslinked layer serving both as a lamination adhesive and as a barrier layer.

Fig. 3 shows another schematic cross-section through a provided with a barrier layer 1 Object 2. This is provided on both main surfaces with a barrier layer 1 , 1 ', so that the object is protected by both sides. The substrate 2 can also be a flat or sheet-like material here. However, it is also possible to provide solid objects with barrier layers on several or all surfaces. It is also possible in this way to provide fiber-like material all around with barrier layers and in particular to provide textile fibers with appropriate equipment.

On the basis of the exemplary embodiments, the invention is only described preferably described to the feasibility and thus to demonstrate achieved properties. Here is the he However, the invention is not restricted to the exemplary embodiments, but extends across the entire range of variation  components possible for the invention and for the com specified ranges of components.

The invention is true for the production of barrier layers especially on the specified substrates and surfaces suitable, but not on the specified substrates (upper areas) limited. Rather, almost with the invention any surfaces can be provided with barrier layers, the method of coating in a simple manner the surface to be coated or otherwise layering material can be adjusted. The properties The barrier layer are not of the type and material of the coated surface dependent.

Claims (17)

1. Process for producing a barrier layer with low permeability on a surface,

• a silane mixture which is condensable to a siloxane, has alkoxy groups and contains organic, crosslinkable functional groups bonded to silicon is reacted with an acidic silica sol to form a precondensate,
• in which a coating solution having the precondensate as at least the main constituent is applied in a thin layer to the surface, and
• - In which the thin layer is crosslinked thermally and / or under the action of ionizing radiation with the aid of the organic polymerizable functional groups.

2. The method of claim 1, wherein the silane mixture contains at least one silane of formula 1:
R _a ¹ R _b ² Si (OR) _c 1
wherein R ^{1 is} a group bonded to Si via an Si-C bond with at least one organically crosslinkable functional group selected from carbon-carbon double or triple bond or epoxy group,
R ^{2 represents} an optionally substituted, saturated aliphatic or an aromatic hydrocarbon group, R represents an alkyl radical, a = 1 or 2, b = 0 or 1, c = 2 or 3 and c = 4 - (a + b). 3. The method of claim 2, wherein the silane mixture contains at least one other silane of formula 2:
R _d ² R _e ³ Si (OR) _f 2
wherein R and R ^{2 are} as defined above, R ^{3 is} independently of R ² as R ² , d = 1 or 2, e = 0 or 1 and (d + e + f) = 4. 4. The method according to any one of claims 1 to 3, in which a 10 up to 55% by weight of pre-condensate containing silica sol Det, which is by adding up to 20 wt .-% water and / or organic solvent to a coating capable sol is processed. 5. The method according to any one of claims 1 to 4, that of the coating solution or one of its stocks some fillers added before coating those that are selected from the group waxes, poly mer or dispersions of oligomeric substances. 6. The method according to any one of claims 1 to 5, in the case of silanes containing epoxy groups for the preparation of the Pre-condensate are used and in which the coating solution before coating with the epoxy groups co polymerizable bis- or multifunctional starting materials added be set. 7. The method according to any one of claims 1 to 6, where the coating solution before coating thermal and / or photochemical initiators added become. 8. The method according to any one of claims 1 to 7, at which the precondensate is at a temperature between 20 and 80 ° C is produced. 9. Object with a barrier layer wherein the barrier layer according to a method according to ei nem of claims 1 to 8 is made and the through casualness of the surface towards at least one of the Substances selected from water, oxygen, oils, fats and  Flavorings is lowered. 10. The article of claim 9, where the barrier layer is on an outer surface of the object is arranged and a thickness of approx. 1- 10 µm. 11. The article of claim 9 or 10, in which the surface provided with the barrier layer a first layer of paper, plastic, cardboard or Contains cardboard. 12. The article of claim 11, consisting of a composite material, which at least another layer connected to the first layer the same or a different material points, which is selected from paper, plastic, Cardboard, cardboard, felt, textile or other fabrics. 13. Object according to one of claims 9 to 12, in the barrier layer is an intermediate layer, which as Laminating adhesive layer between the first layer and the another layer is arranged. 14. Article according to one of claims 9 to 13, wherein the barrier layer has fluorinated groups which represent one of the radicals R ² . 15. Object according to one of claims 9 to 14, where all outer surfaces are barrier layers. 16. Object according to one of claims 9 to 14, at least one cavity with an inner surface having a barrier layer.   17. Use of an object according to one of claims 1 to 15 for packaging food or fabrics are sensitive to moisture or aromas, or where moisture or flavorings in the packaging to be held back.