DE102004017241A9 - Composite material and method for its production - Google Patents

Abstract

The invention relates to a substrate material, in particular made of plastic, and a coating on at least one side of the substrate material and a method for producing this composite material. The coating has an organic adhesion promoter layer made of a silicon oxide lying on a surface of the substrate material, a predominantly organic coupling layer made of a silicon oxide and a final inorganic barrier layer made of silicon oxide.

Description

The invention relates to a composite material comprising a substrate material and a 3-layer coating applied to at least one side of the substrate material, comprising a primer layer, a coupling layer and a barrier layer and a method for producing the composite material comprising a substrate material and the 3-layer coating, in particular for internal coating of hollow bodies.

Background of the invention:

Plastics, in particular transparent plastics, are becoming increasingly important and are replacing glass as the preferred material in many areas.

An example of this are plastic bottles for storing liquids, especially for drinks, which a few years ago consisted almost exclusively of glass and are nowadays already produced to a large extent from PET plastic.

Plastic bottles have many advantages, such as low weight, low unit price and stability against mechanical stresses due to the high elasticity compared to glass containers.

However, the plastic bottles generally have a relatively high permeation for gases. Carbonic acid escapes over time from carbonated drinks stored in such containers, significantly reducing the shelf life of the beverages. In addition, oxygen can penetrate through the plastic and initiate oxidation processes in the drinks or liquids, which also significantly shortens their shelf life.

In order to combine the advantages of plastic containers with those of glass containers with their extremely good barrier effect, it is known to provide plastic containers with barrier coatings, or diffusion barrier layers in order to reduce their permeability to gases and liquids, and these against chemical attack or UV radiation to protect. The barrier effect of such coated containers is improved by orders of magnitude.

In this case, for example, the deposition of thin SiO _x coatings or coating systems on polymer substrates is of interest in order to reduce their permeability, especially for oxygen and water vapor, and in particular to obtain the transparency of the material at the same time.

For applying thin SiO _x coatings on polymeric substrates, the plasma-assisted CVD method has proven to be very suitable. Plasma assisted CVD technology, particularly plasma polymerization, enables the deposition of very thin silicon oxide containing layers having a thickness of about 40 to 60 nm. To produce such a barrier layer, mainly silicon-organic precursors such as HMDSO precursors (hexamethyldisiloxanes) or HMDSN precursors (hexamethyldisilazane) are used today.

Suitable designs are inter alia in the US 6,001,429 A and the WO 01/44538 A1 described in which a barrier coating on the inner surface of a plastic container is generated from the starting compound HMDSO while supplying oxygen as the process gas.

In Scripture DE 101 39 305 A1 For example, in order to improve the barrier effect of a plastic substrate, it is proposed to apply a barrier coating which essentially comprises constituents metal oxides, in particular silicon oxide.

However, inorganic barrier single layers have the disadvantage that they generally become very brittle and are thus susceptible to cracking under strain load and ultimately the barrier effect is permanently impaired. This aspect plays a crucial role in flexible substrates, such as PET.

Furthermore, inorganic barrier layers do not adhere optimally to polymeric substrates because, for example, there are only low binding energies between a silicon oxide layer and the surface of a PET substrate.

To increase the adhesion of barrier coatings, it is for example from the WO 01/10725 A1 , of the DE 198 49 205 A1 . EP 0 997 551 A2 , of the WO 03/100 120 A2 . DE 102 58 681 A1 . DE 102 58 678 A1 and JP 2 526 766 B2 It is known to apply so-called adhesion promoter layers between the substrate and the barrier layer.

In the patent JP 2 526 766 B2 For example, the use of an organic adhesion promoter layer lying between the plastic substrate and the inorganic silicon oxide barrier layer and comprising essentially silicon, oxygen and carbon as constituents is proposed. The synergy effect of barrier layer and adhesive layer leads to a improved barrier effect. The US 2003/0215652 A1 . DE 102 58 681 A1 and WO 03/100 120 A2 describe suitable plasma-assisted methods for producing such a layer system. The DE 102 58 680 A1 describes the deposition of the barrier layer by means of chemical vapor deposition.

In order to produce an optimum barrier layer on flexible substrates, in particular polymers, however, it is not sufficient to consider only the binding ability of the barrier layer to the substrate or via an adhesion-promoting layer and / or their chemical compositions. In addition, the roughness of the barrier layer and / or the adhesion promoting layer and the density of internal interfaces with respect to diffusion paths within the applied layers must be considered.

There are model ideas that such layers, which are grown very rough, have a high density of internal interfaces, thus allowing short diffusion paths along these layers, through which a rapid diffusion can take place and therefore have a reduced barrier effect.

Against this background, therefore, the present invention has the object to avoid the above-mentioned disadvantages of the prior art. In particular, it is an object of the invention to provide a composite material and a method for producing such a composite material, which is characterized by a good adhesion and optimized barrier effect.

This object is achieved in a surprisingly simple way already by the composite material according to claim 1 and a method according to claim 25. Advantageous embodiments are the subject of the dependent claims.

The composite material according to the invention comprises a substrate material and a coating on at least one side of the substrate material. The coating has a lying on a surface of the substrate material adhesive layer which _y1 with 1.0 ≤ x ₁ ≤ 2.8 and 0.1 ≤ y ≤ comprises SiO _x1 C ₁ 2.8, coupling an overlying layer which SiO _x2 C _y2 with 1.0 ≤ x ₂ ≤ 2.8 and 0.1 ≤ y ₂ ≤ 2.8, and a final barrier layer comprising SiO _x3 with 1.0 ≤ x ₃ ≤ 2.8. For the compositions of the adhesion promoter layer and the coupling layer, the condition y ₂ > y ₁ applies.

In particular, the coupling layer allows optimized coupling of the barrier layer to the adhesion promoter layer and the formation of a smooth, flexible and extremely dense surface of the barrier layer to obtain an optimized barrier effect. The barrier layer forms a barrier against substances from the atmosphere and / or substances which are in direct contact with the composite material and / or are contained in the substrate material or are split off from it. Due to the reduced permeability of the substrate to gases, the storage stability of liquids, in particular by the predominantly organic coupling layer is significantly improved, especially for substrates made of plastic.

Such plastic substrates preferably comprise one or more of the following materials:
polycyclic hydrocarbons,
polycarbonates,
Polyester,
Polyethylene terephthalate,
polystyrene,
Polyethylene, in particular HDPE,
polypropylene,
polymethyl methacrylate,
Polyolefins and
PES.

The composite material is in an advantageous embodiment, a hollow body, in particular a container for storing liquid substances. In order to ensure an optimized barrier effect against gases, the hollow body is coated from the inside.

The organic adhesion promoter and overlying mostly organic coupling layers of silicon oxide and carbon and an overlying final inorganic barrier layer of silicon oxide offer optimum adhesion to plastic substrates and very good barrier effects.

Plastic composites having a bonding layer of SiO _x1 C _y1 with 1.1 ≦ x ₁ ≦ 2.0; 0.5 ≤ y ₁ ≤ 2.0,
a coupling _layer of SiO _x2 C _y2 with 1.1 ≤ x ₂ ≤ 2.4; 1.1 ≤ y ₂ ≤ 2.8 and a barrier layer of SiO _x3 with 1.5 ≤ x ₃ ≤ 2.5, in particular 1.7 ≤ x ₃ ≤ 2.4 proven.

• i) eine Kopplungsschicht mit y₂ > y₁;
• ii) eine Kopplungsschicht mit x₂ < 1,5;
• iii) eine Kopplungsschicht mit x₂ < x₁;
• iv) eine Kopplungsschicht x₂ > x₁.

The coupling layer in the composite system is also characterized in that one or more of the following features are fulfilled:

• i) a coupling layer with y ₂ > y ₁ ;
• ii) a coupling layer with x ₂ <1.5;
• iii) a coupling layer with x ₂ <x ₁ ;
• iv) a coupling layer x ₂ > x ₁ .

The adhesion promoter layer has a thickness <200 nm, in particular <100 nm, particularly preferably <50 nm, the coupling layer has a thickness <20 nm, in particular <10 nm, more preferably at least one closed monomolecular layer and the barrier layer has a thickness <100 nm, in particular <50 nm, more preferably at least one closed monomolecular layer. Such coatings also have high flexibility in addition to good barrier and protective properties. Furthermore, in such thin layers in particular, intrinsic stresses that can lead to flaking of the layers can be avoided.

• i) durch die Kopplungsschicht wird die Barrierewirkung gegenüber einem Schichtsystem ohne Kopplungsschicht verbessert, wobei als Barriereverbesserungsfaktor für Sauerstoff wenigstens ein Faktor 3, vorzugsweise ein Faktor größer als 10 erreicht wird.
• ii) durch die Kopplungsschicht wird die Dehnfähigkeit des Schichtsystems verbessert, insbesondere eine Rissbildung in der Barriereschicht unter elastischen Dehnungen und/oder plastischen Verformungen > 1%, vorzugsweise > 3% verhindert.

The composite system is characterized by the following features:

• i) by the coupling layer, the barrier effect is improved over a layer system without coupling layer, wherein at least a factor of 3, preferably a factor greater than 10 is achieved as a barrier improvement factor for oxygen.
• ii) by the coupling layer, the extensibility of the layer system is improved, in particular cracking in the barrier layer under elastic strains and / or plastic deformation> 1%, preferably> 3% prevented.

• i) durch die Kopplungsschicht wird die Morphologie der Barriereschicht derart beeinflusst, dass diese glatt im Lagenwachstum aufwächst.
• ii) durch die Kopplungsschicht wird die Morphologie der Barriereschicht derart beeinflusst, dass diese im Säulenwachstum aufwächst.

The composite system has one of the following features:

• i) through the coupling layer, the morphology of the barrier layer is influenced so that it grows smoothly in the layer growth.
• ii) by the coupling layer, the morphology of the barrier layer is influenced so that it grows in the column growth.

For a particularly preferred composite layer, a sharp interface may exist in the layer composition between the coupling layer and the adhesion promoter, in which the transition region between the layers is less than 5 nm, in particular less than 2 nm.

Furthermore, the composite material may additionally have a sharp interface in the layer composition between the coupling layer and the barrier layer, in which the transition region between the layers is smaller than 5 nm, in particular smaller than 2 nm.

The coupling layer increases the density at the interfaces, in particular interfaces parallel to the substrate.

In another advantageous embodiment, in order to increase the strength of the layer composite and for optimal adhesion of the layers to one another, from the adhesion promoter layer to the coupling layer and from the coupling layer to the barrier layer, a transition region in which the carbon content gradually decreases can be formed.

• – zumindest ein Substrat wird in eine Vakuumkammer eingebracht,
• – die Vakuumkammer und/oder das Substrat werden evakuiert,
• – in die Vakuumkammer wird ein erstes Prozess-Gas, welches zumindest ein Metall und Kohlenstoff umfasst, und ein erstes Reaktionsgas eingeleitet und mittels Einleitung elektromagnetischer Energie ein Plasma erzeugt, wodurch auf dem Substrat eine organische Haftvermittlerschicht mit der Zusammensetzung SiO_x1C_y1 mit 1,0 ≤ x1 ≤ 2,8 und 0,1 ≤ y1 ≤ 2,8 abgeschieden wird,
• – in die Vakuumkammer wird ein zweites Prozess-Gas, welches zumindest ein Metall und Kohlenstoff umfasst, und ein zweites Reaktionsgas eingeleitet und mittels Einleitung elektromagnetischer Energie ein Plasma erzeugt, wodurch auf dem Substrat eine Kopplungsschicht mit der Zusammensetzung SiO_x2C_y2 mit 1,0 ≤ x2 ≤ 2,8 und 0,1 ≤ y2 ≤ 2,8 und y2 > y1 abgeschieden wird,
• – in die Vakuumkammer wird ein drittes Prozess-Gas, welches zumindest ein Metall umfasst, und ein drittes Reaktionsgas eingeleitet und mittels Einleitung elektromagnetischer Energie ein Plasma erzeugt, wodurch auf dem Substrat eine Barriereschicht aus einer Metallverbindung umfassend SiO_x3 mit 1,0 ≤ x₃ ≤ 2,8 abgeschieden wird,
• – die Vakuumkammer wird belüftet und
• – das Verbundmaterial wird entnommen.

The composite substrate according to the invention can be produced with a plasma-assisted CVD method. The method according to the invention for producing the composite substrate comprises the following steps:

• At least one substrate is placed in a vacuum chamber,
• The vacuum chamber and / or the substrate are evacuated,
• A first process gas, which comprises at least one metal and carbon, and a first reaction gas are introduced into the vacuum chamber and a plasma is generated by introduction of electromagnetic energy, whereby an organic adhesion promoter layer with the composition SiO _x1 C _y1 with 1, 0 ≤ x1 ≤ 2.8 and 0.1 ≤ y1 ≤ 2.8,
• - In the vacuum chamber, a second process gas, which comprises at least one metal and carbon, and a second reaction gas is introduced and generated by introduction of electromagnetic energy, a plasma, whereby on the substrate, a coupling _layer having the composition SiO _x2 C _y2 with 1.0 ≤ x2 ≤ 2.8 and 0.1 ≤ y2 ≤ 2.8 and y2> y1 is deposited,
• - In the vacuum chamber, a third process gas, which comprises at least one metal, and a third reaction gas is introduced and generated by introduction of electromagnetic energy, a plasma, whereby on the substrate, a barrier layer of a metal compound comprising SiO _x3 with 1.0 ≤ x ₃ ≤ 2.8 is deposited,
• - The vacuum chamber is ventilated and
• - The composite material is removed.

The introduction of electromagnetic energy is preferably carried out by coupling microwave energy, in particular by coupling pulsed microwave energy. The pulsed process control allows fast and precise process control, allows the deposition of very thin, even layers and the setting of exact proportions in the layers.

In preferred embodiments modes are excited by the microwave pulses, in particular TE or TEM modes in the plasma, wherein substrates of any geometry can be uniformly coated. Typical pulse durations are between 0.4 and 5 ms, the pulse pauses in the range of 10 to 300 ms.

The advantages of the coating according to the invention with the aid of pulses lies in the low heat load of the plastic substrate. Furthermore, a complete gas exchange can be carried out within the pauses between pulses so that an ideal gas composition is always present at the beginning of the next microwave pulse.

A further advantage of plasma excitation with the aid of microwaves, ie a frequency of 900-3000 MHz, compared to a high frequency (RF) excitation, is in particular the thinner boundary layer when excited with microwaves. In a thin surface layer, the ions of the plasma can absorb only little energy, so that they only hit the substrate to be coated with low kinetic energy and can cause only minor damage, for example due to heat input or charging. Because of these advantages, the plasma can be operated in microwaves at much higher powers and higher pressures, resulting, for example, in advantages in the deposition rate.

By suitable choice of pulse duration and pulse pause, the heating of the samples during the coating can be specifically influenced. With 1000 W microwave power, with pulse durations of 0.5 ms and pulse pauses of 200 ms, heating rates of less than 0.3 ° C / s can be achieved. Especially for the coating of plastics, this is advantageous because many plastics, such as PET, deform and crystallize even at temperatures above 80 ° C, which can cause cracking in the layer or the layer can chip off from the plastic substrate.

To produce the organic adhesion promoter layer on the substrate, a first process gas is preferably introduced from an organosilicon compound, in particular HMDSN or HMDSO, and oxygen.

To produce the predominantly organic coupling layer on the adhesion promoter layer, a second process gas is preferably introduced from an organosilicon compound, in particular HMDSN or HMDSO, and oxygen. To produce the inorganic barrier layer on the adhesion promoter layer, a third process gas is preferably introduced from a compound comprising silicon, in particular HMDSO or HMDSN and oxygen.

This preferably comprises the adjustment of the parameters of the coupled-in electromagnetic energy and / or flow parameters. In the case of an unpulsed plasma, the proportions are set in particular by the setting of the average power. The proportions in pulsed plasma are adjusted in particular by adjusting the pulse power, pulse duration and pulse pause.

A flexible, accurate and effective process control and adjustment of process parameters for the production of the composite substrate is, for example, with methods on rotary machines according to the patent applications WO 03/100 120 A2 . WO 03/100 121 A2 . WO 03/100 122 A2 and WO 03/100 129 A1 possible, the disclosure content of which is included in full.

As an alternative to the coating of hollow bodies, it is also possible according to the invention to coat sheet-like substrates, for example films.

The invention will be explained in more detail below with reference to an exemplary embodiment:

Embodiment 1

a) 3 layers:  Adhesive layer, coupling layer, barrier layer

A bottle of polyethylene terephthalate (PET) with a filling volume of 0.4 l is placed in a vacuum chamber and evacuated on the outside to a pressure of 50 mbar and the inside initially pumped to a base pressure lower than 0.1 mbar.

Subsequently, a mixture of oxygen and HMDSO with an HMDSO concentration of 30% is passed into the interior of the bottle at a pressure of 0.5 mbar. Then pulsed microwave energy is coupled with a pulse power of 0.95 kW, a pulse duration of 0.3 ms, a pulse pause of 20 ms and a frequency of 2.45 GHz and ignited a plasma in the container.

During a time of 0.9 seconds, the container is coated on the inside with a primer layer having a thickness of 20 nm and a composition of SiO _1.4 C _1.2 .

Subsequently, a mixture of oxygen and HMDSO with an HMDSO concentration of 20% is passed into the interior of the bottle at a pressure of 0.40 mbar. Then pulsed microwave energy is coupled with a pulse power of 0.95 kW, a pulse duration of 0.5 ms, pulse pause of 40 ms and a frequency of 2.45 GHz and ignited a plasma in the container.

During a period of 2.7 seconds, the container is coated on the inside with a coupling layer with a thickness of 20 nm and a composition of SiO _1.3 C _0.8 .

Subsequently, a mixture of oxygen and HMDSN with an HMDSN concentration of 1.4% is passed into the interior of the bottle at a pressure of 0.45 mbar. The process gas exchange takes place in a gas exchange break, it continues to be pulsed microwave energy with a pulse power of 0.9 kW, a pulse duration of 0.2 ms, a pulse pause of 50 ms and a frequency of 2.45 GHz coupled and ignited a plasma in the container.

During a period of 3.5 seconds, the container is coated on the inside with a barrier layer having a thickness of 15 nm and a composition of SiO ₂ .1.

Immediately afterwards, the bottle is fumigated and removed.

b) Only 2 layers: Adhesive layer, barrier layer

A bottle of polyethylene terephthalate (PET) with a filling volume of 0.4 l is placed in a vacuum chamber and evacuated on the outside to a pressure of 50 mbar and the inside initially pumped to a base pressure lower than 0.1 mbar.

Subsequently, a mixture of oxygen and HMDSO with an HMDSO concentration of 30% is passed into the interior of the bottle at a pressure of 0.5 mbar. Then pulsed microwave energy is coupled with a pulse power of 0.95 kW, a pulse duration of 0.3 ms, pulse pause of 20 ms and a frequency of 2.45 GHz and ignited a plasma in the container.

During a time of 0.9 seconds, the container is coated on the inside with a primer layer having a thickness of 20 nm and a composition of SiO _1.4 C _1.2 .

Subsequently, a mixture of oxygen and HMDSN with an HMDSN concentration of 1.4% is passed into the interior of the bottle at a pressure of 0.45 mbar. The process gas exchange takes place in a gas exchange break, it is further coupled pulsed microwave energy with a pulse power of 0.9 kW, a pulse duration of 0.2 ms, a pulse pause of 50 ms and a frequency of 2.45 GHz and ignited a plasma in the container. During a period of 3.5 seconds, the container is coated on the inside with a barrier layer having a thickness of 15 nm and a composition of SiO ₂ .1.

Immediately afterwards, the bottle is fumigated and removed.

Measurement results for example a and example b:

In a stress test (creep test), the bottles of Examples a) and b) are stretched under the same conditions at an internal pressure of 5 mbar and a temperature of 38 ° C and plastically deformed with a maximum total strain of 5%. The remanent elongation (plastic) is greater than 2%.

Measurements of oxygen permeability after DIN 53380-3 with an electrochemical sensor after stress test for the coated with Example a) bottle with an additional coupling layer a value of 0.017 cm ³ / (sample × day × bar), for the coated with Example b) bottle without coupling layer has a value of 0.052 cm ³ / (Sample × day × bar) and for an uncoated bottle a value of 0.196 cm ³ / (sample × day × bar), so that after load test for example a) with coupling layer of the barrier improvement factor for oxygen (O2-BIF) 11.2 and for Example b) without coupling layer is 3.7.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US6001429A [0009]
• WO 01/44538 A1 [0009]
• DE 10139305 A1 [0010]
• WO 01/10725 A1 [0013]
• DE 19849205 A1 [0013]
• EP 0997551 A2 [0013]
• WO 03/100120 A2 [0013, 0014, 0042]
• DE 10258681 A1 [0013, 0014]
• DE 10258678 A1 [0013]
• JP 2526766 B2 [0013, 0014]
• US 2003/0215652 A1 [0014]
• DE 10258680 A1 [0014]
• WO 03/100121 A2 [0042]
• WO 03/100122 A2 [0042]
• WO 03/100129 A1 [0042]

Cited non-patent literature

• DIN 53380-3 [0059]

Claims (37)

A composite material comprising a substrate material and a coating on at least one side of the substrate material, wherein the coating has a primer layer on a surface of the substrate material which is SiO _x1 C _{y1 of} 1.0 ≤ x ₁ ≤ 2.8 and 0.1 ≤ y ₁ ≤ 2.8 includes; coupling an overlying layer comprising SiO _{x2 y2} C with 1.0 ≤ x ₂ ≤ 2.8 and 0.1 ≤ y ≤ ₂ 2.8; and a final barrier layer comprising SiO _x3 with 1.0 ≦ x ₃ ≦ 2.8; characterized in that the condition y ₂ > y ₁ applies to the compositions of the adhesion promoter layer and coupling layer. Composite material according to claim 1, characterized in that the substrate is a plastic substrate. Composite material according to claim 2, characterized that the plastic substrate one or more of the following materials polycyclic hydrocarbons, polycarbonates, Polyester, Polyethylene terephthalate, polystyrene, Polyethylene, in particular HDPE, polypropylene, polymethyl methacrylate, PES polyolefins includes. Composite material according to one of the preceding claims, characterized in that for the adhesion promoter layer: 1.1 ≤ x ₁ ≤ 2.0 and 0.5 ≤ y ₁ ≤ 2.0. Composite material according to one of the preceding claims, characterized in that the adhesion promoter layer has a thickness <200 nm, in particular <100 nm, particularly preferably <50 nm. Composite material according to one of the preceding claims, characterized in that the following applies to the coupling layer: x ₂ <x ₁ . Composite material according to one of the preceding claims 1 to 6, characterized in that the following applies to the coupling layer: x ₂ > x ₁ . Composite material according to one of the preceding claims, characterized in that for the coupling layer: 1.1 ≤ x ₂ ≤ 2.4 and 1.1 ≤ y ₂ ≤ 2.8. Composite material according to one of the preceding claims, characterized in that the following applies to the coupling layer: x ₂ <1.5. Composite material according to one of the preceding claims, characterized in that the coupling layer has a thickness of <20 nm, in particular <10 nm. Composite material according to one of the preceding claims, characterized in that the coupling layer has at least one closed monomolecular layer. Composite material according to one of the preceding claims, characterized in that between the coupling layer and the adhesion promoter there is a sharp interface in the layer composition in which the transitional area between the layers is less than 5 nm, in particular less than 2 nm. Composite material according to one of the preceding claims, characterized in that the barrier _layer comprises as material SiO _x3 with 1.5 ≤ x ₃ ≤ 2.5, in particular with 1.7 ≤ x ₃ ≤ 2.4. Composite material according to one of the preceding claims, characterized in that the barrier layer has a thickness of <100 nm, in particular <50 nm. Composite material according to one of the preceding claims, characterized in that the barrier layer has at least one closed monomolecular layer. Composite material according to one of the preceding claims, characterized in that the barrier layer is grown in the layer growth. Composite material according to one of the preceding claims 1 to 16, characterized in that the barrier layer is grown in the column growth. Composite material according to one of the preceding claims, characterized in that between the coupling layer and the barrier layer there is a sharp interface in the layer composition in which the transition region between the layers is less than 5 nm, in particular less than 2 nm. Composite material according to one of the preceding claims 1 to 17, characterized in that from the coupling layer to the barrier layer, a transition region is formed, in which the proportion of carbon gradually decreases. Composite material according to one of the preceding claims, characterized in that it has a barrier oxygen improving factor of at least 3, preferably a factor greater than 10. Composite material according to one of the preceding claims, characterized in that the barrier layer under elastic strains and / or plastic deformations greater than 1%, preferably greater than 3% has no cracking. Composite material according to one of the preceding claims, characterized in that the coupling layer couples the barrier layer to the adhesion promoter layer and the barrier layer has a smooth, flexible and extremely dense surface. Composite material according to one of the preceding claims, characterized in that the substrate material is a hollow body. Composite material according to claim 23, characterized in that the hollow body is coated from the inside. Method for producing a composite material according to claims 1 to 24, comprising the following steps: - at least one substrate is introduced into a vacuum chamber, - the vacuum chamber and / or the substrate are evacuated, - a first process gas, which is at least one, enters the vacuum chamber Metal and carbon and introduced a first reaction gas and generated by introduction of electromagnetic energy, a plasma, whereby on the substrate an organic primer layer having the composition SiO _x1 C _y1 with 1.0 ≤ x1 ≤ 2.8 and 0.1 ≤ y1 ≤ A second process gas, comprising at least one metal and carbon, and a second reaction gas are introduced into the vacuum chamber and a plasma is generated by introduction of electromagnetic energy, whereby a coupling layer having the composition SiO _{x 2} C is deposited _y2 with 1.0 ≤ x2 ≤ 2.8 and 0.1 ≤ y2 ≤ 2.8 and y2> y1, in the vacuum chamber, a third process gas comprises at least one metal, and a third reaction gas is introduced and a plasma is generated by means of introduction of electromagnetic energy, whereby on the substrate, a barrier layer of a metal compound comprising SiO _x3 with 1.0 ≤ x ₃ ≤ 2,8 is deposited, - the vacuum chamber is vented and - the composite material is removed. A method according to claim 25, characterized in that the introduction of electromagnetic energy comprises the coupling of microwave energy. A method according to claim 26, characterized in that the introduction of electromagnetic energy comprises the coupling of pulsed microwave energy. A method according to claim 27, characterized in that the microwave pulses in the frequency range of 900 to 3000 MHz. A method according to claim 27 or 28, characterized in that are excited by the microwave pulses modes, in particular TE or TEM modes in the plasma. Method according to one of the preceding claims 25 to 29, characterized in that as the first process gas, an organosilicon compound is introduced. A method according to claim 30, characterized in that is introduced as the first process gas hexamethyldisiloxane or hexamethyldisilazane and preferably additionally oxygen. Method according to one of the preceding claims 25 to 31, characterized in that as the second process gas, an organosilicon compound is introduced. A method according to claim 32, characterized in that is introduced as the second process gas hexamethyldisiloxane or hexamethyldisilazane and preferably additionally oxygen. Method according to one of the preceding claims 25 to 33, characterized in that as the third process gas, an organosilicon compound is introduced. A method according to claim 34, characterized in that is introduced as the third process gas hexamethyldisiloxane or hexamethyldisilazane and preferably additionally oxygen. Method according to one of the preceding claims 25 to 35, characterized in that as reaction gas O ₂ , N ₂ or N ₂ + NH _{3 is} introduced. Method according to one of the preceding claims 25 to 36, characterized in that O _{2 is} introduced as the first, second and third reaction gas.