BARRIER LAYER AND ITS USE IN PLASTIC SUBSTATE COATING SYSTEMS

Abstract

The invention relates to a coating material for producing a barrier layer on plastic substrates, comprising a hydroxyl-functionalized binder component and a hardening component containing an isocyanate. The binder component comprises aqueous dispersions of polymers containing polyphenylene ethers or ethylene-vinyl fluorinated ether copolymers, hollow glass bodies, and inorganic fillers and / or pigments. The coating material can be used in coating systems to prime plastic substrates, particularly internal components made of thermoplastic materials or plastic fiber composites. The invention further relates to a method for producing a barrier-containing coating.

Description

[0001] The present invention relates to coating materials for producing a barrier layer and their use in coating systems for substrates made of plastics, as well as methods for producing a barrier-layer-containing coating.

[0002] Components made from fiber-reinforced plastics or thermoplastics typically have an uneven, rough surface. The embedded fibers stand upright on the surface, resulting in pores and voids that occur during the solidification of thermoplastics or the curing of a thermoset resin matrix. These surface defects are particularly undesirable in edge and visible areas.

[0003] Fiber-reinforced composite components are frequently used for the construction or lining of vehicle interiors. These components, used for the construction or lining of passenger vehicle interiors, are referred to as interior components. To enhance the interior design and appearance of the vehicle, the visible surfaces of these components are finished with a customized decor. This decor can include both colored patterns and three-dimensional surface textures.

[0004] Interior components typically require a multi-layer primer to achieve a smooth, paintable surface. The commonly used coating systems consist of two primer layers and two topcoat layers. This results in a high basis weight, which is particularly disadvantageous in vehicles where weight is a critical factor, such as aircraft. Another drawback of conventional coating systems is the lengthy application process, necessitated by the required flash-off and curing times for each layer. Furthermore, the primer layers must be sanded before applying the next layer to ensure a smooth surface. Therefore, the currently used methods are very labor-intensive and correspondingly expensive.

[0005] It is therefore an object of the present invention to provide improved coatings for plastic substrates, in particular for substrates made of thermoplastic materials and substrates made of fiber-reinforced plastic composites, which, with easier handling, form improved surfaces, in particular smoother surfaces. This object is achieved by coating materials according to the main claim, by their use in coating systems for priming according to the dependent claim, and by coating methods according to the dependent claim. Preferred embodiments are disclosed in the dependent claims and the description.

[0006] The problem underlying the invention is solved by a coating material for producing a barrier layer, comprising a hydroxy-functional binder component and an isocyanate-containing hardener component. The binder component contains a combination of hydroxy-functional aqueous polymer dispersions, glass particles, and inorganic fillers and / or inorganic pigments. During curing, the glass particles and fillers are surprisingly embedded in a densely cross-linked resin matrix without significant adverse effects. A stable coating with a very smooth surface is formed. A good result is achieved with the application of a single layer to the surface of a component. The coating materials according to the invention can therefore be used to build up primers.The primers obtained in this way can be directly coated with the desired decorative and topcoats without further post-treatment. At a dry film thickness of a maximum of 50 µm, the coatings according to the invention exhibit particularly high resistance to mechanical and chemical stresses.

[0007] According to the invention, the binder component contains hydroxy-functional polymer dispersions in water with a non-volatile content of 20 to 60 wt.% based on the total mass of the dispersion, preferably 30 to 50 wt.%, particularly preferably 35 to 45 wt.%. Suitable polymers are polyphenylene ethers or copolymers of fluorinated ethylene and vinyl ethers. Copolymers of fluorinated ethylene and vinyl ethers are preferred. The polymer dispersions according to the invention have a hydroxyl value of 60 to 100 mg KOH / g based on the polymer, preferably 70 to 90 mg KOH / g, particularly preferably 75 to 85 mg KOH / g. The polymer dispersion is used in proportions of 10 to 40 wt.% based on the total weight of the binder component, preferably in proportions of 15 to 35 wt.%, particularly preferably 20 to 30 wt.%.

[0008] In one embodiment of the invention, the coating materials have a pigment volume concentration of 40 to 80%, preferably 50 to 70%, and particularly preferably 55 to 65%. The pigment volume concentration is defined as the ratio of the total volume of all solid particles not involved in film formation to the total volume of the non-volatile components.

[0009] In a further embodiment of the invention, the binder component contains 10 to 30 vol%, preferably 15 to 25 vol%, and particularly preferably 16 to 20 vol% of hollow glass bodies based on the total volume of the binder component. Suitable hollow glass bodies are, for example, hollow glass spheres. Thin-walled, single-cell hollow glass spheres made of borosilicate glasses with a wall thickness of 0.65 to 0.80 µm, preferably 0.70 to 0.75 µm, are preferably used. Furthermore, the hollow glass spheres have an average particle size of 10 to 40 µm, preferably 13 to 32 µm, and particularly preferably 18 to 23 µm. They also have a nominal density of 0.4 to 0.5 g / m³, preferably about 0.46 g / m³. At a filling level of 5%, they exhibit an alkaline pH value in water in the range of 8 to 12, preferably from 9 to 11.

[0010] In a further embodiment of the present invention, the binder component contains 5 to 40 wt.%, preferably 10 to 30 wt.%, particularly preferably 15 to 25 wt.%, inorganic fillers and / or inorganic pigments based on the total weight of the binder component.

[0011] Suitable fillers include, for example, carbonates such as chalk, limestone flour, calcite, precipitated calcium carbonate, dolomite, and barium carbonate; sulfates such as barite, blanc fixe, and calcium sulfate; silicates such as talc, pyrophyllite, chlorite, hornblende, and mica; kaolin, wollastonite, slate flour, precipitated calcium silicates, precipitated aluminum silicates, precipitated calcium aluminum silicates, precipitated sodium aluminum silicates; feldspars; mullite; silicas such as quartz, quartzite, cristobalite, diatomaceous earth, silica, precipitated silica, and pyrogenic silica; pumice flour; perlite; calcium metasilicates; fibers from melts of glass or basalt; glass flour; and slags. Preferred fillers according to the invention are precipitated calcium carbonate, sulfates such as barite and blanc fixe, and silicates such as talc, pyrophyllite, chlorite, hornblende, and mica. Talc is particularly preferred.

[0012] Suitable pigments include all known and familiar inorganic pigments such as titanium dioxide, zinc sulfide, lithopone, basic lead carbonate, basic lead sulfate, basic lead silicate, zinc oxide, antimony oxide, iron oxide yellow, chrome yellow, cadmium yellow, nickel titanium yellow, chrome orange, molybda orange, cadmium orange, iron oxide red, cadmium red, copper oxide, molybda red, ultramarine red, mixed-phase red, mineral violet, manganese violet, ultramarine violet, iron blue, ultramarine blue, cobalt blue, chrome oxide green, chromium oxide hydrate green, ultramarine green, mixed-phase green pigments, iron oxide brown, mixed-phase brown, iron oxide black, antimony sulfide, graphite, gas soot, thermal soot, furnace soot, flame soot, or acetylene soot.Preferred pigments include titanium dioxide, zinc sulfide, lithopone, zinc oxide, antimony oxide, iron oxide yellow, nickel titanium yellow, molybda orange, iron oxide red, copper oxide, molybda red, ultramarine red, mixed-phase red, mineral violet, manganese violet, ultramarine violet, iron blue, ultramarine blue, cobalt blue, chromium oxide green, chromium oxide hydrate green, ultramarine green, mixed-phase green pigments, iron oxide brown, mixed-phase brown, iron oxide black, antimony sulfide, graphite, gas soot, thermal soot, furnace soot, flame soot, or acetylene soot.

[0013] In a preferred embodiment, the coating materials according to the invention additionally incorporate flame retardants. Passenger transport vehicles are generally subject to fire protection regulations, which the interior components used in the interior must comply with. The requirements regarding the flammability, smoke development, and toxicity of the substances released in the event of a fire are usually referred to as FST properties (Flammability, Smoke, Toxicity). Flame resistance is the property of materials, products, or components to withstand the effects of flames or ignition sources, or the ability to prevent the spread of fire by energetic, kinetic, chemical, or mechanical means.

[0014] In a preferred embodiment of the invention, the binder component contains 10 to 40 wt.%, preferably 15 to 35 wt.%, and particularly preferably 20 to 30 wt.%, flame retardants based on the total weight of the binder component. Suitable flame retardants are, for example, inorganic flame retardants, halogen-, nitrogen-, or boron-containing flame retardants, intumescent flame retardants, or mixtures thereof. Preferred flame retardants are hydroxides, oxide hydrates, and phosphates of Mg, Ca, Sr, Ba, Zn, and Al; ammonium polyphosphates; borates such as barium metaborate, calcium metaborate, sodium tetrafluoroborate, potassium tetrafluoroborate, zinc borates, and sodium tetraborate decahydrate; antimony oxides such as antimony trioxide and antimony pentoxide in combination with halogen-containing organic flame retardants such as decabromobiphenyl; red phosphorus; borax; and expandable graphite.Particularly preferred flame retardants are hydroxides, oxide hydrates and borates of Al, Mg and Zn, antimony pentoxide in combination with halogenated organic flame retardants such as decabromobiphenyl, as well as mixtures of two or more of the aforementioned flame retardants.

[0015] The hardener component of the coating material according to the invention contains one or more isocyanates. Suitable isocyanates are all isocyanates commonly used for hardening coating materials, such as diphenylmethane diisocyanate (MDI), as well as oligomers or polymers based on toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4'-diisocyanato-dicyclohexylmethane (HMDI), m-xylylene diisocyanate (XDI), 1,6-diisocyanatotrimethylhexane (TMDI), or tetramethylxylylene diisocyanate (TMXDI). Mixtures of the aforementioned isocyanates can also be used. Preferred hardeners are oligomers based on hexamethylene diisocyanate (HDI).

[0016] The binder component and the hardener component are used in a molar ratio of the OH groups of the binder to the NCO groups of the hardener in the range of 1 : 0.8 to 1 : 2.6, preferably from 1 : 1 to 1 : 2.2, particularly preferably 1 : 1.5 to 1 : 2.

[0017] Furthermore, the coating materials according to the invention can comprise the usual auxiliary materials and additives known to those skilled in the art, such as wetting agents, rheology additives, or adhesion promoters. The coating materials can contain up to 15 wt.% additives and auxiliary materials based on the total mass of the coating material.

[0018] The coating according to the invention is particularly suitable as a barrier layer in coating systems for priming plastics and fiber-reinforced plastic composites, preferably for priming glass- or carbon-fiber-reinforced plastics. Due to their manufacturing process, these substrates have particularly uneven, rough surfaces. Known coating materials must be applied in at least two layers to obtain a paintable surface. The coatings according to the invention exhibit very smooth surfaces even with a single-layer application and a dry film thickness of a maximum of 50 µm, onto which conventional decorative and topcoats can be applied. Because of their very smooth surface, they are also particularly suitable as a primer for high-gloss coatings.

[0019] Compared to previously used coating systems as primers, the coating systems according to the invention are significantly lighter. Furthermore, due to the reduced number of layers required, each of which must be applied and cured, the coatings according to the invention can also be produced with considerably shorter process times.

[0020] By adding flame retardants, coatings according to the invention, which are used as barrier layers in coating systems, exhibit fire behavior and FST properties that meet the fire protection requirements customary in aviation. Furthermore, the surfaces according to the invention exhibit high abrasion and scratch resistance as well as good cleanability. The coatings according to the invention are therefore preferably applied to the surfaces of interior components. Such components include, for example, hatchbacks, ceiling panels, storage cabinets, especially doors and side panels, partitions, cove light panels, doors and door frame trims, handrails, passenger service units (PSUs), and window panels.The coatings according to the invention are particularly preferred in coating systems for decorating interior components made of plastic fiber composites in monolithic or sandwich construction, as are commonly used for interior fittings in aircraft or railway carriages.

[0021] The problem underlying the present invention is also solved by a method for coating components made of plastics. Suitable plastics include, for example, thermoplastics such as polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyetherimide (PEI), or polytetrafluoroethene (PTFE). High-temperature thermoplastics are particularly suitable. Furthermore, the method is preferably used for coating components made of fiber-reinforced plastic composites.

[0022] In step a, the component is prepared by cleaning, drying, and then sanding the surface. In the following step b, a coating material according to the invention is applied and dried or cured. In the final step c of the process according to the invention, the usual decorative and topcoats are applied and dried.

[0023] The components to be coated must be free of release agents and other contaminants. They can be cleaned with cold cleaners such as isopropanol before the application of the first layer. In one embodiment of the inventive method, the components can be coated with a conductive primer before the first layer is applied. Components intended for electrostatic application (ESTA) processes, such as fiber-reinforced plastics and high-temperature-resistant thermoplastics, are particularly well-suited for this purpose. A conductive primer is defined as a coating that creates conductive surfaces, as required by electrostatic application processes.

[0024] In a preferred embodiment of the invention, the component surface is filled with putty before the primer is applied to compensate for larger surface defects. Components containing thermoplastic or thermoset plastics, in particular, often exhibit voids. These voids are cavities that occur during the solidification or curing of the plastic resins. These surface defects are undesirable in the edge and visible areas. To obtain a smooth surface, putty or filler is applied, cured, and then sanded smooth. According to the invention, preferably a coarse layer of putty is first applied, cured, and sanded. Then, a fine layer of putty is applied, cured, and sanded. The applied putties can be cured, for example, by convection drying or infrared drying.In convection drying, the applied layer of filler is first vented at room temperature for 5 to 40 minutes, preferably 20 to 35 minutes, particularly preferably about 30 minutes, and then cured at 50 to 70 °C, preferably at about 60 °C, for a period of 25 to 60 minutes, preferably about 30 minutes.

[0025] In step b, the coating material according to the invention is applied to the prepared surface to create a barrier layer and then cured. Suitable application methods include, for example, electrostatic application methods and pneumatic compressed air spraying methods. In electrostatic application methods, for example, a material pressure of 2.3 to 25 bar is used at 50 mA; in pneumatic application methods, for example, nozzles of 1.1 to 1.8 mm are used at an atomizing pressure of 3 to 4 bar. After curing, the coating obtained in step b is deburred, for example with 150-grit sandpaper.

[0026] The coating system obtained by the inventive method has a dry film thickness of 30 to 50 µm. This is significantly less than that obtained by conventional methods. In one embodiment of the inventive method, the coating materials described above, which contain additional inorganic flame retardants, are used. This results in fire-resistant coatings and components with a dry film thickness of 30 to 50 µm, which meet the FST requirements of the aerospace industry. Conventional fire-resistant coating systems used for coating interior components in the aerospace sector have dry film thicknesses between 100 and 200 µm. Unlike the coating systems according to the inventive method, they additionally contain at least two fire-resistant filler layers. Examples Example 1 Composition of a barrier layer according to the invention Binder component

[0027] Percentage by weight raw material 27,0 Aqueous polymer dispersion containing copolymers of fluorinated ethylene and vinyl ethers with 40 wt% non-volatile components and a hydroxyl value of 85 mg KOH / g based on the polymer 13,0 TiO2 (pigments) 26,5 Barium sulfate (filler) 3,8 Glass hollow spheres 7,2 Talc (filler) 7,5 Dispersing aids 0,5 Defoamer 1,0 Thickener 13,5 Water Hardener component

[0028] Percentage by weight raw material 80,0 aliphatic polyisocyanate based on HDI 15,0 Liability mediator 5,0 aromatic hydrocarbons Example 2 Composition of an FST barrier layer according to the invention Binder component

[0029] Percentage by weight raw material 27,0 Aqueous polymer dispersion containing copolymers of fluorinated ethylene and vinyl ethers with 40 wt% non-volatile components and a hydroxyl value of 85 mg KOH / g based on the polymer 13,0 TiO2 (pigments) 26,5 Al(OH) 3 (flame retardant) 3,8 Glass hollow spheres 7,2 Talc (filler) 7,5 Dispersing aids 0,5 Defoamer 1,0 Thickener 13,5 Water Hardener component

[0030] Percentage by weight raw material 80,0 aliphatic polyisocyanate based on HDI 15,0 Liability mediator 5,0 aromatic hydrocarbons

[0031] Specimens made from various substrates were coated with the inventive coatings and examined. Sandwich panels with a honeycomb core of phenol-resin-impregnated paper and facings of phenol-resin-impregnated glass fiber fabric were used as substrate A. Monolithic glass fiber laminates made from phenol-resin-impregnated glass fiber fabric were used as substrate B, and aluminum plates as substrate C. To prepare the specimens, the binder component and the hardener component were mixed in a molar ratio of 1:1.8 based on the amounts of OH groups of the binder and NCO groups of the hardener. The resulting mixture was applied to the surfaces of substrates A, B, and C by spray application. The applied layer was allowed to flash off for 15 minutes at room temperature and then cured for 30 minutes at 60 °C. The cured coatings exhibit dry film thicknesses of 40 to 45 µm.Specimens A1 and A2 are made of substrate A coated with the composition according to Examples 1 and 2. Specimens B1 and B2 are made of substrate B coated with the composition according to Examples 1 and 2. Specimens C1 and C2 are made of substrate C coated with the composition according to Examples 1 and 2.

[0032] The resistance to a 5% by weight solution of the cleaning agent Turco 5948-DPM (manufacturer: Henkel KG) in tap water and to isopropanol was tested. For this purpose, the test specimens were completely immersed in the cleaning agent solution or in isopropanol for 168 hours at 23°C. Afterwards, the test specimens were wiped clean and conditioned for 24 hours at 23°C and 50% relative humidity. Determination of scratch resistance:

[0033] In this test, a weighted scribing tool was placed with its tip on the coating to be tested and held vertically across the surface. The testers then visually assessed whether the coating showed any scratch marks. The maximum weight the scribing tool could bear without damaging the coating during the test is a measure of the coating's scratch resistance. Determination of adhesion (cross-cut test):

[0034] For a cross-cut test, six parallel cuts are made into the coating of the test specimens using a utility knife. The cuts into the coating are deep enough to reach the substrate surface without damaging it. Six more parallel cuts are then made perpendicular to the first, forming a uniform square or grid. The grid spacing is 1 mm. A strip of clear film or masking tape with an adhesive strength of 8 to 10 N / 25 mm is applied to the resulting square. This tape is then peeled off at an angle of 60° within 0.5 to 1 second. The grid or coating is then visually evaluated. A cross-cut test value of Gt 0 corresponds to very good adhesion, while a value of Gt 5 corresponds to very poor adhesion.

[0035] The results are summarized in the following tables. Liability

[0036] Sample body A1 B1 C1 A2 B2 C2 168 h at room temperature GT 0 GT 0 GT 0 GT 0 GT 0 GT 0 168 h at 60° C GT 0 GT 0 GT 0 GT 0 GT 0 GT 0 in Turco solution, 24 h at 23°C GT 0 GT 0 GT 0 GT 0 GT 0 GT 0 in isopropanol, 24 h at 23° C GT 0 GT 0 GT 0 GT 0 GT 0 GT 0 Scratch resistance

[0037] Coating after Example 1 Example 2 168 h at room temperature 3800 g 4000 g 168 h at 60° C 4000 g 4000 g in Turco solution, 24 h at 23°C 4100 g 4200 g in isopropanol, 24 h at 23° C 3500 g 3500 g

[0038] All test specimens show consistently good adhesion (Gt 0) of the coating to the substrate and high scratch resistance, which is not affected by thermal stress or exposure to chemicals.

[0039] Specimens coated with the coating according to Example 2 were additionally tested for their fire behavior. All fire behavior tests were carried out in accordance with the regulations of the Federal Aviation Administration of the United States of America (see Code of Federal Regulations 14 CFR Ch. I (1-1-92) Federal Aviation Administration, US Department of Transportation). Determination of flammability:

[0040] The flammability of the coatings was tested according to Pt. 25 App. F part. I paragraph 5. A horizontally arranged coated specimen was exposed to a gas burner for 60 seconds. The length of the coating burned (burn length) was then determined. Additionally, the time during which the coating continued to burn (afterburn time) or during which burning material dripped from the specimen after the gas burner was removed (after-drip time) was determined. Sandwich panels A2 and monolithic glass fiber laminate B2 were used as specimens for this test. Determination of the specific flue gas density:

[0041] The specific optical density of the flue gases produced during the combustion of the coating was determined according to Pt. 25 App. F part. V. Sandwich panels A2 were used as test specimens for this test. Determination of flue gas composition:

[0042] The composition of the flue gases produced during the combustion of the coatings was investigated for toxic components. For this purpose, the smoke generated during the aforementioned test of specific optical flue gas density was analyzed, and the concentrations of hydrogen cyanide (HCN), carbon monoxide (CO), nitrous oxide (NOx), sulfur dioxide (SO2), hydrogen chloride (HCl), and hydrogen fluoride (HF) in the flue gas were determined. Sandwich panels A2 were used as test specimens for this test. Determination of heat release:

[0043] The heat release was determined according to Pt. 25 App. F part. IV. The total heat release occurring during the burning of the coating, as well as the maximum heat output, were measured. Sandwich panels A2 and aluminum plates C2 were used as test specimens for this test.

[0044] The results are summarized in the following tables. Flammability

[0045] Test specimen A2 B2 Burn length [mm] 47 25 Afterburn time [s] 3 0 Drop time [s] 0 0 Specific flue gas density and flue gas composition

[0046] Test specimen A2 specific flue gas density 15 c(HCN) in [ppm] 2,5 c(CO) in [ppm] 80 c(NO x ) in [ppm] 7 c(SO 2 ) in [ppm] 4 c(HF) in [ppm] 0 c(HCl) in [ppm] 0 Heat release

[0047] Test specimen A2 C2 Total heat release in [kW / m 2< ] 29 8 Maximum heating output in [kW min / m²< ] 30 5

Claims

1. A coating material for producing a barrier layer on plastic substrates comprising a hydroxy-functional binder component and an isocyanate-containing hardener component, characterised in that the binder component contains - aqueous polymer dispersions comprising polyphenylene ethers or copolymers of fluorinated ethylenes and vinyl ethers, - glass hollow bodies as well as - inorganic fillers and / or inorganic pigments.

2. A coating material according to claim 1, characterised in that the binder component has a pigment volume concentration of 40 to 80%, preferably from 50 to 70%, particularly preferably 55 to 65%.

3. A coating material according to claim 1 or 2, characterised in that the binder component contains the polymer dispersion in proportions of 10 to 40 wt .-%, preferably 15 to 35 wt .-%, particularly preferably 20 to 30 wt .-%, based on the total weight the binder component.

4. A coating material according to one of the preceding claims, characterised in that the polymer dispersion contains copolymers of fluorinated ethylene and vinyl ethers.

5. A coating material according to one of the preceding claims, characterised in that the binder component has 10 to 30 vol.-%, preferably 15 to 25 vol.-%, particularly preferably 16 to 20 vol .-% glass hollow body based on the total volume of the binder component.

6. A coating material according to one of the preceding claims, characterised in that the binder component contains 5 to 40 wt.-% of inorganic fillers and / or inorganic pigments based on the total weight of the binder component.

7. A coating material according to claim 6, characterised in that the fillers are selected from the group comprising precipitated calcium carbonate, barite, blanc fixe, talc, pyrophyllite, chlorite, hornblende and mica.

8. A coating material according to claim 6, characterised in that the pigments are selected from the group consisting of titanium dioxide, zinc sulfide, lithopone, zinc oxide, antimony oxide, iron oxide yellow, nickel titanium yellow, molybdate orange, iron oxide red, copper oxide, molybdate red, ultramarine red, mixed phase red, mineral violet, manganese violet, ultramarine violet, iron blue, ultramarine blue, cobalt blue, chrome oxide green, chromium oxide hydrate green, ultramarine green, mixed phase green pigments, iron oxide brown, mixed phase brown, iron oxide black, antimony sulfide, graphite, gas black, thermal black, furnace black, flame black and acetylene black.

9. A coating material according to one of the preceding claims, characterised in that the binder component further contains flame retardants, wherein the flame retardants are selected from the group consisting of hydroxides, oxide hydrates and phosphates of Mg, Ca, Sr, Ba, Zn and Al, ammonium polyphoshate, borates, antimony oxides in combination with halogen-containing organic flame retardants, red phosphorus, borax and expandable graphite.

10. A coating material according to one of the preceding claims, characterised in that the hardener component comprises polyisocyanates selected from the group comprising diphenylmethane diisocyanate MDI as well as oligomers or polymers based on tolylene diisocyanate TDI, diphenylmethane diisocyanate MDI, hexamethylene diisocyanate HDI, isophorone diisocyanate IPDI, 4,4'- Diisocyanato-dicyclohexylmethane HMDI, m-xylylene diisocyanate XDI, 1,6-diisocyanatotrimethylhexane TMDI, tetramethylxylylene diisocyanate TMXDI and mixtures thereof.

11. A coating material according to one of the preceding claims, characterised in that the coating material binder component and hardener component in a molar ratio of OH groups of the binder to NCO groups of the curing agent in the range of 1:0.8 to 1:2.6.

12. The use of the coating material according to one of claims 1 to 11 in a coating system for priming the surfaces of plastic substrates or substrates made of fibre-plastic composite materials.

13. A method for producing a coating system on a component made of plastics or fibre-plastic composite materials comprising the steps: a preparing the surface, b applying and curing a coating material according to one of claims 1 to 11 and c varnishing.

14. A method according to claim 13, characterised in that the coating material is applied in step b by means of electrostatic application method or pneumatic compressed air spraying process.

15. An interior component made of plastic or fibre-plastic composite material having at least one coating produced from a coating material according to one of claims 1 to 11.