WO2005053861A1 - Thermosetting, transparent coating lacquers, method for the production thereof, and use thereof - Google Patents

Abstract

Disclosed are thermosetting, transparent coating lacquers which have a layer thickness of 5 to 100 µm and contain 0.1 to 10 percent by weight of olefinically unsaturated double bonds (>C=C<; Mn = 24 Dalton), the percentage being in relation to the coating lacquer. Also disclosed are methods for the production thereof by (1) applying a thermosetting coating material that can also be hardened by means of actinic radiation and contains 1 to 50 percent by weight of at least one compound (A) comprising at least one olefinically unsaturated double bond to a substrate, the percentage being in relation to the non-volatile matter of the coating material, and (2) thermosetting the obtained coating lacquer layer. The invention further relates to the use of said coating lacquers.

Description

Thermally hardened, transparent topcoat, production process and its use

The present invention relates to a new, thermally hardened, transparent topcoat. The present invention also relates to a new process for producing a thermally hardened, transparent topcoat. Furthermore, the present invention relates to the use of the new, thermally cured, transparent topcoat and the thermally cured, transparent topcoat produced by the new process as a clearcoat for coated and uncoated substrates, in particular as a constituent of color and / or effect multicoat paint systems.

Thermally hardened, transparent top coats, in particular clear coats, are known to serve for the protective and / or decorative coating of coated and uncoated substrates of all kinds. In particular, the clear coats are a component of coloring and / or effect-giving multi-layer coats of the kind used for high-quality painting of cars. These multi-layer coatings must have the so-called automotive quality (cf. European Patent EP 0 352 298 B1, page 15, line 42 to page 17, line 40), i. that is

1) a high gloss, 2) a high level of image differentiation, 3) a high and uniform hiding power, 4) a uniform dry film thickness, 5) a high gasoline resistance, 6) a high solvent resistance, 7) a high acid resistance, 8) high hardness, 9) high abrasion resistance, 10) high scratch resistance, 11) high impact resistance, 12) high interlayer adhesion and adhesion to the substrate and 13) high weather stability and UV resistance

need to have. Other essential technological properties are (14) high resistance to condensation, (15) no tendency to tarnish, and (16) high stability to tree resin and bird droppings. The clear coats in particular shape such essential technological properties as

(1) gloss,

(2) distinctiveness of the reflected image (DOI), (5) petrol resistance,

(6) solvent resistance,

(7) acid resistance,

(8) hardness,

(9) abrasion resistance, (10) scratch resistance,

(13) weather stability and UV resistance,

(14) resistance to condensation,

(15) White Tarnish Resistance and

(16) Stability to tree sap and bird droppings.

The quality of the clear coats is particularly high.

Weather stability and UV resistance are a particular problem. These essential technological properties need a long time

Time, especially several years, ideally for the entire life of a

Cars, be guaranteed. Whether clearcoats these particularly demanding

Conditions will meet long-term weathering tests that span multiple

Years can be tested. A particularly tough test of this kind is the weathering of clearcoats in Florida, USA. Only clear coats that

Surviving Florida weathering without damage can be considered for application in the field of painting cars (see also A. Goldschmidt and H.-J. Streitberger, BASF Handbuch Lackiertechnik, Vincentz Verlag, Hanover,

2002, 3.3.2 Aging tests, 3.3.2.1 Test methods for surface resistance, pages 429 to 439). The weather stability and UV resistance of clearcoats can be improved by adding light stabilizers such as UV stabilizers and reversible radical scavengers (HALS). However, the light stabilizers cannot be added in any amount because this can damage other essential technological properties of the clearcoats.

The object of the present invention is to provide a new, thermally hardened, transparent topcoat, in particular a clearcoat, which no longer has the disadvantages of the prior art, but rather, in particular as a component of color and / or effect multicoat paint systems, as used for the high-quality painting of cars is used, the required automotive quality (cf. European Patent EP 0352298 B1, page 15, line 42 to page 17, line 40) and

1) high gloss, 2) high image differentiation, 3) high and uniform hiding power, 4) uniform dry film thickness, 5) high gasoline resistance, 6) high solvent resistance, 7) high acid resistance, 8) high hardness, 9) high abrasion resistance, 10) high scratch resistance, 11) high impact resistance, 12) high interlayer adhesion and adhesion to the substrate, 13) high weather stability and UV resistance 14) high resistance to condensation water, 15) no tendency for tarnishing and 16) high stability against tree resin and bird droppings

Has. In particular, the new, thermally hardened, transparent topcoat, especially the clearcoat, should be weather-resistant and UV-resistant for a long time, preferably for several years, ideally for the life of a car.

The new, thermally hardened, transparent top coat, especially the clear coat, should be easily reproducible. The clearcoats from which these clearcoats are produced should also be able to be produced in a simple and reproducible manner. Last but not least, they must also be able to be applied in-line at the automobile manufacturer with the help of modern application methods in dry layer thicknesses of 45 μm and more without the formation of surface defects such as specks, pinholes, runners or cookers.

Accordingly, the new, thermally hardened, transparent topcoat with a layer thickness of 5 to 100 μm was found, which, based on the topcoat, contained 0.1 to 10% by weight of olefinically unsaturated double bonds (> C = C <; Mn = 24 Dalton) contains and which is referred to below as "top coat according to the invention".

In addition, the new process for producing a thermally hardened, transparent topcoat was found, in which the topcoat was finished by

(1) Application of a coating material curable thermally and with actinic radiation, containing, based on the solids content of the coating material, 1 to 50% by weight of at least one compound (A) with at least one olefinically unsaturated double bond, on a substrate and

(2) thermal curing of the resulting topcoat layer

is produced and is referred to below as the "inventive method".

Further subjects of the invention are evident from the description.

In view of the prior art, it was surprising and unforeseeable for the person skilled in the art that the object on which the present invention was based could be achieved with the aid of the topcoat according to the invention and the method according to the invention.

In particular, it was surprising that the topcoat according to the invention, in particular the clearcoat according to the invention, which has the disadvantages of the prior art

Technology no longer had, but in particular as a component of color and / or effect multi-layer coatings, such as those for high quality Painting of cars can be used, could be used with advantage. The topcoat according to the invention, in particular the clearcoat according to the invention, had the required automotive quality (cf. European Patent EP 0 352298 B1, page 15, line 42 to page 17, line 40) and showed

(1) high gloss, (2) high image differentiability, (3) high and uniform hiding power, (4) uniform dry film thickness, (5) high gasoline resistance,

(6) high solvent resistance,

(7) high acid resistance,

(8) high hardness,

(9) high abrasion resistance, (10) high scratch resistance,

(11) high impact resistance,

(12) high interlayer adhesion and adhesion to the substrate,

(13) high weather stability and UV resistance

(14) high resistance to condensation water, (15) no tendency to tarnish and

(16) high stability against tree resin and bird droppings.

In particular, the topcoat according to the invention, especially the clearcoat according to the invention, was weather-resistant and UV-resistant for many years, in many cases for the life of a car.

The topcoat according to the invention, especially the clearcoat according to the invention, could be produced very reproducibly in a particularly simple manner using the method according to the invention. It was possible to use known clearcoats, which could also be produced in a simple and reproducible manner. In particular, these clear coats could be applied in line with the automobile manufacturer with the help of modern application methods in dry layer thicknesses of 45 μm and more without the formation of surface defects such as specks, pinholes, runners or cookers.

The top coating according to the invention has a layer thickness of 5 to 100 μm, preferably 10 to 80 μm, in particular 20 to 70 μm. Based on their total amount, it contains 0.1 to 10% by weight, preferably 0.5 to 8% by weight and in particular 0.5 to 5% by weight of olefinically unsaturated double bonds (> C = C <; Mn = 24 daltons).

The olefinically unsaturated double bonds can preferably be activated with actinic radiation. Here and below, actinic radiation includes electromagnetic radiation, such as near infrared (NIR), visible light, UV radiation, X-rays and gamma radiation, in particular UV radiation, and corpuscular radiation, such as electron radiation, beta radiation, alpha radiation, neutron radiation or proton radiation, in particular electron radiation , Roger that. After activation with actinic radiation, the activated olefinically unsaturated double bonds can undergo polyaddition reactions with one another which proceed according to ionic or radical, in particular radical, mechanisms.

The olefinically unsaturated double bonds can be present in different organic groups. Examples of suitable organic groups are (meth) acrylate, ethacrylate, crotonate, cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, allyl or butenyl groups; Dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, allyl or butenyl ether groups or dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, allyl or butenyl ester groups, but especially acrylate groups.

The organic groups containing the olefinically unsaturated double bonds can be directly, i.e. H. be connected to the three-dimensional network of the top coat according to the invention via ionic and / or covalent bonds, preferably covalent bonds. However, they can also exist in connections that are embedded in the three-dimensional network without being directly connected to it.

The topcoat according to the invention preferably contains, based on its total amount, 0.05 to 5% by weight, preferably 0.1 to 4% by weight and in particular 0.1 to 3% by weight of at least one photoinitiator, preferably at least two photoinitiators. Examples of common and known photoinitiators are known from Römpp Online, Georg Thieme Verlag, Stuttgart, New York, 2002, "Photoinitiators".

The topcoat according to the invention is preferably produced from a coating material which is curable thermally and with actinic radiation (hereinafter referred to as “dual-cure coating material”) by thermal curing.

The usual and known dual-cure coating materials can be used, such as one- or two- or multi-component clearcoats, selected from the group consisting of conventional, organic solvents containing clearcoats, aqueous clearcoats which contain little or no organic solvents, essentially or completely solvent-free and water-free liquid clear lacquers (100% systems), essentially or completely solvent-free and water-free, solid, finely divided powders (powder clearcoats) or essentially or completely solvent-free powder clearcoat suspensions (powder slurries), as described, for example, in German patent applications DE 19800528 A1, DE 198 18 735 A1, DE 199 08018 A1, DE 19947523 A1, DE 10027290 A1, DE 10027292 A1, DE 100 42 152 A1 or DE 101 15 605 A1, the international patent applications WO 98/40170 A1 or WO 03/016411 A1, the European patent applications EP 0 952 170 A1 or EP 0 928 800 A. 1 or the American patents US 4,342,793 A or US 5,234,970 A are known. Aqueous clearcoats, in particular powder slurries, are particularly preferably used.

The dual-cure coating material preferably contains, based on its solids, 1 to 50% by weight, preferably 2 to 40% by weight and in particular 3 to 30% by weight of at least one compound (A) with at least one organic group containing at least one, especially one, olefinically unsaturated double bond. Compound (A) preferably contains at least two groups with at least one, in particular one, olefinically unsaturated double bond. Examples of suitable organic groups with olefinically unsaturated double bonds are those described above.

Here and in the following, “solids of the coating material” is understood to mean the sum of all the constituents of the coating material that build up the top coat according to the invention. The compounds (A) are preferably selected from the group consisting of low molecular weight, oligomeric and polymeric compounds which contain at least one organic group with at least one olefinically unsaturated double bond.

Examples of suitable low molecular weight, oligomeric and / or compounds (A) are found in Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, "Reaktivverdünner" pages 491 and 492, in German patent application DE 199 08 013 A1, Column 6, line 63, to column 8, line 65, in German patent application DE 199 08 018 A1, page 11, lines 31 to 33, in German patent application DE 198 18 735 A1, column 7, lines 1 to 35 , German patent application DE 100 27290 A1, page 9, paragraph [0063], German patent DE 197 09 467 C1, page 4, line 36, to page 5, line 56, or European patent application EP 0 650 979 A 1 or described. Pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate and / or aliphatic urethane acrylates with six acrylate groups in the molecule are preferably used.

The compounds (A) may also contain at least one, in particular at least two, group (s) (a1) which are associated with a group (a1) of their own type ("with themselves) and / or with a complementary reactive functional group (b1 ) can initiate thermally initiated reactions Examples of suitable groups (a1) and (b1) can be found in German patent application DE 100 27 290 A1, page 4, paragraph [0039], to page 7, paragraph [0043], The group (a1) is preferably an isocyanate group.

Examples of suitable compounds (A) of this type are described in European patent application EP 0 928 800 A1, page 3, lines 17 to 54 and page 4, lines 41 to 54, or in German patent application DE 198 18735 A1, column 3 , Line 16, to column 6, line 33. Isocyanatoacrylates which can be prepared from polyisocyanates and hydroxyl-containing, olefinically unsaturated monomers are preferably used. For use in one-component systems, the isocyanate groups of the isocyanatoacrylates are blocked with customary and known blocking agents. The blocked and unblocked isocyanatoacrylates are commercially available compounds and are sold by Bayer AG under the Roskydal ® brand. The dual-cure coating material preferably contains at least one, in particular at least two, of the photoinitiators (B) described above, preferably in an amount of 0.05 to 5% by weight, preferably 0.1 to 4% by weight and in particular 0 , 1 to 3 wt .-%, each based on the solids of the coating material.

The dual-cure coating material preferably contains at least one oligomeric and / or polymeric, physically or thermally, in particular thermally, curable binder (C). The thermally curable binder (C) preferably contains at least one, in particular at least two, of the reactive functional groups (b1) described above, particularly preferably at least two isocyanate-reactive functional groups (b1), very particularly preferably at least two hydroxyl groups, thiol groups and / or primary and / or secondary amino groups (b1), in particular at least two hydroxyl groups (b1). It can also contain at least one, preferably at least two, of the organic groups described above with at least one olefinically unsaturated double bond. Examples of suitable thermally curable binders (C) are known from German patent application DE 10027290 A1, page 4, paragraph [0035], to page 8, paragraph [0050]. The binders (C) in the dual-cure coating material are preferably in an amount of 10 to 80% by weight, preferably 20 to 70% by weight and in particular 20 to 60% by weight, in each case based on the solid of the coating material.

The dual-cure coating material preferably also contains at least one, in particular one, customary and known, thermally curable crosslinking agent (D). The thermally curable crosslinking agent (D) preferably contains at least two of the reactive functional groups (a1) described above, in particular at least two blocked or unblocked isocyanate groups (a1). Examples of suitable crosslinking agents (D) are known from German patent application DE 10027 290 A1, pages 9 to 10, paragraph [0070]. The crosslinking agents (D) in the dual-cure coating material are preferably in an amount of 5 to 70% by weight, preferably 10 to 60% by weight, in particular 20 to 50% by weight, in each case based on the solids content of the coating material , contain.

The dual-cure coating material preferably also contains at least one functional additive (E), in particular at least two functional additives (E). The functional additive (E) is or are particularly preferred Additives (E) from the group consisting of coloring, optically effecting, fluorescent, phosphorescent, electrically conductive, magnetically shielding, corrosion-inhibiting, optionally nano-scale, transparent pigments; molecularly dispersible dyes; Light stabilizers, UV absorbers, reversible radical scavengers (HALS); antioxidants; Wetting agents; emulsifiers; slip additives; polymerization inhibitors; Thermal crosslinking catalysts; thermolabile free radical initiators; photocoinitiators; Adhesion promoters; Leveling agents; film-forming aids; Rheology aids and rheology control additives (thickeners and pseudoplastic Sag control agents, SCA); Flame retardants; Corrosion inhibitors; To grow; driers; biocides; flatting agents; degassing; organic solvents and water; selected. Examples of suitable additives (E) are known from German patent application DE 10027290 A1, pages 10 to 11, paragraph [0073].

The production of the dual-cure coating material has no special features in terms of method, but can be achieved by mixing the above-described components (A) to (E) and homogenizing the resulting mixture using customary and known processes in suitable mixing units, such as stirred kettles, dissolvers and inlines -Dissolver, agitator mills, microfluidizer or extruder.

The dual-cure coating material is used to produce the top coat of the invention. The method according to the invention is preferably used here.

The dual-cure coating material is particularly excellent for painting bodies of all kinds of means of transportation (in particular means of transportation powered by muscle power, such as bicycles, carriages or trolleys, aircraft, such as airplanes or zeppelins, floating bodies, such as ships or buoys, rail vehicles and motor vehicles, such as motorcycles, buses, trucks or cars) or parts thereof; of buildings indoors and outdoors; of furniture, windows and doors; of small industrial parts, of coils, containers and packaging; of white goods; of foils; of optical, electrotechnical and mechanical components as well as of glass hollow bodies and objects of daily use. The dual-cure coating material is preferably used as a clear lacquer. In particular, it is suitable for the production of clear coats in the context of color and / or effect multi-coat coatings, in particular using the wet-on-wet process, as is described, for example, in German patent application DE 10027 292 A1, page 13, paragraph [0109]. until page 14, paragraph [0118].

Depending on its physical state (liquid or powder), it can be applied to the substrates in question using customary and known application methods, as described, for example, in German patent application DE 10027292 A1, page 14, paragraphs [0121] to [0126], is described.

The thermal curing of the applied dual-cure coating material likewise has no special features in terms of method, but is instead carried out with the aid of customary known methods and devices, as described, for example, in German patent application DE 100 27 292 A1, page 15, paragraph [0130] and [0131].

Thermal curing can be supplemented to a minor extent by curing with actinic radiation, as described, for example, in German patent application DE 100 27 292 A., 1, page 15, paragraphs [0132] to [0134]. However, preferably no additional curing with actinic radiation is carried out.

In the method according to the invention, the curing, in particular the thermal curing, is preferably carried out in such a way that only a maximum of 70%, preferably a maximum of 60%, particularly preferably a maximum of 50% and in particular a maximum of 40% of the olefinic originally present in the dual-cure coating material unsaturated double bonds are implemented so that the topcoat according to the invention preferably contains at least 30%, preferably at least 40%, particularly preferably at least 50% and in particular at least 60% of the olefinically unsaturated double bonds originally present in the dual-cure coating material after its production.

The top coat according to the invention has the automotive quality described above. In particular, the topcoat of the invention, especially the clearcoat of the invention, is for several years, in many cases for Lifespan of a car, weather-resistant and UV-resistant, which is clear from the Florida weather.

Examples 1 to 6 and comparative experiments V1 to V3

The production of color and / or effect multi-layer coatings with clear coats I and II

Two dual-cure coating materials I and II were first prepared by mixing the constituents listed in Table 1 in the order given, homogenizing the resulting mixtures and distilling off the organic solvent present (methyl ethyl ketone, MEK).

Table 1: The material composition of the dual-cure coating materials (clear coats) I and II

Ingredient parts by weight in the clear coat: I

Methacrylate copolymer (C) (acid number: 34.4 mg KOH / g; hydroxyl number: 150 mg KOH / g; glass transition temperature: 12.7 ° C; solids content: 57.6% by weight in

Methyl ethyl ketone, MEK): 173.61 173.61

Crosslinking agent (D) (isocyanurate based on hexamethylene diisocyanate blocked with dimethylpyrazole; isocyanate equivalent weight: 283 g / mol; solids content: 79.3% by weight in MEK): 80.02 80.02

Dimethylethanolamine (E): 2.31 2.85

Commercial isocyanatoacrylates (A) blocked with dimethylpyrazole Bayer AG: Roskydal ® UA LP FWO 3705-13 (double bond content: 5.31 equ./kg; isocyanate equivalent weight: 1,448 g / mol; solids content: 80% by weight in MEK) 62.5 Roskydal ® UA LP FWO 3705-14

(Double bond content: 5.52 equ./kg; isocyanate equivalent weight: 1,500 g / mol;

Solids content: 80% by weight in MEK) - 62.5

Photoinitiators (B):

Irgafos © 184 (commercially available photoinitiator from Ciba Specialty Chemicals) and

Lucirin © TPO (commercially available photoinitiator from BASF Aktiengesellschaft) in a weight ratio of 5: 1: 2 2

Commercial light stabilizers (E) from Ciba Specialty Chemicals: Tinuvin® 123: 1, 63 1, 63 Tinuvin® 400: 1, 63 1, 63

Deionized Water (E): 388.7 390.39

Commercial leveling agent (E) from the company

Bayer AG Baysilone® AI3468: 0.3 0.31

Commercial thickener (E) Acrysol® RM 8W: 6.1 6.1

Degree of neutralization: 45% 45%

Solids content (60 minutes / 125 ° C): 36.7 37.4

The clear varnish I was used for Examples 1, 3 and 5 and for the comparative experiments V1 to V3.

Clearcoat II was used for Examples 2, 4 and 6. The clear coats I and II were applied pneumatically with flow cup guns to steel sheets, which - in the order given above - were pre-coated with an electro-dip coating, a filler coating and a water-based coating.

A silver metallic basecoat was used in Examples 1 and 2 and Comparative Experiment V1.

A black basecoat was used in Examples 3 and 4 and Comparative Experiment V2.

A white basecoat was used in Examples 5 and 6 and Comparative Experiment V3.

The wet layer thickness of the applied clearcoat layers I and II was chosen such that the cured clearcoats I and II had a dry layer thickness of 50 μm.

The applied clear lacquer layers I and II were predried in Examples 1 to 6 for 5 minutes at 60 ° C. and thermally cured for 30 minutes at 150 ° C. For the thermal hardening, convection ovens from Heraeus were used.

In the comparative experiments V1 to V3, the applied clearcoat films I were predried for 5 minutes at 60 ° C., thermally cured for 15 minutes at 150 ° C., irradiated with UV radiation at a dose of 1.5 mJ / cm ² and for 15 minutes at 150 ° C thermally hardened again.

The resulting clearcoats I and II of Examples 1 to 6 and Comparative Experiments V1 to V3 were high-gloss, highly scratch-resistant, chemical-stable and free from surface defects.

Their double bond content was determined using confocal Raman spectroscopy (Raman spectrometer LABRAM from Jobin-Yvon: HeNe-Laser: 5 mW @ 632.8 nm; microscope objective: 100x, corresponding to approximately 1 μm ² lateral resolution; confocal

Pinhole: 200 μm, corresponding to approximately 1.5 μm axial resolution; Grid: 1,800 l / mm, corresponding to 2.5 crrr ¹ spectral resolution; Measuring time single spectrum: 180 s) determined. The spectra were smoothed, baseline corrected and normalized to the isocyanurate band at 1760 cncr ¹ . The band of the double bonds at about 1,635 cm ^{1 was} evaluated: while in the clearcoats of Examples 1 to 6 there were still 50% of the double bonds originally present, in the clearcoats I of the comparative tests V1 to V3 more than 90% of the originally present double bonds were converted ,

The gloss (20 °) of clearcoats I and II in Examples 1 to 6 and Comparative Experiments V1 to V3 was measured immediately after they were produced.

The test panels were then subjected to Florida weathering for one year.

The test panels were then washed and the gloss of the

Clearcoats I and II of Examples 1 to 6 and clearcoats I of

Comparative tests V1 to V3 measured again. The results can be found in Table 2. They underline that the clearcoats of the invention

Examples 1 to 6 were particularly weather-stable and significantly less

Loss of gloss than the clearcoats of Examples V1 to V3 not according to the invention suffered. Surprisingly, the Florida weathering even improved the scratch resistance of the clearcoats of Examples 1 to 6 compared to the scratch resistance of the corresponding non-weathered clearcoats.

Table 2: The gloss (20 °) of clearcoats I and II of examples 1 to 6 and clearcoats I of comparative tests V1 to V3 before and after Florida weathering

Example / gloss:

Comparison test AAnnffaannggggllaannzz EEnnddwweerrtt DDiiffferenz

1 87 80 7 2 86 80 6 V1 91 76 24

3 82 62 20 4 81 67 14 V2 86 55 31 5 84 79 5

6 82 76 6

V3 87 71 16

Claims

claims 1. Thermally hardened, transparent topcoat with a layer thickness of 5 to 100 μm, containing, based on the topcoat, 0.1 to 10% by weight of olefinically unsaturated double bonds (> C = C <; Mn = 24 Dalton). 2. Top coat according to claim 1, characterized in that the olefinically unsaturated double bonds can be activated with actinic radiation. 3. Top coat according to claim 1 or 2, characterized in that it contains, based on the top coat, 0.05 to 5 wt .-% of at least one photoinitiator. 4. Top coat according to one of claims 1 to 3, characterized in that it consists of a thermally and with actinic radiation coating material containing, based on the solids of the coating material, 1 to 50 wt .-% of at least one compound (A) with at least an organic group containing at least one olefinically unsaturated double bond, can be produced by thermal curing. 5. Top coat according to one of claims 1 to 4, characterized in that the coating material, based on its solid, contains 0.5 to 5 wt .-% of at least one photoinitiator (B). 6. Top coat according to claim 4 or 5, characterized in that max. 70% of the olefinically unsaturated double bonds originally present in the coating material have been converted during thermal curing. 7. Top coat according to claim 6, characterized in that max. 60% of the olefinically unsaturated double bonds have been converted. 8. Top coat according to claim 7, characterized in that max. 50% of the olefinically unsaturated double bonds have been converted. Top coat according to claim 8, characterized in that a maximum of 40% of the olefinically unsaturated double bonds have been converted. 10. A method for producing a thermally cured, transparent topcoat according to one of claims 1 to 9, characterized in that it (1) Application of a coating material curable thermally and with actinic radiation, containing, based on the solids content of the coating material, 1 to 50% by weight of at least one compound (A) with at least one olefinically unsaturated double bond, on a substrate and (2) thermal curing of the resulting top coat layer is produced. 11. The method according to claim 10, characterized in that the compound (A) contains at least two organic groups with at least one olefinically unsaturated double bond. 12. The method according to claim 10 or 11, characterized in that the compound (A) from the group consisting of low molecular weight, oligomeric and polymeric compounds which contain at least one organic group with at least one olefinically unsaturated double bond are selected. 13. The method according to any one of claims 10 to 12, characterized in that the compound (A) at least one reactive functional group (a1) with a group of its own kind ("with itself") and / or with a complementary reactive functional group (b1) can initiate thermally initiated reactions. 14. The method according to claim 13, characterized in that the group (a1) is an isocyanate group. 15. The method according to any one of claims 10 to 14, characterized in that the coating material contains at least one photoinitiator (B). 16. The method according to any one of claims 10 to 15, characterized in that the coating material contains at least one oligomeric and / or polymeric, physically or thermally curable binder (C). 17. The method according to claim 16, characterized in that the thermally curable binder (C) contains at least one reactive functional group (b1). 18. The method according to any one of claims 10 to 17, characterized in that the coating material contains at least one thermally curable crosslinking agent (D). 19. The method according to claim 18, characterized in that the thermally curable crosslinking agent (D) contains at least one reactive functional group (a1). 20. The method according to any one of claims 10 to 19, characterized in that the coating material contains at least one functional additive (E). 21. The method according to claim 19, characterized in that the functional additive from the group consisting of coloring, optically effecting, fluorescent, phosphorescent, electrically conductive, magnetically shielding, corrosion-inhibiting, optionally nanoscale transparent pigments; molecularly dispersible dyes; Light stabilizers, UV absorbers, reversible radical scavengers (HALS); antioxidants; Wetting agents; emulsifiers; slip additives; polymerization inhibitors; Thermal crosslinking catalysts; thermolabile free radical initiators; photocoinitiators; Adhesion promoters; Leveling agents; film-forming aids; Rheology aids and rheology control additives (thickeners and pseudoplastic Sag control agents, SCA); Flame retardants; Corrosion inhibitors; To grow; driers; biocides; flatting agents; degassing; organic solvents and water; to be selected. 22. Use of the thermally cured, transparent topcoat according to one of claims 1 to 9 and of the thermally cured, transparent produced by the method according to one of claims 10 to 21 Top coat as clear coat for coated and uncoated substrates. 23. Use according to claim 22, characterized in that the clearcoat is part of a color and / or effect multi-layer coating.