paint that are applied one over the other and have different properties. For example, an electrodeposition layer primer (electrocoating), a primer-smoothing layer or stone chip primer, a basecoat and a clearcoat are successively applied to a substrate. In this system the electrocoating serves in particular to protect the sheet metal against corrosion. For those experts in the field, it is often called as the primer. The primer-surfacer coating layer serves to cover the lack of uniformity in the substrate and due to its elasticity imparts resistance to the stone chips. The coating of primer-smoothing can also serve to reinforce the power of hidden and deepen the tone of the paint system. The base coat contributes to the effects of colors and / or optics. The transparent coating is used to intensify the optical effects, and to protect the paint system against mechanical and chemical damage. The basecoat and the clearcoat are also often collectively called the topcoat. For further details refer to Ropp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, pages 49 and 51, "Automotive Finishes". In the text below these multi-layer paint systems or coatings are called as multi-layer color system and / or effect paint. More recently, transparent coatings in particular have been produced from transparent coating materials that are thermally curable and with actinic radiation. Actinic radiation, down and down, means electromagnetic radiation, such as near-infrared radiation, visible light, UV radiation or X-ray or gamma radiation, especially UV radiation, and corpuscular radiation, such as electronic beams, proton beams, alpha radiation, beta radiation or neutron beams, especially electronic beams. The combined curing by means of heat and actinic radiation is also referred to by those skilled in the art as double curing. Double-cured coating materials, especially double-curing clearcoat materials, have the key advantage that, even in shaded areas of three-dimensional substrates, such as car bodies, radiators or electrically wound articles, and still in the absence of optimal exposure - in particular, complete - of the shadow areas to actinic radiation, they provide coatings whose profile of operating properties approach that of the coatings outside the shadow areas. As a result, the coatings in the shadow areas are no longer easily damaged by mechanical and / or chemical attack, as can occur, for example, on the production line during the installation of additional motor vehicle components towards the coated bodies. . In addition, curing with actinic radiation can compensate for incomplete thermal curing, if, for example, double curing coating materials can not be heated to the temperatures required for rapid progression of thermal crosslinking reactions, due to temperature sensitivity. of the coated substrates. Double curing coating materials and their use for producing multi-layer color systems and / or high quality effect paint are known, for example, from patent applications DE 42 15 070 A 1, DE
198 18 735 A 1, DE 199 08 018 A 1, DE 199 30 665 A 1, DE
199 30 067 A 1, DE 199 30 664 A 1, DE 199 24 674 A 1, DE "199 20 799 A1, DE 199 58 726 A1, DE 199 61 926 A1, DE 100 42 152 A1, DE 100 47 989 A1, DE 100 55 549 A1, DE 101 29 970 A1, DE 102 02 565 A1, DE 102 044 114 A1, EP 0 928 800 A1 1 or EP 0 952 170 A1 or DE patent 101 29 660 C 1. In spite of all the advantages that double-coating materials offer, the coating or painting of highly complex car bodies is still accompanied in practice over and over again by problems., often the radiation of shadow areas sufficiently in the sense mentioned above - for example, under the trunk lid and the engine hood and in the region of the door frames, the trunk and the interiors of the doors and windows, Even when the doors, lids and chests are kept wide open, it is not possible to the desired degree. An adequate profile of performance properties, therefore they have to cause (forcibly) in the shadow areas through thermal crosslinking, which, however, can lead to problems, especially if the painting operation is intended to span components Body-mounted bodies that are made of plastic and should not be exposed to elevated temperatures. In other words, the problem arises that thermal crosslinking is unable to compensate for deficiencies in curing by inadequate radiation to the extent required. A possible solution to this problem is to use a special coating material for the interior (internal coating material) which is particularly reactive in the sense of thermal crosslinking. Highly reactive coating materials of this kind have been known for a long time and usually comprise binders containing isocyanate-reactive groups and, as cross-linking agents, polyisocyanates (two-component systems). By means of said materials, it would be possible for the profile of performance properties of the coating in the shadow areas to coincide with the profile of performance properties of the coating in the areas that have been cured with a sufficient radiation dose and thermally cured. It has proven to be the case, however, that then, in those body regions where the inner lining material and the outer lining material (i.e., the lining material for the outer area) overlap, severe paint defects occur. These defects are caused in particular by incompatibility between the internal and external coating materials when applied wet on wet. The effect of this incompatibility is that the spray mist of a coating material can not be absorbed by the wet film of the other coating material. Therefore, an object of the present invention is to provide a new integrated double curing material system which no longer has the disadvantages of the previous branch, but instead allows the coating of three-dimensional substrates of complex shape, especially vehicle bodies. of engine, specifically automotive bodies, internally and externally without problems and that provides a coating that even internally has a profile of operating properties that at least coincides with the profile of performance properties of the coating externally that it has been possible to cure with a dose of sufficient radiation. The intention is that, in those areas in which the lining of the interior (internal lining) merges into the outer lining (external lining), there should no longer be any defects in the lining (paint defects). Accordingly, the invention provides the new dual-curing coating material system comprising at least two double-curing multi-component systems (A) and (B) which are composed predominantly or wholly of the same constituents and comprise in each case at least two components stored separately from each other.
(I) at least one component that contains (1.1) isocyanate-reactive functional groups and (1.2) reactive functional groups that contain at least one link that can be activated with actinic radiation, (1.3) flexibilize structural units that as parts of three-dimensional networks reduce their glass transition temperature Tg, and / or (1.4) harden structural units that as part of three-dimensional networks raise their glass transition temperature Tg and (II) at least one component containing (11.1) free isocyanate groups, ( 11.2) reactive functional groups containing at least one bond that can be activated with actinic radiation and (ii.3) structural units of flexibilization that as parts of three-dimensional networks reduce their glass transition temperature Tg, and / or (ii. 4) structural hardening units that, as part of three-dimensional networks, raise their glass transition temperature Tg. the double curing coating system (B) (B) having (a) above all a lower amount of reactive functional groups containing at least one bond that can be activated with actinic radiation, and / or (b) especially one higher amount of structural hardening units that as part of three-dimensional networks raise their glass transition temperature Tg, than the system (A) of double curing coating material. The new dual-curing coating material system is referred to below as the "system of the invention". The invention further provides the novel use of the system of the invention for the internal and external coating of three-dimensional substrates completely, this being referred to below as "use in accordance with the invention". The invention also provides a new process for the internal and external coating of three-dimensional substrates of complex shape covering the use according to the invention and comprises (1) preparing in each case at least one material (A) and (B) coating double curing, in each case, at least one system (A) and (B) of multiple double curing components, mixing in each case at least one component (I) and (II) and homogenizing the resulting mixture, and ( 2) coating the outside of the three-dimensional substrate with the double-curing coating material (A) and the interior of the three-dimensional substrate with the double-curing material (B), and then
(3) cure the resulting coatings thermally and with actinic radiation to provide the internal and external coating. The new process for the internal and external coating of three-dimensional substrates of complex shape is referred to below as "process of the invention". Subject matter of the invention will come out after reading the description. In the light of the previous branch it was surprising and unexpected for the skilled worker that the object on which the present invention was based could be achieved by means of the system of the invention, the use according to the invention and the process of the invention, respectively.
In particular it was surprising that the system of the invention no longer had the disadvantages of the previous branch, but instead, in the context of the use according to the invention, allowed the coating of three-dimensional substrates of complex shape, particularly vehicle bodies. of motor, especially automobile bodies, internally and externally in accordance with the process of the invention, without problems, and provided coatings that even internally have a profile of operating properties that at least coincide with the profile of operating properties of the coatings externally it was possible to cure with a sufficient dose of radiation. In the areas in which the linings of the interior (internal lining) are fused to that of the exterior (external lining) there were no defects in the linings (paint defects) "The system of the invention comprises at least two, especially two, systems (A) and (B) of multiple components of double curing, in particular two systems (A) and (B) of two components of double curing. Systems (A) and (B) of multiple dual curing components are predominantly or entirely composed of the same constituents. "Predominantly" herein means that systems (A) and (B) of multiple double curing components differ by no more than three and preferably in no more than two constituents and in particular in only one constituent of the other. Each of the systems (A) and (B) of multiple dual curing components comprises at least two, especially two, components (I) and (II) which are stored separately from each other until the materials (A) and ( B) of double curing coating are prepared in the context of the use according to the invention. In each system (A) and (B) of multiple double curing components the at least one, especially one, component (I) contains isocyanate-reactive functional groups (il) which are preferably selected from the group consisting of hydroxyl groups, thiol groups and primary and secondary amino groups, especially hydroxyl groups. It additionally contains reactive functional groups (i. 2) containing at least one, especially a link that can be activated with actinic radiation. Examples of suitable linkages that can be activated with actinic radiation and reactive functional groups (i.2) - comprising them are known from the German patent application DE 101 29 970 A1, page 8 paragraphs [0059] to [0061] ] The acrylate groups (i.2) in particular are used.
They can also include structural flexibilization units (i.3) which, as parts of three-dimensional networks, reduce their glass transition temperature Tg. Examples of suitable structural flexibilization units (i.3) are also known from German patent application DE 101 29 970 A 1, page 8, paragraph [0064] to page 9, paragraph [0072]. Not less important, they comprise structural hardening units (i.4) which, as part of the three-dimensional network, raise their glass transition temperature Tg. Examples of suitable structural hardening units (i.4) are also known from German patent application DE 101 29 970 A1, page 9, paragraph [0079] to page 10, paragraph [0085]. The "three-dimensional networks" are present in the thermosetting solids of the coatings or paint systems (A) and (B) produced from the systems (A) and (B) of multiple components of double curing and form the main constituent or the only constituent of these coatings or systems (A) and (B) of paint. The glass transition temperatures Tg of the coatings or systems (A) and (B) of paint are therefore determined in particular by the physical composition and structure of the three-dimensional networks. The physical composition and the structure of the three-dimensional networks are in turn adjusted through the selection of the constituents of the systems (A) and (B) of multiple dual curing components. Preferably / the component (I) comprises at least one polymeric and / or oligomeric binder; in particular it comprises two oligomeric and / or polymeric binders, some or all of the isocyanate-reactive functional groups (i.l.) being present in the binder or binders. The binders may contain reactive functional groups (i.2). Preferably, however, they are free of these groups. The binder consists of or comprises structural units (i.3) and (i.4). The structural units (i.3) and (i.4) are used in such a ratio that the binders, after their incorporation into the three-dimensional networks, contribute to adjust the desired glass transition temperature Tg. Examples of suitable binders and the amounts in which they are preferably used in the components (I) are known from the German patent application DE 101 29 970 A 1, page 3, paragraph [0018] to page 6, paragraph [0041] ] Use is made in particular of (meth) acrylate copolymers. Preferably they have a glass transition temperature of -50 to + 110 ° C, preferably -30 to +80 ° C, more preferably -15 to + 70 ° C, most preferably -15 to + 50 °. C, with very particular preference of -15 to + 40 ° C and in particular of -15 to + 30 ° C. Their acid number is guided in particular in case they are to be used in aqueous coating materials of the invention; preferably the acid number is from 5 to 100 mg KOH / g. Similarly, the amount of isocyanate-reactive groups they contain, hydroxyl groups in particular, can vary widely; preferably its hydroxyl number is from 20 to 300, more preferably from 30 to 250, most preferably from 40 to 200, very particular preference from 60 to 190 and in particular from 80 to 180 mg KOH / g. The component (I) preferably comprises at least one, in particular a constituent of molecular and / or oligomeric mass containing at least one reactive functional group (i.2) and preferably at least two, more preferably at least three and in particular at least four reactive functional groups (i-2). This constituent may also contain at least one, in particular, a isocyanate-reactive functional group (i.l.). Preferably the predominant proportion of all reactive functional groups (i.2) of component (I) are present in this constituent. Examples of suitable constituents of this class and the amounts in which they are preferably used in the components (I) are known from the German patent application DE 101 29 970 A1, page 11, paragraphs [0101] to [0103]. The component (I) may further comprise conventional coating additives such as are described, for example, in the German patent application DE 101 29 970 A1, page 12, paragraph [0123]. Particular use is made of pseudoplastic sinking control agents (SCAs). Component (I) may additionally comprise conventional pigments such as described, for example, in the German patent application DE 101 29 970 A 1, page 11, paragraph [0104] to page 12, paragraph [0121]. In particular, nanoparticles are used. The preparation of component (I) has no special characteristics as regards its method, but instead it occurs mixing the constituents described above and mixing and homogenizing the resulting mixtures by means of conventional mixing techniques and apparatus such as stirred tanks , stirring mills, extruders, kneading apparatus, Ultraturrax, in-line solvents, static mixers, cogwheel dispersers, pressure release nozzles and / or microfluidizers, preferably in the absence of actinic radiation.
For each system (A) and (B) of multiple double curing components, the at least one, in particular one, component (II) contains free (II.l) isocyanate groups. It may additionally contain, to a lesser extent, blocked isocyanate groups, as described, for example, in German patent application DE 101 29 970 A1 in paragraph [0058] by bridge to sheets 7 and 8. Component (II) it also contains reactive functional groups (ii.2) which contain at least one bond that can be activated with actinic radiation. Examples of suitable reactive functional groups (ii.2) are the reactive functional groups (i.2) described above. The component (II) also comprises units
(11.3) structural flexibilization that, as part of three-dimensional networks reduce their glass transition temperature Tg. Examples of suitable structural flexure units (ii.3) are the structural units (i.3) described above. Component (II) no less comprises units
(11.4) structural hardening that as part of the three-dimensional networks raise their glass transition temperature Tg. Examples of suitable structural hardening units (ii.4) are the structural units (i.) Described above. The component (II) preferably consists of or comprises at least one constituent that mandatorily exhibits the features (ii.l) and (ii.2). Examples of appropriate components (II) and appropriate constituents of the features (ii.l) and. { ii.2), processes for preparing them and the amounts in which they are preferably used in systems (A) and (B) of multiple dual curing components are known in detail from the German patent application DE 101 29 970? 1, page 6, paragraph [0042] to page 11, paragraph [0100]. Component (II) may further comprise the coating additives described above as long as they do not react with isocyanate groups (ii.l) under the conditions in which the component (II) is prepared, stored and used. The preparation of component (II) also does not require special features in regard to its method; instead, the apparatuses and techniques described above can be used. For the system of the invention it is essential that the system (B) of double-cured coating material has above all a lower level of reactive functional groups (i.2) + (ii.2) and / or above all a higher level of hardening structural units (i.4) + (ii.4) than the system (A) of double curing coating material. The system of the invention serves to coat internally and externally three-dimensional substrates of complex shape. Examples of three-dimensional substrates of complex shape are bodies of transport means, including transport means operated by motor power and / or muscular energy, such as automobiles, commercial vehicles, trucks, motorcycles, bicycles, rail vehicles, watercraft. and aircraft, and parts thereof, constructions and parts thereof, doors, windows, furniture and mechanical, optical and electronic components. The system of the invention serves in particular to internally and externally coat both motor vehicle bodies, especially automobile bodies. In the context of the use according to the invention, the double curing coating materials (A) and (B) are prepared from systems (A) and (B) of double-curing coating material by mixing the components (I) and (II) described above and homogenizing the resulting mixtures. The resulting dual curing coating materials (A) and (B) are preferably conventional coating materials, containing organic solvents / aqueous coating materials and liquid coating materials substantially or completely solvent-free and water-free (100% systems). Can be used to produce coating or paint systems, such as primer-surfacer coatings, base coatings and solid colored top coatings. In particular, they are surprisingly suitable for producing single transparent coating and multilayer transparent coating systems, and also multi-layer, color and / or effect transparent coatings, electrically conductive, magnetically protective and / or fluorescent coatings, in particular by the method wet-on-wet, in which case a basecoat material, in particular an aqueous basecoating material, is applied to the surface of the substrate and then the resulting basecoat film is dried without being cured, and coated envelope with a transparent coating film. Then the two films are curated jointly. In terms of method of application of materials (A) and (B) of double curing coating have no special features, but instead can occur by any customary application method, such as spraying, knife coating, brushing, coating of flow, immersion, runoff or roller, for example. Preference is given to employ spray application methods. It is generally advisable to operate in the absence of actinic radiation in order to prevent premature cross-linking of the coating materials, adhesives and sealants of the invention. In this context it is preferred to employ the process of the invention. In other words, the exterior or areas of the exterior of the three-dimensional substrate are coated with the double-curing coating material (A) and the interior or areas of the interior of the three-dimensional substrate are coated with the double-curing coating material (B). Subsequently, the resulting uncured coatings (A) and (B), together when appropriate with other uncured coatings present, are cured thermally and with actinic radiation, providing the integrated internal and external coating or integrated internal / external painting system ( B / A). The curing itself has no particular aspects in terms of method; instead, it is possible to carry out the curing with the aid of the apparatuses and techniques described in the German patent application DE 102 02 565 A 1, page 9, paragraph [0090] to page 10, paragraph [0107]. The resulting inner liner or internal paint system (B) of the invention is hard and scratch resistant, and is no longer damaged when additional motor vehicle components are installed or assembled. It has amazing optical properties and stabilized in very high light, and chemical resistance, to water, condensation, weathering and engraving. His ability to overcoat is amazing. The external coating (A) resulting from the invention is highly resistant to scratching and hard, and thus satisfies all the requirements imposed by car manufacturers and their customers. In particular, its transparent coating, produced from the double-curing coating material (A), has a storage modulus E 'on the elastic rubber scale of at least 107 · 5 Pa and a tanning loss factor of 20 ° C. of max. 0.1, the storage module E 'and the loss factor having been measured by means of dynamomechanical thermal analysis (DMTAO, on free films having a thickness of 40 + 10 μm (cf. German patent application DE 102 02 565 A 1 They also have notorious optical properties and very high light stability and chemical resistance, to water, weathering and chemical attack.Their ability to overcoat is notorious.In addition, the system (B / A) of internal and external paint integrated The invention is free of paint defects, such as strips, craters, spots or runs, in areas where the internal paint system (B) and the external paint system (A) overlap. of integrated dual-curing coating material systems Dual-curing two-component systems (Al and (A2): To prepare the dual-curing coating material systems integrated to produce c) internal and external painting systems (B / A) integrated in automotive bodies first of all the dual-curing systems (Al) and (A2) of dual-curing components listed in Table 1 were prepared by mixing the constituents to their components ( I) and (II) and homogenizing the resulting mixtures (I) and (II) in the absence of UV radiation. The respective components (I) and (II) were stored separately from one another before use. Table 1: The physical composition of systems (Al) and (A2) of two components of double curing. Constituent (Al) (A2)
Methacrylate copolymer (solids: 65% by weight, hydroxyl number 175 mg KOH / g, glass transition temperature: -21 ° C) 39.9 39.9
Rheological assistant (SCA) based on urea as in the preparation of Example 3, page 11 lines 31 to 51, DE 102 04 114 A 1 (solids: 59% by weight) Aerosil paste (R! (Solids: 28.47% by weight) Dipentaerythrityl pentaacrylate (solids: 100% by weight) Tinuvin (R) 292 (commercial light stabilizer from Ciba Specialty Chemicals; solids: 100% by weight) TinuvinIR) 400 commercial light stabilizer from Ciba Specialty Chemicals; solids: 85% by weight) Byk (R) 358 (commercial coating additive from Byk Chemie, solids: 52% by weight) Irgacure (R) TPO (commercial photoinitiator from Ciba Specialty Chemicals, solids: 50% by weight) LucirinÍR) TPO (commercial photo-initiator from BASF Aktiengesellschaft; solids:
% by weight) Metoxipropanol Butyl diglycol acetate Butyl acetate 5.5 5.5
Component (II): Roskydalt® isocyanate acrylate) US VPLS 2337 from Bayer AG (base: trimeric hexamethylene diisocyanate, isocyanate equivalent weight: 329 g, solids: 100% by weight) 55.02 55.02
Isocyanate acrylate RoskydalÍR > UA VP FWO 3003-77 from Bayer AG based on the trisomer of isophorone diisocyanate (solids: 70.5% by weight, equivalent weight, isocyanate: 609 g) 13.77 22.3
Polyisocyanate based on isophorone diisocyanate (Desmodur (R) from Bayer AG) 9.79 12.8 Butyl acetate 98/100 · 21.42 16.8
Dual-curing two-component systems (Bl) and (B5): To prepare integrated dual-curing coating material systems to produce internal (and external) paint systems (B / A) integrated into automotive bodies first of the systems (Bl) a (B5) of two double curing components listed in Table 2 were prepared by mixing the constituents to their components (I) and (II) and homogenizing the resulting mixtures (I) and (II) in the absence of UV radiation . The respective components (I) and (II) were stored separately from one another before use. Table 2: The physical composition of systems (Bl) to (B5) of two components of double curing. Constituent (Bl) (B2) (B3) (B4) (B5)
Methacrylate copolymer) - - 58.7 - - Methacrylate copolymer > 39.9 39.9 - 38.7 38.7
Rheological Assistant (SCA) C) 17.1 17.1 17.1 16.6 16.6
Pata Aerosil ™ d) 3.3 3.3 3.3 3.3 3.3
Diphenyl-erythritylose pentaacrylate) 22.8 22.8 4.7 22.1 22.1
TinuvintR) 292f) 1.1 1.1 1.1 1.1 1.1
Tinuvin (R) 400g) 1.1 1.1 1.1 1.1 1.1
Byk (R) 358h) 0.9 0.9 0.9 0.9 0.9
Irgacure (R> 184i5 2.2 2.2 2.2 2.1 2.1
Lucirin (R) TPOj > 5.5 5.5 5.5 5.3 5.3
Methoxypropanol 3 3 3 2.9 - Butyl diglycol acetate 2 2 2 1.9 8.9
Butyl acetate 1.1 1.1 0.4 4.1 - Component (II): Isocyanate acrylate) - 9.2 9.2 9.2 9.2
Isocyanate acrylate1 '8.3 67.9 67.9 67.9 67.9
Poliisocianatom) 5.9 7.2 7.2 7.2 7.2
Isocyanate acrylate 11 '74 - Butyl acetate 98/100 12.8 15.7 15.7 15.7 15.7 a) solids: 65% by weight; hydroxyl number: 175 mg KOH / g, glass transition temperature: -21 ° C; b) solids: 65% by weight; hydroxyl number: 175 mg KOH / g; Glass transition temperature: + 11 ° C; c) Urea-based SCA as Preparation Example 3, page 11, lines 41 to 51, of DE 102 04 114 A Io (solids: 59% by weight); d) solids: 28.47% by weight; e) solids: 100% by weight; f) commercial light stabilizer from Ciba Specialty Chemicals; solids: 100% by weight; g) commercial light stabilizer from Ciba Specialty Chemicals; solids: 85% by weight; h) commercial coating additive from Byk Chemie; solids: 52% by weight; i) commercial photoinitiator from Ciba Specialty Chemicals; solids: 50% by weight; j) commercial photoinitiator from BASF Aktiengesellschaft; solids: 10% by weight; k) RoskydalÍR) UA VPLS 2337 from Bayer AG (base: trimeric hexamethylene diisocyanate, isocyanate group content: 12% by weight, solids: 100% by weight); 1) Roskydalífi) UA VP FWO 3003-77 from Bayer AG, based on trimeric isophorone diisocyanate (solids: 70.5% by weight; isocyanate group content: 6.7% by weight); m) polyisocyanate based on isophorone diisocyanate (Desmodur (R) N 3300 from Bayer AG); n) isocyanate acrylate based on A, 4 '-dicylohexylmethane (Desmodur®) W of Bayer AG) and 4-hydroxybutyl acrylate (solids: 70% by weight, isocyanate equivalent weight 724 g). The systems of coating material of double curing integrated: Each of the systems (Al) or (A2) of multiple components of double curing described above was combinable with each of the systems (Bl), (B2), (B3) , (B4) or (B5) of multiple dual curing components described above to form an integrated double curing coating system system, providing a total of 10 of these systems. Use 2 Car body coating with multi-layer effect · coating systems comprising clearcoat systems produced using the integrated dual cure coating material systems. General experimental instructions For the internal painting of car bodies under the trunk lid and engine hood and in the area of door frames, trunk and interiors of the doors and windows the materials (Bl) a (B5) double curing were prepared shortly before the application of the systems (Bl) to (B5) of multiple double curing components described above (cf. Example 1, Table 2), by mixing the respective components (I) and (II) in the following mixing ratios of (I) / (II) (% by weight): (Bl): 100/111; (B2): 100/111; (B3): 100/91; (B4): 100/89; (B5): 100/89. For automotive body painting systems, the dual curing coating materials (Al) and (A2) were prepared shortly before the application of the dual curing two-component systems (A1) and (A2) described above ( cf. Example 1, Table 1), mixing the respective components (I) and (II) in the following mixing ratios (I) / (II) (I by weight): (Al): 100/67; (A2): 100/65. Car bodies that have been coated with a conventional electrocoat and a conventional primer-surfacer coating were coated with a commercially customary aqueous basecoat material comprising aluminum effect pigments. The aqueous basecoat films were briefly evaporated at room temperature and dried at 80 ° C for 10 minutes. The wet film thicknesses were selected so as to provide film thicknesses of 12 to 15 um after drying and curing. The water-based coating film inside five automobile bodies was coated wet-on-wet with one each of the materials (Bl) to (B5) of double-curing coating, and the aqueous-based coating film on the outside was coated wet on wet with the material (Al) of double curing coating. The wet film thicknesses of the transparent coating films were adjusted so as to provide film thicknesses of 40 to 45 um after curing. The water-based coating film inside five car bodies was coated wet on wet with one of each of the materials
(Bl) to (B5) of double-curing coating, and the water-based coating film on the outside was wet-on-wet coated with the double curing coating material (A2). The wet film thicknesses of the transparent coating films were adjusted so as to provide film thicknesses of 40 to 45 um after curing. The aqueous-based coating films and the transparent coating films of the automobile bodies were previously dried together at room temperature for 5 minutes and at 80 ° C for 10 minutes, exposed to a UV radiation dose of 1500 mJ. / cm2 and subsequently cured at 140 ° C for 20 minutes. The resulting internal paint systems (B) were hard and scratch resistant, allowing the installation of additional automotive components without any problems. The resulting external paint systems (A) were highly scratch resistant and hard. Both paint systems had notorious optical properties and very high light stability and chemical resistance, to water, condensation, weathering and chemical attack. His ability to overcoat was notorious. In particular, however, there were no paint defects in the areas where the internal (B) and external (A) paint systems overlapped.