WO2003000432A2

WO2003000432A2 - Method for retouching or revarnishing coatings

Info

Publication number: WO2003000432A2
Application number: PCT/EP2002/006699
Authority: WO
Inventors: Hubert Baumgart; Heinrich Wonnemann
Original assignee: Basf Coatings Ag
Priority date: 2001-06-20
Filing date: 2002-06-18
Publication date: 2003-01-03
Also published as: AU2002345057A1; DE10129660C1; WO2003000432A3

Abstract

The invention relates to a method for retouching or revarnishing a coating (2) produced from at least one coating material (2), which can be cured thermally and by means of actinic radiation. Said method is characterized by the following: (I) at least one coating material (2), which can be cured thermally and by means of actinic radiation, is applied to a substrate or to at least one uncured, partially cured or completely cured layer of a coating material (1); (II) the resulting layer is cured by means of actinic radiation; (III) the resulting coating(s) (2) is coated with at least one coating material (3), which can be cured thermally and by means of actinic radiation; (IV) the resulting layer (s) (3) is cured by means of actinic radiation; (V) the coatings (2) and (3) and the uncured or partially cured layer (s) (1) are thermally treated. The invention also relates to the use of the method in coating motor vehicles, buildings, windows, doors or furniture, industrial coating and the coating of white goods.

Description

Process for refinishing or double coating of coatings, made from thermal and actinic radiation curable coating materials

The present invention relates to a new process for refinishing or double coating of coatings, produced from coating materials curable thermally and with actinic radiation. In addition, the present invention relates to the new coatings which can be produced with the aid of the new process for refinishing or double coating.

Coloring and / or effect painting of

Motor vehicle bodies, in particular car bodies, today preferably consist of several layers of paint which are applied one above the other and have different properties.

For example, an electrically deposited electrodeposition coating (ETL) as a primer, a filler coating or stone chip protection primer, a base coat and a clear coat are applied to a substrate in succession. Here, the ETL serves in particular to protect the sheet against corrosion. It is often referred to by experts as a primer. The filler coating is used to cover unevenness in the surface and, due to its elasticity, ensures resistance to stone chips. If necessary, the filler coating can also serve to increase the hiding power and to deepen the color of the coating. The base coat contributes the colors and / or the optical effects. The clear coat serves to enhance the optical effects and to protect the paint from mechanical and chemical damage. Basecoat and clearcoat are also common collectively referred to as top coat. In addition, reference is also made to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, pages 49 and 51, "Automobile Lacquers". In the following, these multi-layer coatings are referred to as color and / or effect multi-layer coatings.

Commercial vehicles are often only provided with a pigmented coating, a so-called solid color coating, because of their size and because they are almost always retrofitted with logos, lettering and / or color fields or images.

Recently, the clear coats in particular have been produced from clear coats which are curable thermally and with actinic radiation. Actinic radiation is to be understood here and below as electromagnetic radiation, such as near infrared, visible light, UV radiation or X-rays, in particular UV radiation, and corpuscular radiation, such as electron beams. The combined hardening by heat and actinic radiation is also called dual-cure by experts.

Dual-cure coating materials, in particular dual-cure clearcoats, have the significant advantage that they can also be used in the shadow zones of complexly shaped three-dimensional substrates, such as car bodies, radiators or electrical winding goods, even without optimal, in particular complete, illumination of the shadow zones with actinic Radiation supplies coatings whose application properties profile at least approximates that of the coatings outside the shadow zones. As a result, the coatings located in the shadow zones are no longer easily damaged by mechanical and / or chemical action, which for example in the line when installing further components of motor vehicles in the coated bodies.

On the other hand, curing with actinic radiation can compensate for incomplete thermal curing if, for example, the dual-cure coating materials, because of the temperature sensitivity of the coated substrates, must not be heated to the temperatures necessary for the rapid course of the thermal crosslinking reactions.

Dual-cure coating materials and their use for producing high-quality color and / or effect multi-layer coatings are known, for example, from German patent applications DE 42 15 070 A1, DE 198 18 735 A1, DE 199 08 018 A1, DE 199 30 665 A. 1, DE 199 30 067 A1, DE 199 30 664 A1, DE 199 24 674 A1, DE 199 20 799 A1, 199 58 726 A1 or DE 199 61 926 A1 or are known from the previously unpublished German Patent applications DE 100 42 152.0, DE 100 47 989.8 or DE 100 55 549.7 are described.

The refinishing or double lacquering of these high-quality color and / or effect multi-layer lacquers places the highest demands on the refinish coatings and the refinishing processes. This is particularly the case for the refinishing of painted bodies in the line, in which the original or initial painting (OEM) has to be painted over a large area or as a whole (double painting). The colors and / or the optical effects in the refinish should not differ from those of the first coat. In addition, the refinish paint must adhere firmly to the original paint. If, however, the original paintwork is produced using the technologically particularly advantageous dual-cure clearcoats, liability problems arise which are due to the particularly high crosslinking density of the radiation-hardened systems. In these cases, good adhesion can only be achieved by physical treatment, for example treatment with ultrasound and / or heat, mechanical treatment, for example by grinding, polishing and / or buffing, and / or chemical treatment, for example etching with suitable chemicals , such as acids or bases, and / or flame treatment. These measures may still be justifiable in the case of small-area refinishing, on a large industrial scale they practically prohibit themselves because they are too time-consuming and energy-consuming and often unsafe in terms of safety. If the measures are not taken, however, the double lacquering tends to delaminate, which is not acceptable with high-quality products such as motor vehicles. These major disadvantages stand in the way of the widespread use of the otherwise so advantageous dual-cure coating materials in industrial coating.

These problems also occur in the case of refinishing or double coating of solid-color coatings which have been produced from pigmented coating materials which are curable thermally and with actinic radiation.

The object of the present invention is to find a new process which is used for the refinishing or double coating of coatings which have been produced from coating materials curable thermally and with actinic radiation. In particular, the new process of refinishing or double coating of clear coats and solid-color coats, which were produced from coating materials curable thermally and with actinic radiation, and from multi-layer coatings which give color and / or effect, wherein at least the clear coats were produced from coating materials curable thermally and with actinic radiation , serve.

The new method should no longer have the disadvantages of the prior art described, but should allow the above-mentioned coatings to be provided with a refinish or double coating over a large area or overall without any physical, mechanical or chemical pretreatment and / or Flaming the surface of the clear covers is necessary to avoid liability problems.

Accordingly, the new process for refinishing or double-coating a coating which was produced from at least one thermally and with actinic radiation-curable coating material was found, in which

(I) at least one coating material (2) curable thermally and with actinic radiation is applied to a primed or unprimed substrate or at least one uncured, partially cured or fully cured layer of a coating material (1),

(II) curing the resulting layer (s) (2) with actinic radiation, (III) coating the resulting coating (s) (2) with at least one coating material (3) curable thermally and with actinic radiation and

(IV) curing the resulting layer (s) (3) with actinic radiation, after which

(V) the coatings (2) and (3) or the coatings (2) and (3) as well as the existing uncured or partially cured layers (1) are subjected to a thermal treatment.

In the following, the new process for refinishing or double-coating a coating which was produced from at least one coating material which is curable thermally and with actinic radiation is referred to as the process according to the invention.

In view of the prior art, it was surprising and unforeseeable for the person skilled in the art that the object underlying the invention could be achieved with the aid of the method according to the invention. In particular, it was surprising that the measure essential to the invention initially hardened the coating (2) to be repaired or double-coated only with actinic radiation, in order to then heat treat it with the repair or double coating (3) hardened with actinic radiation undergo a significant improvement in interlayer adhesion. It was even more surprising that this measure could be applied to pigmented and unpigmented coatings (2) and (3). Above all, it was surprising that this measure was not only limited to single-layer coatings (2), but also that other coatings (1), such as, for example are present in color and / or effect multi-layer coatings, which could also be included in the process according to the invention. Thus, with the aid of the method according to the invention, a surprisingly large number of repair or double lacquers according to the invention could be realized, which no longer showed adhesion problems, but rather had excellent interlayer adhesion. This excellent interlayer adhesion was retained in its entirety even after the repair or double coatings according to the invention had been exposed to condensation.

The method according to the invention is used above all in automotive painting for large-area refinishing or double painting of bodies and parts thereof. However, it is not limited to this, but can just as well be used for the large-scale refinishing or double painting of structures indoors and outdoors, of furniture, doors and windows and as part of the industrial painting of coils, containers, packaging or white goods, such as radiators, Household appliances, refrigerator panels or washing machine panels are used.

The method according to the invention is therefore based on primed or unprimed substrates made of metal, plastic, glass, wood, textile, leather, natural and artificial stone, concrete, cement or composites of these materials, as are usually used in the technical fields mentioned above, where the electrically conductive substrates are preferred.

The substrates can be primed. In the case of plastics, customary and known primer layers or adhesive layers can be used as primers, or the plastic surfaces can be provided with reactive compounds such as fluorine by flame treatment or etching.

In the case of electrically conductive substrates, in particular metals, primers can be used as primers, as are found in Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, "Primer", page 473, "Wash Primer", page 618 , or "Production Coating", page 230.

In the case of electrically conductive substrates based on aluminum, an aluminum oxide layer produced by anodic oxidation is preferably used as the primer.

In the process according to the invention, in the first process step (I) at least one, in particular one, dual-cure coating material (2) is applied to the above-described primed or unprimed substrate or to an uncured, partially cured or fully cured layer of a coating material already located thereon (1) applied, whereby at least one, in particular one, layer (2) results.

The coating materials (1) can be pigmented or unpigmented. They are preferably pigmented.

They are selected from the group consisting of physically, thermally, with actinic radiation and thermally and with actinic radiation coating materials. They are preferably thermally curing. The coating materials (1) can be conventional coating materials containing organic solvents, aqueous coating materials, essentially or completely solvent-free and water-free liquid coating materials (100% systems), essentially or completely solvent-free and water-free solid coating materials (powder coatings) or essentially or be completely solvent-free powder coating suspensions (powder slurries). In addition, they can be single-component systems in which the binders and the crosslinking agents are present side by side, or two- or multicomponent systems in which the binders and the crosslinking agents are stored separately until shortly before application because of their high reactivity.

The coating materials (1) are preferably electrocoat materials, fillers and / or basecoats.

The electrocoat layers, filler layers and / or

Basecoat layers (1) can be cured separately before application of the coating materials (2) or - if there are at least two layers (1) - also cured together (wet-on-wet process).

On the other hand, the electrocoat layers, filler layers and / or basecoat layers (1) can be unhardened or partially hardened and can only be hardened (wet-in) with layers (2) and / or (3) and optionally (4) in the further course of the process according to the invention - wet process).

The structures shown in overview 1 result from the coating materials (1). In overview 1, the abbreviations have the following meaning: S = substrate; ETL = electro dip painting; FL = filler paint and BL = basecoat.

Overview 1: Multi-layer painting with coating materials (1)

S / (1) ETL S / (1) FL S / (1) BL

S / (1) ETL / (1) FL S / (1) ETL / (1) BL S / (1) FL / (1) BL S / (1) ETL / (1) FL / (1) BL

Examples of suitable electrocoating materials (1) and, if appropriate, wet-on-wet processes are described in Japanese Patent Application 1975-142501 (Japanese Patent Application Laid-Open No. 52-065534 A 2, Chemical Abstracts Unit No. 87: 137427) or in the patent documents and applications US 4,375,498 A1, US 4,537,926 A1, US 4,761,212 A1, EP 0529335 A1, DE 4125459 A1, EP 0595186 A1, EP 0074634 A1, EP 0505445 A1, DE 4235778 A1, EP 0646420 A1 1, EP 0639660 A1, EP 0817648 A1, DE 19512017 C1, EP 0192113 A2, DE 4126476 A1 or WO 98/07794.

Suitable fillers (1), in particular aqueous fillers, which are also referred to as stone chip protection primers or functional layers, are known from the patents and applications US 4,537,926 A1, EP 0529335 A1, EP 0595186 A1, EP 0639660 A1, DE 4438504 A 1, DE 43 37 961 A 1, WO 89, / 10387, US 4,450,200 A 1, US 4,614,683 A 1 or WO 490/26827 are known.

Suitable basecoats (1), in particular waterborne basecoats, are known from patent applications EP 0 089 497 A1, EP 0 256 540 A1, EP 0 260 447 A1, EP 0 297 576 A1, WO 96/12747, EP 0 523 610 A 1, EP 0 228 003 A 1, EP 0 397 806 A 1, EP 0 574 417 A 1, EP 0 531 510 A 1, EP 0 581 211 A 1, EP 0 708 788 A 1, EP 0 593 454 A 1, DE-A-43 28 092 A1, EP 0 299 148 A1, EP 0 394 737 A1, EP 0 590 484 A1, EP 0 234 362 A1, EP 0 234 361 A1, EP 0 543 817 A 1, WO 95/14721, EP 0 521 928 A 1, EP 0 522 420 A 1, EP 0 522 419 A 1, EP 0 649 865 A 1, EP 0 536 712 A 1, EP 0 596 460 A 1 , EP 0 596 461 A1, EP 0 584 818 A1, EP 0 669 356 A1, EP 0 634 431 A1, EP 0 678 536 A1, EP 0 354 261 A1, EP 0 424 705 A1, WO 97/49745, WO 97/49747, EP 0 401 565 A1 or EP 0 817 684, column 5, lines 31 to 45, are known.

In terms of method, the application of the coating materials (1) and dual-cure coating materials (2) to be used in the process according to the invention has no peculiarities, but can be done by all customary and known application methods suitable for the respective coating material, such as, for example, electrocoating, spraying, spraying, Squeegee, brush, pour, dip, trickle or roll. Spray application methods are preferably used, such as compressed air spraying, airless spraying, high rotation, electrostatic spray application (ESTA), optionally combined with hot spray application such as hot air hot spraying, unless it is powder coatings (1) or (2) or electrodeposition paints (1). The application of powder coatings (1) or (2) has no special features in terms of method, but is carried out, for example, using the customary and known fluidized bed processes, such as those found in the company publications of BASF Coatings AG, "Powder coatings for industrial applications", January 2000, or "Coatings Partner, Pulverlack Spezial", 1/2000, or Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, pages 187 and 188, "Electrostatic Powder Spraying", "Electrostatic Spraying" and "Electrostatic Whirl Bath Process", are known.

When applying, it is advisable to work with the exclusion of actinic radiation in order to avoid premature crosslinking of the dual-cure coating materials (2) to be used according to the invention.

The composition of the dual-cure coating materials (2) to be used according to the invention is not critical, but all coating materials that can be cured thermally and with actinic radiation can be used.

The dual-cure coating materials (2) can also be conventional coating materials containing organic solvents, aqueous coating materials, essentially or completely solvent-free and water-free liquid coating materials (100% systems), substantially or completely solvent-free and water-free solid coating materials (powder coatings ) or essentially or completely solvent-free powder coating suspensions (powder slurries). In addition, they can be one-component systems in which the binders and the crosslinking agents are present side by side, or two- or multi-component systems in which the binders and the Crosslinking agents should be stored separately until shortly before application because of their high reactivity.

The dual-cure coating materials (2) can be pigmented. It is then preferably a dual-cure filler, a dual-cure basecoat or a dual-cure solid-color topcoat (2).

Dual-cure coating materials (2) can be unpigmented. It is then preferably dual-cure clearcoats (2).

Examples of suitable dual-cure coating materials (2) are from German patent applications DE 42 15 070 A1, DE 198 18 735 A1, DE 199 08 018 A1, DE 199 30 665 A1, DE 199 30 067 A1, DE 199 30 664 A 1, DE 199 24 674 A 1, DE 199 20 799 A 1, 199 58 726 A 1 or DE 199 61 926 A 1 or the European patent application EP 0 928 800 A 1 or are known in the unpublished German Patent applications DE 100 42 152.0, DE 100 47 989.8 or DE 100 55 549.7 are described.

The dual-cure coating materials can also be obtained, inter alia, by adding to the fillers (1) or basecoats (1) described above or to clearcoats such as those found in patent applications, patent specifications and publications DE 42 04 518 A1, EP 0 594 068 A 1, EP 0 594 071 A 1, EP 0 594 142 A 1, EP 0 604 992 A 1, EP 0 596 460 A 1, WO 94/10211, WO 94/10212, WO 94/10213, WO 94 / 22969 or WO 92/22615, US 5,474,811 A 1, US 5,356,669 A 1 or US 5,605,965 A 1, DE 42 22 194 A 1, product information from BASF Lacke + Farben AG, "Powder Coatings", 1990, company name of BASF Coatings AG "Powder coatings, powder coatings for industrial applications", January 2000, US 4,268,542 A 1, DE 195 40 977 A 1, DE 195 18 392 A 1, DE 196 17 086 A 1, DE-A-196 13 547, DE 196 52 813 A1, DE-A-198 14 471 A1, EP 0 928 800 A1, EP 0 636 669 A1, EP 0 410 242 A1, EP 0 783 534 A1, EP 0 650 978 A1, EP 0 650 979 A1, EP 0 650 985 A1, EP 0 540 884 A1, EP 0 568 967 A1, EP 0 054 505 A1, EP 002 866 A1, DE 197 09 467 A1, DE 42 03 278 A1, DE 33 16 593 A1, DE 38 36 370 A1, DE 24 36 186 A1, DE 20 03 579 B1, WO 97/46549 , WO 99/14254, US 5,824,373 A 1, US 4,675,234 A 1, US 4,634,602 A 1, US 4,424,252 A 1, US 4,208,313 A 1, US 4,163,810 A 1, US 4,129,488 A1, US 4,064,161 A 1, US 3,974,303 A 1, EP 0 844 286 A1, DE 43 03 570 A1, DE 34 07 087 A1, DE 40 11 045 A1, DE 40 25215 A1, DE 3828 098 A1, DE 4020 316 A1 or DE 41 22 743 A 1 are known, low molecular weight, oligomeric and / or polymeric, in particular low molecular weight or oligomeric, compounds are added which are curable with actinic radiation.

Examples of suitable compounds curable with actinic radiation are described in detail in Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, "Reaktiwerdünner" 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, or the German patent DE 197 09 467 C 1, page 4, line 36, to page 5, line 56, European patent application EP 0 928 800 A 1, page 3, lines 17 to 54, and page 4, lines 41 to 54, or in the German patent application DE 198 18 735 A1, column 3, line 16 to column 6, line 33. Pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate and / or aliphatic urethane acrylates with six acrylate groups in the molecule and / or isocyanatoacrylates, which can be prepared from polyisocyanates and hydroxyl-containing olefinically unsaturated monomers, are preferably used. According to the invention, the resulting layer (2) is cured with actinic radiation in process step (II).

The curing of the dual-cure coating materials (2) used in the process according to the invention generally takes place after a certain resting time or flash-off time. It can have a duration of 5 s to 2 h, preferably 1 min to 1 h and in particular 1 to 45 min. The rest period is used, for example, for the course and degassing of the paint layers and for the evaporation of volatile constituents such as any solvent and / or water present. The ventilation can be accelerated by an increased temperature, which is not yet sufficient for hardening, and / or by a reduced air humidity.

Within the scope of the method according to the invention, this method measure is also used for drying the applied lacquer layers (1) and / or (4) which are not to be hardened or only partially hardened.

For curing with actinic radiation, in particular UV radiation, a dose of 500 to 4,000, preferably 1,000 to 2,900, particularly preferably 1,200 to 2,800, very particularly preferably 1,300 to 2,700 and in particular 1,400 to 2,600 mJ / cm ^{2 is} preferably used.

The usual and known radiation sources and optical auxiliary measures are used for curing with actinic radiation.

Examples of suitable radiation sources are flash lamps from VISIT, high-pressure or low-pressure mercury vapor lamps, which, if appropriate are doped with lead to open a beam window up to 405 nm, or electron beam sources. Their arrangement is known in principle and can be adapted to the conditions of the workpiece and the process parameters. In the case of workpieces of complex shape, such as those intended for automobile bodies, the areas which are not directly accessible to radiation (shadow areas), such as cavities, folds and other design-related undercuts, can be combined with spotlights, small-area or all-round emitters, with an automatic movement device for the irradiation of Cavities or edges, are cured.

The facilities and conditions of these curing methods are described, for example, in R. Holmes, U.V. and E.B. Curing Formulations for Printing Inks, Coatings and Paints, SITA Technology, Academic Press, London, United Kindom 1984, or in German patent application DE 198 18 735 A1, column 10, line 31, to column 11, line 16.

The curing can take place in stages, i. H. by multiple exposure or exposure to actinic radiation. This can also take place alternately, i. that is, for example, alternately curing with UV radiation and electron radiation.

Curing with actinic radiation is preferably carried out under inert gas in order to avoid the formation of ozone.

In process step (III), at least one, in particular one, dual-cure coating material (3) is applied to the coating (s) (2) resulting in process step (II), after which the resulting layer (s)) ( 3) cures with actinic radiation. Here, the Methods described above in the dual-cure coating materials (2) applied

All dual-cure coating materials (2) described above are suitable as dual-cure coating materials (3). The dual-cure coating materials (3) and (2) can have different material compositions. They preferably have an identical or almost identical composition in order to have the same or essentially the same application properties.

The dual-cure coating materials (3) can be pigmented. It is then preferably a dual-cure filler and / or solid-color topcoat (3).

The dual-cure coating materials (3) can also not be pigmented. It is then preferably dual-cure clearcoats (3).

In a variant of the method according to the invention, at least one layer of at least one coating material (4) is applied to the coating (s) (2) before the dual-cure coating materials (3) are applied, the methods described above being used.

This variant is preferably used if the coating (s) (2) are not pigmented and in particular are clear coatings (2).

The variant is particularly preferred if the coating (s) (2), in particular the clear coatings (2), are on pigmented layers (1), located or located in particular on filler paints and / or basecoats (1).

The coating materials (4) are preferably pigmented. They are preferably selected from the coating materials (1) described above, in particular the fillers and basecoats (1) described above.

The coating materials (4) and (1) can have different material compositions. They preferably have an identical or almost identical composition in order to have the same or essentially the same application properties.

In the further course of the method according to the invention

the coatings (2) and (3),

the coatings (2) and (3) as well as the existing uncured or partially cured layers (1) or

the coatings (2) and (3) as well as the existing uncured or partially cured layers (1) and (4)

subjected to a thermal treatment, as a result of which the coatings (2) and (3) and any uncured or partially cured layer (s) (1) and / or (4) that are present are thermally cured. The thermal treatment can be carried out after a certain period of rest, whereby the conditions described above can be applied. The thermal treatment is carried out, for example, with the aid of a gaseous, liquid and / or solid, hot medium, such as hot air, heated oil or heated rollers, or using microwave radiation, infrared light and / or near infrared light (NIR). The heating is preferably carried out in a forced air oven or by irradiation with IR and / or NIR lamps. As with curing with actinic radiation, thermal curing can also be carried out in stages. The thermal treatment is advantageously carried out at temperatures above room temperature, preferably up to a maximum of 200 ° C. In special cases, higher temperatures can also be used.

With the aid of the method according to the invention, an astonishing number of different repair or double coatings according to the invention can thus be realized. Examples of repair or double lacquering according to the invention are shown in the following overview. In the overview, the abbreviations have the following meaning:

S = substrate; ETL = electro dip painting;

FL = filler paint or stone chip protection primer;

KL = clear painting;

UL = solid color finish;

BL = basecoat;

Overview: Repair or double coating according to the invention

S / (2) KL / (3) KL S / (1) ETL / (2) KL / (3) KL S / (1) FL / (2) KL / 3 (KL) S / 1) ETL / (1) FL / (2) KL / (3) KL s / 1) FL / (2) KL / (4) FL / (3) KL

S / 1) ETL / (1) FL / (2) KL / (4) FL / (3) KL

S / 2) FL / (3) FL S / 1) ETL / (2) FL / (3) FL

S / 2) UL / (3) UL S / 1) ETL / (2) UL / (3) UL S / 1) FL / (2) UL / (3) UL S / 1) ETL / (1) FL / (2) UL / (3) UL S / 1) FL / (2) UL / (4) FL / (3) UL s / 1) ETL / (1) FL / (2) UL / (4) FL / (3) UL

S / 1) BL / (2) KL / (3) KL S / 1) BL / (2) KL / (4) BL / (3) KL S / 1) ETL / (1) BL / (2) KL / (3) KL S / 1) ETL / (1) BL / (2) KL / (4) BL / (3) KL S / 1) FL / (1) BL / (2) KL / (3) KL S / 1) FL / (1) BL / (2) KL / (4) BL / (3) KL S / 1) ETL / (1) FL / (1) BL / (2) Kl / (4) FL / (4) BL / (3) KL S / 1) ETL / (1) FL / (1) BL / (2) KL / (3) KL S / 1) ETL / (1) FL / (1) BL / (2) KL / (4) BL / (3) KL S / 1) ETL / (1) FL / (1) BL / (2) Kl / (4) FL / (4) BL / (3) KL

The layer thicknesses of the coatings are preferably in the customarily used ranges:

Electric dip painting (1): Preferably 10 to 60, preferably 15 to 50 and in particular 15 to 40 μm;

Filler coating (1), (2) and (4): preferably 20 to 150, preferably 25 to 100 and in particular 30 to 80 μm;

Basecoat (1), (2) and (4):

Preferably 5 to 30, preferably 7.5 to 25 and in particular 10 to 20 μm;

Solid color coating (2) and (3):

Preferably 10 to 60, preferably 15 to 50 and in particular 15 to 40 μm;

Clear coat (2) and (3):

Preferably 10 to 100, preferably 15 to 80 and in particular 20 to 70 μm;

The repair and double coatings according to the invention have excellent optical properties. The adhesion between the first coat and the second coat is excellent even after exposure to a constant condensation water climate.

It should be particularly emphasized that the process according to the invention can also be used for the production of third-party coatings. This may be necessary if the secondary paint is damaged during its manufacture or shows color deviations and therefore has to be repaired over a large area or completely. Examples and comparative tests

Production Example 1

The production of a thermally curable binder

In a suitable reactor, equipped with a stirrer, two dropping funnels for the monomer mixture and the initiator solution, nitrogen inlet tube, thermometer, heater and reflux condenser, 650 parts by weight of a fraction of aromatic hydrocarbons with a boiling range of 158 to 172 ° C. were weighed out. The solvent was heated to 140 ° C. Thereafter, a monomer mixture of 652 parts by weight of ethylhexyl acrylate, 383 parts by weight of 2-hydroxyethyl methacrylate, 143 parts by weight of styrene, 212 parts by weight of 4-hydroxybutyl acrylate and 21 parts by weight of acrylic acid were added within four hours and an initiator solution of 113 parts by weight of the aromatic solvent and 113 parts by weight of tert-butyl perethylhexanoate , Evenly metered into the template for 5 hours. The metering of the monomer mixture and the initiator solution was started simultaneously. After the initiator feed had ended, the resulting reaction mixture was heated to 140 ° C. with stirring for a further two hours and then cooled. The resulting solution of the methacrylate copolymer (A) was diluted with a mixture of 1-methoxypropylacetate-2, butylglycol acetate and butyl acetate. The resulting solution had a solids content of 65% by weight, determined in a forced air oven (one hour / 130 ° C.) and an acid number of 15 mg KOH / g solids.

Preparation example 2 The production of a dual-cure clear coat

The dual-cure clearcoat was prepared by mixing the ingredients listed in the table in the order listed and homogenizing the resulting mixture.

Table: The material composition of the dual-cure clearcoat

Part by weight

Master batch:

Binder of preparation example 1 35.9

Dipentaerythritol pentaacrylate 20

UV absorber (substituted hydroxyphenyltriazine) 1, 0

HALS (N-methyl-2,2,6,6-tetramethylpiperidinyl ester) 1.0

Wetting agent (Byk ® 306 from Byk Chemie) 0.4

Butyl acetate 27.4

Solventnaphtha ® 10.8

Irgacure © 184 (commercially available photoinitiator from Ciba Specialty Chemicals) 2.0 Genocure ® MBF (commercial photoinitiator from Rahn) 1, 0

Lucirin ® TPO (commercially available photoinitiator from

BASF AG) 0.5

Sum: 100

Crosslinking agent component (B):

Total: 38.28

Crosslinking agent (B1): Roskydal® UA VPLS 2337 isocyanatoacrylate from Bayer AG (based on: trimer hexamethylene diisocyanate; content of isocyanate groups: 12% by weight) 27.84

Crosslinking agent (B 2): isocyanatoacrylate based on the trimer of isophorone diisocyanate (70.5% in butyl acetate; viscosity: 1,500 mPas; content of isocyanate groups: 6.7% by weight; prepared as in Example 1 of EP 0 928 800 A 1) 6.96

Thinner 3.48

Examples 1 to 3 and comparative experiments V1 to V3 The production of double coats by the process according to the invention (Examples 1 to 3) and by a process not according to the invention (comparative tests V1 to V3)

To produce the double lacquers of Examples 1 to 3 according to the invention, steel panels were coated in succession with a cathodic electrodeposition coating which had been baked at 170 ° C. for 20 minutes and had a dry layer thickness of 18 to 22 μm. The steel sheets were then coated with a commercially available two-component water filler from BASF Coatings AG, as is usually used for plastic substrates. The resulting filler layer was baked at 90 ° C. for 30 minutes, so that a dry layer thickness of 35 to 40 μm resulted. A commercial black waterborne basecoat from BASF Coatings AG was then applied with a layer thickness of 12 to 15 μm, after which the resulting waterborne basecoat films were flashed off at 80 ° C. for ten minutes. Then the clear coats with a layer thickness of 40 to 45 μm were applied pneumatically in a cloister with a gravity cup gun.

In Examples 1 and 2, the clear lacquer layers were flashed off at room temperature for 5 minutes and at 80 ° C. for 5 minutes; in Example 3, the clear lacquer layers were flashed off at room temperature for 5 minutes and at 80 ° C. for 10 minutes.

The clear lacquer layers of Examples 1 to 3 were then cured by irradiation with UV light at a dose of 1,500 mJ / cm ² . Examples 1 to 3 were repeated for the comparative experiments V1 to V3, except that the clearcoat layers after curing with UV radiation

of comparative experiment V1 for 30 minutes at 90 ° C. and

the comparative experiments V2 and V3 for 20 minutes at 140 ° C

were thermally hardened.

In Examples 1 to 3 and Comparative Experiments V1 to V3, the clear finishes were coated with the black basecoat in the manner described above, after which the resulting water-based basecoat films were flashed off at 80 ° C. for ten minutes.

In each case a clear lacquer layer was applied wet-on-wet to the water-based lacquer layers.

In Examples 1 to 3 and in comparative experiments V1 to V3, the clear lacquer layers were flashed off at room temperature for 5 minutes. Subsequently, in Examples 1 and 2 and in Comparative Experiments V1 and V2, the clear lacquer layers were flashed off at 80 ° C. for 5 minutes and in Example 3 and Comparative Experiment V1 for 10 minutes at 80 ° C.

The vented clear lacquer layers were hardened by irradiation with UV light at a dose of 1,500 mJ / cm ² . Then, in Example 1 and Comparative Experiment V1, the test panels were heated to 90 ° C. for 30 minutes. In Examples 2 and 3 and comparative experiments V2 and V3, the test panels were heated to 140 ° C. for 20 minutes.

The result was the double lacquers 1 to 3 according to the invention from Examples 1 to 3 and the double lacquers V1 to V3 according to the invention from the comparative tests V1 to V3.

Some of the test panels were subjected to the cross-cut test (cross-cut with tesa tear according to DIN EN ISO 2409) and the VDA stone chip test after their production. Another part of the test panels was subjected to a condensation water constant climate (SKK) for 240 hours in accordance with DIN 50017 and DIN 53209. Some of the loaded test panels were subjected to the cross-cut test according to DIN EN ISO 2409 1 hour and another 97 hours after the load. The results can be found in the table.

The liability according to the cross-cut test was graded as follows:

GT0-1 = OK, no or only very little delamination (small splinters on the cut edges); GT2 = just OK, minor detachment, approx. 15% of the sections; GT3-4 = not ok, larger delamination areas, approx. 35 to 65% of the sections; GT5 = complete release.

The stone chip resistance was graded as follows: 0-2 = OK, good resistance, no or very little detachment; 2-3 = not ok, larger delamination areas;

4 = not ok, extensive delamination; 5 = complete release.

"OK" means "OK", "NOK" means "Not OK".

Table: The adhesion properties and the stone chip resistance of the invention

Double paintwork 1 to 3 and the non-inventive double paints V1 to V3

Example or crosscut rockfall comparison test A B grade

GT0.5 GT0.5 GT05 2.0

2 GT0.5 GT0.5 GT05 2.0

GT0.5 GT0.5 GT05 2.0

V1 GT5 5.0 V2 GT5 5.0

V1 GT5 5.0

A = measurement 1 day after production; B = measurement 1 hour after 240 hours SSK;

C = measurement 97 hours after 240 hours SSK;

The results corroborated that only the process according to the invention gave double coatings with excellent interlayer adhesion.

Claims

Process for refinishing or double coating of coatings, made from coating materials curable thermally and with actinic radiation

1. A process for the refinishing or double coating of a coating (2), which was produced from at least one thermally and with actinic radiation curable coating material (2), characterized in that

(I) at least one coating material (2) curable thermally and with actinic radiation onto a substrate or onto at least one uncured, partially cured or fully cured layer of a coating

Applied coating material (1),

(II) curing the resulting layer (s) (2) with actinic radiation,

(III) coating the resulting coating (s) (2) with at least one coating material (3) curable thermally and with actinic radiation and

(IV) the resulting layer (s) (3) with actinic

Radiation cures what you want

(V) the coatings (2) and (3) or the coatings (2) and (3) as well as the existing uncured or partially hardened layer (s) (1) undergoes a thermal treatment.

2. The method according to claim 1, characterized in that it is pigmented in the coating materials (1)

Coating materials.

3. The method according to claim 2, characterized in that the pigmented coating materials (1) from the group consisting of physically, thermally, with actinic radiation and thermally and with actinic radiation curable coating materials are selected.

4. The method according to claim 3, characterized in that the coating materials (1) electrocoat materials, filler and / or

Basecoats are.

5. The method according to any one of claims 1 to 4, characterized in that the coating materials (2) are pigmented coating materials.

6. The method according to claim 5, characterized in that the coating material (2) is a solid color.

7. The method according to claim 6, characterized in that the coating materials (1) are electrocoat materials and / or fillers.

8. The method according to any one of claims 5 to 7, characterized in that the coating material (3) is a pigmented coating material.

, A method according to claim 8, characterized in that the coating materials (2) and the coating materials (3) are of identical or almost identical material composition.

10. The method according to any one of claims 1 to 4, characterized in that the coating material (2) is a non-pigmented coating material

11. The method according to claim 10, characterized in that the coating material (2) is a clear lacquer.

12. The method according to claim 10 or 11, characterized in that the coating material (3) is a non-pigmented

Is coating material.

13. The method according to claim 12, characterized in that the coating material (3) is a clear lacquer.

14. The method according to any one of claims 10 to 13, characterized in that the coating materials (2) and (3) are of identical or almost identical material composition.

15. The method according to any one of claims 10 to 14, characterized in that before the application of the coating material (3) at least one layer of a coating material (4) is applied.

16. The method according to claim 15, characterized in that the coating material (4) is a pigmented coating material

17. The method according to claim 16, characterized in that the coating material (4) from the group consisting of physically, thermally, with actinic radiation and thermally and with actinic radiation curable coating materials is selected.

18. The method according to claim 17, characterized in that the coating materials (4) are fillers and / or basecoats.

19. The method according to any one of claims 15 to 18, characterized in that the coating materials (4) and the coating materials (1) are of identical or almost identical material composition.

20. The method according to any one of claims 1 to 19, characterized in that the substrates are motor vehicle bodies or parts thereof.