MXPA06008161A - Process for producing two-tone coated substrates - Google Patents

Abstract

A process for producing two-tone coated substrates, comprising the successive steps:a) providing a non-color-imparting pre-coated substrate, b) applying a color-imparting coating of Color 1 at least to one or more regions of the substrate side facing an external observer, c) curing the coating of Color 1, d) masking the desired region of the coating of Color 1, e) applying a color-imparting coating of Color 2 to the unmasked regions of the substrate side facing the external observer without deliberately curing the coating of Color 2, f) unmasking the regions masked in step d), g) applying a clear coat to the whole of the substrate side facing the external observer and h) curing the clear coat.

Description

PROCESS FOR PRODUCING TWO-TONE COATED SUBSTRATES FIELD OF THE INVENTION The invention relates to a process for producing substrates coated with two shades, in particular the bodywork of motor vehicles. BACKGROUND OF THE INVENTION Currently, motor vehicle finishes generally consist of a multilayer coating consisting of an anticorrosive primer coating applied by electrodeposition, a filler coating (surface coating primer) and a topcoat applied to the coating. same consisting of a base coating that imparts color and / or effect and a transparent protective coating that provides shine. For producing two-tone multi-layer coatings, it is known to apply paint coating that imparts color from two coating agents of different colors, whereby an overlap zone is deliberately created. between the two regions of different colors. The overlap zone is visible through a transparent cover layer that is subsequently applied. If, instead of an overlap zone, a clear separation is to be obtained between the two regions of different colors, a conventional process used to form a Ref. 174144 two-tone multi-layer coating envisages covering a cover with a transparent cover / single layer multi-layer basecoat, which leaves a region of the uncoated coating that will be coated with a second, color coating. This region is then additionally coated with a second top covering that imparts color or a second base coat that imparts color and / or effect and subsequently the mask is removed. An undesirable perceptible edge is formed along the mask, which clearly delineates the regions of different colors one from the other. It would be desirable to have a process for forming a two-tone multilayer coating that would not result in a visible overlap zone or a perceptible edge between the colors. BRIEF DESCRIPTION OF THE INVENTION The invention provides an economical process, i.e. one that can be carried out with a small number of curing or baking steps, to produce coated substrates of two tones, in particular motor vehicle bodies, wherein the regions of different colors are clearly delimited one from the other and where the formation of a visible and perceptible edge between the regions of different colors is avoided. The novel process of the present invention forms two-tone coated substrates and comprises the following steps: a) providing a previously coated substrate that does not impart color, b) applying a coating that imparts color of a color 1 to at least one or more regions on the side of the substrate facing an external observer, c) curing the color coating 1, d) covering the desired region of the color coating 1, e) applying a coating that imparts color 2 color to the uncovered regions on the side of the substrate oriented towards the external observer without deliberately curing the color coating 2, f) discovering the covered regions in step d), g) applying a transparent covering to the entire side of the substrate facing the external observer, and h) curing the coverage transparent . DETAILED DESCRIPTION OF THE INVENTION A particular embodiment of the process, according to the invention. It is related to a process for producing two-tone motor vehicle bodies, which comprises the following successive steps: a) providing a motor vehicle body previously coated without imparting color, b) applying a coating that imparts color of a color 1 to at least one or more regions of the outer layer of the body, c) curing the color coating 1, d) covering the desired region of the color coating 1, e) applying a coating that imparts color 2 color to the uncovered regions of the outer layer of the body without deliberately curing the color coating 2, f) discovering the regions covered in step d), g) applying a transparent cover to the entire outer layer of the body, and h) cure the transparent cover. In the description and in the claims, reference is made to the substrate oriented towards an external observer, i.e., the visible external surface. In the case of motor vehicle bodies this is the outer layer of the body. This in no way means that there is no coating on the substrate side that is not oriented towards the external observer or, in the particular case of motor vehicle bodies, the regions of the body that are not directly accessible to the external observer, for example, engine, trunk or passenger compartments. In the present description, the nature of the coating of such substrate regions is simply not discussed; finally this also does not make sense given the nature of the invention. In the description and in the claims, a distinction is made between "imparting color" and "not imparting color", for example, between coatings that impart color in colors 1 and 2 and coatings that do not impart color. By "color imparting coatings" it is meant that they are coatings that give the color impression to an external observer of a double-tone coated coated substrate, i.e. color coatings 1 and 2 covered with the transparent coating applied in step g ). Colors 1 and 2 can be both solid colors (single tone colors) or special effects colors (colors characterized by 'color and / or change in brightness depending on the angle of observation) or a solid color and a special effect color.

Coating agents or coatings that are described as not imparting color do not contribute in the context of the present invention to the color printing of a two-tone finished coated substrate; they may naturally consist of a colored or non-colored paint. In process step a) a previously coated substrate is provided which does not impart color, for example, a plastic substrate previously coated with a conductive primer, a metal substrate previously coated with an anti-corrosive primer or a pre-coated substrate made from a combination of different materials, for example metal and plastic parts. The pre-discovery is in each case a cured pre-discovery. The pre-coating that does not impart color covers at least the entire side of the substrate facing the external observer. In the case of a pre-coated motor vehicle body, the pre-coating generally consists of a primer coating applied by conventional electrodeposition, optionally together with an additional coating that similarly does not impart color applied thereto, for example, a coating of conventional filling. The production of corresponding pre-coatings is known to the person skilled in the art and therefore does not require further explanation. In process step b) a coating imparting color color 1 is applied from the color agent 1 to at least one or more regions on the side of the previously coated substrate facing the external observer, e.g., regions of the layer external body previously coated, preferably by spray application. The expression "at least one or more regions" means that at least that or those regions that will appear with the color 1 on the finished substrate (target regions), and which are therefore covered in process step d), are coated.

Since an exact limitation of the application of the color coater 1 to the target regions as a rule is not possible, particularly with spray application, the application of the color coating agent 1 will in each case cover regions slightly larger than simply target regions, and at least will exceed them to such a degree that a coating of the target regions with the coating composition is guaranteed. of color 1 in a cover thickness that complies with the respective specification. As a result, at least one region of the previously coated substrate side facing the external observer is coated with color 1 and the remaining region (s) is left uncoated. It is also possible to coat all the side of the previously coated substrate facing the external observer with the color 1, for example, the entire external layer of the previously coated body; in the context of the process according to the invention only the region that is covered in process step d) will be understood, however, as coated in such a way as to impart color. As a further alternative it is possible to coat with the color 1 that or those regions to be coated with color 1 on the finished substrate and therefore they are covered in process step d), and to coat the remaining regions on the substrate side oriented towards the external observer, using an additional coating agent that does not impart color. The color coating agent 1 and the additional coating agent that does not impart color can also be applied separately and in any order one after the other or with an overlap in time. For example, they can also be applied simultaneously using a plurality of application equipment, for example, multiple spray nozzles. In each case, they will be applied in a single coating stage without drying or curing taking place between the two applications. The formation of the overlapping areas of the color coating composition 1 and the additional coating composition that does not impart color will take place, with the overlapping areas being located outside the regions appearing with color 1 on the finished substrate. The color coating 1 can be applied by means of any coating system known per se to someone with experience, in particular those conventional in the coating of motor vehicles and in particular those that can be cured chemically (crosslinkable). Liquid coating systems based on solvent and / or water, powder coatings or dispersions of powder coatings may be included.

Conventional paints containing solvents or aqueous fillers, such as those used in the coating of motor vehicles, color 1 or conventional base coat systems of color 1 that fulfill both filler coverage functions (eg, resistance to chipping with stones, equalization of the surface of the substrate) and functions of base coatings (imparting color and / or effect) are particularly suitable in the case of motor vehicle bodies previously coated only with a primer coating applied by electrodeposition. The basecoat systems are preferably aqueous basecoating systems. In the description and in the claims, reference is made to base coverage or a distinction is made in relation to the aforementioned base coverage systems between unmodified base coverages and modified base coverages. If reference is made only to base coatings, it is understood that they are conventional base covering coating agents that impart color and / or effect (base coatings of solid colors; base coatings of special effects that impart color and effect or that only impart effect due to its content of imparting agents, such as aluminum pigments or interference pigments) known to the person skilled in the art. These are, in particular, aqueous base coatings, such as those conventionally used to produce the base cover layer that determines the tone of the double layer coatings of transparent cover / base coat that imparts color and / or effect. On the contrary, in the case of base coverage systems already discussed, a system consisting of a modified base coverage and, applied to it, is understood to be an unmodified base coverage. Whereas, the unmodified base coatings are the above-mentioned conventional base coat coating compositions known to someone skilled in the art, the modified base coat systems are produced therefrom by mixing with a blending component.

Preferably, the mixing component causes the base coatings modified therewith to acquire typical properties of fill coverage (resistance to chipping with stones, equalization of the substrate surface). Suitable mixing components for such modification of the base coatings are known from WO 97/47401, US 5,976,343, US 5,709,909 and US 5,968,655. These patent documents describe processes for producing multi-layer decorative coatings in which a multi-layer coating structure consisting of a modified base coat, an unmodified base coat subsequently applied and a transparent coat applied finally on a coating is produced. of baked primer applied by electrodeposition by the wet-on-wet method. First, the modified base coat is produced in said process from a base coat subsequently applied by the addition of a blending component and replaces the function of a conventional fill coat. While, WO 97/47401 recommends the addition of a polyisocyanate link crosslinking agent, in US 5,976,343, the addition of polyurethane resin or in US 5,709,909 and in US 5,968,655, the addition of a filling paste (paste) is described diluent) as a mixing component. The modified and unmodified basic cover base coats systems described in the aforementioned patent documents are examples of base coats systems usable in the process according to the invention. Therefore, these patent documents are explicitly but not restrictively referred to. If a base coat system of color 1 is used in the process, according to the invention, this includes at least one at least one modified base coverage. In particular, in the case of colors 1 of special effects. The base coat systems also preferably include the corresponding unmodified base coatings from which, as explained above, the modified base coatings applied in advance are produced by mixing with a mixing component. In the case of 1 solid colors, it is sufficient and preferable to apply only the modified base coverage; _ On the other hand, in the case of special effect colors 1, it is preferable to apply the base coverage of modified special effects and subsequently, the basic coverage of special effects without modifying the cured coverage of the modified special effects base coverage. Whereas, the modified base coats are preferably applied by high-speed rotary electrostatic application, the unmodified base coats are preferably applied by pneumatic means in the case of a special effects base coat. It can be explicitly emphasized at this point that the color coatings 1 produced with the described basecoat systems are understood as a single color coating layer 1 irrespective of whether they have been produced only from modified basecoats or by a combination of base covers modified in the first place and of unmodified base covers applied subsequently to them. In the case of motor vehicle bodies previously coated with a primer coating applied by electrodeposition and with a filler cover, in general, the base cover systems described above are not used. Instead, conventional color basecoats 1 are preferably used, i.e., unmodified. With respect to the nature of the coating compositions that do not comprise color 1 and that are optionally used for coatings that do not impart color in process step b), it is applied, having made the necessary changes, which is established with respect to to the color coating compositions 1. It is preferable, if the coating compositions are compatible with the color coating compositions 1, in particular, if they differ only slightly from the latter in their composition, for example, they are simply of different pigmentation and inherently belong to the same coating system.

The color coating compositions 1 and the non-imparting coating compositions optionally applied are applied in a dry film thickness in the range of, for example, 8 to 50 μm. In the case of the base coverage systems of modified and unmodified base covers, the dry film thickness is the sum of the two individual cover thicknesses. In the process step c) the applied coating of the color coating composition 1 and optionally, the additional coating composition that does not impart color in the process step b) is generally, first of all, exposed to air, or in the case of powder coatings or dispersions of powder coatings fused thereon, before curing takes place. The curing is carried out, in general by the supply of thermal energy, for example, by baking and / or by irradiation with infrared and / or near infrared radiation. The curing temperature that takes place during the thermal energy supply and the duration of the effect of the temperature are determined by the chemistry of the binder system in the used color coating composition 1 or in the coating compositions used. In process step d), the desired region of the color coating 1 is covered, that is, the region of the cured coating, which will appear with color 1 on the finished substrate coated with two shades. The plugging action is carried out with conventional means known to the person skilled in the art, for example, covering and / or preferably lining. In process step e), a color coating 2 is applied in a dry film thickness of, for example, 8 a 50 μm to the uncovered regions on the substrate side facing the external observer, for example, the outer layer of the body, in particular by spraying. The application of the color coating 2 takes place without a deliberate curing, that is, a subsequent curing step is not carried out. In other words, a curing of the color coating 2 is not carried out deliberately and generally does not "take place in the process step e." The color coating 2 can be applied by any coating system known per se to the person with experience in the art, in particular, conventional ones for the coating of motor vehicles, in particular, chemically curable ones.In particular, coating systems based on solvent and / or water are included.Conventional base coatings, that is to say without modifying color 2 or color base coatings systems 2 are in particular suitable for motor vehicle bodies, where it applies having made the necessary changes in both cases, with respect to the nature of the coating compositions and also their actual application (uncured), which was always stated above in relation to the process step b) for the base coverages and the systems Base color coverage 1.

After discovering in process step f), a transparent coating is applied in process step g) to a dry film thickness of, for example, 25 to 70 μm to the entire substrate facing the external observer, in the case of motor vehicle bodies to the entire outer layer of the body, that is, the transparent cover is applied in the region of the coating of color 1 to a coating-cure, while for the region of color 2 in general takes place a moist wet application of the clear coat to an uncured coating. Any clear cover composition can be used to produce the transparent cover layer. At first. all known transparent coats are suitable as transparent cover, which can be cured thermally and / or by exposure to high energy radiation, for example, UV radiation. Transparent coats containing one-component (1C) or two-component (2C) solvents, transparent 1C or 2C water-thin coatings, transparent powder coatings or dispersions of transparent powder coatings can be used in the present transparent coatings. In the final process step h) the curing of the transparent coating takes place and in general also that of the color coating 2. The nature of the curing depends in particular on the transparent covering system used. In the case of transparent coatings curable by exposure to high energy radiation, in particular UV radiation, curing is effected by corresponding radiation. In the case of transparent, thermally curable coatings, curing is effected by supplying thermal energy, for example, by baking and / or by irradiation with infrared or near infrared radiation. In the case of transparent coats that are thermally curable and curable by exposure to high-energy radiation, the so-called transparent coats of dual curing, curing takes place both by the supply of thermal energy and by corresponding irradiation. The process according to the invention produces substrates coated in two tones on its side facing the external observer, the multilayer coating structure which, as explained in more detail below by means of examples 1 to 8, can be of a different nature In the case of motor vehicle bodies, there is provided, both in the region of color 1 and in the region of color 2, between the primer applied by electrodeposition and the transparent cover, at least one coating layer which performs the functions of fill coverage, for example, a fill coverage that counts as a pre-cover or applied in process step b) or a modified base cover in process step b) and / or e). Some preferred examples of two-tone finishes that can be produced on substrates with the process according to the invention are shown below in the form of a table, avoiding the formation of a notorious edge between the areas of color 1 and color 2. Examples 1 , 3, 5, 6, and 7 are particularly preferred in relation to the bodies of motor vehicles. Unless the distinction is explicitly made between a solid color base coverage and a special effect base coverage in the examples, the term "base coverage" means a base coverage of special effect or a base coverage of solid color. For example, example 5 therefore includes four variants of two-tone finishes (color 1: solid color / color 2: solid color); color 1; solid color / color 2: special effect color; color 1: special effect color / color 2: solid color; color 1: special effect color / color 2: special effect color). EXAMPLES Applied in Coverage System the base color stage 2 that process e) consists of unmodified base coverage on modified and applied base coverage previously produced from the unmodified base coverage by mixing with a mixing component Applied in Coating of filling of the stage of color 1 process b) Prerecovering by Coating by electrodeposition bridging electrodeposition Applied in Coverage System the base color stage 2 that process e). Consists of unmodified base coverage on modified and previously applied base coverage produced from the unmodified base coverage by mixing with a mixed component Applied in Coverage System the base color stage 1 which process b) consists of unmodified base coverage and previously applied base coverage produced from the unmodified base coverage by mixing with a mixing component Prerecovery Coating by electrodeposition electrodeposition coating? j 6 Structure Structure of layer coating layering of multiple layers of area that multiple of "area appearing with color 1 appears with color 2 Applied in transparent Coverage Transparent coverage the process stage g) Applied in Coverage System the modified base stage of process e) solid color 2 produced from. the solid color base coat mixing with a mixed component Applied in Coverage System, the base color stage 1 of process b) special effect consisting of base coverage of special effect without modifying a base coverage of modified special effect and Applied Example 7 Structure structure of layer coating layer of multiple layers of the area that multiple of the area that appears with color 1 appears with color 2 Applied in transparent Coverage Transparent coverage in the process stage g) Applied in the Coverage System in the base stage of process color 2 e) special effect consisting of base coverage of special effect without modifying a base coverage of modified and applied special effect previously produced from the base coverage of special effect without modifying by mixing with a mixing component Applied in Base Coverage the stage of color modification process b) solid 1 produced from an unmodified solid color base covering by mixing with a component of mixing Prerecovery by Coating by electrodeposition electrodeposition coating Example 8 Structure of layer coating structure coating of multiple layers of the area that multiple of the area that appears with color 1 appears with color 2 Applied in transparent Coverage Transparent coverage in the process stage g) Applied in Base Coverage the stage of color modification 2 process e) produced from a base cover of solid color without modifying by mixing with a mixing component Applied in Base Coverage stage of color modified process b) solid 1 produced from a solid color base coat without modifying by blending with a blending component. Prerequisite Coating by electrodeposition electrodeposition coating Example 9 Production of a two-layered multi-layered coating light blue (solid color l) / dark blue (special effect color 2) of the type of example 7 One half of a steel panel of 30 cm x 60 cm in size and provided with a primer coat applied by electrodeposition is coated in a dry film thickness of 30 μm by high speed rotating electrostatic application with a modified light colored solid water base coat (produced by mixing a light blue aqueous base coat, Herberts Aqua Base, R 76013 with a mixed modifier component containing polyisocyanate, R 65400, in the weight ratio of 10: 1; both from DuPont Performance Coatings GmbH & Co. KG, Wuppertal). At the same time, an over sprayed area of light blue is produced in the other half of the panel. After everything is exposed to air for 5 minutes at 20 ° C, it is previously dried for 5 minutes at 80 ° C and baked for 20 minutes at 140 ° C. Half of the light blue painted panel is then lined and half of the unlined panel is coated with a dry film thickness of 16 μm by high-speed rotary electrostatic application with a dark blue special effect water-based coating (produced by mixing the dark blue special effect aqueous base coat, Herberts Water Base, R 76079 with a mixed modifier containing component, polyisocyanate, R 65400, in the weight ratio of 10: 1, both from DuPont Performance Coatings GmbH & Co. KG, Wuppertal) and then in a dry film thickness of 6 μm with the water-based coverage of special dark blue unmodified effect (Herberts Water Base, R 76079) by pneumatic application. After exposure to air for 5 minutes at 20 ° C and pre-drying for 5 minutes at 80 ° C, the liner is removed from the middle of the panel painted light blue and the entire panel is spray-coated to a dry film thickness 40 μm with a transparent two-component coating (produced by mixing 100 parts by weight of base R 40473 and 30 parts by weight of hardener containing polyisocyanate R 65430, both from DuPont Performance Coatings GmbH &Co. KG, Wuppertal). After exposure to air for 5 minutes at 20 ° C, baking was carried out for 20 minutes at 140 ° C. The resulting panel has a two-tone light blue / dark blue coating and does not have a noticeable border between the light blue and dark blue areas. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (11)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. Process for producing two-tone coated substrates, characterized in that it comprises the successive steps of: a) providing a previously coated substrate that does not impart color, b) applying a coating that imparts color of a color 1 to at least one or more regions on the substrate side facing an external observer, c) curing the color coating 1, d) covering the desired region of the color coating 1, e) applying a coating imparting color color 2 to the uncovered regions of the substrate side facing the external observer without. deliberately curing the color coating 2, f) discovering the capped regions in step d), g) applying a transparent cover to the entire side of the substrate facing the external observer, and h) curing the transparent cover.
2. 2. The process according to claim 1, characterized in that the substrates are bodies of motor vehicles and the side of the substrate facing an external observer is the outer layer of the body.
3. 3. The process according to claim 1 or 2, characterized in that the pre-coating is selected from the group consisting of a primer applied by electrodeposition and a primer applied by electrodeposition with a filler cover applied thereto. .
4. The process according to claim 1, 2 or 3, characterized in that in step b) the entire side of the substrate facing the external observer is coated with the color coating composition 1 or the region (s) to be covered in step d) is or are coated with the color coating composition 1 and the remaining regions or regions on the side of the substrate facing the external observer is either coated with a coating composition that does not impart color or is left uncoated .
5. The process according to claim 1 or 2, characterized in that the substrate is precoated with a primer applied by electrodeposition, the coating imparting color color 1 applied in step b) is applied from a coating composition selected from the group consisting of a filler coating composition, a modified base coat and a modified base coat applied first and an unmodified base coat applied subsequently and the coating imparting color 2 color applied in step e) is applies from a composition selected from the group consisting of a modified base coverage and a modified base coverage applied first and an unmodified base coverage subsequently applied, wherein the base coverages modified in steps b) and e) are in each case produced by mixing an unmodified base covering with a mixing component.
6. The process according to claim 5, characterized in that in step b) a modified solid color base coat is used, and in step e) a modified special effect base coat and subsequently the base coat of special effect without modifying corresponding.
7. The process according to claim 5, characterized in that in step b) a base cover of modified special effect is used, and subsequently the base coverage of special effect without modifying corresponding and in stage e) a base cover is used solid color
8. 8. The process according to claim 5, characterized in that solid color base coatings are used both in step b) and in step e).
9. 9. The process according to claim 5, characterized in that both a modified special effect base cover and subsequently the corresponding unmodified special effect base cover are used first in both step b) and in step e).
10. 10. The process according to claim 1 or 2, characterized in that the substrate is precoated with a primer applied by electrodeposition and a filler cover and both the coating imparting color color 1 applied in step b) and the coating imparting color 2 color applied in step e) they are applied from an unmodified base coverage.
11. 11. Substrates characterized in that they are coated by means of a process according to any of the preceding claims.