EP1414589B1 - Scratch-resistant finish for coated substrates - Google Patents

Abstract

The invention relates to use of plasma polymerisation and plasma polymers for the scratch-resistant finishing of coated substrates, a method for the production of a scratch-resistant finish on a coated substrate by application of at least one scratch-resistant layer on the coated substrate by plasma polymerisation and a coated substrate with a scratch-resistant finish, comprising at least one layer made from a plasma polymer produced by plasma polymerisation as outermost layer.

Description

The present invention relates to the novel use of plasma polymerization and plasma polymers for the scratchproofing of coated substrates. In addition, the present invention relates. Invention a novel process for producing a scratch-resistant finish on a coated substrate by applying at least one scratch-resistant layer on the coated substrate by plasma polymerization. Furthermore, the present invention relates to novel scratch-resistant coated substrates having at least one layer of a plasma polymer produced by plasma polymerization as the top layer.

Made of e.g. EP 0 349 749 discloses a plasma pretreatment, but no plasma coating.

DE 197 32 217 discloses the plasma coating of photovoltaic semiconductor components as substrates and WO 01/41541 of plastics as substrates.

The production of layers of plasma polymers on metallic substrates by plasma polymerization of suitable compounds is known from the thesis of G. Grundmeier, "Interface Chemical and Corrosion Analytical Investigations of Plasma Polymer Coatings on Steel", Faculty of Engineering of the University of Erlangen-Nuremberg, 1997, patents EP 0 533 606 B 1, EP 0 619 847 B 1 or EP 0 515 373 B 2 or from the articles of Tinghao F. Wang et al., "Corrosion protection of cold rolled steel by low temperature plasma interface engineering", in progress in Organic Coatings, Vol 28, pages 291 to 297, 1996, by MP Bonnar, B.M. Bumside, A. Little, RL Reuben and JIB Wilson, "Plasma Polymer Films for Dropwise Condensation of Steam", Chemical Vapor Deposition, 1997, Vol. 3, No. 4 , Pages 201 to 207, or by G. Grundmeier and M. Stratmann, "Plasma polymerization - a new and promising way for the corrosion protection of steel ", Materials and Corrosion, Vol. 49, pages 150 to 160, 1998.

US Pat. No. 4,980,196 discloses the plasma coating of metallic substrates, it being possible to apply a further layer to a first layer produced by means of plasma coating.

These plasma polymer layers are mainly used for the corrosion protection of metal surfaces. The question as to whether the plasma polymer layers are scratch-resistant does not arise at all in this context, because the layers are overcoated with other coatings (cf the above-mentioned thesis by Grundmeier).

The scratch resistance of coatings on substrates often leaves much to be desired. Insufficient scratch resistance leads to unsightliness of protective and / or decorative coatings.

Problems of scratch resistance are of great economic and aesthetic importance, above all in vehicle paintwork, in particular car paintwork.

On the one hand, pre-painted automobile bodies can be scratched in the factory during final assembly if, for example, test cards are pushed over the bonnet or the bodies are unintentionally struck by the fitter. These, though often only light, scratches are particularly unpleasant in bright light, especially in brand new cars.

Furthermore, it comes in car washes, especially in dirty washing water to the so-called Waschkratzem that make quite noticeable especially in the sunshine.

The automotive industry is therefore anxious to get the problem of insufficient scratch resistance by the use of scratch-resistant coatings under control.

One possibility is the coating of the series finishes with a so-called scratch-resistant sealer based on sol-gel clearcoats, as described for example in the patent applications DE 43 03 570 A1, DE 34 07 087 A1, DE 40 11 045 A1, DE 40 25 215 A 1, DE 38 28 098 A 1, DE 40 20 316 A 1 or DE 41 22 743 A 1 are known. These sol-gel clearcoats or the layers produced therefrom are also referred to by the experts as organically modified ceramic materials. One of their main applications is the scratch-resistant equipment of glasses or visors of motorcycle helmets.

The known scratch-resistant equipment on the basis of sol-gel clearcoats, however, have a low solids content, which is forcibly accompanied by a high solvent content. This high solvent content is questionable and disadvantageous for reasons of safety and environmental protection.
Usually, the known scratch-resistant equipment has a dry film thickness of 10 microns. They have a sufficient overall appearance (appearance). At this layer thickness, generally only relatively minor problems of adhesion between the scratch resistant finish and the underlying paint occur. But if you want to further improve the scratch resistance and further reduce the dry film thickness, for example, to 3 to 5 microns, the Appearance deteriorates.

The object of the present invention is to provide a new scratch-resistant equipment for coated substrates, in particular painted automobile bodies, specially painted passenger car bodies, which no longer has the disadvantages of the prior art, but which reliably provide the coated substrates even in a small layer thickness Protects against scratches and has a good appearance and adheres firmly to the coatings. In addition, the new scratch-resistant equipment should be produced in a simple manner, without solvents and without a large amount of material and have a very good Appearance.

Accordingly, the novel use of plasma polymerization and plasma polymers for scratch resistant finishing of coated substrates has been found, hereinafter referred to as "inventive use".

In addition, the novel process for producing scratch resistant equipment on a coated substrate has been found by depositing at least one scratch resistant plasma polymer layer on the coated substrate by plasma polymerisation, hereinafter referred to as the "process of the invention".

Last but not least, the novel scratch-resistant coated substrate with at least one layer of a plasma polymer produced by plasma polymerization was found to be the uppermost layer, which is referred to below as the "inventive substrate".

In view of the prior art, it was surprising and unforeseeable for the skilled person that the object on which the present invention was based could be achieved with the aid of the use according to the invention. This was all the more surprising as the plasma polymer layers were applied so far only for purposes of corrosion protection or for the modification of metallic surfaces directly on this.

The inventive method is based on a coated metallic substrate.

Examples of suitable metals to be used according to the invention are titanium, iron, cobalt, nickel, magnesium, aluminum, zinc or their alloys with each other or with other suitable metals such as copper, vanadium, tungsten, molybdenum, chromium, manganese or tin. According to the invention, those metals are of advantage, which are commonly used in the automotive industry for the production of bodies. They are therefore preferred. Examples of suitable metals to be used according to the invention of this type are Steels, in particular cold-rolled steels and metallic coated steel sheets.

In and of itself, the substrate may have any shape, such as the shape of a fender, a car door, a hood or a boot lid. According to the invention, it is advantageous if the substrate is planar and is present in particular as a metal sheet or strip.

The thickness of the substrate can vary widely and depends on the particular intended use of the substrate according to the invention. Advantageous in this case thicknesses of 0.05 mm to 10 mm, as they are commonly used in the automotive industry.

The substrate is coated, i. h. That there is at least one lacquer film and / or at least one lacquer thereon.

The coating serves to protect the substrate from corrosion, the absorption and dissipation of mechanical energy, the clearcoat and / or the color and / or effect.

Examples of suitable anticorrosive coatings are electrodeposition electrodeposition coatings such as disclosed in Japanese Patent Application 1975-142501 (Japanese Laid-open Patent Publication JP 52-065534 A2, Chemical Abstracts Unit No. 87: 137427) or US Pat. Nos. 4,375,498 and 4,375,498 4,537,926 A, US Pat. No. 4,761,212 A, EP 0 529 335 A1, DE 41 25 459 A1, EP 0 595 186 A1, EP 0 074 634 A1, EP 0 505 445 A1, DE 42 35 778 A1, EP 0 646 420 A1, EP 0 639 660 A1, EP 0 817 648 A1, DE 195 12 017 C1, EP 0 192 113 A2, DE 41 26 476 A1 or WO 98/07794.

Examples of suitable coatings for the absorption and dissipation of mechanical energy are surfacer coats and antistonechip primers, as described, for example, in the patent applications and patents EP 0 427 028 A 1, DE 41 42 816 A 1, DE 38 05 629 C 1, DE 31 08 861 C 2 or DE 195 04 947 A1 are described.

Examples of suitable color and / or effect coatings are solid-color topcoats or basecoats, as described, for example, in 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 A1, EP 0 228 003 A1, EP 0 397 806 A1, EP 0 574 417 A1, EP 0 531 510 A1, EP 0 581 211 A1, EP-0 708 788 A1, EP 0 593 454 A1, 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 A1, WO 95/14721, EP 0 521 928 A1, EP 0 522 420 A1, EP 0 522 419 A1, EP 0 649 865 A1, EP 0 536 712 A 1, EP 0 596 460 A1, 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 A 1, EP 0 424 705 A1, WO 97/49745, WO 97/49747, EP 0 401 565 A1, EP 0 496 205 A1, EP 0 358 979 A1, EP 469 389 A1, DE 24 46 442 A 1, DE 34 09 080 A 1, DE 195 47 944 A 1, DE 197 41 554 A 1 or EP 0 817 684, column 5, lines 31 to 45, are described in detail.

Examples of suitable clearcoats are those which are prepared from single-component or multicomponent clearcoats, powder clearcoats, powder clearcoat materials, UV-curable clearcoats or sealants, as disclosed in the patent applications, patents and publications DE 42 04 518 A1, EP 0 594 068 A1, EP O 594 071 A1, EP 0 594 142 A1, EP 0 604 992 A1, EP 0 596 460 A1, WO 94/10211, WO 94/10212, WO 94/10213, WO 94/22969 or WO92 / 22615, US Pat. No. 5,474,811 A1, US Pat. No. 5,356,669 A1 or US Pat. No. 5,605,965 A1, DE 42 22 194 A1, BASF Lacke + Farben AG, "Powder Coatings", 1990, BASF Coatings AG "Powder Coatings, Powder Coatings for Industrial Applications", January 2000 DE 195 18 392 A1, DE 196 17 086 A1, DE-A-196 13 547, DE 196 52 813 A1, DE-A-198 14 471 A 1, 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 0 002 866 A1, DE 197 09 467 A 1, 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 Nos. 4,324,252 A, 4,634,602 A, 4,424,252 A, 4,208,313 A, US Pat. No. 4,163,810 A, US Pat. No. 4,129,488 A, US Pat. No. 4,064,161 A, US Pat. No. 3,974,303, EP 0 844 286 A1, DE 43 03 570 A 1, DE 34 07 087 A 1, DE 40 11 045. A 1, DE 40 25 215 A 1, DE 38 28 098 A 1, DE 40 20 316 A 1 or DE 41 22 743 A 1 are known.

Examples of suitable paint films are known from patent applications WO94 / 09983 A, EP 0 361 823 A1, DE 195 35 934 A1, DE 195 17 069 A1, DE 195 17 067 A1 or 195 17 068 A1 or the publications of E. Bürkle in Kunststoffe 87 (1997), 320-328; Modem Plastics International Volume 11, 1997, 33-34, or by G. Steinbichler and J. Gießauf in Kunststoffe 87 (1997), 1262-1270.

In the context of the method according to the invention, the coatings described above are preferably pretreated with an oxidizing plasma. The pre-treatment serves to clean and activate the surface of the coatings. Examples of suitable oxidizing agents for producing the oxidizing plasma are fluorine, chlorine or oxygen, in particular oxygen. The oxidizing plasma may also contain noble gases and / or nitrogen.

The conditions of the pretreatment can vary widely and depend on the requirements of each individual case. In particular, the applied pressure in the plasma, depending on the material composition, be up to 1 bar.

In the oxygen plasma, oxygen partial pressures of from 0.01 to 3, preferably from 0.02 to 2.5, more preferably from 0.03 to 2, very preferably from 0.04 to 1.5 and in particular from 0.05 to 1 mbar, are preferably voltages from 200 to 800, preferably 210 to 750, particularly preferably 220 to 700, very particularly preferably 230 to 650 and in particular 240 to 600 V, current strengths of 0.1 to 5, preferably 0.2 to 4.8, particularly preferably 0, 3 to 4.4, very particularly preferably 0.4 to 4.2 and in particular 0.5 to 4 mA, volume flows from 0.1 to 3, preferably 0.2 to 2.8, particularly preferably 0.3 to 2.4, very particularly preferably 0.4 to 2.2 and in particular 0.5 to 2 st. cm3 / min and frequencies of 0.1 to 3, preferably 0.2 to 2.7, particularly preferably 0.3 to 2.3, very particularly preferably 0.4 to 2 and in particular 0.5 to 1.5 kHz applied ,

In the course of the process according to the invention, at least one, preferably one, layer of at least one plasma polymer is deposited on the preferably cleaned and activated surface of the coatings by plasma polymerization.

For plasma polymerization, a wide variety of organic and inorganic compounds can be used. According to the invention, it is advantageous to use at least one elemental organic compound.

In the context of the present invention, organometallic, in particular organometallic, compounds are compounds in which at least one element other than carbon is linked to organic radicals, such as substituted or unsubstituted alkyl, cycloalkyl and / or aryl radicals, which may also contain heteroatoms.

Suitable organometallic compounds are organometallic compounds of metals of the subgroups of the Periodic Table of the Elements. Examples of suitable elements are scandium, yttrium, lanthanum, the lanthanides, titanium, zirconium, hafnium, vanadium, niobium, chromium, tungsten, manganese, iron, cobalt, nickel, copper or zinc. The organometallic compounds may contain one or more metal atoms in the molecule. If they contain several metal atoms in the molecule, they can be one and the same metal or at least two different metals.

Other suitable organometallic compounds are organic compounds of metals and nonmetals of the main groups of the Periodic Table of the Elements. Examples of suitable metals and non-metals are boron, Aluminum, gallium, indium, silicon, germanium, tin or phosphorus. Particularly suitable is silicon.

Further suitable organometallic compounds are organic compounds which contain at least one of the abovementioned metals of the subgroups of the Periodic Table of the Elements and at least one of the abovementioned metals or nonmetals of the main groups of the Periodic Table of the Elements.

According to the invention, it is advantageous to use organic compounds of silicon, such as hexamethyldisilane or hexamethyldisiloxane, in particular hexamethyldisilane.

The organic compounds of silicon which are preferably used according to the invention may contain at least one further of the above-described organometallic compounds in minor amounts.

In the context of the present invention, "subordinate amounts" are to be understood here and below as amounts which advantageously vary the property profile of the plasma polymer layer but do not determine its basic properties.

Furthermore, the above-described organoelement compounds to be used according to the invention may contain purely organic compounds in minor amounts. Preferably, polymerizable organic compounds are used. Examples of suitable polymerizable organic compounds are olefins and acetylenes, in particular olefins such as cyclohexene.

The plasma polymerization of the compounds described above can be carried out in the presence of at least one oxidizing agent. Examples of suitable oxidizing agents are those described above.

In addition, the plasma polymerization can be carried out in the presence of at least one noble gas, in particular argon.

From a methodological point of view, the plasma polymerization has no special features, but can be carried out by the methods and with the aid of the devices as described in the patents, patent applications and publications mentioned in the introduction.

Preferably, the plasma polymerization is carried out for 10 minutes to 3 hours, preferably 15 minutes to 2.5 hours, more preferably 20 minutes to 2 hours and 15 minutes, most preferably 30 minutes to 2 hours and especially 40 minutes to 1.5 hours. Partial pressures of organometallic compound of from 0.001 to 0.2, preferably from 0.002 to 0.18, particularly preferably from 0.003 to 0.16, very particularly preferably from 0.004 to 0.14 and in particular from 0.005 to 0.12 mbar, if used, argon partial pressures, are preferably used from 0.01 to 2, preferably from 0.02 to 1.8, particularly preferably from 0.03 to 1.6, very particularly preferably from 0.04 to 1.4 and in particular from 0.0 to 1 mbar, if used, oxygen partial pressures of 0.001 to 0.2, preferably 0.002 to 0.18, more preferably 0.003 to 0.16, most preferably 0.004 to 0.14 and especially 0.005 to 0.12 mbar, tensions of 200 to 800, preferably 210 to 750, especially preferably 220 to 700, very particularly preferably 230 to 650 and in particular 240 to 600 V, current strengths of 0.1 to 5, preferably 0.2 to 4.8, particularly preferably 0.3 to 4.4, very particularly preferably 0, 4 to 4.2 and in particular 0.5 to 4 mA, volume flows of 0.1 to 3, preferably 0.2 to 2.8, particularly preferably 0.3 to 2.4, very particularly preferably 0.4 to 2.2 and in particular 0.5 to 2 st. cm3 / min and frequencies of 0.1 to 10, preferably 0.2 to 9, more preferably 0.3 to 8, most preferably 0.4 to 7 and in particular 0.5 to 6 kHz applied.

Preferably, the deposited plasma polymer layer is 0.001 to 10, preferably. 0.01 to 9, particularly preferably 0.1 to 8, very particularly preferably 0.5 to 7 and in particular 1 to 6 microns thick.

The composition of the plasma polymer layer may be homogeneous or it may vary vertically in different ways. First, the concentration of a component within the plasma polymer layer may decrease or increase continuously or discontinuously. When the concentration of functional groups varies, the plasma polymer is called "gradient plasma monolayer". This gradient plasma polymer is characterized by having special functional groups at the phase boundary coating / plasma polymer, for example, organosilicon functional groups. As a result, the adhesion is optimized at the interfaces, which leads to an optimal stability of the scratch-resistant equipment. However, the plasma polymer layer can also consist of layers of different composition.

The plasma polymer layer according to the invention or the scratch-resistant coated substrates are of very good optical quality (appearance), so that they also come into consideration for the scratch-resistant painting of cars of the automotive upper class. The scratch-resistant equipment according to the invention adheres extremely firmly to the coated bodies and shows no damage or spalling even under mechanical action. It is stable to weather and chemical stable and is not attacked by bird droppings. The scratch-resistant in accordance with the invention equipped motor vehicles therefore have a particularly long service life and a particularly high utility value.

example The preparation of a scratch resistant equipment according to the invention by Plasmapotymerisation

A body panel conventionally coated with a cathodic electrodeposition paint, a filler, a metallic basecoat, and a clearcoat was coated in a plasma reactor comprising an evacuable bell jar with internal electrodes, gas metering systems, and a high vacuum pump grounded electrode placed.

The painted surface of the body panel was exposed to an oxygen plasma for 5 minutes at an oxygen partial pressure of 0.3 mbar, a voltage of 400 V, a current of 2 mA and a volume flow of 1.5 st. pretreated cm ³ / min and a frequency of 1 kHz.

The plasma polymer was heated for one hour at an argon partial pressure of 0.2 mbar, an oxygen partial pressure of 0.05 mbar and a hexamethyldisilane partial pressure of 0.05 mbar, a voltage of 400 V, a current of 1 mA and a volume flow of 1, 5 st. cm ³ / min and a frequency of 4 kHz.

The plasma polymer layer was 3 μm thick. She was firmly attached to the paint job. Delamination was also not observed after loading in the constant condenser climate. The plasma polymer layer was highly scratch resistant and could be among the usual and well-known. Conditions of the brush test (see P. Betz and A. Bartelt, Progress in Organic Coatings, 22 (1993), pages 27-37, especially Fig. 2, page 28; used weight: 2000 g instead of 280 g) are not damaged. It was therefore excellently suitable as scratch-resistant equipment. The scratch-resistant equipment and the paint overall had a good overall appearance.

Claims (12)

1. Use of plasma polymerization and of plasma polymers for the scratchproofing of coated metallic substrates, wherein the coating on the substrate comprises at least one dry-paint film and/or at least one paint coat.
2. Process for producing a scratchproof finish on a coated metallic substrate by applying at least one scratchproof film to the coated substrate, characterized in that the scratchproof film is deposited by plasma polymerization, and wherein the coating on the substrate comprises at least one dry-paint film and/or at least one paint coat.
3. Scratchproofed coated metallic substrate comprising as its topmost layer at least one film of a plasma polymer prepared by plasma polymerization, wherein the coating on the substrate comprises at least one dry-paint film and/or at least one paint coat.
4. The use according to Claim 1, the process according to Claim 2, or the substrate according to Claim 3, characterized in that the coating on the substrate serves to protect against corrosion, to absorb and dissipate mechanical energy, as a clearcoat, and/or to impart colour and/or effect.
5. The use according to one of Claims 1 or 4, the process according to one of Claims 2 or 4, or the substrate according to one of Claims 3 or 4, characterized in that the coating on the substrate is pretreated with an oxidizing plasma.
6. The use, process or substrate according to Claim 5, characterized in that an oxygen plasma is used as oxidizing plasma.
7. The use according to one of Claims 1 and 4 to 6, the process according to one of Claims 2 and 4 to 6 or the substrate according to one of Claims 3 to 6, characterized in that at least one organoelemental compound is used for the plasma polymerization.
8. Use, process or substrate according to Claim 7, characterized in that at least one organometallic compound of metals from the transition groups of the Periodic Table of the Elements, at least one organic compound of metals and nonmetals from the main groups of the Periodic Table of the Elements and/or at least one organic compound containing at least one metal from the transition groups and at least one metal or nonmetal from the main groups of the Periodic Table of the Elements is used as organoelemental compound.
9. Use, process or substrate according to Claim 8, characterized in that at least one silicon compound is used as organoelemental compound.
10. Use, process or substrate according to Claim 9, characterized in that hexamethyldisilane is used as silicon compound.
11. Use according to one of Claims 1 and 4 to 10, process according to one of Claims 2 and 4 to 10 or substrate according to one of Claims 3 to 10, characterized in that the plasma polymerization is conducted in the presence of an oxidizing agent and/or a noble gas.
12. Use, process or substrate according to Claim 11, characterized in that oxygen is used as oxidizing agent and argon is used as noble gas.