DE102014004430A1 - Self-adhesive plastic for the insulation of metal surfaces - Google Patents

Abstract

A method of coating a metal surface with a plastic and a component having a plastic surface coated with a plastic, the method comprising: providing a component with a metal surface; Providing a plastic having at least one functional group of an acid compound and / or silane compound, thereby producing a pressure-sensitive plastic; Injection molding or extruding the self-adhesive plastic on the component, so that it is applied directly to the metal surface and so at least partially coated the metal surface.

Description

Technical area

The invention relates to a method for coating a metal surface with a plastic and a component having a metal surface coated with a plastic.

Background of the invention

When coating or coating of metal profiles with a plastic, a bonding agent is common for material connection of the two materials, as for example in the EP 1 024 244 B2 is described. In particular, in vehicle applications resulting from this approach disadvantages, which are set out below:
In the context of the increasing weight reduction, aluminum components are used in vehicle construction, even with components of the power supply. For the interfaces with consumers, copper components are usually used. Due to the different potentials in the electrochemical series, corrosion between copper and aluminum takes place in the presence of moisture and oxygen. To prevent corrosion, the transition area between the materials must be hermetically sealed. In particular, the functionality of the transition region over the vehicle life is to be guaranteed. Due to the low material costs, the low processing temperature and the low process time are offered for isolation, ie for sheathing the current-carrying metal components, polypropylene or generally polyolefins and copolymers or blends of this plastic group.

In the above-mentioned material connection between different metals (such as copper and aluminum), manufacturing free often spaces, gaps or other openings are present, penetrate into the air and water deposits can occur. Furthermore, moisture accumulation may occur by capillary action effects. This leads to electrochemical corrosion of the metals.

For this reason, optimum adhesion between the metal component and the applied plastic is desirable. For this purpose, in the prior art, an adhesion promoter or primer was applied to the metal surface to be coated or coated, for example by spraying or rolling, painting, printing, etc. As a result, the plastic adheres well to the portions of the metal on which an adhesive has been applied However, a fissure, d. H. The ability of the plastic column to fill capillary clearances or non-adhesive areas and to enter into a firm bond with the metal, greatly reduced. An adhesion of the plastic in the gap and thus a sealed, filled space can be achieved very difficult. In particular, this capillary space can again be created by this non-adhesive plastic mass, can penetrate into the moisture (delamination effect). If this area lies in the dew point of a component or vehicle, moisture will be deposited after a long period of time, which can lead to field failures after years.

Description of the invention

It is an object of the invention to provide a method for coating a metal surface with a plastic and a component having a plastic surface coated with a plastic, whereby the life of the coated component can be increased, especially if they have a connection area of different metals, gaps, cut edges and / or has other openings.

The object is achieved with a method according to claim 1 and with a component according to claim 8. Advantageous developments follow from the subclaims, the following general description of the invention and the description of preferred embodiments.

Whenever a coating or casing of a metal surface is mentioned below, this does not mean that the entire metal surface or the entire component carrying the metal surface, such as a flat conductor, a contact lug or a contact plug, must be completely coated or sheathed. Rather, it is important that the plastic is at least partially applied directly to the metal surface, d. H. without an intermediate layer of an adhesion promoter (also referred to as "primer" or simply "adhesive"). The metal surface and the plastic go so far at least partially directly a cohesive connection. This is achieved in that the plastic is provided with at least one functional group of an acid compound and / or silane compound, whereby a self-adhesive plastic is produced.

It can thus be dispensed with an order of a bonding agent on the metal surface, which not only simplifies the coating process, ie specifically the injection molding or extrusion process, but also entails a number of other beneficial effects: Instead of a priming of the metal surface with masking, one additional, costly Materials, a preheating, the actual coating process and the process infrastructure (for example, with ventilation system, etc.) can be achieved in a process (injection molding, extrusion) insulation and sealing of the metal surface. This results in a time saving and cost savings due to the lower process cost. In addition, free spaces, gaps, openings and the like can be produced without cavity formation and with excellent durability, since they are easily filled by injection molding or extrusion. A detachment of the plastic does not take place due to the self-adhesive properties.

According to a particularly preferred embodiment, the component to be coated has a first and a different second metal, which are interconnected. The two metal components can be designed, for example, as a roll-plated bimetal or as overlapping metal wafers welded together. In the automotive sector, in particular copper or copper alloys and aluminum or aluminum alloys are used here. The coating or sheathing with the self-adhering plastic includes the bonding region of the two metals. "Enclosing" is of course not to be understood here as an all-round, hermetically sealed enclosure, but in such a way that the transition area or contact area of the two metal components is coated with the self-adhesive plastic. Through injection molding or extrusion, it is now ensured that the self-adhesive plastic completely penetrates into corners, edges, surfaces, cavities, gaps, openings that may be present in the joining region of the two metals, fills and seals them, insulates them and connects them. This ensures that no air or moisture can reach the sensitive areas of the metal transitions, thus preventing or at least minimizing corrosion.

In one embodiment, the component to be coated has a first and a different second metal, which are separated from each other. A compound of the two components is generated with the self-adhesive plastic.

The method described above is used in particular for the sheathing of flat conductors with lateral outlets. The lead can then be made of the first metal, for. As aluminum or an aluminum alloy, and the lateral outlets may be made of the second metal, for. B. of copper or a copper alloy exist. Here, all the lateral outlets, which are realized for example by tabs, sealed in a simple yet extremely reliable way and isolated. Of course, the application of the concept presented here is more extensive, with contact plugs, multilayer flat conductors, so-called B + leads and other current-carrying metal components being mentioned. In particular, a compound of metals with different electrochemical potentials can be effectively protected against corrosion.

An improvement in the surface adhesion of the pressure-sensitive plastic on the metal surface can be achieved by an anodization (eg 'flash anodization') of at least part of the metal surface.

Furthermore, at least part of the metal surface can be completely or partially tin-plated, nickel-plated, silver-plated, gold-plated or chrome-plated.

Polypropylene or polyethylene copolymers with incorporated functional groups of acid compounds or silane compounds are preferably used as self-adhesive plastics. As a suitable acid compound here maleic anhydride has been found. It is also possible to use a thermoplastic elastomer, polyvinyl chloride (PVC), styrene polymers or blends with styrene polymers, a polyamide (PA) or a polyamide blend and silicone.

By applying a common process pressure during injection molding (including reprinting) or extrusion, excellent adhesion is achieved. Preferably, the melt temperature of the plastic during injection molding or extrusion is within the usual range. By a polymer modification of the molecular weight or molecule chain length or by additives, the viscosity, d. H. the splitting of the self-adhesive plastic can be increased. A preheating of the metals to be joined with the plastic mass between 120 ° C to 220 ° C is preferred for an optimal, chemical compound in the injection molding or extrusion.

The present invention is particularly suitable for coating or sheathing current-carrying components in the automotive industry. Because especially in the automotive industry, in the ruling competition, it depends on extremely efficient manufacturing process, yet excellent quality and durability. The coating technique shown here is suitable in view of these objectives, since an increase in the life of the coated components can be achieved with simplified production. Nonetheless, the invention is also feasible and useful in other areas. Examples include: the transport area in general, ie in addition to Automotive, aerospace, aerospace, shipping, rail transport; Mechanical engineering, furniture construction, electrical and electronics, in particular consumer electronics, medical technology, building technology, the structural engineering and dry construction sector and the civil engineering and road construction sector. In addition, other advantages and features of the present invention will become apparent from the following description of preferred embodiments. The features described therein may be implemented alone or in combination with one or more of the above-mentioned features insofar as the features are not contradictory. The following description of the preferred embodiments will be made with reference to the accompanying drawings.

Brief description of the drawings

The 1a to 1h show cross sections of elongated jacketed profiles.

The 2a and 2 B show cross-sections through a respective connection region of two different metals, which once using a welding process ( 2a ) and once using roll cladding ( 2 B ) are connected.

The 3a to 3d show locally overmolded or extrusion-jacketed connection areas of two metal components.

4a to 4d show variations of the cross sections of the 3a to 3d , wherein the metal components are already partially coated.

The 5a and 5b show cross-sections of a locally overmolded flat metal and a welded stranded conductor.

The 6 shows an example of a locally overmolded or extrusion-coated component mounted on an insulated flat conductor, wherein the contact side is coated with a metallization.

The 7 shows schematically and exemplarily a production route with an extrusion tool and other stations.

Ways to carry out the invention

The 1a to 1h show cross sections through various exemplary profiles with continuous and / or discontinuous departures. Here and in all other figures, the reference numeral designates 10 a profile main body, in the 1a to 1h is elongated perpendicular to the plane of the paper. The profile main body are current-conducting components, such as aluminum. Departures attached to the profile main body 10 are provided are generally denoted by the reference numeral 20 designated. The attachments 20 consist of the same or a different material than the profile main body 10 , Various outlets 20 can also be provided from different materials. The departures 20 are usually laterally on the profile main body 10 provided, they can on several sides of the profile main body 10 be provided continuously or discontinuously.

The profile main body shown here 10 are particularly suitable for use as a single-layer or multi-layer flat conductor for building in the automotive industry. The profile main body 10 and the side exits 20 , which together form a "component" in general terms, are thus preferably current-carrying. The profiles in the 1a to 1h show, however, that other variants are possible; The cross sections illustrated here illustrate, by way of example, the scope of application of the sheathed profiles across many branches of industry. In the 1d For example, a sheathed profile is shown, which is not just two main body formed as a flat conductor 10 with associated lateral outlets 20 but also another extruded or jacketed material 100 , which may be about a light guide or stranded conductor comprises. In general, the profile main body 10 and the side exits 20 current-carrying, photoconductive, fluid-conducting, mechanically stabilizing, be provided for attachment or for another purpose. In the case of the electric wire, the profile main body 10 and / or the side outlets 20 preferably made entirely of metal, in particular of aluminum or copper. The profile main body 10 and / or the side outlets 20 may comprise glass fibers and / or consist of a transparent plastic, such as polycarbonate or PMMA, if they have a metal surface. The side branches 20 may also be composed of a plurality of interconnected metals, in particular of aluminum and copper. Basically, in this case, the profile main body 10 and / or the lateral departure 20 consist of conductive or non-conductive materials or components.

The above-mentioned attachment function as a possible embodiment of the outlets is in the 1f illustrated in the profile main body 10 a partially sheathed fastener 20 , which may be about a metal clip is provided. Such a fastener 20 with respect to a tubular profile main body 10 is in the 1h shown.

From the 1g goes out a profile in which one from the profile main body 10 punched out, partially covered outlet (notch) is provided. It may be a contact lug for electrical contacting or a fastener.

In all figures, the reference numeral designates 30 a plastic component (or "plastic") used as a sheath with the profile main body 10 cohesively connected. The plastic component 30 encases the profile main body 10 partially or completely, but without the disposals 20 completely encase, with the 1g an exception to this. It should be mentioned at this point that the plastic component 30 the lateral departures 20 Although not completely encase, but at least in the area of the transitions between the side outlets 20 and the profiles 10 is available. The cohesive connection of the plastic component 30 with the profile main body 10 is at least partially achieved in that the plastic component 30 a self-adhesive plastic is. The self-adhesive plastic has, in addition to a base plastic component - such as polypropylene, polyethylene or generally polyolefin - and one or more built-in functional groups of acid compounds and / or silane compounds.

In the 1g an embodiment is shown in which in addition to the cohesive sheath with the plastic component 30 yet another plastic component 31 on the main body or on the plastic component 30 attached and / or materially connected. This can be formed for example as a sealing lip.

The 2a and 2 B each show a connection region of two different metal elements, in which case a connection lug 20 , such as copper, with a profile main body 10 , such as aluminum, in the connection area 50 connected to each other. In the 2a were the two parts 10 and 20 welded together. In the 2 B the connection was carried out by means of roll cladding. In both cases, gaps or generally free spaces S may remain due to the injection molding or extrusion of the self-adhesive plastic component 30 water and airtight filled. In the case of the previously customary use of a bonding agent to achieve the connection between the plastic component 30 and the profile main body 10 or the departures 20 Often enough, there was not enough cohesive bond between the metal and the plastic in the gap areas S, so that these locations were susceptible to corrosion.

In the 3a to 3d are locally overmolded or jacketed profiles or elements with outlets 20 shown. In the connection area 50 The two metal parts became the self-adhesive plastic component 30 extruded or sprayed. The 3a and 3b correspond to the 2a and 2 B , wherein the coating or sheath in the connection area 50 is shown. Other profiles are in the 3c and 3d shown. From the 3c shows that openings 40 , which serve as areas of "clawing", with the self-adhesive plastic 30 can be filled. Such a claw becomes effective by the self-adhering plastic used here 30 allows. Another geometry comes from the 3d out.

The profiles of 4a to 4d correspond to the profiles of 3a to 3d wherein cases are shown in which the profile main body 10 already an existing sheathing 31 and / or the departures 20 already a plastic casing 32 exhibit. The self-adhesive plastic 30 and the plastic jacketing applied here before 31 and 32 partially overlap and form a tight and secure connection, providing even greater protection of the sheathed component, especially the joint area 50 between the two metal parts 10 and 20 will be produced.

The 5a and 5b show further embodiments in which the profile main body 10 or the departure 20 a stranded conductor 60 is welded. The welded stranded conductor 60 is also at least partially with a plastic component 33 jacketed. The strands of the stranded conductor 60 are denoted by the reference numeral 61 designated. Due to the direct cohesive connection of the self-adhesive plastic 30 is a complete seal even in the connection area 50 possible with a stranded conductor, which was previously extremely difficult with the aid of a bonding agent.

The 6 shows an example of a flat conductor 11 mounted component with a profile main body 10 and a finish 20 , where the contact area of the departure 20 with a metallization 70 is coated. In the metallization 70 it may be an at least partial tinning, nickel plating, silver plating, gold plating or chrome plating. The flat conductor 11 is already with a plastic sheath 31 coated as insulation material. The self-adhesive plastic component 30 The plastic coating overlaps or overlaps the material 31 of the flat conductor 11 , the flat conductor 11 , the profile main body 10 , the finish 20 as well as the metallized surface 70 the departure 20 , The self-adhesive plastic component 30 thus isolates another plastic, three different metal surfaces and a metallized surface to the outside and thus prevents penetration of z. B. moisture to the critical transition areas 50 ,

The 7 schematically shows an extrusion process with extrusion die and other stations. The extrusion tool is denoted by the reference numeral 200 and the extruder with 201 designated. Before extrusion in the extrusion tool 200 that an extruder 201 has, there is a preheating of the component to be covered, ie about the profile main body 10 with departures 20 , to a temperature preferably between 150 ° C to 220 ° C instead. To preheat a polypropylene on aluminum, a preheating of 180 ° C has been found to be suitable. This preheating happens at the station 210 , By preheating the component to be coated, the cohesive connection with the self-adhesive plastic 30 significantly improved or even made possible in some cases, depending on the materials used. At the as "coil" 220 designated station, the provision of the component to be coated takes place, here as an aluminum strip for producing a flat conductor as a profile main body 10 is provided. This is of course very exemplary, and whether now an aluminum strip is unwound from a roll and then the heater 210 and then the extrusion tool 200 is supplied, or whether the component to be coated is supplied in another way, is not crucial here. After the extrusion (or alternatively the injection molding), a calibration may be carried out in a calibrating device 230 , whereby the product is brought to the later product dimension, followed by a cooling in a water bath 240 at about 10 ° C, and finally the jacketed component in a blanking device 250 by means of a knife or a saw 251 tailored and at the station 260 packed up. In the process shown here is about a transport or belt speed of about 4 to 5 m per minute into consideration.

• – Selbsthaftende Polyolefine, besonders selbsthaftendes Polypropylen und Polyethylen; Ethylen/Ethylacrylat-Copolymere;
• – Maleinsäureanhydrid gepfropftes EPM oder EPDM (Ethylen/Propylen/Dien-Copolymere); Ethylen/Buten-Copolymer;
• – Thermoplastische Elastomere (TPE), d. h. Blends wie z. B. TPE-V Thermoplast/Elastomerblends vernetzt (PTV) oder TPE-O Thermoplast/Elastomerblends unvernetzt (TPO) bzw. Copolymere wie z. B. TPE-U thermoplastische Polyurethane (TPU), TPE-E thermoplastische Copolyester (TPC), TPE-A Polyether-Blockamide (TPA) oder TPE-S Styrol-Blockcopolymere (TPS); die polar bzw. Metall-anhaftend sind; eine Oberflächenaktivierung über Plasmabehandlung kann von Vorteil sein;
• – Polyvinylchlorid (PVC) als ein polares Polymermaterial; so können beispielsweise Drähte, Profile usw. mit PVC im Extrusionsprozess ummantelt werden;
• – Styrolpolymerisate, wie etwa Polystyrol (PS), deren Homopolymere und Copolymere, Acrylnitril/Butadien/Styrolpfropfpolymere (ABS), Styrol/Acrylnitrilcopolymere (SAN), Styrol/Butadien/Styrol-Blockpolymere (SBS) können ebenfalls mit einem Haftvermittler, wie z. B. MAH (Maleinsäure Anhydrid) gepfropft werden;
• – Polyamide (PA) und deren Copolymerisate oder Blends (Mischungen);
• – Silikone, insbesondere LSR-Varianten (Liquid Silicone Resins).

The following plastics, for example, are suitable for the described embodiments:

• - Self-adhesive polyolefins, especially self-adhesive polypropylene and polyethylene; Ethylene / ethyl acrylate copolymers;
• Maleic anhydride grafted EPM or EPDM (ethylene / propylene / diene copolymers); Ethylene / butene copolymer;
• - Thermoplastic elastomers (TPE), ie blends such. B. TPE-V thermoplastic / elastomer blends crosslinked (PTV) or TPE-O thermoplastic / elastomer blends uncrosslinked (TPO) or copolymers such. TPE-U thermoplastic polyurethanes (TPU), TPE-E thermoplastic copolyesters (TPC), TPE-A polyether block amides (TPA) or TPE-S styrene block copolymers (TPS); which are polar or metal-adherent; surface activation via plasma treatment may be beneficial;
• Polyvinyl chloride (PVC) as a polar polymeric material; For example, wires, profiles, etc. can be encased with PVC in the extrusion process;
• Styrene polymers, such as polystyrene (PS), their homopolymers and copolymers, acrylonitrile / butadiene / styrene graft polymers (ABS), styrene / acrylonitrile copolymers (SAN), styrene / butadiene / styrene block polymers (SBS) can also be treated with a coupling agent, e.g. B. MAH (maleic anhydride) are grafted;
• - polyamides (PA) and their copolymers or blends (mixtures);
• - Silicones, in particular LSR variants (Liquid Silicone Resins).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1024244 B2 [0002]

Claims (16)

A method of coating a metal surface with a plastic, the method comprising: providing a component ( 10 . 20 ) with a metal surface; Providing a plastic having at least one functional group of an acid compound and / or silane compound, whereby a self-adhesive plastic ( 30 ) will be produced; Injection molding or extrusion of the self-adhesive plastic ( 30 ) on the component ( 10 . 20 ), so that it is applied directly to the metal surface and so at least partially coated the metal surface. A method according to claim 1, characterized in that the component to be coated has a first and a different second metal, which are connected to each other, wherein the coating of the connection area ( 50 ) of the two metals. A method according to claim 1, characterized in that the component to be coated has a first and a different second metal, which are separated from each other, wherein a compound of the two components ( 10 . 20 ) with the self-adhesive plastic ( 30 ) is produced. A method according to claim 2 or 3, characterized in that the first metal is aluminum or an aluminum alloy and the second metal is copper or a copper alloy. Method according to one of the preceding claims, characterized in that the component to be coated ( 10 . 20 ) has a flat conductor and / or one or more contact lugs. Method according to one of the preceding claims, characterized in that the component ( 10 . 20 ) a gap (S), a cut edge or an opening ( 40 ), which during injection molding or extrusion with the self-adhesive plastic ( 30 ) is filled. Method according to one of the preceding claims, characterized in that the loading of the self-adhesive plastic ( 30 ) takes place on the preheated to a temperature of 120 to 220 ° C metal surface. Component ( 10 . 20 ) with one with a plastic ( 30 ) coated metal surface, wherein the plastic ( 30 ) has at least one functional group of an acid compound and / or silane compound. Component ( 10 . 20 ) according to claim 8, characterized in that the coated metal surface has a first and a different second metal, which are connected to one another, wherein the coating covers the connecting region ( 50 ) of the two metals. Component ( 10 . 20 ) according to claim 8, characterized in that the coated metal surface comprises a first and a different second metal, which are separated from each other, wherein a compound of the two metal surfaces of the self-adhesive plastic ( 30 ) consists. Component ( 10 . 20 ) according to claim 9 or 10, characterized in that the first metal is aluminum or an aluminum alloy and the second metal is copper or a copper alloy. Component ( 10 . 20 ) according to one of claims 8 to 11, characterized in that the coated component ( 10 . 20 ) has a flat conductor and / or one or more contact lugs. Component ( 10 . 20 ) according to one of claims 8 to 12, characterized in that it has a gap (S), a cut edge or an opening ( 50 ) which is in contact with the plastic ( 30 ) is filled. Method or component ( 10 . 20 ) according to one of the preceding claims, characterized in that the self-adhesive plastic ( 30 ) has at least one of the following: • polypropylene copolymer or polyethylene copolymer, • thermoplastic elastomer, • polyvinyl chloride (PVC), • styrene polymers or blends with styrene polymers, • a polyamide (PA) or a polyamide blend, • silicone. Method or component ( 10 . 20 ) according to any one of the preceding claims, wherein the acid compound of the plastic ( 30 ) comprises a maleic anhydride. Method or component ( 10 . 20 ) according to one of the preceding claims, wherein the metal surface is at least partially tinned, nickel-plated, silvered, gold-plated or chrome-plated.

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