FR3018827A1 - PROCESS FOR REALIZING METALLIC PARTS - Google Patents

Abstract

The invention relates to a method for modifying a metallized part in which a metallized piece is provided comprising a non-metallic support (S) successively having a tie layer (C1), a reinforcing layer (C2), a layer of nickel (C3), and a layer of chromium (C4 '). The chromium layer (C4 ') is removed, then a layer of varnish (C4) is deposited on the nickel layer (C3).

Description

BACKGROUND OF THE INVENTION The present invention relates to the field of metallization processes for parts, and in particular non-metallic supports. There are different ways to achieve a metallization of a non-metallic support. We know in particular the processes by dry plasma, or flame. Vacuum metallization processes such as the PVD method are also known. However, these methods have the disadvantage of being relatively expensive because of the energy required and the conditions under which they must be performed. Moreover, they present difficulties of industrialization. Electrolytic metallization processes in which a layer of chromium is deposited are also known. An advantage of this type of process is the production of metallized parts having a metallic appearance. These parts are used in particular in the automotive field. However, chromium, and in particular hexavalent chromium, used in the context of metallization, has the disadvantage of being a toxic product for the environment. Hexavalent chromium requires sewage treatment plants to reduce its impact on the environment. It therefore represents a significant cost in the production of metallized parts. Trivalent chromium is also a toxic chemical. Trivalent chromium poses the same problems as hexavalent chromium. Another disadvantage of the use of chromium is that the production has a high scrap rate of the parts produced. This high scrap rate therefore increases the cost of producing parts. OBJECT AND SUMMARY OF THE INVENTION An object of the invention is to propose a method that overcomes the aforementioned drawbacks. To this end, the invention relates to a metallization process of a non-metallic support for obtaining a metallized part, in which: a non-metallic support having a surface is provided; a tie layer is made on said surface; at least one reinforcing layer is produced on the tie layer; In this process, at least one layer of lacquer is produced above the reinforcing layer. Advantageously, at least one layer of nickel is produced on the reinforcing layer and in which said at least one layer of varnish is made on the nickel layer. According to one embodiment of the method, the metal appearance is given by the presence of at least one layer of nickel that is available on the reinforcing layer. We dispense with the use of chromium. In other words, the metallized part obtained by the implementation of the process is devoid of chromium. The lacquer layer is deposited on the reinforcing layer or on the nickel layer to protect the reinforcing layer or the nickel layer and the lower layers from the risk of corrosion and shocks from the environment in which the piece is used. Furthermore, the varnish layer may comprise several layers of varnish obtained by successive deposits of varnished layers. In addition, when the deposition step is performed, it is understood that the varnish layer covers the reinforcing layer or the nickel layer in order to improve the resistance of the piece to impact and corrosion. The part obtained by the implementation of the method thus has a metallic appearance while being robust. Advantageously, a drying step is carried out of the varnish layer during which the varnish layer is exposed to ultraviolet radiation. This is a crosslinking step. Thus, the varnish deposited is dried by a device emitting ultraviolet rays which will allow the crosslinking of the varnish. In addition, the ultraviolet drying step is preferably carried out over a range of 150 nm to 400 nm. Preferably, the drying step is carried out at a temperature below 60 ° C.

It is understood that the ultraviolet drying step has an operating temperature lower than a more conventional thermal drying temperature whose temperature is above 120 ° C. Thus, the non-metallic support is subjected to a lower temperature range in which the risk of degradation of said non-metallic support is decreased. In addition, in another embodiment, the step of drying the lacquer layer is performed by means of a device that pulses hot air on the lacquer layer at temperatures below 120 ° C. Thus, in the same way as ultraviolet drying, the use of hot air at temperatures below 120 ° C decreases the risk of damaging the non-metallic support. Preferably, the lacquer layer is transparent or colored. Thus, thanks to the invention the transparent varnish layer reveals the natural color of the reinforcing layer or the nickel layer located under the varnish layer. Moreover, the varnish layer may have a colored hue in order to obtain a colored metallized part. Thus, the piece adapts to the aesthetic environment in which said piece is integrated. Preferably, the lacquer layer is an electrolytic lacquer layer. It is understood that the varnish layer is deposited chemically. The parts are arranged to be immersed in an electrolytic bath through which the layer of varnish is deposited on the reinforcing layer or on the nickel layer. Preferably, according to one embodiment, not limiting, the lacquer layer comprises a succession of layers of varnish. It is understood that the varnish layer thus obtained has a transparency or a hue that vary according to the number and thickness of successive varnish layers. According to a preferred embodiment, but not exclusive, the non-metallic support consists of acrylonitrile butadiene styrene. The non-metallic support is a copolymer of acrylonitrile, butadiene and styrene. It has the advantage of having high physical and chemical properties such as rigidity, impact resistance, heat resistance.

According to another embodiment, the non-metallic support is made of polyamide or polypropylene. It is understood that the non-metallic support is made of polyamide homopolymer. In addition, the polyamides exhibit good mechanical strength. Furthermore, advantageously, the non-metallic support may consist of a copolymer comprising acrylonitrile butadiene styrene associated with a polycarbonate. This polymer blend has better low temperature impact strength than acrylonitrile butadiene styrene or polycarbonate alone. According to another embodiment, but not limiting, the non-metallic support comprises a polymer of the polypropylene type. Thus, the non-metallic support has good fatigue resistance and has the advantage of being recyclable. Advantageously, the bonding layer is obtained by successively carrying out a chemical etching of the surface of the non-metallic support, an activation of said chemically etched surface, and a deposition of a first layer of nickel or copper on the activated surface. Thus, the surface is first etched, for example by means of an acid in the case of a non-metallic support comprising acrylonitrile butadiene styrene, or a base in the case of a support comprising a polyamide. This gives a certain roughness of said surface. Then, the activation step is performed by depositing a catalyst compatible with the material of said surface. In this way, a deposition layer is deposited on the activated surface in order to improve the adhesion of the reinforcing layer. Preferably, the reinforcing layer comprises at least one layer of copper. Advantageously, the nickel layer comprises a microporous or microcracked nickel layer. An interest of the microporous or microcracked structure is to obtain a more resistant to corrosion. In addition, the nickel layer can be subdivided into three successive layers of semi-gloss nickel, bright nickel and microporous nickel.

Given the above, it is understood that the metallized part obtained by the implementation of the process is advantageously free of chromium. The invention also relates to a metallized part that can be obtained by implementing the metallization process according to the invention. Advantageously, the metallized part according to the invention is devoid of chromium. Moreover, it preferably comprises, successively, a non-metallic support having a surface, a first layer made of copper or nickel disposed on the surface, a layer of copper disposed on the first layer, at least one second layer of nickel disposed on the layer of copper, and a layer of varnish disposed on the second layer of nickel. Consequently, the second nickel layer gives the metallic appearance while the layer of varnish disposed on the second nickel layer makes it possible to protect the metallized part from corrosion and the various attacks of the environment in which the metal part is arranged. . The invention finally relates to a method of modifying a metallized part in which a metallized piece is provided comprising a non-metallic support successively having a tie layer, a reinforcing layer, a nickel layer, and a chromium layer. The chromium layer is removed, then a layer of varnish is deposited on the nickel layer. The removal of the chromium layer is carried out by immersing the metallized part in an electrolytic bath for a predetermined time. Preferably, the nickel layer comprises a microporous or microcracked nickel layer. Advantageously, the tie layer is a nickel layer. Advantageously, the reinforcing layer is a copper layer.

One of the advantages of this modification process is to decompose existing parts inventories in order to improve their environmental impact while preserving their metallic appearance. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood on reading the following description of the embodiments of the invention given as non-limiting examples, with reference to the appended drawings, in which: FIG. schematic a metallized part according to the invention which is devoid of chromium and which comprises a non-metallic support and different successive layers arranged on the non-metallic support; FIG. 2 illustrates the different steps of the metallization process according to the invention making it possible to produce a metallized piece devoid of chromium; and FIG. 3 schematically illustrates the modification method according to the invention in which an existing metallized piece is dechromed. DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, a metallized piece 10 in accordance with the invention is schematically represented. This part comprises a non-metallic support S on which the layers C1 to C4 will be deposited. The non-metallic support S has a surface 11. In this example, the non-metallic support S is a plastic part. In this example, the support consists of ABS (Acrylonitrile Butadiene Styrene) which has good mechanical resistance and corrosion. In a variant, a copolymer comprising acrylonitrile butadiene styrene and a polycarbonate is used. In addition, in another example, the metal support may be composed of polyamide. In another variant, the non-metallic support S comprises polypropylene. In FIG. 2, a first step S100 is the step during which the plastic support S receives a chemical treatment on its surface 11 so as to obtain a roughness of said surface 11.

In this example, the etching of the surface 11 of a part, comprising an acrylonitrile butadiene styrene polymer, is carried out by immersing the pieces in a bath comprising sulfuric acid which oxidizes the butadiene present on the surface of the support S.

In addition, the bath is thermostated at a temperature of 65 ° C which oscillates by plus or minus 5 ° C. Thus, after a certain time of immersion, the surface has a roughness. Then, a step 5102 for activating the etched surface 11 of said support S is carried out so as to deposit a catalyst based on tin and palladium. In one embodiment in which the part comprises a polyamide-type polymer, the part is immersed in a bath comprising a solvent-based base and thermostatically controlled at a temperature of 40 ° C. plus or minus 5 ° C. In the same way, a roughness of the surface 11 is obtained. In this embodiment, the step 5102 of activating the surface of said support S is carried out by depositing a palladium catalyst on the surface 11 of the support S which has been previously activated. According to FIG. 2, a step 5104 for depositing a tie layer is then performed. It can be seen in FIG. 1 that a first layer C1 is deposited on the surface 11 of the non-metallic support S. The first layer C1 is a tie layer which comprises a nickel layer or a layer of copper. In this example, the cling layer C1 is made by immersing the non-metallic support S, the surface of which is activated, in a nickel bath. The attachment layer C1 preferably has a thickness between 0.15 micrometer and 0.25 micrometer. Said nickel is catalyzed by palladium and tin in the example where the non-metallic support comprises acrylonitrile. In one embodiment in which the non-metallic support comprises polyamide, the nickel is catalyzed by palladium. A deposition step 5106 of a reinforcing layer C2 is made to reinforce the cling layer C1 in order to obtain a homogeneous metal layer. In this example, said reinforcement layer C2 is composed of copper.

This deposition step S106 of the reinforcing layer makes it possible to deposit said layer C2 by immersing the non-metallic support S in a copper bath. Thus, the reinforcing layer C2 is disposed on the tie layer Cl.

The reinforcing layer C2 has a thickness of between 0.45 micrometer and 0.55 micrometer. In another embodiment, said reinforcing layer C2 is composed of nickel. In the same way, the reinforcement layer C2 is deposited on the tie layer Cl.

A depositing step 5108 of a layer of nickel C3 deposited on the reinforcing layer C2 is then carried out. In this example, the nickel layer C3 has a thickness of between 10 micrometers and 20 microns. The nickel layer C3 is subdivided into three layers of nickel: a layer of semi-gloss nickel; - a layer of shiny nickel; and a microporous nickel layer. A deposition step 5110 of a layer of varnish C4 is then performed on the nickel layer C3. The layer of varnish C4 is preferably deposited by immersing the metallized part in a bath containing said varnish. A drying step 5112 comprising a step of crosslinking the lacquer layer C4 is carried out by means of an ultraviolet radiation device which comprises a set of ultraviolet lamps which will expose the metallized part, comprising the layer of varnish C4, ultraviolet radiation for a predetermined time so that the varnish layer is completely dry. This gives a chromium-free metallized part comprising the nonmetallic support S made of polyamide or acrylonitrile butadiene styrene, the cladding layer C1 comprising nickel, the reinforcing layer C2 comprising copper, and the nickel layer C3 comprising three nickel forms, and the layer of C4 varnish. Referring to FIG. 3, an embodiment of the modification method according to the invention will now be described.

The process starts with a chrome piece 100 having a non-metallic support S, a cling layer C1 deposited on the surface of the non-metallic support S, a reinforcement layer C2 deposited on the cling layer C1, the nickel layer. C3 deposited on the reinforcing layer C2 and a chromium layer C4 '. According to the method, the chromed part comprising the chromium layer C4 'is immersed in a bath in which the chromium layer will be removed, so as to obtain a part 102 comprising the non-metallic support S, the cling layer C1, the reinforcing layer C2 and the nickel layer C3. This step therefore has the effect of removing the chromium layer.

Subsequently, a layer of lacquer C4 is deposited on the nickel layer C3 which becomes the top layer of the part from which the chromium layer C4 'has been removed. The C4 lacquer layer deposited on the nickel layer is subjected to the drying step 5112 in order to fix the C4 lacquer layer on said C3 nickel layer. This gives a metallized piece 104 devoid of chromium.

Claims (9)

REVENDICATIONS1. Process for modifying a metallized part, in which: a metallized piece is provided comprising a non-metallic support (S) successively having a tie layer (Cl), a reinforcing layer (C2), a nickel layer (C3 ), and a layer of chromium (C4 '); the chromium layer (C4 ') is removed, then a layer of varnish (C4) is deposited on the nickel layer (C3). 2. The method of claim 1, wherein the nickel layer (C3) comprises a microporous or microcracked nickel layer. 3. The method of claim 1 or 2, wherein the tie layer (Cl) is a layer of nickel. 4. Process according to any one of claims 1 to 3, wherein the reinforcing layer (C2) is a layer of copper. 5. Method according to any one of claims 1 to 4, wherein is further carried out a drying step of the varnish layer (C4) during which the varnish layer is exposed to UV radiation. The method of claim 5, wherein the drying step is performed at a temperature below 60 ° C. 7. Method according to any one of claims 1 to 6, wherein the varnish layer (C4) is transparent or colored. 8. A process according to any one of claims 1 to 7, wherein the lacquer layer (C4) is an electrocoating layer. 9. A process according to any one of claims 1 to 8, wherein the chromium layer (C4 ') is removed by immersing the metallized part in an electrolytic bath for a predetermined time.