Gold or silver metallized plastic product free of any gold and silver element and method for manufacturing it

Abstract

The invention relates to a method for manufacturing a metallized plastic product with a gold or silver hue, comprising the steps: galvanization of a surface of the plastic body for forming a galvanized chromium layer; deposition by evaporation of a metal layer directly on the galvanized chromium layer, the metal being copper, a mixture of metals comprising at least 70% by weight of copper, a copper alloy comprising at least 70% by weight of copper, or aluminum. The invention also relates to a metallized plastic product (1) with a gold or silver hue, comprising a plastic body (2), a galvanized chromium layer (3, 4, 5, 6), and a metal layer (7), the metal being copper, a mixture of metals comprising at least 70% by weight of copper, an alloy containing copper in an amount of at least 70% by weight, or aluminum.

Claims

1. An at least partly metallized plastic product of a gold or silver hue and free of any gold and silver element, comprising a plastic body, a galvanized chromium layer covering a surface of the plastic body to be metallized, without an organic sublayer between the plastic body and galvanized chromium layer, and a metal layer directly on the galvanized chromium layer, the metal layer being copper, a mixture of metals comprising at least 70% by weight of copper, a copper alloy comprising at least 70% by weight of copper, or aluminum, wherein the galvanized chromium layer comprises both (i) a preparation layer deposited on the substrate and comprising nickel or copper and (ii) a copper cover layer deposited on the preparation layer, wherein both (i) and (ii) are deposited between the substrate and a chromium layer.

2. The plastic product according to claim 1, wherein the metal layer comprises a CuAl alloy comprising at least 70% by weight of copper.

3. The plastic product according to claim 2, wherein the CuAl alloy comprises between 80-95% by weight of copper, between 5-20% by weight of aluminum, and less than 5% by weight of impurity.

4. The plastic product according to claim 1, wherein the metal layer comprises aluminum.

5. The plastic product according to one of claims 1 to 4, wherein the galvanized chrome layer comprises a chromium layer having a thickness between 0.1 and 2 m.

6. The plastic product according to one of claims 1 to 4, wherein the metal layer has a thickness between 30 and 100 nm.

7. The plastic product according to one of claims 1 to 4, further comprising a transparent protection overlayer directly on the metal layer.

8. The plastic product according to claim 7, wherein the transparent protection overlayer is a transparent organic overlayer.

9. The plastic product of claim 8, wherein the transparent organic overlayer comprises an organic polymer selected from the group consisting of a polyester, an acrylic polymer, an acrylate polymer, and polyurethane.

10. The plastic product of claim 7, wherein the transparent protection overlayer is a transparent inorganic layer.

11. The plastic product of claim 10, wherein the transparent inorganic layer comprises a silicon oxide.

12. The plastic product of claim 1, wherein the galvanized chromium layer comprises (i) the preparation layer comprising nickel or copper, (ii) the copper cover layer, (iii) a nickel cover layer, and (iv) the chromium layer, wherein the preparation layer is deposited on the substrate, the copper cover layer is deposited on the preparation layer, the nickel cover layer is deposited on the copper cover layer, and the chromium layer is deposited on the nickel cover layer.

13. The plastic product of claim 12, wherein the metal layer comprises a copper alloy comprising at least 70% by weight of copper.

14. The plastic product of claim 1, wherein the metal layer comprises a mixture of metals comprising at least 70% by weight of copper.

15. The plastic product of claim 3, wherein the CuAl alloy comprises about 92% by weight of copper and about 8% by weight of aluminium.

16. A method for manufacturing the at least partly metallized plastic product of claim 1, the method comprising the following steps: galvanization of a surface of the plastic body to be metallized for forming a galvanized chromium layer on the surface of the plastic body to be metallized, without an organic sublayer between the plastic body and galvanized chromium layer; deposition by evaporation, preferably by cathode sputtering, of a metal layer directly on the galvanized chromium layer, the metal layer being copper, a mixture of metals comprising at least 70% by weight of copper, a copper alloy comprising at least 70% by weight of copper, or aluminum.

17. The method according to claim 16, wherein the metal layer comprises a CuAl alloy comprising at least 70% by weight of copper.

18. The method according to claim 17, wherein the CuAl alloy comprises between 80-95% by weight of copper, between 5-20% by weight of aluminum, and less than 5% by weight of impurity.

19. The method according to claim 16, wherein the metal layer comprises aluminum.

20. The method according to any of claims 16 to 19, wherein the galvanization step comprises the following sub-steps: the plastic body is made conducting by acid etching followed by a deposition of nickel or copper via a chemical route activated with palladium in order to form a preparation layer; a copper cover is electrolytically deposited directly on the preparation layer; and the chromium layer is deposited via an electrolytic route on the copper cover, wherein the galvanized chromium layer comprises the preparation layer, the copper cover and the chromium layer.

21. The method according to one of claims 16 to 19, further comprising a step for applying a transparent protection overlayer directly on the metal layer.

Description

PRESENTATION OF THE DRAWINGS

(1) FIG. 1 schematically illustrates an at least partly metallized plastic product with a gold or silver hue free of any gold and silver elements. This plastic product 1 is obtained with the method of the present invention. This plastic product 1 comprises a plastic body 2 successively covered with a preparation layer in nickel or in copper 3, with a copper cover 4, with a nickel cover 5, with a chromium layer 6, with a metal layer 7 (copper, mixture of metals comprising at least 70% by weight of copper, copper alloy comprising at least 70% by weight of copper, silver) and with a transparent protective organic overlayer 8.

(2) FIG. 2 is a diagram schematically illustrating an exemplary embodiment of the method according to the invention.

MEASUREMENT METHOD

(3) The gold or silver hue is measured in the CIE model for representing colors, L*a*b* which represents a color with three components: the component L* is luminosity ranging from zero (black) to 100 (white); the component a* represents the chromatic range of the red-green axis (respectively positive and negative values); the component b* represents the chromatic range of the yellow-blue axis (respectively positive and negative values).

(4) The value of the component L* represents luminosity. The greater the value of L* and the more significant is the brightness.

(5) The components a* and b* correspond to the color.

(6) The measurement is conducted with a spectro-colorimeter BYK-Gardner No. 6834. Before the measurement, the calibration of the apparatus is checked by means of standard plates provided with the spectro-colorimeter.

(7) The sample should be clean and free of scratches and have a surface adapted to the apparatus.

(8) For each sample, five measurements are carried out and the average for each of the components L*, a* and b* is calculated.

EXAMPLES

Example 1

(9) An exemplary method for manufacturing an at least partly metallized plastic product with a gold hue and free of any gold elements is described below.

(10) First of all, a plastic body is provided. The plastic body is in ABS. The plastic body has a suitable shape for manufacturing a plug of a perfume bottle.

(11) The outer surface of the plastic body is subject to acid etching with sulfochromic acid by soaking in a solution of chromic acid with a concentration of 400 g/L and of sulfuric acid with a concentration of 400 g/L at a temperature of 65 C. for 6 minutes. Next, a preparation layer in nickel is deposited at the surface of the plastic body by chemical deposition with palladium in a catalytic amount. This preparation layer has a thickness of 1 m. This preparation layer allows the plastic body to be made electrically conducting, which is required in order to be able to then carry out electrolyses.

(12) A copper cover is consequently deposited on the first nickel or copper layer by electrolysis. In order to carry out the electrolysis, the plastic body covered with the preparation layer is soaked in a tank filled with a mixture of copper sulfate and of sulfuric acid in solution for 22 minutes. The electrolysis is stopped when the copper cover on the plastic body has a thickness of 12 m.

(13) A nickel cover is then deposited on the copper cover by electrolysis. The plastic body is soaked in a tank filled with a mixture of nickel sulfate, nickel chloride and boric acid in solution for 10 minutes. The nickel cover has a thickness of 6 m.

(14) A chromium layer is then deposited via an electrolytic route on the nickel cover. The plastic body is soaked in a tank filled with a solution of chromic acid for 2 minutes and 30 seconds. The chromium layer has a thickness of 0.9 m.

(15) A CuAl alloy (UNS C61000) layer consisting of 92% by weight of copper, 8% by weight of aluminum and less than 0.85% by weight of impurity is deposited by cathode sputtering directly on the chromium layer for 2.3 seconds. The target is a 420 mm100 mm plate, with a thickness of 10 mm in a CuAl alloy of the same composition as the CuAl alloy layer to be formed on the chromium layer. The distance from the plastic body to the target is 100 mm. The cathode sputtering power is adjusted to 30 kW. The speed of rotation is adjusted to 100 rpm. The argon flow is set to a value of 500 cm.sup.3/mn. A CuAl alloy layer with a thickness of 50 nm is obtained.

(16) Finally, a transparent organic acrylate overlayer is applied on the CuAl alloy layer. The overlayer has a thickness of 12 m.

(17) The color and brightness measurements give the coordinates (79.6; 3.95; 21.16) in the L*a*b* model.

Example 2

(18) Example 2 is carried out in the same way as Example 1 with the only exception that the duration of the cathode sputtering is 1.4 seconds.

(19) The color and brightness measurements give the coordinates (80.93; 3.05; 19.48) in the L*a*b* model.

Example 3

(20) An exemplary method for manufacturing an at least partly metallized plastic product with a silver hue and free of any silver elements is described below.

(21) The method used is identical with the one of Example 1 with the only exception that the metal used for cathode sputtering is aluminum (UNS A6061).

(22) The color and brightness measurements give the coordinates (87.85; 0.95; 6.97) in the L*a*b* model.

Comparative Examples

(23) Table 1 hereafter reports the different methods used for 13 examples as well as their color.

(24) TABLE-US-00001 TABLE 1 Galvanization Cathode (metal sputtering used) (metal Overlayer Color Example 1 chromium CuAl* (2.3 colorless gold Example 2 chromium CuAl* (1.4 colorless gold Example 3 chromium Al**( . . . ) colorless silver Example 4 gold without without gold Example 5 gold without without gold Example 6 nickel without without nickel Example 7 chromium without without chromium Example 8 nickel without gold- gold colored Example 9 chromium without gold- gold colored Example 10 without CuAl* colorless gold Example 11 silver without without silver Example 12 chromium aluminum without aluminum Example 13 without aluminum colorless silver *The CuAl alloy (UNS C61000) comprising 92% by weight of copper, 8% by weight of aluminum and less than 0.85% by weight of impurity; **aluminum UNS A6061.

(25) Table 2 hereafter reports the hue coordinates measured for each of the 13 examples listed in Table 1.

(26) TABLE-US-00002 TABLE 2 L* a* b* Example 1 79.6 3.95 21.16 Example 2 80.93 3.05 19.48 Example 3 87.85 0.95 6.97 Example 4 86.9 2.96 22.97 Example 5 82.75 2.12 16.32 Example 6 81.6 0.84 6.46 Example 7 83.41 0.82 2.03 Example 8 73.87 1.92 19 Example 9 74.32 0.74 12.17 Example 10 80.92 5.15 19.25 Example 11 95.15 0.8 7.95 Example 12 90.99 0.57 4.4 Example 13 90 0.87 1.39

(27) It is seen that Examples 8 and 9, although their color is close to that of Examples 4 and 5 (standards), suffer from too low brightness relatively to the Examples 1 and 2 corresponding to the present invention. Moreover, the fact that the overlayer used is colored, the hue of the Examples 8 and 9 is not constant over time and becomes duller.

(28) Example 10 gives a good result as regards the hue, although redder than that of the Examples 1 and 2. However, the touch obtained with Example 10 is not metallic, in other words it is not cold.

(29) It is seen that Examples 1 and 2 have a hue closer to those of Examples 4 and 5 (standard for the gold hue), indeed their coordinates a* and b* are closer to those of Examples 4 and 5 than the coordinates a* and b* of Examples 8, 9 and 10. Moreover, the brightness of Examples 1 and 2 is greater than that of Examples 8 and 9.

(30) Example 13 also gives a good result, although the hue is less yellow than Example 11 which forms a reference example for the silver hue. Just like in Example 10, the obtained touch is not metallic.

(31) Example 3, although the brightness is less than that of Example 13 has coordinates a*b* closer to Example 11 than the coordinates of Example 13.