Plastic part with selective metallization and corresponding manufacturing process

Abstract

The present invention relates to a plastic part (1) with selective metallization comprising at least one first non-metallized portion (7) made from a first plastic material that cannot be metallized by electroplating and at least one second metallized portion (9) made from a second metallizable plastic material, the first plastic material being a mixture of polycarbonate and of a semiaromatic polyester and the second plastic material being a polyamide.

Claims

1. A process for manufacturing a plastic part with selective metallization, comprising the following stages: providing a plastic part comprising at least one first nonmetallized portion made from a mixture of polycarbonate and a semiaromatic polyester and at least one second portion made from a polyamide, electroplating the plastic part in order to obtain selective metallization of the second portion; wherein the mixture of the polycarbonate and the semiaromatic polyester is reinforced by the addition of filler of a glass bead.

2. The manufacturing process as claimed in claim 1, wherein the semiaromatic polyester is chosen from polyethylene terephthalate and polybutylene terephthalate.

3. The manufacturing process as claimed in claim 1, wherein the metal deposited during the metallization is chromium.

4. The method of claim 1, wherein electroplating the plastic part comprises: passing the plastic part through a plurality of baths; depositing a metal on the second portion of the plastic part.

5. The manufacturing process as claimed in claim 4, wherein the metal is provided in a solution.

6. The manufacturing process as claimed in claim 1, wherein the at least one first nonmetallized portion and the at least one second portion are produced simultaneously or separately.

7. A process for manufacturing a plastic part with selective metallization, comprising the following stages: providing a plastic part comprising at least one first nonmetallized portion made of a semiaromatic polyester and at least one second portion made from a polyamide, electroplating the plastic part in order to obtain selective metallization of the second portion; wherein the semiaromatic polyester is reinforced by the addition of filler of a glass bead.

8. The manufacturing process as claimed in claim 7, wherein the semiaromatic polyester is chosen from polyethylene terephthalate and polybutylene terephthalate.

9. The manufacturing process as claimed in claim 7, wherein the metal deposited during the metallization is chromium.

10. The method of claim 7, wherein electroplating the plastic part comprises: passing the plastic part through a plurality of baths; depositing a metal on the second portion of the plastic part.

11. The manufacturing process as claimed in claim 10, wherein the metal is provided in a solution.

12. The manufacturing process as claimed in claim 7, wherein the at least one first nonmetallized portion and the at least one second portion are produced simultaneously or separately.

Description

(1) Other characteristics and advantages of the invention will become more clearly apparent on reading the following description, given by way of illustrative and nonlimiting example, and FIG. 1, representing a plastic part with selective metallization.

(2) FIG. 1 shows a plastic part 1 with selective metallization comprising at least one first nonmetallized portion 7 and at least one second metallized portion 9.

(3) The example of plastic part 1 illustrated by FIG. 1 is a motor vehicle identifier, more specifically a key comprising a key bit 3, a plastic shell comprising a first nonmetallized portion 7, a metallized part 9 and a push button 5 for controlling the key bit 3.

(4) The first nonmetallized portion 7 is made from a first plastic material, such as a semiaromatic polyester mixed or not mixed with polycarbonate, said semiaromatic polyester advantageously being chosen from polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), due to their mechanical properties and properties of resistance to chemical attacks.

(5) The mechanical properties of this first material can be enhanced by adding thereto fillers of glass fiber or glass bead type.

(6) It is thus possible to obtain, for example for a PC/PBT/glass fiber mixture, an isostatic modulus of elasticity of the order of 10 000 MPa and a strain at break of 130 MPa.

(7) The second metallized portion 9 is made from a second plastic material, such as a polyamide (PA).

(8) The metallization of the PA by electroplating requires the use of baths which are much less corrosive than for the metallization of ABS; thus, the first portions 7 made of semiaromatic polyester mixed or not mixed with polycarbonate have less risk of being attacked and damaged during the electroplating of the plastic part.

(9) The present invention also relates to a process for the manufacture of a plastic part 1 with selective metallization, comprising the following stages: providing a plastic part 1 comprising at least one first portion 7 made from a semiaromatic polyester mixed or not mixed with polycarbonate and at least one second portion 9 made from a polyamide, the electroplating of the plastic part 1 in order to obtain selective metallization of the second portion or portions 9.

(10) During the manufacture of the plastic part 1, at least one first nonmetallized portion 7 is made from a semiaromatic polyester mixed or not mixed with polycarbonate, advantageously chosen from PET or PBT. The semiaromatic polyester mixed or not mixed with polycarbonate can also be reinforced by the addition of fillers of glass fiber or glass bead type.

(11) Still during the manufacture, at least one second metallized portion 9 is made of PA.

(12) As shown by FIG. 1, there may very obviously be one or more portions 7, 9 of each material on the same plastic part 1, according to the requirements related to the use of the plastic part 1, according to esthetic criteria or else according to the criteria defined by the client.

(13) The different portions 7, 9 can be produced separately and then assembled to form the plastic part 1 or certain portions 7, 9 can be overmolded onto others or else produced simultaneously according to methods well known to a person skilled in the art, this being a function of the final plastic part 1 and of the result desired after metallization.

(14) During the electroplating, the plastic part 1 passes through different baths, making it possible to apply, by means of a direct electrical current, a metal deposition at the surface of the plastic part 1 on the second portion or portions 9 made of polyamide, the metal being initially in the form of cations in solution in a solvent.

(15) Generally, out of concern for attractiveness and protection, the selective metallization is a deposition of chromium on the second portion or portions 9 made of polyamide. In another embodiment, the deposition of chromium is replaced by a deposition of nickel.

(16) Thus, by virtue of the mechanical and chemical properties of these materials, it is possible to obtain a plastic part 1 with selective metallization itself having sufficient mechanical properties to be suitable, for example, for the preparation of a shell of a motor vehicle identifier.