Laser-marked polymer workpiece

Abstract

A laser-marked polymer workpiece is described. The workpiece has a transparent component and an opaque component applied to at least one region of the transparent component. A mark is introduced onto a surface of the opaque component facing the transparent component with at least one laser. The mark is introduced, via a laser, through the transparent component. The mark is a lightening of the surface of the opaque component on which the mark was introduced.

Claims

1. A method for producing a laser-marked polymer workpiece, comprising: bonding a transparent component having a transmission in visible spectral range equal to or greater than 50% and an opaque component having a transmission in visible spectral range equal to or less than 20% via multi-component injection molding to form a polymer workpiece, the opaque component containing at least one colorant, and irradiating the opaque component through the transparent component with at least one laser thereby introducing a mark on a surface of the opaque component, wherein the mark is a brightening of the opaque component, wherein the opaque component is devoid of a laser sensitive additive, and wherein the at least one colorant comprises at least one black pigment.

2. The method according to claim 1, wherein the mark is introduced on the surface of the opaque component by a movement of a beam of the laser.

3. The method according to claim 1, wherein a beam of the laser is focused on a boundary surface between the transparent component and the opaque component.

4. The method according to claim 1, wherein an emission wavelength of the laser is from 600 nm to 3000 nm.

5. The method according to claim 1, wherein the laser is operated in pulsed mode and a pulse duration is from 5 ns to 300 ns, and a pulse repetition frequency is from 1 kHz to 500 kHz.

6. The method according to claim 1 wherein an output power of the laser is from 1 W to 50 W.

7. The method according to claim 2, wherein the beam of the laser is moved at a speed from 200 mm/s to 5000 mm/s.

8. The method according to claim 1, wherein an emission wavelength of the laser is from 900 nm to 1500 nm.

9. The method according to claim 1, wherein the laser is operated in pulsed mode and a pulse duration is from 5 ns to 300 ns, and a pulse repetition frequency is from 20 kHz to 150 kHz.

10. The method according to claim 1 wherein an output power of the laser is from 15 W to 35 W.

11. The method according to claim 1, wherein the black pigment comprises one or more of carbon black, aniline black, bone black, iron oxide black, spinel black, and graphite.

12. The method according to claim 1, wherein the workpiece comprises one or more of polycarbonate, polyethylene terephthalate, and polymethyl methacrylate.

Description

(1) The invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are schematic representations and not true to scale. The drawings in no way restrict the invention. They depict:

(2) FIG. 1 a top plan view of one embodiment of the laser-marked polymer workpiece according to the invention,

(3) FIG. 2 a cross-section along A-A′ through the laser-marked polymer workpiece according to the invention of FIG. 1,

(4) FIG. 2a an enlarged view of the detail Z of FIG. 2,

(5) FIG. 3 a cross-section along A-A′ through the polymer workpiece according to the invention of FIG. 1 during the laser marking,

(6) FIG. 4 a detailed flow chart of the method according to the invention.

(7) FIG. 1 and FIG. 2 each depict a detail of the polymer workpiece 1 according to the invention. It is a side window pane of a passenger car and has a height of 30 cm and a width of 28 cm. The polymer workpiece 1 contains a transparent component 2. An opaque component 3 with a width of 4 cm is arranged circumferentially on the transparent component 2 in the edge region of the polymer workpiece 1. FIG. 1 depicts the top plan view of the surface of the transparent component 2 turned away from the opaque component 3. The opaque component 3 can be discerned in the top plan view through the transparent component 2. The polymer workpiece 1 was produced by multi-component injection molding. The transparent component 2 has a thickness of 4 mm and contains polycarbonate (PC). The opaque component 3 has a thickness of 2 mm. The opaque component 3 contains a mineral-filled polycarbonate (PC)-polyethylene terephthalate (PET) mixture. The starting material for the injection molding of the opaque component 3 was prepared by the company Teijin Chemicals Ltd. (Panlite Y-0346 Color No. TG6654). The polymer workpiece 1 is not transparent in the region of the opaque component 3. The side window pane can thus be connected, for example, glued, to the vehicle body in a manner not visible to the observer, with the opaque component 3 preferably arranged facing the interior of the vehicle.

(8) A mark 4 is arranged in at least one region of the opaque component 3. The mark 4 is introduced according to the invention into the opaque component 3 on the boundary surface between the transparent component 2 and the opaque component 3. The mark 4 is realized as a brightened region on the surface of the opaque component 3. The mark 4 is depicted for the sake of simplicity as a filled-in circle. In practice, the mark 4 can be, for example, a manufacturers symbol, a trademark symbol, a manufacturers code, a production date, and/or an approval mark.

(9) By means of the arrangement according to the invention of the mark 4 in the interior of the polymer workpiece 1 on the boundary surface between the transparent component 2 and the opaque component 3, the mark 4 is advantageously protected against environmental influences, such as mechanical damage, for example. In addition, the mark 4 does not result in coating distribution problems, with the application of a coating (not shown) of the polymer workpiece 1, for example, a protective lacquer coating, after laser marking.

(10) FIG. 2a depicts an enlarged view of the detail Z identified by a circle in FIG. 2. A region of the transparent component 2, a region of the opaque component 3 as well as the mark 4 introduced into the surface of the opaque component 3 facing the transparent component 2 can be seen.

(11) FIG. 3 depicts a cross-section A-A′ through the polymer workpiece of FIG. 1 during the laser marking according to the invention. The beam of the laser 5 enters the polymer workpiece 1 via the surface of the transparent component 2 facing away from the opaque component 3. The beam of a laser 5 is focused by means of a lens 6 on the boundary surface or interface between the transparent component 2 and the opaque component 3 of the polymer workpiece 1. The focal length of the lens 6 is 160 mm. The laser 5 is a diode-pumped fiber laser with a 2-m-long ytterbium-doped glass fiber as the active medium. The emission wavelength of the laser 5 is about 1063 nm. The laser 5 is operated in pulsed mode with a pulse duration of of 110 ns and a pulse frequency of 60 kHz. A mirror 7 is arranged in the beam path of the laser 5. By moving the mirror 7, the focus of the beam of the laser 5 can be moved over the boundary surface between the transparent component 2 and the opaque component 3 of the polymer workpiece 1.

(12) The beam of the laser 5 results, already after an exposure time in the range of a few milliseconds, in a clear brightening on the surface of the opaque component 3. By means of the movement of the focused beam of the laser 5 over the boundary surface between the transparent component 2 and the opaque component 3 of the polymer workpiece 1, a mark 4, for example, a manufacturers symbol, a manufacturers code, a production date, or an approval mark, can thus be permanently applied.

(13) FIG. 4 depicts, by way of example, the method according to the invention for producing a laser-marked polymer workpiece 1.

(14) Test specimens of laser-marked polymer workpieces 1 according to the invention according to FIG. 1 were made with the method according to the invention. The laser marking was performed with the laser marking system DP20F of the company FOBA, comprising a laser 5, a mirror 7 and a lens 6. The mark 4 comprised letters, numbers, and geometric figures. With all test specimens, the mark 4 was clearly recognizable. The minimum line width of the mark 4 was roughly 0.1 mm.

(15) It was unexpected and surprising for the person skilled in the art that a mark 4 of a polymer workpiece 1 can be provided in a simple and reliable manner without altering the surface of the polymer workpiece 1.

LIST OF REFERENCE CHARACTERS

(16) (1) polymer workpiece (2) transparent component (3) opaque component (4) mark (5) laser (6) lens (7) adjustable mirror A-A′ section line Z detail of the polymer workpiece 1