Laser-markable plastics

• US 6,214,917 B1
• Filed: 12/15/1999
• Issued: 04/10/2001
• Est. Priority Date: 05/05/1994
• Status: Expired due to Term

• Current Assignee: BASF SE
• Original Assignee: BASF AG (BASF SE), Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Prissok, Frank, Krietsch, Burkhard, Linzmeier, Rainer
• Primary Examiner(s): Seidleck, James J.
• Assistant Examiner(s): Asinovsky, Olga
• Application Number:
  US09/461,032
• Time in Patent Office: 482 Days
• Field of Search: 524/430, 524/440, 524/408, 524/409, 524/449, 428/403, 523/137, 106/415, 106/417, 106/441, 106/442, 106/455
• US Class Current: 524/430
• CPC Class Codes: B41M 5/267 Marking of plastic artifacts, e.g. with laser
• CPC Class Codes: B44C 1/228 by laser radiation
• CPC Class Codes: C08K 9/02 Ingredients treated with inorganic substances
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

The present invention relates to laser-markable plastics, in particular thermoplastic polyurethanes, which are distinguished by the fact that they contain pigments having a coating of doped tin dioxide.

Claims

1. A laser-markable plastic which comprises a thermoplastic containing a pigment having a platelet-shaped substrate which has been coated with an optionally hydrated silicon dioxide coating or a coating of another insoluble silicate and over that coating another coating of tin dioxide doped with 0.5-50% by weight of antimony, arsenic, bismuth, copper, gallium, germanium, or a corresponding oxide thereof.

2. The laser-markable plastic of claim 1, wherein the proportion of the pigment is 0.1-3% by weight based on the plastic.

3. A laser-markable plastic according to claim 1, wherein the platelet-shaped substrate is mica platelets, SiO₂ flakes or mica platelets coated with one or more metal oxides.

4. A laser-markable plastic according to claim 1, wherein the proportion of pigment is 0.1-2% by weight, based on the plastic.

5. A laser-markable plastic according to claim 1, wherein the tin dioxide coating of the pigment is doped with 0.5-50% by weight of antimony, or a corresponding oxide thereof.

6. A laser-markable plastic according to claim 1, wherein the thermoplastic is a thermoplastic polyurethane.

7. A laser-markable plastic according to claim 1, wherein the thermoplastic is a polyether ester or polyester ester.

8. A laser-markable plastic according to claim 1, which additionally comprises a colored pigment.

9. A plastic molding comprising a laser-markable plastic according to claim 1.

10. A method for making a molding laser-markable which comprises incorporating in the molding a laser-markable plastic according to claim 1.

11. A laser-markable plastic according to claim 1, which is markable by a Nd-YAG laser.

16. The laser-markable plastic of claim 1, wherein the tin dioxide coating of the pigment is doped with 0.5-20% by weight of antimony, arsenic, bismuth, copper, gallium, germanium, or a corresponding oxide thereof.

12. A process for the preparation of a laser-markable plastic, which comprises:

mixing thermoplastic granules with a pigment having a platelet-shaped substrate which has been coated with an optionally hydrated silicon dioxide coating or a coating of another insoluble silicate and over that coating another coating of tin dioxide doped with 0.5-50% by weight of antimony, arsenic, bismuth, copper, gallium, germanium, or a corresponding oxide thereof, and

then molding at elevated temperature.

17. The process of claim 12, wherein the tin dioxide coating of the pigment is doped with 0.5-20% by weight of antimony, arsenic, bismuth, copper, gallium, germanium, or a corresponding oxide thereof.

13. A pigment having a platelet-shaped substrate which has been coated with an optionally hydrated silicon dioxide coating or a coating of another insoluble silicate and over that coating another coating of tin dioxide doped with 0.5-50% by weight of antimony, arsenic, bismuth, copper, gallium, germanium, or a corresponding oxide thereof.

14. The pigment according to claim 13, wherein the platelet-shaped substrate is mica platelets, SiO₂ flakes or mica platelets coated with one or more metal oxides.

15. The pigment according to claim 13, wherein the tin dioxide coating of the pigment is doped with 0.5-50% by weight of antimony, or a corresponding oxide thereof.

18. The pigment of claim 13, wherein the tin dioxide coating of the pigment is doped with 0.5-20% by weight of antimony, arsenic, bismuth, copper, gallium, germanium, or a corresponding oxide thereof.