Antimony free composition for laser marking thermoplastic compounds

Patent metadata

Field	Value
Publication number	US-11780255-B2
Application number	US-201816486854-A
Country	US
Kind code	B2
Filing date	Feb 20, 2018
Priority date	Feb 20, 2017
Publication date	Oct 10, 2023
Grant date	Oct 10, 2023

Abstract

It has been found, that when co-absorbing substances are added to intrinsic laser-absorbing bismuthoxide, the marking performance with a Nd.YAG-laser is improved or at least kept at the same level by reducing the costs. It is suspected, that the co-absorbing additive is not simply adding a contrast to the polymer by carbonizing the surrounding polymer but helping the bismuthoxide to couple the laser radiation and to ease the color change of this additive. This so found effect helps to cheapen the replacement of antimony trioxide and therewith have a safer and more sustainable solution for the current and future technology of laser marking.

First claim

The invention claimed is:

1. A laser-markable plastic, comprising:
a thermoplastic polymer, bismuth oxide having a formula Bi 2 O 3 , and a co-absorbing additive comprising platelet-shaped silicates,
wherein an amount of the bismuth oxide is in a range of from 0.5 to 5 wt.-%, relative to a total weight of the laser-markable plastic,
wherein an amount of the co-absorbing additive relative to the bismuth oxide is from 5 to 40 wt.-%,
wherein the bismuth oxide has a d 50 particle size of from 2 microns to 10 microns, and
wherein the co-absorbing additive has a d 50 particle size from 3 to 10 microns.

2. The laser-markable plastic according to claim 1 , wherein the amount of the co-absorbing additive relative to the bismuth oxide is from 10 to 30 wt.-%.

3. The laser-markable plastic according to claim 1 , wherein the thermoplastic polymer is a thermoplastic polyurethane, acrylonitrilebutadiene-styrene, or other non-intrinsically laser-markable polymer.

4. The laser-markable plastic according to claim 1 , comprising from 0.2 to 5 wt.-% of bismuth oxide, relative to the total weight of the laser-markable plastic.

5. The laser-markable plastic according to claim 1 , wherein the platelet-shaped silicates are phyllosilicates.

6. The laser-markable plastic according to claim 1 , wherein the platelet-shaped silicates are selected from the group consisting of mica, talc, and kaolin.

7. A method for preparing the laser-markable plastic according to claim 1 , comprising the step of dispersing the bismuth oxide and the co-absorbing additive into the thermoplastic polymer in a melt-mixing process.

8. The laser-markable plastic according to claim 1 , in the form of industrial products, consumer products, or plastic marks for the individual tagging of animals.

9. The laser-markable plastic according to claim 1 , wherein the laser-markable plastic is antimony free.

10. The laser-markable plastic according to claim 1 , wherein the co-absorbing additive consists of platelet-shaped silicates and in the amount of 10 to 40 wt.-%. relative to the bismuth oxide.

11. A laser-markable plastic, comprising:
a thermoplastic polymer, bismuth oxide having a formula Bi 2 O 3 , and a co-absorbing additive comprising platelet-shaped silicates,
wherein an amount of the bismuth oxide is in a range of from 0.5 to 5 wt.-%, relative to a total weight of the laser-markable plastic,
wherein an amount of the co-absorbing additive relative to the bismuth oxide is from 5 to 40 wt.-%, and
wherein the thermoplastic polymer is a thermoplastic polyurethane.

Assignees

• Clariant Plastics & Coatings Ltd

Inventors

• WOLF JüRGEN
• Pang Chun Yip

Classifications

• B41M5/267 Primary

  Marking of plastic artifacts, e.g. with laser · CPC title

• B41M5/262

  recording or marking of inorganic surfaces or materials, e.g. glass, metal, or ceramics (marking of plastic artifacts with inorganic additives B41M5/267) · CPC title

• C01G29/00

  Compounds of bismuth · CPC title

• C01G49/0018

  Mixed oxides or hydroxides, (C01G49/0009 takes precedence) · CPC title

• C08K3/22

  of metals · CPC title