# US 5,350,792 A · Pigment-containing plastic molding composition

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- Number: US 5,350,792 A
- Document ID: US5350792A
- Status: Granted
- Kind: A
- Application number: 07/906,266
- Filed: 1992-06-26
- Granted: 1994-09-27
- Earliest claimed: 1991-06-29
- Assignees: Hoechst Aktiengesellschaft
- Inventors: Gerhard Hess; Ulrich Haack; Klaus Kurz
- Web page: https://patentgrep.com/patent/US5350792A

## CPC

- C08K 3/32: Phosphorus-containing compounds
- B41M 5/267: {Marking of plastic artifacts, e.g. with laser}
- C08K 3/04: Carbon
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- B41M: PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING, (correction of typographical errors B41J; processes for applying transfer pictures or the like B44C1/16; fluid media for correction of typographical errors by coating C09D10/00; printing textiles D06P)

## Abstract

A plastic molding composition based on an organic thermoplastic polymer containing a black mineral pigment suitable as a material for the preparation of shaped articles which can be provided with symbols by exposure to laser radiation. The black pigment used is in particular animal charcoal, and the thermoplastic polymer is in particular a polyoxymethylene.

## Claims

### Claim 1

A plastic molding composition essentially comprising at least one organic polymer and at least one carbon-containing pigment, wherein (a) the polymer is a thermoplastic polymer which is at least partially transparent to light in the wavelength range from 180 to 1200 nm, (b) the pigment is animal charcoal, bone black or ivory black.

### Claim 2 (depends on 1)

A plastic molding composition as claimed in claim 1, wherein the thermoplastic polymer (a) is a polyolefin, which may contain fluorine atoms, or a polymer containing amide or acetal groups in the main chain.

### Claim 3 (depends on 1)

A plastic molding composition as claimed in claim 1, wherein the thermoplastic polymer (a) is a polyoxymethylene.

### Claim 4 (depends on 3)

A plastic molding composition as claimed in claim 3, wherein the thermoplastic polymer (a) is an oxymethylene copolymer.

### Claim 5 (depends on 1)

A plastic molding composition as claimed in claim 1, wherein the amount of the pigment (b) is from 0.001 to 10 percent by weight (based on the plastic molding composition).

### Claim 6 (depends on 1)

A plastic molding composition as claimed in claim 1, wherein the pigment ( b ) contains from 70 to 90 percent by weight of calcium phosphate and from 30 to 10 percent by weight of carbon.

### Claim 7 (depends on 1)

A plastic molding composition as claimed in claim 1, wherein the particle diameter of the pigment (b) is in the range from 1 to 50 .mu.m.

### Claim 8 (depends on 1)

A plastic molding composition as claimed in claim 1, including (c) an inorganic pigment containing no free carbon and wherein the pigment (b) is mixed with component (c).

### Claim 9 (depends on 8)

A plastic molding composition as claimed in claim 8, wherein component (c) is titanium dioxide.

### Claim 10 (depends on 1)

A shaped article provided with symbols with the aid of laser radiation and produced from a plastic molding composition as claimed in claim 1.

### Claim 11

A process for the production of a molding provided with symbols from a plastic molding composition through the action of laser radiation, where the molding composition essentially comprises at least one organic polymer and at least one carbon-containing pigment, wherein a plastic molding composition is used which comprises (a) a thermoplastic polymer which is at least partially transparent to light in the wavelength range from 180 to 1200 nm, and (b) a pigment which is animal charcoal, bone black or ivory black and the molding is exposed to laser radiation having a principal wavelength of 1064 nm or 532 nm or 351, 308 and 248 nm.

### Claim 12 (depends on 11)

A process as claimed in claim 11, wherein the plastic molding composition includes (c) an inorganic pigment containing no free carbon.