Pigments

Abstract

The present invention relates to pigments based on bismuth compounds and to the use thereof, preferably as laser-absorbent additive, and to a process for the preparation thereof.

Claims

1. Pigment of the formula I,
mBi.sub.2O.sub.3*nBiOX*oBi.sub.aTi.sub.bO.sub.c*pTi.sub.xO.sub.yI where X denotes halogen, a denotes 1-15, b denotes 1-5, c denotes 1-15, m denotes 0-5, n denotes 1-5, o denotes 1-5, p denotes 0-5, x denotes 1-8, y denotes 1-10.

2. Pigment according to claim 1, characterised in that X denotes chlorine.

3. Pigment according to claim 1, characterised in that n=1.

4. Pigment according to claim 1, characterised in that a=1-3.

5. Pigment according to claim 1, characterised in that b=2-5.

6. Pigment according to claim 1, characterised in that c=5-20.

7. Pigment according to claim 1, characterised in that it comprises one or more compounds from the group of the compounds Bi.sub.2Ti.sub.4O.sub.11 Bi.sub.2Ti.sub.2O.sub.7 Bi.sub.1.74Ti.sub.2O.sub.6.62.

8. Pigment according to claim 1, characterised in that the pigment comprises the following mixed phases: BiOCl, Bi.sub.2Ti.sub.4O.sub.11, TiO.sub.2 or BiOCl, Bi.sub.2Ti.sub.2O.sub.7 or BiOCl, Bi.sub.1.74Ti.sub.2O.sub.6.62 or BiOCl, Bi.sub.2Ti.sub.4O.sub.11.

9. Pigment according to claim 1, characterised in that the pigment has particle sizes of 0.01-100.5 m.

10. Process for the preparation of the pigment according to claim 1, characterised in that a bismuth compound selected from the group Bi.sub.2O.sub.3, BiOCl, BiONO.sub.3, Bi(NO.sub.3).sub.3, Bi.sub.2O.sub.2CO.sub.3, BiOOH, BiOF, BiOBr, BiOC.sub.3H.sub.5O.sub.7, Bi(C.sub.7H.sub.5O.sub.2).sub.3, BiPO.sub.4, Bi.sub.2(SO.sub.4).sub.3, Bi.sub.aM.sub.bO.sub.c where M=Zn, Ti, Fe, Cu, Al, Zr, P, Sn, Sr, Si, Y, Nb, La, Ta, Pr, Ca, Mg, Mo, W, Sb, Cr, Ba, Ce and a=0.3-70, b=0.05-8 and c=1-100 is coated with TiO.sub.2 and subsequently calcined at temperatures of 300-815 C.

11. Process according to claim 10, characterised in that the bismuth compound is Bi.sub.2O.sub.3.

12. A composition comprising a pigment according to claim 1 as additive for laser marking, for laser welding, in paints, coatings, powder coatings, printing inks, plastics, or granules.

13. Polymer matrix comprising at least one pigment according to claim 1 and a polymer.

Description

EXAMPLES

Example 1 (100% of TiO2 Based on the Substrate; Calcination Temperature 750 C.)

(1) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 m, 5N Plus Lbeck GmbH) are heated to 75 C. in 2 l of demineralised water with stirring.

(2) The pH of the suspension is then adjusted to 2.2 using 25% hydrochloric acid. A 32% titanium tetrachloride solution (400 g of TiCl.sub.4 solution; w=60%, dissolved in 350 g of demineralised water) is then metered in, during which the pH is kept constant by simultaneous dropwise addition of 32% sodium hydroxide solution.

(3) When the addition is complete, the mixture is stirred for a further 0.5 h. The product is filtered, washed, dried for 12 h, calcined at 750 C. for 0.5 h, sieved through a 100 m sieve and investigated with the aid of XRD.

(4) The slightly yellowish material obtained in this way is incorporated into polyamide in a proportion of 0.25% by means of an extruder. This compound is then shaped into test plates on an injection-moulding machine. A test grid, by means of which a large band width of various laser settings with respect to energy of the laser, speed of the laser beam and frequency of the laser pulse can be depicted, is marked onto these plates using an Nd:YAG laser (Trumpf: writing speed: 500-5000 mm/s, pulse frequency: 20-100 kHz). The additive from Example 1 exhibits a uniform black mark of excellent contrast over virtually the entire spectrum of different laser parameters.

Comparative Example 1

Incorporation of Bi2O3 into Polyamide

(5) Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 m, 5N Plus Lbeck GmbH) is incorporated into polyamide in a proportion of 1% by means of an extruder. Decomposition reactions occur even during processing in the extruder, and a dark to black-discoloured product forms.

(6) The compound is then shaped into dark-brown to black test plates on an injection-moulding machine. A test grid is marked onto these plates using an Nd:YAG laser (Trumpf: writing speed: 500-5000 mm/s, pulse frequency: 20-100 kHz). The contrast of the dark inscription on a dark background is virtually invisible to the eye.

Example 2 (12.5% of TiO2, Based on the Substrate; Calcination Temperature 600 C.)

(7) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 m, 5N Plus Lbeck GmbH) are heated to 75 C. in 2 l of demineralised water with stirring.

(8) The pH of the suspension is then adjusted to 2.2 using 25% hydrochloric acid. A 32% titanium tetrachloride solution (50 g of TiCl.sub.4 solution; w=60%, dissolved in 44 g of demineralised water) is then metered in, during which the pH is kept constant by simultaneous dropwise addition of 32% sodium hydroxide solution.

(9) When the addition is complete, the mixture is stirred for a further 0.5 h. The product is filtered, washed, dried for 15 h, calcined at 600 C. for 0.5 h, sieved through a 100 m sieve and investigated with the aid of XRD.

(10) The slightly yellowish material obtained in this way is incorporated into polyamide in a proportion of 0.5% by means of an extruder. This compound is then shaped into test plates on an injection-moulding machine. A test grid, by means of which a large band width of various laser settings with respect to energy of the laser, speed of the laser beam and frequency of the laser pulse can be depicted, is marked onto these plates using an Nd:YAG laser (Trumpf: writing speed: 500-5000 mm/s, pulse frequency: 20-100 kHz). The additive from Example 2 exhibits a uniform black mark of excellent contrast over virtually the entire spectrum of different laser parameters.

Example 3 (6.25% of TiO2, Based on the Substrate; Calcination Temperature 750 C.)

(11) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 m, 5N Plus Lbeck GmbH) are heated to 75 C. in 2 l of demineralised water with stirring.

(12) The pH of the suspension is then adjusted to 2.2 using 25% hydrochloric acid. A 32% titanium tetrachloride solution (25 g of TiCl.sub.4 solution; w=60%, dissolved in 22 g of demineralised water) is then metered in, during which the pH is kept constant by simultaneous dropwise addition of 32% sodium hydroxide solution.

(13) When the addition is complete, the mixture is stirred for a further 0.5 h. The product is filtered, washed, dried for 12 h, calcined at 750 C. for 2 h, sieved through a 100 m sieve and investigated with the aid of XRD.

(14) The slightly yellowish material obtained in this way is incorporated into polyamide in a proportion of 1.0% by means of an extruder. This compound is then shaped into test plates on an injection-moulding machine. A test grid, by means of which a large band width of various laser settings with respect to energy of the laser, speed of the laser beam and frequency of the laser pulse can be depicted, is marked onto these plates using an Nd:YAG laser (Trumpf: writing speed: 500-5000 mm/s, pulse frequency: 20-100 kHz). The additive from Example 3 exhibits a uniform black mark of excellent contrast over virtually the entire spectrum of different laser parameters.

Example 4 (6.25% of TiO2, Based on the Substrate; Calcination Temperature 600 C.)

(15) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 m, 5N Plus Lbeck GmbH) are heated to 75 C. in 2 l of demineralised water with stirring.

(16) The pH of the suspension is then adjusted to 2.2 using 25% hydrochloric acid.

(17) A 32% titanium tetrachloride solution (25 g of TiCl.sub.4 solution; w=60%, dissolved in 22 g of demineralised water) is then metered in, during which the pH is kept constant by simultaneous dropwise addition of 32% sodium hydroxide solution.

(18) When the addition is complete, the mixture is stirred for a further 0.5 h. The product is filtered, washed, dried for 12 h, calcined at 600 C. for 1 h, sieved through a 100 m sieve and investigated with the aid of XRD.

(19) The slightly yellowish material obtained in this way is incorporated into polyamide in a proportion of 1.0% by means of an extruder. This compound is then shaped into test plates on an injection-moulding machine. A test grid, by means of which a large band width of various laser settings with respect to energy of the laser, speed of the laser beam and frequency of the laser pulse can be depicted, is marked onto these plates using an Nd:YVO.sub.4 laser (Trumpf: writing speed: 4000-10000 mm/s, pulse frequency: 20-60 kHz). The additive from Example 4 exhibits a uniform black mark of excellent contrast over virtually the entire spectrum of different laser parameters.

Example 5 (50% of TiO2, Based on the Substrate; Calcination Temperature 750 C.)

(20) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 m, 5N Plus Lbeck GmbH) are heated to 75 C. in 2 l of demineralised water with stirring.

(21) The pH of the suspension is then adjusted to 2.2 using 25% hydrochloric acid. A 32% titanium tetrachloride solution (200 g of TiCl.sub.4 solution; w=60%, dissolved in 175 g of demineralised water) is then metered in, during which the pH is kept constant by simultaneous dropwise addition of 32% sodium hydroxide solution.

(22) When the addition is complete, the mixture is stirred for a further 0.5 h. The product is filtered, washed, dried for 12 h, calcined at 750 C. for 1 h, sieved through a 100 m sieve and investigated with the aid of XRD.

(23) The slightly yellowish material obtained in this way is incorporated into polyamide in a proportion of 0.25% by means of an extruder. This compound is then shaped into test plates on an injection-moulding machine. A test grid, by means of which a large band width of various laser settings with respect to energy of the laser, speed of the laser beam and frequency of the laser pulse can be depicted, is marked onto these plates using an Nd:YVO.sub.4 laser (Trumpf: writing speed: 4000-10000 mm/s, pulse frequency: 20-60 kHz). The additive from Example 5 exhibits a uniform black mark of excellent contrast over virtually the entire spectrum of different laser parameters.

Example 6 (12.5% of TiO2, Based on the Substrate; Calcination Temperature 750 C.)

(24) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade; average particle size: 4 m, 5N Plus Lbeck GmbH) are heated to 75 C. in 2 l of demineralised water with stirring.

(25) The pH of the suspension is then adjusted to 2.2 using 25% hydrochloric acid. A 32% titanium tetrachloride solution (50 g of TiCl.sub.4 solution; w=60%, dissolved in 44 g of demineralised water) is then metered in, during which the pH is kept constant by simultaneous dropwise addition of 32% sodium hydroxide solution.

(26) When the addition is complete, the mixture is stirred for a further 0.5 h. The product is filtered, washed, dried for 12 h, calcined at 750 C. for 0.5 h, sieved through a 100 m sieve and investigated with the aid of XRD.

Example 7 (25.0% of TiO2, Based on the Substrate; Calcination Temperature 750 C.)

(27) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade; average particle size: 4 m, 5N Plus Lbeck GmbH) are heated to 75 C. in 2 l of demineralised water with stirring.

(28) The pH of the suspension is then adjusted to 2.2 using 25% hydrochloric acid. A 32% titanium tetrachloride solution (100 g of TiCl.sub.4 solution; w=60%, dissolved in 88 g of demineralised water) is then metered in, during which the pH is kept constant by simultaneous dropwise addition of 32% sodium hydroxide solution.

(29) When the addition is complete, the mixture is stirred for a further 0.5 h. The product is filtered, washed, dried for 15 h, calcined at 750 C. for 1 h, sieved through a 100 m sieve and investigated with the aid of XRD.

(30) The following phases are found according to XRD in the products of Examples 1 to 7:

(31) TABLE-US-00001 TABLE Calcination temperature TiO.sub.2 Example ( C.) (% based on Bi.sub.2O.sub.3) Bi.sub.2O.sub.3:TiO.sub.2 Finding 1 750 100 50:50 BiOCl, Bi.sub.2Ti.sub.4O.sub.11, TiO.sub.2 2 600 12.5 90:10 BiOCl, Bi.sub.2Ti.sub.2O.sub.7 3 750 6.25 94.6:6 BiOCl, Bi.sub.1.74Ti.sub.2O.sub.6.62 4 600 6.25 94.6:6 BiOCl, Bi.sub.2Ti.sub.2O.sub.7 5 750 50 67:33 BiOCl, Bi.sub.2Ti.sub.4O.sub.11 6 750 12.5 90:10 BiOCl, Bi.sub.2Ti.sub.4O.sub.11 7 750 25 80:20 BiOCl, Bi.sub.2Ti.sub.4O.sub.11