Pigments based on bismuth compounds

Abstract

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

Claims

1. A pigment of formula I
nBi.sub.2O.sub.3*mBiOX*oBi.sub.xX.sub.yO.sub.z*pBi.sub.aSi.sub.bO.sub.cI where X denotes halogen x denotes 2-30, y denotes 1-15, where, in the case y=1, z is then >1, z denotes 1-35 a denotes 0-15 b denotes 1-5 c denotes 1-25, n denotes 0-5 m denotes 0-5 o denotes 1-5 p denotes 1-5.

2. The pigment according to claim 1, wherein X denotes chlorine.

3. The pigment according to claim 1, wherein o=1.

4. The pigment according to claim 1, wherein x=2-25.

5. The pigment according to claim 1, wherein c=1-20.

6. The pigment according to claim 1, which comprises one or more of the following compounds Bi.sub.4Cl.sub.2O.sub.5 Bi.sub.12Cl.sub.6O.sub.15 Bi.sub.24Cl.sub.10O.sub.31 Bi.sub.2SiO.sub.5 Bi.sub.4(SiO.sub.4).sub.3 Bi.sub.12SiO.sub.20.

7. The pigment according to claim 1, which comprises the following mixed phase: Bi.sub.24Cl.sub.10O.sub.31+Bi.sub.2SiO.sub.5+Bi.sub.4(SiO.sub.4).sub.3 or Bi.sub.24Cl.sub.10O.sub.31+BiOCl or Bi.sub.24Cl.sub.10O.sub.31+BiOCl+Bi.sub.4O.sub.5Cl.sub.2 or Bi.sub.12Cl.sub.6O.sub.15+BiOCl+Bi.sub.2O.sub.3 or Bi.sub.24Cl.sub.10O.sub.31+Bi.sub.4 Cl.sub.2O.sub.5 or Bi.sub.12SiO.sub.20+Bi.sub.2SiO.sub.5+Bi.sub.4(SiO.sub.4).sub.3 or Bi.sub.24Cl.sub.10O.sub.31+Bi.sub.2SiO.sub.5.

8. The pigment according to claim 1, which has particle sizes of 0.01-100.5 ?m.

9. A process for preparing the pigment according to claim 1, comprising coating a bismuth compound selected from the group consisting of 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 with SiO.sub.2 in the presence of a chlorine compound and subsequently calcining at a temperature of 300-815? C., wherein M=Zn, Ti, Fe, Cu, Al, Zr, P, Sn, Sr, Si, Y, Nb, La, Ta, Pr, Ca, Mg, Mo, W, Sb, Cr, Ba or Ce, a=0.3-70, b=0.05-8 and c=1-100.

10. The process according to claim 9, wherein the bismuth compound is Bi.sub.2O.sub.3.

11. An additive for laser marking, for laser welding, or in a product selected from the group consisting of paints, coatings, powder coatings, printing inks, plastics, preparations, and granules, comprising a pigment according to claim 1.

12. A polymer matrix comprising at least one pigment according to claim 1.

13. The process according to claim 9, wherein the bismuth compound has a shape that is spherical or oval.

14. The process according to claim 9, wherein the bismuth compound has a shape that is amorphous.

15. The process according to claim 9, wherein the SiO.sub.2 in the presence of a chlorine compound is coated directly onto the bismuth compound, which is uncoated before the coating with the SiO.sub.2 in the presence of a chlorine compound.

16. A method for laser marking a polymer matrix, comprising laser marking a matrix according to claim 12.

Description

EXAMPLES

Example 1: 50% of SiO2, Based on the Substrate; Calcination Temperature: 700? C.

(1) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 ?m, 5N Plus L?beck GmbH) are heated to 75? C. in 2 l of demineralised water with stirring. The pH of the suspension is then adjusted to 7.5 using 10% hydrochloric acid. This is followed by metered addition of a sodium water-glass solution (182 g of sodium water-glass solution, comprising 27.5% of SiO.sub.2, are dissolved in 182 g of deionised water), where the pH is kept constant by simultaneous dropwise addition of 10% hydrochloric acid. When the addition is complete, the mixture is stirred for a further 0.5 h.

(2) The product is filtered, washed, dried at 120? C. for 12 h, calcined at 700? C. for 0.5 h, sieved through a 100 ?m sieve and investigated with the aid of XRD.

(3) The slightly yellowish material obtained in this way is incorporated into polyamide in a concentration of 0.2% by means of an extruder. This compound is then moulded in an injection-moulding machine to give test plates. A test grid by means of which a wide band width of various laser settings with respect to energy of the laser, speed of the laser beam and frequency of the laser pulses can be represented 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 marking with excellent contrast over virtually the entire spectrum of different laser parameters.

Comparative Example 1: Incorporation of Bi2O3 into Polyamide

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

(5) The compound is then moulded in an injection-moulding machine to give dark-brown to black test plates. 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: 6.25% of SiO2, Based on the Substrate; Calcination Temperature: 700? C.

(6) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 ?m, 5N Plus L?beck GmbH) are heated to 75? C. in 2 l of demineralised water with stirring. The pH of the suspension is then adjusted to 7.5 using 10% hydrochloric acid. This is followed by metered addition of a sodium water-glass solution (23 g of sodium water-glass solution, comprising 27.5% of SiO.sub.2, are dissolved in 46 g of deionised water), where the pH is kept constant by simultaneous dropwise addition of 10% hydrochloric acid. When the addition is complete, the mixture is stirred for a further 0.5 h.

(7) The product is filtered, washed, dried at 140? C. for 12 h, calcined at 700? C. for 1 h, sieved through a 100 ?m sieve and investigated with the aid of XRD.

Example 3: 100% of SiO2, Based on the Substrate; Calcination Temperature: 500? C.

(8) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 ?m, 5N Plus L?beck GmbH) are heated to 75? C. in 2 l of demineralised water with stirring. The pH of the suspension is then adjusted to 7.5 using 10% hydrochloric acid. This is followed by metered addition of a sodium water-glass solution (364 g of sodium water-glass solution, comprising 27.5% of SiO.sub.2, are dissolved in 364 g of deionised water), where the pH is kept constant by simultaneous dropwise addition of 10% hydrochloric acid. When the addition is complete, the mixture is stirred for a further 0.5 h.

(9) The product is filtered, washed, dried at 120? C. ? C. for 12 h, calcined at 500? C. for 2 h, sieved through a 100 ?m sieve and investigated with the aid of XRD.

Example 4: 12.5% of SiO2, Based on the Substrate; Calcination Temperature: 700? C.

(10) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 ?m, 5N Plus L?beck GmbH) are heated to 75? C. in 2 l of demineralised water with stirring. The pH of the suspension is then adjusted to 7.5 using 10% hydrochloric acid. This is followed by metered addition of a sodium water-glass solution (46 g of sodium water-glass solution, comprising 27.5% of SiO.sub.2, are dissolved in 46 g of deionised water), where the pH is kept constant by simultaneous dropwise addition of 10% hydrochloric acid. When the addition is complete, the mixture is stirred for a further 0.5 h.

(11) The product is filtered, washed, dried at 110? C. for 12 h, calcined at 700? C. for 0.5 h, sieved through a 100 ?m sieve and investigated with the aid of XRD.

Example 5: 25% of SiO2, Based on the Substrate; Calcination Temperature: 500? C.

(12) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 ?m, 5N Plus L?beck GmbH) are heated to 75? C. in 2 l of demineralised water with stirring. The pH of the suspension is then adjusted to 7.5 using 10% hydrochloric acid. This is followed by metered addition of a sodium water-glass solution (91 g of sodium water-glass solution, comprising 27.5% of SiO.sub.2, are dissolved in 91 g of deionised water), where the pH is kept constant by simultaneous dropwise addition of 10% hydrochloric acid. When the addition is complete, the mixture is stirred for a further 0.5 h.

(13) The product is filtered, washed, dried at 130? C. for 15 h, calcined at 500? C. for 0.5 h, sieved through a 100 ?m sieve and investigated with the aid of XRD.

Example 6: 100% of SiO2, Based on the Substrate; Calcination Temperature: 300? C.

(14) 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 ?m, 5N Plus L?beck GmbH) are heated to 75? C. in 2 l of demineralised water with stirring. The pH of the suspension is then adjusted to 7.5 using 10% hydrochloric acid. This is followed by metered addition of a sodium water-glass solution (364 g of sodium water-glass solution, comprising 27.5% of SiO.sub.2, are dissolved in 364 g of deionised water), where the pH is kept constant by simultaneous dropwise addition of 10% hydrochloric acid. When the addition is complete, the mixture is stirred for a further 0.5 h.

(15) The product is filtered, washed, dried at 120? C. for 12 h, calcined at 300? C. for 1 h, sieved through a 100 ?m sieve and investigated with the aid of XRD.

Example 7: 25% of SiO2, Based on Bi2O3; Calcination Temperature: 300? C.

(16) Preparation of a bismuth-containing additive having the composition Bi.sub.2O.sub.3/SiO.sub.2 and incorporation into polyamide 100 g of Bi.sub.2O.sub.3 (bismuth oxide, varistor grade fine; average particle size: 2 ?m, 5N Plus L?beck GmbH) are heated to 75? C. in 2 l of demineralised water with stirring. The pH of the suspension is then adjusted to 7.5 using 10% hydrochloric acid. This is followed by metered addition of a sodium water-glass solution (91 g of sodium water-glass solution, comprising 27.5% of SiO.sub.2, are dissolved in 91 g of deionised water), where the pH is kept constant by simultaneous dropwise addition of 10% hydrochloric acid. When the addition is complete, the mixture is stirred for a further 0.5 h.

(17) The product is filtered, washed, dried at 110? C. for 15 h, calcined at 300? C. for 1 h, sieved through a 100 ?m sieve and investigated with the aid of XRD.

Example 8: 50% of SiO2, Based on the Substrate; Calcination Temperature: 300? C.

(18) 100 g of BiOCl (bismuth oxycloride, average particle size: 8-18 ?m, Merck KGaA) are heated to 75? C. in 2 l of demineralised water with stirring. The pH of the suspension is then adjusted to 7.5 using 10% sodium hydroxide solution. This is followed by metered addition of a sodium water-glass solution (182 g of sodium water-glass solution, comprising 27.5% of SiO.sub.2, are dissolved in 182 g of deionised water), where the pH is kept constant by simultaneous dropwise addition of 10% hydrochloric acid. When the addition is complete, the mixture is stirred for a further 0.5 h.

(19) The product is filtered, washed, dried at 110? C. for 12 h, calcined at 300? C. for 0.5 h, sieved through a 100 ?m sieve and investigated with the aid of XRD.

(20) The compounds prepared in accordance with Examples 1-8 exhibit the following phases according to XRD (Stoe):

(21) TABLE-US-00001 TABLE SiO.sub.2 (% based on substrate Substrate:SiO.sub.2 Calcination before the before the temperature calcination calcination Example (? C.) process process Finding 1 700 50 67:33 Bi.sub.24Cl.sub.10O.sub.31 + Bi.sub.2SiO.sub.5 + Bi.sub.4(SiO.sub.4).sub.3 2 700 6.25 94:6 BiOCl + Bi.sub.24Cl.sub.10O.sub.31 + Bi.sub.12SiO.sub.20 3 500 100 50:50 Bi.sub.24Cl.sub.10O.sub.31 + BiOCl + Bi.sub.4(SiO.sub.4).sub.3 4 700 12.5 89:11 Bi.sub.24Cl.sub.10O.sub.31 + Bi.sub.24O.sub.31Cl.sub.10 + Bi.sub.12SiO.sub.20 5 500 25 80:20 BiOCl + Bi.sub.24Cl.sub.10O.sub.31 + Bi.sub.4O.sub.5Cl.sub.2 6 300 100 50:50 BiOCl + Bi.sub.24Cl.sub.10O.sub.31 + Bi.sub.4(SiO.sub.4).sub.3 7 300 25 80:20 BiOCl + Bi.sub.2O.sub.3 + Bi.sub.12Cl.sub.15O.sub.6 8 300 50 67:33 Bi.sub.24Cl.sub.10O.sub.31 + BiOCl + Bi.sub.2SiO.sub.5