Pigment finishing by microwave heating
View Patent ↗The invention relates to a process for aftertreating organic pigments which comprises heating the unground or ground organic crude pigment in water and/or organic solvents by means of microwave irradiation, under pressure if desired, so that the mass temperature of the mixture reaches 30 to 250° C.
1. A process for aftertreating an organic pigment comprising the steps of providing a mixture of an unground or ground organic crude pigment in a carrier and heating the mixture by microwave irradiation to achieve a mass temperature of the mixture, wherein the mass temperature of the mixture reaches 30 to 250° C., and wherein the carrier is water, an organic solvent or a mixture thereof, wherein the process results in a pigment having a defined morphology and crystal phase.
2. The process as claimed in claim 1 , wherein the carrier is water.
3. The process as claimed in claim 1 , wherein the heating step is carried out continuously.
4. The process as claimed in claim 1 , wherein the heating step has a duration and wherein the duration is 0.5 to 30 min.
5. The process as claimed in claim 1 , wherein the heating step has a duration and wherein the duration is 2 to 10 min.
6. The process as claimed in claim 1 , wherein the microwave irradiation has a frequency of 2450 MHz.
7. The process as claimed in claim 1 , wherein the organic crude pigment is an azo pigment or a polycyclic pigment.
8. The process as claimed in claim 1 , wherein the organic crude pigment is an azo pigment and wherein the azo pigment is a monoazo, disazo, disazo condensation, naphthol or metal complex pigment.
9. The process as claimed in claim 1 , wherein the organic crude pigment is an azo pigment, and wherein the azo pigment is C.I. Pigment Yellow 16, 32, 83, 97, 120, 151, 154, 155, 175, 180, 181, 191, 194, 213, 214, Pigment Orange 34, 36, 38, 62, 72, 74, Pigment Red 53:2, 112, 122, 137, 144, 170, 171, 175, 176, 185, 187, 158, 208, 214, 242, 247, 253; Pigment Violet 32; or Pigment Brown 25.
10. The process as claimed in claim 1 , wherein the crude organic pigment is a polycyclic pigment, and wherein the polycyclic pigment is an isoindolinone, isoindoline, anthanthrone, thioindigo, quinophthalone, anthraquinone, dioxazine, phthalocyanine, quinacridone, perylene, perinone, diketopyrrolopyrrole, thiazoindigo or azomethine pigment.
11. The process as claimed in claim 1 , wherein the organic crude pigment is C.I. Pigment Violet 19, 23, Pigment Blue 15, Pigment Green 7, 36, 37, Pigment Red 122, 254, 264 or Pigment Yellow 139.
12. The process as claimed in claim 1 , wherein the heating step occurs under pressure.