Glycol based pigment preparation for mass dyeing of polyacrylonitrile fibers

1. A process for mass dyeing of polyacrylonitrile, comprising the step of incorporating a pigment preparation into a solution of acrylonitrile polymer or copolymer, wherein the pigment preparation comprises

10 to 60% by weight of a pigment,

15 to 85% by weight of a glycol-based solvent,

5 to 25% by weight of a surfactant, and

0 to 10% by weight of additives,

the percentages being based on the total weight of the pigment preparation.

2. The process as claimed in claim 1 , wherein the pigment preparation is incorporated in an amount of 2 to 20% by weight, based on the weight of the dyed polyacrylonitrile mass.

3. The process as claimed in claim 1 , further comprising the step of extruding the mixture of acrylonitrile polymer or copolymer and pigment preparation into a bath to obtain polyacrylonitrile fibers already coloured.

4. The process as claimed in claim 1 , wherein the glycol-based solvent comprises a glycolic compound selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butylene glycol, triethylene glycol, polyethylene glycol, alpha-methyl-omega-hydroxy-polyethylene glycol ether, dimethyl polyethylene glycol ether, polypropylene glycol, dimethyl polypropylene glycol ether, and copolymers of ethylene glycol and propylene glycol.

5. The process as claimed in claim 1 , wherein the pigment is an organic pigment selected from the group consisting of monoazo, disazo, laked azo, β-naphthol, naphthol AS, benzimidazolone, disazo condensation, and azo metal complex pigments, phthalocyanine, quinacridone, perylene, perinone, thioindigo, anthanthrone, anthraquinone, flavanthrone, indanthrone, isoviolanthrone, pyranthrone, dioxazine, quinophthalone, isoindolinone, isoindoline, diketopyrrolopyrrole pigments, and acidic to alkaline carbon black.

6. The process as claimed in claim 1 , wherein the pigment is an inorganic pigment selected from the group consisting of titanium dioxides, zinc sulfides, zinc oxides, iron oxides, manganese iron oxides, chromium oxides, ultramarine, nickel or chromium antimony titanium oxides, cobalt oxides, mixed oxides of cobalt and aluminum, rutile mixed-phase pigments, sulfides of rare earths, bismuth vanadates, and extender pigments.

7. A pigment preparation comprising

10 to 60% by weight of a pigment,

15 to 85% by weight of propylene glycol,

5 to 25% by weight of a surfactant, and

0 to 10% by weight of additives,

the percentages being based on the total weight of the pigment preparation and wherein the pigment preparation is substantially free of water.

8. The pigment preparation as claimed in claim 7 , consisting of

10 to 60% by weight of a pigment,

15 to 85% by weight of propylene glycol,

5 to 25% by weight of a surfactant, and

0 to 10% by weight of additives selected from the group consisting of thickeners, preservatives, biocides, viscosity stabilizers, emulsifiers, grinding assistants, fillers, hydrotropic retention agents, antisettling agents, light stabilizers, antioxidants, devolatilizers, defoamers, foam reducers, anticaking agents and rheology improvers, the percentages being based on the total weight of the pigment preparation.

9. The pigment preparation as claimed in claim 7 , wherein the pigment is selected from the group consisting of C.I. Pigment Black 7, C.I. Pigment Blue 15:3, C.I. Pigment Green 7, C.I. Pigment Yellow 213, and C.I. Pigment Red 254.

10. A process for producing a pigment preparation as claimed in claim 7 , comprising the step of dispersing the pigment in the form of powder or granules in propylene glycol and surfactant, optionally milling, until the particle size reaches less than 1 μm, and optionally mixing in the presence of additives.