Bitumen composition

1. Bitumen composition comprising a lignin compound or derivative thereof, wherein 25 wt. % or more by weight of said lignin compound or derivative thereof is molecularly dissolved in said bitumen composition,

wherein the molecularly dissolved lignin compound or derivative thereof has an average particle size of 100 μm or less,

wherein said lignin compound or derivative thereof is a chemically modified lignin, and

wherein said chemically modified lignin is chemically modified with one or more groups selected from anhydrides, epoxy carrying reactants, and halide containing compounds.

2. Bitumen composition according to claim 1 , wherein said composition comprises 10 wt. % or more by weight of the bitumen composition of said lignin compound or derivative thereof.

3. Bitumen composition according to claim 1 , wherein said composition comprises 20 wt. % or more by weight of the bitumen composition of said lignin compound or derivative thereof.

4. Bitumen composition according to claim 1 , wherein said composition comprises 25-50 wt. % by weight of the bitumen composition of said lignin compound or derivative thereof.

5. Bitumen composition according to claim 1 , wherein said lignin compound or derivative thereof is substantially free of sulfur.

6. Bitumen composition according to claim 1 , wherein said lignin compound or derivative thereof is completely free of sulfur.

7. Bitumen composition according to claim 1 , wherein said chemically modified lignin compound comprises one or more units represented by formula (II) below

wherein

R represents a lignin residue;

R′ is selected from the group consisting of C 1-20 alkyl, C 2-20 alkenyl, (C 1-20 alkyl)-phenyl, (C 2-20 alkenyl)-phenyl, C 1-20 alkoxy, (C 1-20 alkoxy)-phenyl, C 3-6 cycloalkyl,

aryl-(C 1-6 alkyl), aryl-(C 2-6 alkenyl), and (C 1-4 alkyl)-aryl-(C 1-4 alkyl);

X 1 is OH or H; and

X 2 is OH or H, and X 2 is different from X 1 .

8. Bitumen composition according to claim 1 , wherein said lignin compound or derivative thereof has a bimodal distribution of molecular weight.

9. Bitumen composition according to claim 1 , wherein the lignin compound or derivative thereof comprises 1-5 wt. % based on total weight of the lignin compound or derivative thereof of a first component having a M n of 100,000-150,000 g/mol and 95-99 wt. % based on total weight of the lignin compound or derivative thereof of a second component having a M n of 1500-2000 g/mol.

10. Bitumen composition according to claim 1 , wherein 50 wt. % or more by weight of said lignin compound or derivative thereof is molecularly dissolved in said bitumen composition.

11. Bitumen composition according to claim 1 , wherein 75 wt. % or more by weight of said lignin compound or derivative thereof is molecularly dissolved in said bitumen composition.

12. Bitumen composition according to claim 1 , having a dynamic viscosity (η*) at 20° C. and 10 rad/s in the range of

1.0×10 4 -5.0×10 6 , as determined by dynamic shear rheometer.

13. Bitumen composition according to claim 1 ,

having a complex modulus G*:

at 20° C. and 1×10 −4 rad/s in the range of 1×10 1 -1×10 5 Pa,

at 20° C. and 1 rad/s in the range of 1×10 5 -1×10 8 Pa, and

at 20° C. and 1×10 5 rad/s in the range of 1×10 7 -1×10 9 Pa;

having a corresponding phase angle δ:

at 20° C. and 1×10 −4 rad/s in the range of 30-90°,

at 20° C. and 1 rad/s in the range of 50-80°, and

at 20° C. and 1×10 5 rad/s in the range of 10-40°,

as determined by dynamic shear rheometer.

14. Bitumen composition according to claim 1 , further comprising one or more selected from the group consisting of a filler, sand, and rubble.

15. Paving comprising a bitumen composition according to claim 1 .

16. Roofing comprising a bitumen composition according to claim 1 .

17. Method of preparing a bitumen composition comprising molecularly dissolving 25 wt. % or more by weight of a lignin compound or derivative thereof into a bitumen composition, wherein the molecularly dissolved lignin compound or derivative thereof has an average particle size of 100 μm or less, wherein said lignin compound or derivative thereof is a chemically modified lignin, and wherein said chemically modified lignin is chemically modified with one or more groups selected from anhydrides, epoxy carrying reactants, and halide containing compounds.

18. Method according to claim 17 , wherein said lignin compound or derivative thereof is substantially or completely free of sulfur.