Conductive carbon powder, a method for the manufacturing thereof and use thereof

Abstract

The present invention relates to a conductive carbon powder emanating essentially from lignin, a method for the manufacturing thereof and use thereof. Said powder may emanate from an electrically conductive carbon intermediate product, in turn emanating essentially from lignin. Further, uses thereof and compositions comprising said carbon powder are disclosed. Additionally methods for manufacturing said conductive carbon powder, also involving an electrically conductive carbon intermediate product emanating essentially from lignin, are disclosed together with a method for making said compositions.

Claims

1. A method for manufacturing an electrically conductive carbon powder comprising: i) providing a lignin and at least one additive, ii) mixing the lignin and the at least one additive to form a mixture, iii) shaping the mixture to form a shaped body, iv) performing a thermal treatment of the shaped body in which a first step of the thermal treatment comprises a temperature ramp from room temperature to a temperature of up to 300 C. or less and in which a last step of the thermal treatment comprises a temperature ramp from room temperature to a temperature of up to about 2000 C. or less in an inert atmosphere to provide a conductive carbonized intermediate product, and v) pulverizing the conductive carbonized intermediate product to provide a conductive carbon powder.

2. A method according to claim 1 wherein the at least one additive comprises a plasticizer, a reactive agent that renders the lignin melt extrudable, an aliphatic acid, a lignin solvent, an aprotic polar solvent, an aliphatic amide, dimethylformamide (DMF), dimethylacetamide (DMAc), a tertiary amine oxide, N-methylmorpholine-N-oxide (NMMO), dimethylsulfoxide (DMSO), ethylene glycol, di-ethylene glycol, a low-molecular-weight poly ethylene glycol (PEG) having a molecular weight between 150 to 20,000 g/mol, ionic liquids, or combinations thereof.

3. A method according to claim 1 wherein the at least one additive is a poly ethylene glycol.

4. A method according to claim 1 wherein the temperature ramp of the last step is from room temperature up to the temperature of about 1600 C. or less.

5. A method according to claim 1 wherein the temperature ramp of the last step is from room temperature up to the temperature of about 1400 C. or less.

6. A method according to claim 1 wherein the first step takes place in air.

7. A method for manufacturing a conductive carbon powder comprising the following steps: a) thermal treatment of a lignin comprising compound to increase the carbon content to at least 80% to obtain an electrically conductive carbonized lignin intermediate product wherein a first step of the thermal treatment comprises a temperature ramp from room temperature to a temperature of up to 300 C. or less; and b) mechanical treatment of the electrically conductive carbonized lignin intermediate product to obtain a carbonized lignin powder which is electrically conductive.

8. A method according to claim 7 wherein a last step of the thermal treatment comprises a temperature ramp from room temperature to a temperature of up to about 2000 C. or less in an inert atmosphere.

9. A method according to claim 7 wherein a last step of the thermal treatment comprises a temperature ramp from room temperature to a temperature of up to about 1600 C. or less.

10. A method according to claim 7 wherein a last step of the thermal treatment comprises a temperature ramp from room temperature to a temperature of up to about 1400 C. or less.

11. A method according to claim 7 wherein the lignin comprising compound comprises lignin and at least one additive.

12. A method according to claim 7 wherein the at least one additive comprises a plasticizer, a reactive agent that renders the lignin melt extrudable, an aliphatic acid, a lignin solvent, an aprotic polar solvent, an aliphatic amide, dimethylformamide (DMF), dimethylacetamide (DMAc), a tertiary amine oxide, N-methylmorpholine-N-oxide (NMMO), dimethylsulfoxide (DMSO), ethylene glycol, di-ethylene glycol, a low-molecular-weight poly ethylene glycol (PEG) having a molecular weight between 150 to 20,000 g/mol, ionic liquids, or combinations thereof.

13. A method according to claim 7 wherein the at least one additive is a poly ethylene glycol.

14. A method according to claim 7 wherein the mechanical treatment comprises pulverizing the electrically conductive carbonized lignin intermediate product.

15. A method according to claim 7 wherein the first step takes place in air.

16. A method for manufacturing a carbonized intermediate product in filament form, comprising: providing a lignin and at least one additive, mixing the lignin and the at least one additive to form a mixture, melt spinning the mixture to a monofilament or multifilament bundle component, performing a thermal treatment of monofilament or multifilament bundle in which a first step of the thermal treatment comprises a temperature ramp from room temperature to a temperature of up to 300 C. or less and a last step comprises a temperature ramp from room temperature to a temperature of up to about 2000 C. or less in an inert atmosphere to provide a conductive carbonized intermediate product in filament form.

17. A method according to claim 16 wherein the at least one additive comprises a plasticizer, a reactive agent that renders the lignin melt extrudable, an aliphatic acid, a lignin solvent, a aprotic polar solvent, an aliphatic amide, dimethylformamide (DMF), dimethylacetamide (DMAc), a tertiary amine oxide, N-methylmorpholine-N-oxide (NMMO), dimethylsulfoxide (DMSO), ethylene glycol, di-ethylene glycol, a low-molecular-weight poly ethylene glycol (PEG) having a molecular weight between 150 to 20,000 g/mol, ionic liquids, or combinations thereof.

18. A method according to claim 16 wherein the at least one additive is a poly ethylene glycol.

19. A method according to claim 16 wherein the temperature ramp of the last step is from room temperature up to the temperature of about 1600 C. or less.

20. A method according to claim 16 wherein the first step takes place in air.

Description

FIGURE

(1) FIG. 1 discloses volume resistivity of compounds comprised of PP (HP 561R from Lyondell Basell) and 5% respectively 10% of the conductive carbon powder described in this invention. For comparison percolation curves are shown for reference compositions comprising PP and three different commercial conductive carbon blacks, respectively.

(2) FIG. 2 discloses a comparison of volume resistivity of compressed carbon powder (applied pressure 31 MPa).

(3) FIG. 3 discloses a comparison of volume resistivity of carbonized fibers.

EXAMPLES

(4) Examples on Lignin-Containing Compound in Form of a Shaped Body

Example 1

(5) A fiber was melt-spun from a mixture comprising of 88 w % softwood Kraft lignin, 7 w % Phthalic anhydride acid and 5 w % DMSO (97% purity, Sigma-Aldrich) using a laboratory twin-screw extruder with a single capillary (DSM Xplore micro-compounder). The obtained lignin-containing compound had the form of a filament with a diameter of 150 m.

Example 2

(6) The mixture from example 1 was extruded with a laboratory twin screw extruder (KEDSE 20/40 from Brabender GmbH & CO. KG) using a multifilament die with 62 capillaries. The obtained lignin-containing compound had the form of a multi-filament bundle with a single filament diameter of 72 m.

Example 3

(7) A mixture comprising 90 w % softwood lignin and 10% PEG 400 (Polyethylene Glycol from Sigma-Aldrich with a molecular weight of 400 Da) was prepared.

(8) The mixture was extruded on a laboratory twin screw extruder using a die with 62 capillaries. The obtained lignin-containing compound had the form of a multi-filament bundle with a single filament diameter of 90 m.

Example 4

(9) A mixture was prepared as described in example three and put in a flat metal tube. Pressure was applied using a piston and as a result the lignin-containing compound attained the shape of a wafer.

(10) Examples on Conductive Carbon Intermediate Products

Example 5

(11) The lignin-containing filament from example 1 was converted in a two-step thermal treatment to obtain a conductive carbon intermediate product. In a first step the filament was heated in air from room temperature to 250 C. with a varying heating rate of between 0.2 C./min and 5 C./min and then heated in the second step in nitrogen from room temperature to 1600 C. with a heating rate of 1 C./min. The obtained conductive carbon intermediate product had the shape of a filament with a diameter of about 60 m and yielded an electrical volume resistivity of 1.410{circumflex over ()}3 Ohm*cm. Volume resistivity was measured using a LCR meter.

Example 6

(12) The obtained spun filaments from example 2 where heat-treated in the same manner as described in example 5. The resulting carbonized multifilaments had a diameter of about 80 m and yielded an electrical volume resistivity of 0.510{circumflex over ()}3 Ohm*cm.

Example 7

(13) The obtained filaments from example 3 were where heat-treated in the same manner as described in example 5. The resulting carbonized multifilaments had a diameter of about 75 m and yielded an electrical volume resistivity of 0.610{circumflex over ()}3 Ohm*cm.

Example 8

(14) The obtained filaments from example 3 were heat-treated according to the following steps. In a first step the filament was heated in air from room temperature to 250 C. with a varying heating rate between 0.2 C./min and 5 C./min and then heated in the second step in nitrogen from room temperature to 1000 C. with a heating rate of 2 C./min. The obtained carbonized fiber yielded an electrical volume resistivity of 0.7210{circumflex over ()}3 Ohm*cm.

Example 9

(15) The obtained filaments from example 3 were heat-treated according to the following steps. In a first step the filament was heated in air from room temperature to 250 C. with a varying heating rate between 0.2 C./min and 5 C./min and then heated in the second step in nitrogen from room temperature to 1200 C. with a heating rate of 2 C./min. The obtained carbonized fiber yielded an electrical volume resistivity of 0.3310{circumflex over ()}3 Ohm*cm.

Example 10

(16) The obtained filaments from example 3 were heat-treated according to the following steps. In a first step the filament was heated in air from room temperature to 250 C. with a varying heating rate between 0.2 C./min and 5 C./min and then heated in the second step in nitrogen from room temperature to 1400 C. with a heating rate of 2 C./min. The obtained carbonized fiber yielded an electrical volume resistivity of 0.2310{circumflex over ()}3 Ohm*cm.

Example 11

(17) The obtained filaments from example 3 were heat-treated according to the following steps. In a first step the filament was heated in air from room temperature to 250 C. with a varying heating rate between 0.2 C./min and 5 C./min and then heated in the second step in nitrogen from room temperature to 1600 C. with a heating rate of 2 C./min. The obtained carbonized fiber yielded an electrical volume resistivity of 0.5410{circumflex over ()}3 Ohm*cm.

Example 12

(18) The wafer from example 4 was heat treated in nitrogen atmosphere by increasing temperature from room temperature to 1600 C. at a heating rate of 1 C./min to obtain a carbonized wafer.

(19) Examples on Conductive Carbon Powder

Example 13

(20) The carbonized wafer from example 12 was manually crushed utilizing a laboratory mortar to obtain a conductive carbonized lignin powder.

(21) Examples on Conductive Polymer Compounds

Example 14

(22) The conductive carbonized lignin powder from example 14 was compounded into a polypropylene matrix (HP 561R from Lyondell Basell) using a DSM Xplore micro-compounder. The MFR was 25 g/10 min (@230 C./2.16 kg/10 min). The composition consisted of 95 w % polypropylene and 5% of conductive carbonized lignin powder. The extruded strands showed a volume resistivity of 5.210{circumflex over ()}5 Ohm*cm, which was many magnitudes lower than the volume resistivity of pure PP, reported in the literature, about 110{circumflex over ()}17 Ohm*cm (Debowska, M. et. al.: Positron annihilation in carbon black-polymer composites, Radiation Physics and Chemistry 58 (2000), H. 5-6, S. 575-579). This example showed that the conductive carbonized lignin powder from example 13 was in fact electrically conductive.

Example 15

(23) The conductive carbon powder from example 14 was compounded into a Polypropylene matrix (HP 561R from Lyondell Basell) using a DSM Xplore micro-compounder. The composition consisted of 90 w % (PP) and 10% conductive carbonized lignin powder. The extruded strands yielded a volume resistivity of 2.610{circumflex over ()}5 Ohm*cm.

(24) Examples on Reference Conductive Polymer Compounds

Example 16

(25) FIG. 1 reflects literature data (Debowska, M. et. al.: Positron annihilation in carbon black-polymer composites, Radiation Physics and Chemistry 58 (2000), H. 5-6, S. 575-579)

(26) regarding volume resistivity of conductive polymer compositions comprising different commercial conductive carbon blacks. The commercial carbon blacks were SAPAC-6 (from CarboChem), Printex XE-2 (from Degussa) and Vulcan XC-72 (Cabot).

(27) FIG. 1 discloses also, additionally, volume resistivity of compositions comprising PP (HP 561R from Lyondell Basell) and 5% and 10%, respectively, of conductive carbon powder described above.

(28) The figure shows that conductive carbonized lignin powder provided by the present invention has at least the same conductivity performance as the best commercial carbon black (Printex XE-2).

Example 17

(29) In order to measure the electrical conductivity of the powder samples, the powder was filled into a hollow cylinder. This cylinder was made of non-conductive PMMA which was cleaned thoroughly between each measurement. The inner diameter was 5 mm. At the bottom of the cylinder there was a gold plated copper plate as a base electrode. The second electrode was a copper stamp which was also gold plated and formed the second electrode. The stamp was then inserted into the cylinder thus slowly compressing the powder. Through a force measurement and online position measurement the applied pressure as well as the volume within the powder filled chamber was plotted. Through applying a DC voltage to the two electrodes the absolute resistance could be measured. Together with the documented position of the stamp a volume resistivity could be calculated. In order to compare various samples with potentially varying specific volumes the resistivity values could only be compared at equal pressure levels. In the presented results the chambers were filled with powder and compressed to the maximal pressure of 31 MPa. The measured value is indicated in FIG. 2.

(30) The results presented in the figure clearly state that the lignin based carbonized powders (CLP) exhibit the same conductivity/resistivity performance as the commercially available grade of Cabot (Cabot Vulcan XC-72-R).

(31) In the figure:

(32) Example 13-1=Example 13 as mentioned above

(33) Example 13-2=Example 13, but not manually crushed with a lab mortar but cryo milled.

Example 18

(34) The products in examples 8-11 set out above earlier was also compared with commercial grade carbon fibres (Toho Tenax HTA40 6 k and Mitsubishi Dialead K13C, respectivelytheir values were taken from a product sheet and the internet, respectively). The results are given in FIG. 3.

(35) Various embodiments of the present invention have been described above but a person skilled in the art realizes further minor alterations, which would fall into the scope of the present invention. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. For example, any of the above-noted compositions or methods may be combined with other known methods. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.