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Method for producing a conductive polyurethane composite material, and said material

20230257548 · 2023-08-17

    Inventors

    Cpc classification

    International classification

    Abstract

    The present invention relates to an electrically conductive polyurethane composite material and a method for producing same and can be used in the manufacture of articles and coatings from polyurethane composite materials having a desired electrical conductivity. The present method for producing an electrically conductive polyurethane composite material by reacting organic polyisocyanates (A) with one or more compounds (B) containing NCO-reactive groups includes a step of mixing a concentrate of carbon nanotubes with compounds (B) or with polyisocyanates (A) or with a mixture containing organic polyisocyanates (A) and compounds (B) at an input energy of less than 0.5 kW.Math.h per 1 kg of mixture and a carbon nanotube content of less than 0.1 mass. % relative to the sum of the masses of (A) and (B).

    Claims

    1. (canceled)

    2. (canceled)

    3. (canceled)

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    17. (canceled)

    18. (canceled)

    19. A method of producing a conductive polyurethane composite, comprising the steps of: (a) mixing a carbon nanotube concentrate with one or several compounds that include NCO-reactive groups (B) or organic polyisocyanates (A), or a mixture of (A) and (B), wherein a content of carbon nanotubes in the carbon nanotube concentrate is less than 0.1 wt. % of a total mass of (A) and (B), and wherein energy input at the mixing step is less than 0.5 kW.Math.h per 1 kg of the mixture; and (b) following the mixing step, curing the mixture to produce the conductive polyurethane composite.

    20. The method of claim 19, wherein the mixing step (a) further comprises introducing one or several auxiliary components selected from a group consisting of a catalyst, an inhibitor, a foaming agent, an antifoaming agent, a dye, a coloring pigment, a filler, a cross-linker, a plasticizer, a thickener, a thixotropic additive, a surface modifier, a flame retardant, a UV-protecting compound, an antioxidant, a stabilizer, an antimicrobial additive, an antifungal additive.

    21. The method of claim 19, wherein, prior to step (a), the carbon nanotube concentrate is pre-mixed with one or several auxiliary components from a group consisting of a catalyst, an inhibitor, a foaming agent, an antifoaming agent, a dye, a coloring pigment, a filler, a cross-linker, a plasticizer, a thickener, a thixotropic additive, a surface modifier, a flame retardant, a UV-protecting compound, an antioxidant, a stabilizer, an antimicrobial additive, an antifungal additive.

    22. The method of claim 19, wherein the carbon nanotube concentrate comprises 1 to 80 wt. % carbon nanotubes.

    23. The method of claim 19, wherein the carbon nanotube concentrate comprises 1 to 80 wt. % single-walled and/or double-walled carbon nanotubes.

    24. The method of claim 19, wherein a ratio of intensities of G and D bands in a Raman spectrum for light wavelength 532 nm from the carbon nanotube concentrate is more than 10.

    25. The method of claim 24, wherein the ratio of intensities is more than 50.

    26. The method of claim 19, wherein the carbon nanotube concentrate comprises 20 to 99 wt. % of one or several esters of aliphatic alcohols with phthalic acid, or sebacic acid, or adipic acid, or 1,2-cyclohexanedicarboxylic acid.

    27. The method of claim 19, wherein the carbon nanotube concentrate comprises 20 to 99 wt. % of one or several alcohols with a general formula C.sub.nH.sub.2n-x(OH).sub.x, where n and x are integers greater than 1.

    28. The method of claim 19, wherein the mixing step (a) includes stirring the carbon nanotube concentrate with (B) and/or (A) using a mixer with a linear speed of an impeller outer edge of less than 15 msec.

    29. The method of claim 19, wherein the mixing step (a) includes stirring with a mixer selected from a group consisting of a planetary mixer, a rotor-stator type mixer, a twin screw mixer, a three-roll mill, a kneader.

    30. A conductive polyurethane composite material produced using the method of claim 19.

    31. The composite material of claim 30, wherein more than 90 wt. % of the carbon nanotubes in the carbon nanotube concentrate are in agglomerates with a diameter of less than 40 μm.

    32. The composite material of claim 31, wherein more than 90 wt. % of the carbon nanotubes in the carbon nanotube concentrate are in agglomerates with a diameter of less than 20 μm.

    33. The composite material of claim 30, wherein the composite material is a foam with a density of 20 to 1000 kg/m.sup.3 and a volume resistivity of 10 to 10.sup.9 Ohm.Math.cm.

    34. The composite material of claim 30, wherein the material is a syntactic cellular plastic with a density of 500 to 2000 kg/m.sup.3 and a volume resistivity of 10 to 10.sup.9 Ohm.Math.cm.

    35. The composite material of claim 30, wherein the composite material is a solid material with a density of 800 to 2000 kg/m.sup.3 and a volume resistivity of 10 to 10.sup.9 Ohm.Math.cm.

    Description

    Brief Description of the Attached Drawings

    [0040] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

    [0041] In the drawings:

    [0042] FIG. 1 shows a microphotograph of single-walled carbon nanotubes in the carbon nanotube concentrate used in Examples 1-3.

    [0043] FIG. 2 shows a microphotograph of the polyurethane composite material of Example 1.

    [0044] FIG. 3 shows a histogram of distribution of the number of agglomerates (N) by their diameter (D) in the material of Example 1.

    [0045] FIG. 4 shows a microphotograph of the polyurethane composite material of Example 2.

    [0046] FIG. 5 shows a histogram of distribution of the number of agglomerates (N) by their diameter (D) in the material of Example 2.

    [0047] FIG. 6 shows a microphotograph of the polyurethane composite material of Example 6.

    [0048] FIG. 7 shows a histogram of distribution of the number of agglomerates (N) by their diameter (D) in the material of Example 6.

    [0049] FIG. 8 shows a microphotograph of the polyurethane composite material of Example 9.

    [0050] FIG. 9 shows a histogram of distribution of the number of agglomerates (N) by their diameter (D) in the material of Example 9.

    [0051] FIG. 10 shows a microphotograph of single-walled and double-walled carbon nanotubes in the carbon nanotube concentrate used in Example 13.

    [0052] FIG. 11 shows a microphotograph of the polyurethane composite material of Example 13.

    [0053] FIG. 12 shows a histogram of distribution of the number of agglomerates (N) by their diameter (D) in the material of Example 13.

    [0054] FIG. 13 shows a microphotograph of the polyurethane composite material of Example 16 (Comparative).

    [0055] FIG. 14 shows a histogram of distribution of the number of agglomerates (N) by their diameter (D) in the material of Example 16 (Comparative).

    Detailed Description of Embodiments of the invention

    [0056] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

    EXAMPLES

    Example 1

    [0057] In a 2 liter metal container, 884.7 g of a commercially available mixture of toluene diisocyanate (A) and polyester comprising NCO-reactive groups (B) (prepolymer SKU-PFL 74 by SUREL LLC, Russian Federation) were mixed with 0.5 g of carbon nanotube concentrate comprising 10 wt. % TUBALL™ single-walled carbon nanotubes and 90 wt. % 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate).

    [0058] FIG. 1 shows a microphotograph of single-walled carbon nanotubes used for producing the carbon nanotube concentrate. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 62. The mixing step was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 15 m/sec (7100 rpm) for 3 min. Then the rotation speed was reduced to 2 m/sec (960 rpm), and the mixture was degassed under vacuum for 5 min upon stirring. The total input energy was 0.16 kW.Math.h, which amounted to 0.18 kW.Math.h per 1 kg mixture. Then 114.8 g of curing agent 4,4′-methylenebis(2-chloroaniline), MOCA, which was pre-melted at 112° C., was added to the mixture, and the mixture was stirred at impeller rotation speed 2 m/sec (960 rpm) for 1 min upon degassing. The SWCNT content in the obtained mixture of polyisocyanates (A) and compounds comprising NCO-reactive groups (B) was 0.005 wt. %. The obtained mixture was poured into a metal mold pre-heated to 110° C. and cured in a drying oven at 110° C. for 1 hour.

    [0059] FIG. 2 shows examples of microphotographs of thus obtained polyurethane composite material. Large, elongated agglomerates (SWCNT bundles) and irregular agglomerates (SWCNT coils) can be readily seen. FIG. 3 shows a histogram of distribution of the number of agglomerates (N) by their diameter (D), which was obtained from the analysis of 50 microphotographs. Diameter (D) was assumed to be the diameter of a circle having the same perimeter as the microphotograph of the agglomerate (Equivalent Circular Perimeter Diameter (ECPD) method).

    [0060] The histograms allow evaluating the minimum mass fraction of agglomerates with diameter less than 40 μm. Since agglomerates differ in shape, the masses of two agglomerates of equal diameter but different shape can be different. A reliable estimate of the minimum mass fraction of agglomerates with diameter less than 40 μm can be obtained by assuming that agglomerate mass it proportional to the third degree of its diameter.

    [0061] For the obtained composite polyurethane material, such estimate demonstrates that more than 90 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has volume resistivity of 10.sup.7 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.005 wt. %. The density of the material is 1100 kg/m.sup.3. The obtained conductive composite polyurethane material has a tensile strength of 45.7 MPa, while the tensile strength of a material of a similar composition without the SWCNT concentrate was 45.3 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 2

    [0062] In a 2 liter metal container, 880.7 g of commercially available mixture of toluene diisocyanate (A) and polyester comprising NCO-reactive groups (B) (prepolymer SKU-PFL 74 by SUREL LLC, Russian Federation) were mixed with 5 g of carbon nanotube concentrate comprising 10 wt. % TUBALL™ single-walled carbon nanotubes and 90 wt. % 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate). FIG. 1 shows a microphotograph of single-walled carbon nanotubes used for producing the carbon nanotube concentrate. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 62. The mixing step was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 15 m/sec (7100 rpm) for 3 min.

    [0063] Then the rotation speed was reduced to 2 m/sec (960 rpm), and the mixture was degassed under vacuum for 5 min upon stirring. The total input energy was 0.2 kW.Math.h, which amounted to 0.23 kW.Math.h per 1 kg mixture. Then 114.3 g of curing agent 4,4′-methylenebis(2-chloroaniline), MOCA, which was pre-melted at 112° C., was added to the mixture, and the mixture was stirred at impeller rotation speed 2 m/sec (960 rpm) for 1 min upon degassing. The obtained mixture was poured into a metal mold pre-heated to 110° C. and cured in a drying oven at 110° C. for 1 hour.

    [0064] FIG. 4 shows an example of microphotograph of thus obtained polyurethane composite material. FIG. 5 shows a histogram of distribution of the number of agglomerates by their diameter, which was obtained from the analysis of 50 microphotographs. For the obtained composite polyurethane material, all observed agglomerates have diameter less than 40 μm, and more than 90 wt. % SWCNT are in agglomerates with diameter less than 20 μm. The obtained composite polyurethane material has a volume resistivity of 10.sup.4 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.05 wt. %. The density of the material is 1100 kg/m.sup.3.

    [0065] The obtained conductive composite polyurethane material has a tensile strength of 45.1 MPa, while the tensile strength of a material of a similar composition without the SWCNT concentrate was 45.3 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 3

    [0066] In a 2 liter metal container, 819.9 g of commercially available mixture of toluene diisocyanate (A) and polyester comprising NCO-reactive groups (B) (prepolymer SKU-PFL 100 by SUREL LLC, Russian Federation), 16.4 g of titanium dioxide, 16.4 g of red pigment paste, 1.5 g of concentrate comprising 10 wt. % TUBALL™ single-walled carbon nanotubes and 90 wt. % 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate) were mixed. FIG. 1 shows a microphotograph of single-walled carbon nanotubes used for producing the carbon nanotube concentrate. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 62. The mixing step was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 15 m/sec (7100 rpm) for 3 min. Then the rotation speed was reduced to 2 m/sec (960 rpm), and the mixture was degassed under vacuum for 5 min upon stirring. The total input energy was 0.1 kW.Math.h, which amounted to 0.12 kW.Math.h per 1 kg mixture. Then 145.8 g of curing agent 4,4′-methylenebis(2-chloroaniline), MOCA, which was pre-melted at 112° C., was added to the mixture, and the mixture was stirred at impeller rotation speed 2 m/sec (960 rpm) for 1 min upon degassing. The obtained mixture was poured into a metal mold pre-heated to110° C. and cured in a drying oven at 110° C. for 1 hour.

    [0067] For the obtained colored polyurethane composite material, more than 92 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 10.sup.6 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.015 wt. %. The density of the material is 1100 kg/m.sup.3. The coating was assigned a color index of 3018 according to the RAL standard. The produced conductive composite polyurethane material has tensile strength 47.1 MPa, while tensile strength of a material of similar composition without SWCNT concentrate was 46.6 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 4

    [0068] In a 2 liter metal container, 99 g of a commercially available polyol based on polyester Isolan 430/150 (B) and 2 g of the SWCNT concentrate comprising 5 wt. % TUBALL™ single-walled carbon nanotubes and 95 wt. % 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate) were mixed. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 61. The mixing step was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 4 m/sec (2100 rpm) for 5 min. The total input energy was 0.08 kW.Math.h, which amounted to 0.09 kW.Math.h per 1 kg mixture. Then 99 g methyl diphenyl diisocyanate (MDI) (A) was added to the mixture, and the mixture was stirred at impeller rotation speed 4 m/sec (2000 rpm) for 6 sec. The obtained mixture was poured into a mold and cured at a room temperature for 1 hour.

    [0069] For the obtained rigid foamed composite polyurethane material, more than 91 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 10.sup.6 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.05 wt. %. The density of the obtained conductive composite rigid foamed polyurethane material was 154 kg/m.sup.3, while the density of a material of a similar composition without the SWCNT concentrate was 150 kg/m.sup.3. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 5

    [0070] In 2 liter metal container, 91.2 g of a polyol based on polyester Voralast XCP-2016 (B) and 14.0 g of concentrate comprising 1 wt. % TUBALL™ single-walled carbon nanotubes and 99 wt. % 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate) were mixed. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 59. At this step, 10.6 g cross-linker Voralast GT 986 is also introduced. The mixing step was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 4 m/sec (2100 rpm) for 5 min. The total input energy was 0.07 kW.Math.h, which amounted to 0.085 kW.Math.h per 1 kg mixture. Then 84.9 g isocyanate Voralast GT 967 (A) was added to the mixture, and the mixture was stirred at impeller rotation speed 4 m/sec (2000 rpm) for 6 sec. The obtained mixture was poured into a mold and cured at a room temperature for 1 hour.

    [0071] For the obtained soft foamed composite polyurethane material, more than 90 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 10.sup.7 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.07 wt. %. The density of the obtained conductive composite rigid foamed polyurethane material was 445 kg/m.sup.3, while the density of a material of a similar composition without the SWCNT concentrate was 450 kg/m.sup.3. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 6

    [0072] In 2 liter metal container, 844.8 g of a commercially available mixture of toluene diisocyanate (A) and polyester comprising NCO-reactive groups (B) (prepolymer SKU-PFL 100 by SUREL LLC, Russian Federation) were mixed with 4.95 g of concentrate comprising 20 wt. % TUBALL™ single-walled carbon nanotubes and 80 wt. % 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate). The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 52. The mixing step was performed using a three-roll mill with roller diameter 150 mm; rotation speed of the fast roller 182 rpm; roller speed ratio 1:2.2:5.3; gaps between all rollers 20 μm; maintained roller temperature 30° C.; number of treatment cycles 7. The total input energy was 0.4 kW.Math.h, which amounted to 0.45 kW.Math.h per 1 kg mixture. Then 150.3 g of curing agent 4,4′-methylenebis(2-chloroaniline), MOCA, which was pre-melted at 112° C., was added to the mixture, and the mixture was stirred using the three-roll mill under the same conditions for 4 more cycles to achieve homogeneous distribution of the components in the mixture. The obtained mixture was spread into a metal mold pre-heated to 110° C. and cured in a drying oven at 110° C. for 1 hour.

    [0073] FIG. 6 shows an example of microphotograph of thus obtained polyurethane composite material. FIG. 7 shows a histogram of distribution of the number of agglomerates by their diameter, which was obtained from the analysis of 50 microphotographs. For the obtained composite polyurethane material, more than 94 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity 50 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.099 wt. %. The density of the material is 1100 kg/m.sup.3. The produced conductive composite polyurethane material has tensile strength 47.3 MPa, while tensile strength of a material of similar composition without SWCNT concentrate was 46.6 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 7

    [0074] In a 2 liter metal container, 885.1 g of a commercially available mixture of toluene diisocyanate (A) and polyester comprising NCO-reactive groups (B) (prepolymer SKU-PFL 74 by SUREL LLC, Russian Federation) were mixed with 0.025 g of the carbon nanotube concentrate comprising 40 wt. % TUBALL™ single-walled carbon nanotubes and 60 wt. % 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate). The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 53. The mixing step was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 15 m/sec (7100 rpm) for 3 min. Then the rotation speed was reduced to 2 m/sec (960 rpm), and the mixture was degassed under vacuum for 5 min upon stirring. Total input energy was 0.02 kW.Math.h, which amounted to 0.023 kW.Math.h per 1 kg mixture. Then 114.9 g of curing agent 4,4′-methylenebis(2-chloroaniline), MOCA, which was pre-melted at 112° C., was added to the mixture, and the mixture was stirred at impeller rotation speed 2 m/sec (960 rpm) for 1 min upon degassing. The obtained mixture was poured into a metal mold pre-heated to 110° C. and cu red in a drying oven at 110° C. for 1 hour.

    [0075] For the obtained composite polyurethane material, more than 92 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 1.Math.10.sup.9 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.001 wt. %. The density of the material is 110 kg/m.sup.3. The produced conductive composite polyurethane material has tensile strength 45.0 MPa, while tensile strength of a material of similar composition without SWCNT concentrate was 45.3 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 8

    [0076] 1 kg of polyurethane antistatic composite material was prepared by reacting an organic polyisocyanate (A) with a compound (B) comprising NCO-reactive groups and mixing the carbon nanotube concentrate with the mixture of (A) and (B) at the energy input 0.22 kW.Math.h per 1 kg mixture. In a 2 liter metal container, 883.6 g of a prepolymer based on polyester and toluene diisocyanate (TDI) SKU-PFL 74 (A), 114.7 g of curing agent 4,4′-methylenebis(2-chloroaniline), MOCA, which was pre-melted at 112° C., (B), and the mixture was stirred at rotation speed of the toothed disk impeller 2 m/sec (960 rpm) for 1 min upon degassing. Then 0.1 g of the carbon nanotube concentrate comprising 30 wt. % TUBALL™ SWCNT and 70 wt. % of a mixture of 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate), dibutylphthalate and dioctylphthalate (2:2:1 wt.) were added to the mixture of (A) and (B). The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 56. Mixing was performed using a dissolver with a 40 mm toothed disk impeller at rotation speed 15 m/sec (7100 rpm) for 3 min. Then the rotation speed was reduced to 2 m/sec (960 rpm), and the mixture was degassed under vacuum for 5 min upon stirring. The obtained mixture was poured into a metal mold pre-heated to 110° C. and cured in a drying oven at 110° C. for 1 hour.

    [0077] For the obtained composite polyurethane material, more than 95 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 1.Math.10.sup.6 Ohm.Math.cm, and it is therefore conductive (antistatic) at SWCNT content of 0.05 wt. %. The density of the material is 1100 kg/m.sup.3. The produced conductive composite polyurethane material has tensile strength 45.8 MPa, while tensile strength of a material of similar composition without SWCNT concentrate was 45.3 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 9

    [0078] 250 g of the polyurethane antistatic composite material were produced by reacting an organic polyisocyanate (A) with a compound (B) comprising NCO-reactive groups and mixing carbon nanotube concentrate into (A) at the energy input 0.12 kW.Math.h per 1 kg mixture. In a 500 ml container, 211.7 g of prepolymer PERMAQURE® EX-HS-2764 (A) and 0.094 g of the carbon nanotube concentrate comprising 15 wt. % TUBALL™ SWCNT, 25 wt. % multi-walled carbon nanotubes with an average diameter 9 nm, and 60 wt. % dibutyl phthalate were mixed. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 12. Mixing was performed using a 500 ml planetary mixer at rotation speed 300 rpm for 20 minutes. Then 38.2 g of cross-linker PERMAQURE® XR-2703 (B) was added to the obtained mixture, and the mixture was stirred using the planetary mixer at rotation speed of 300 rpm for 5 min upon degassing. The obtained mixture was poured into a metal mold pre-heated to 160° C. and cured in a drying oven at 160° C. for 5 minutes.

    [0079] FIG. 8 shows an example of microphotograph of thus obtained polyurethane composite material. FIG. 9 shows a histogram of distribution of the number of agglomerates by their diameter, which was obtained from the analysis of 50 microphotographs. For the obtained polyurethane composite material, more than 90 wt. % carbon nanotubes are in agglomerates with a size of less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 1.Math.10.sup.6 Ohm.Math.cm, and it is therefore conductive (antistatic) at carbon nanotube content of 0.015 wt. %. The density of the material is 900 kg/m.sup.3.

    Example 10

    [0080] In a metal 2 liter container, 98.0 g of a polyol based on Voralast XCP-2016 polyester (B), 10.6 g of cross-linker Voralast GT 986, 0.2 g of concentrate comprising 50 wt. % TUBALL™ single-walled carbon nanotubes and 50 wt. % diethylene glycol were mixed. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 32. The mixing step was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 4 m/sec (2100 rpm) for 5 min. The total input energy was 0.07 kW.Math.h, which amounted to 0.085 kW.Math.h per 1 kg mixture. Then 91.2 g isocyanate Voralast GT 967 (A) was added to the mixture, and the mixture was stirred at impeller rotation speed 4 m/sec (2000 rpm) for 6 sec. The obtained mixture was poured into a mold and cured at a room temperature for 1 hour.

    [0081] For the obtained foamed polyurethane composite material, more than 91 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 1.Math.10.sup.8 Ohm.Math.cm, and it is therefore conductive (antistatic) at SWCNT content of 0.05 wt. %. The density of the obtained conductive foamed composite polyurethane material was 449 kg/m.sup.3, while the density of a material of similar composition without the SWCNT concentrate was 450 kg/m.sup.3. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 11

    [0082] 1 kg of the polyurethane antistatic composite material was produced by reacting an organic polyisocyanate (A) with a compound (B) comprising NCO-reactive groups and mixing carbon nanotube concentrate with the mixture of (A) and (B) and a spherical filler, colloid silicon dioxide. The step of mixing 804.3 g of a prepolymer based on polyester and toluene diisocyanate (TDI) SKU-PFL 100 (A) with 143.0 g of curing agent 4,4′-methylenebis(2-chloroaniline), MOCA, which was pre-melted at 112° C., (B) was performed using a three-roll mill with roller diameter 150 mm; rotation speed of the fast roller 182 rpm; roller speed ratio 1:2.2:5.3; gaps between all rollers 20 μm; maintained roller temperature 30° C.; number of treatment cycles 7. Then 13.2 g of the carbon nanotube concentrate comprising 75 wt. % TUBALL™ SWCNT and 25 wt. % dibutyl phthalate, 40 g of colloid silicon dioxide were added to the mixture, and the mixture was stirred using the three-roll mill under the same conditions for 4 more cycles to achieve homogeneous distribution of the components in the mixture. The ratio of intensities of G and D bands in Raman spectrum for light with wavelength 532 nm by the used carbon nanotube concentrate is 56. The obtained mixture was spread into a metal mold pre-heated to 110° C. and cured in a drying oven at 1 10° C. for 1 hour. The total input energy was 0.4 kW.Math.h, which amounted to 0.45 kW.Math.h per 1 kg mixture.

    [0083] For the obtained syntactic polyurethane composite material, more than 94 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity 50 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.099 wt. %. The density of the material is 960 kg/m.sup.3.

    [0084] The obtained conductive composite polyurethane material had a tensile strength 47.2 MPa, while tensile strength of a material of similar composition without carbon nanotubes was 46.6 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 12

    [0085] In a 2 liter metal container, 925.9 g of a commercially available prepolymer (A) with polyester comprising NCO-reactive groups (B) (prepolymer IMPRAN IL® HS-80) and 0.1 g of the carbon nanotube concentrate comprising 10 wt. % TUBALL™ single-walled carbon nanotubes and 90 wt. % of a mixture of 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate), diethylene glycol and glycerol (2:1:0.5 wt.) were mixed. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 54. The mixing step was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 15 m/sec (7100 rpm) for 3 min. Then the rotation speed was reduced to 2 m/sec (960 rpm), and the mixture was degassed under vacuum for 5 min upon stirring. Total input energy was 0.02 kW.Math.h, which amounted to 0.023 kW.Math.h per 1 kg mixture. Then 174.0 g of cross-linker IMPRAFIX® HS-C was added to the mixture, and the mixture was stirred at impeller rotation speed 2 m/sec (960 rpm) for 1 min upon degassing. The obtained mixture was poured into a metal mold pre-heated to 160° C. and cured in a drying oven at 160° C. for 5 minutes.

    [0086] For the obtained composite polyurethane material, more than 91 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 1.Math.10.sup.9 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.001 wt. %. The density of the material is 1000 kg/m.sup.3. The obtained conductive composite polyurethane material had a tensile strength 24.9 MPa, while tensile strength of a material of similar composition without SWCNT was 25.0 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the carbon nanotube concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the material free of carbon nanotubes.

    Example 13

    [0087] In a 2 liter metal container, 884.4 g of a commercially available prepolymer IMPRANIL® HS-130 (A) with polyester comprising NCO-reactive groups (B) and 0.63 g of the carbon nanotube concentrate comprising 80 wt. % of a mixture of single-walled and double-walled carbon nanotubes and 20 wt. % of a mixture of 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate), dibutyl phthalate and solvent methoxypropyl acetate (2:2:3 wt.) were mixed. FIG. 10 shows a microphotograph of the mixture of single-walled and double-walled carbon nanotubes used for producing the carbon nanotube concentrate. The microphotograph clearly shows single-walled and double-walled carbon nanotubes, as well as particles of the metal catalyst covered with a layer of graphite-like carbon. The ratio of intensities of G and D lines in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 34. The mixing step was performed using a high-speed rotor-stator type mixer (IKA-25) at 15000 rpm for 5 min. Then the rotation speed was reduced to 2 m/sec (1000 rpm), and the mixture was degassed under vacuum for 5 min upon stirring. Total input energy was 0.045 kW.Math.h, which amounted to 0.05 kW.Math.h per 1 kg mixture. Then 114.9 g of cross-linker IMPRAFIX® HS-C was added to the mixture, and the mixture was stirred at impeller rotation speed 1000 rpm for 1 min upon degassing. The obtained mixture was poured into a metal mold pre-heated to 160° C. and cured in a drying oven at 160° C. for 5 minutes.

    [0088] FIG. 11 shows an example of microphotograph of thus obtained polyurethane composite material. FIG. 12 shows a histogram of distribution of the number of agglomerates by their diameter, which was obtained from the analysis of 50 microphotographs. For the obtained foamed polyurethane composite material, more than 90 wt. % carbon nanotubes are in agglomerates with a size of less than 20 μm. The obtained composite polyurethane material has a volume resistivity of 1.Math.10.sup.6 Ohm.Math.cm, and it is therefore conductive (antistatic) at carbon nanotube content of 0.05 wt. %. The density of the material is 1000 kg/m.sup.3. The obtained composite polyurethane material had a tensile strength 25.3 MPa, while tensile strength of a material of similar composition without carbon nanotubes was 25.0 MPa. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the carbon nanotube concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the material free of carbon nanotubes.

    Example 14

    [0089] 250 g of polyurethane antistatic composite material were produced by reacting an organic polyisocyanate (A) with a compound (B) comprising NCO-reactive groups; and mixing the carbon nanotube concentrate was performed simultaneously with mixing the components (A) and (B) using a twin-screw extruder at the energy input 0.32 kW.Math.h per 1 kg mixture. A pre-dispersed mixture of 70 wt. % TUBALL™ single-walled carbon nanotubes and 30 wt. % diethylene glycol was used as the carbon nanotube concentrate. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 55. The ratio of components (A):(B):(SWCNT concentrate) was 140:140:0.2; screw pitch 50 m; screw length (L) to its diameter (D) ratio L/D=50; screw speed 500 rpm; processing temperature 30° C.; the location of introducing polyol based on polyester Isolan 430/150 (B) was 1 to 3 D (50 to 150 mm) from the beginning of the screw; the location of introducing methyl diphenyl diisocyanate (MDI) (A) was 3 to 5 D (150 to 250 mm) from the beginning of the screw; the location of introducing the SWCNT concentrate comprising 70 wt. % TUBALL™ single-walled carbon nanotubes and 30 wt. % diethylene glycol was 5 to 10 D (250 to 500 mm) from the beginning of the screw.

    [0090] For the obtained rigid foamed composite polyurethane material, more than 93 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 5.Math.10.sup.6 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.05 wt. %. The density of the obtained conductive rigid foamed composite polyurethane material was 154 kg/m.sup.3, the density of a material of a similar composition without SWCNT was 150 kg/m.sup.3. Thus, mechanical processing at the step of mixing the components of the polyurethane material with the CNT concentrate did not cause degradation of the components of the polyurethane material and deterioration of its physical and mechanical properties compared to the CNT-free material.

    Example 15

    [0091] 1900 g of polyurethane antistatic composite material were produced by reacting an organic polyisocyanate (A) with a compound (B) comprising NCO-reactive groups, and mixing of carbon nanotube concentrate was performed simultaneously with mixing the components (A) and (B) using a kneader at the energy input 0.4 kW.Math.h per 1 kg mixture. A pre-dispersed mixture of 40 wt. % TUBALL™ single-walled carbon nanotubes and 60 wt. % 1,2-cyclohexanedicarboxylic acid diisononyl ester (diisononylcyclohexane-1,2-dicarboxylate) was used as the carbon nanotube concentrate. The ratio of intensities of G and D bands in the Raman spectrum for light wavelength 532 nm by the carbon nanotube concentrate is 60. The content of the components was as follows: prepolymer PERMAQURE® EX-HS-2764 (A)—1606.1 g; cross-linker PERMAQURE® XR-2703 (B)—290.1 g; SWCNT concentrate—3.8 g; chamber load factor—0.7 (2.1 l); rotor rotation speed—50 rpm; chamber temperature—30° C. The obtained mixture was poured into a metal mold pre-heated to 160° C. and cured in a drying oven at 160° C. for 5 minutes.

    [0092] For the obtained composite polyurethane material, more than 90 wt. % SWCNT are in agglomerates with diameter less than 40 μm. The obtained composite polyurethane material has a volume resistivity of 1.Math.10.sup.3 Ohm.Math.cm, and it is therefore conductive (antistatic) at the SWCNT content of 0.08 wt. %. The density of the material is 900 kg/m.sup.3.

    Example 16 (Comparative)

    [0093] 1 kg of the polyurethane composite material was produced according to the method described in U.S. Pat. No. 8,945,434, although the amount of TUBALL™ carbon nanotubes was chosen so that the finished product would contain 0.09 wt. % SWCNT. In a 2 liter metal container, 884.3 g of prepolymer based on polyester and toluene diisocyanate (TDI) SKU-PFL 74 (A), and 0.9 g of the carbon nanotubes were mixed. Mixing was performed using a disk dissolver with a toothed impeller at the input power density 2.5 kW per 1 liter of mixture for one hour. The energy input was 2.3 kW.Math.h. Then 114.8 g of curing agent MOCA, which was pre-melted at 112° C., was added to the mixture, and the mixture was stirred at impeller rotation speed 2 m/sec (960 rpm) for 1 min upon degassing. The obtained mixture was poured into a metal mold pre-heated to 110° C. and cu red in a drying oven at 110° C. for 1 hour.

    [0094] Microphotographs essentially show coil-like aggregates with the shape close to spherical (FIG. 13). FIG. 14 shows a histogram of distribution of the number of agglomerates by their diameter, which was obtained from the analysis of 40 microphotographs. For the obtained composite polyurethane material, the mass fraction of the carbon nanotubes in particles with a size of less than 40 μm was about 40 wt. %, the fraction of particles with a size of 100 to 200 μm was about 55 wt. %. Thus obtained polyurethane material has a volume resistivity of 5.Math.10.sup.11 Ohm.Math.cm. The obtained composite polyurethane material has a tensile strength 29.0 MPa, while a tensile strength of a material of a similar composition without SWCNT was 45.3 MPa. Thus, mechanical processing at the step of mixing CNT with the components of the polyurethane material led to the deterioration of the physical and mechanical properties compared to the CNT-free material due to degradation of the components of the polyurethane material. Furthermore, the produced material does not have the required conductivity.

    Example 17 (Comparative)

    [0095] The polyurethane composite material was produced according to the method similarly to Example 7, but mixing was performed using an overhead stirrer with a 40 mm toothed disk impeller at rotation speed of 15 m/sec (7100 rpm) for 120 min. Then the rotation speed was reduced to 2 m/sec (960 rpm), and the mixture was degassed under vacuum for 5 min upon stirring. Total input energy was 2.1 kW.Math.h, which amounted to 2.3 kW.Math.h per 1 kg mixture.

    [0096] Thus obtained polyurethane material has a volume resistivity of 1.Math.10.sup.12 Ohm.Math.cm. The obtained composite polyurethane material has a tensile strength 23.9 MPa, while a tensile strength of a material of a similar composition without SWCNT was 45.3 MPa. Thus, mechanical processing at the step of mixing the CNT concentrate with the components of the polyurethane material caused deterioration of the physical and mechanical properties compared to the CNT-free material due to degradation of the components of the polyurethane material. Furthermore, the produced material does not have the required conductivity.

    Example 18 (Comparative)

    [0097] The polyurethane composite material was prepared according to the method similarly to Example 1, although the amount of CNT was chosen so that the finished product would contain 1 wt. % SWCNT. In a 2 liter metal container, 888 g of prepolymer based on polyester and toluene diisocyanate (TDI) SKU-PFL 74, and 1 g of carbon nanotubes were mixed. Mixing was performed using a disk dissolver with a toothed impeller at input power density 0.44 kW per 1 liter of mixture for one hour. The energy input was 0.41 kW.Math.h. Then 112 g of curing agent MOCA, which was pre-melted at 112° C., was added to the mixture, and the mixture was stirred at impeller rotation speed 2 m/sec (960 rpm) for 1 min upon degassing. The obtained mixture had too high viscosity (higher than 1 kPa.Math.s or 10.sup.6 cP) and did not allow for any further processing of the material.

    INDUSTRIAL APPLICABILITY

    [0098] The present invention can be used in the production of articles and coatings made of polyurethane composite materials having the desired conductivity.

    [0099] Having thus described a preferred embodiment, it should be apparent to those skilled in the art that certain advantages of the described method and apparatus have been achieved. It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention.

    PATENT LITERATURE

    [0100] Patent literature 1: U.S. Pat. No. 8,945,434 B2