FORMULATION OF CNT-CONTAINING SILOXANES CONTAINING SILICIC ACID

Abstract

A low-viscosity, electrically conductive, CNT-containing siloxane composition along with processes for producing the same, uses for the same and articles made therefrom. The siloxane composition includes a) 0.1-5 wt % CNTs; b) 70-97.9 wt % of at least one siloxane, which is selected from compounds of the general formula (I); c) 1-20 wt % of at least one hydrophobic silicic acid, which is surface-silylated by at least one organosilicon compound selected from organosilanes of the formula (IV) and organosilazanes of the formula (V); and d) 0-5 wt % of other fillers. Where the proportions relate to the total weight of the composition and the total of all components a) to d) equals 100 wt %.

Claims

1-16. (canceled)

17. A low-viscosity, electrically conductive, CNT-containing siloxane composition comprising: a) 0.1-5% by weight of CNTs; b) 70-97.9% by weight of at least one siloxane selected from compounds of general formula (I)
(SiO.sub.4/2).sub.a(R.sup.xSiO.sub.3/2).sub.b(R.sup.x.sub.2SiO.sub.2/2).sub.c(R.sup.x.sub.3SiO.sub.1/2).sub.d  (I), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) hydrogen, (ii) —CH═CH.sub.2, (iii) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical, (iv) phenyl radical and (v) —OH and wherein the indices a, b, c and d indicate the number of the respective siloxane unit in the compound and independently of one another represent an integer in the range from 0 to 100 000, wherein a+b+c+d≥2; c) 1-20% by weight of at least one hydrophobic silica which is surface-silylated with at least one organosilicon compound selected from organosilanes of formula (IV) and organosilazanes of formula (V)
R.sup.1R.sup.2R.sup.3Si—Y  (IV),
R.sup.1R.sup.2R.sup.3Si—NH—SiR.sup.1R.sup.2R.sup.3  (V), wherein the radicals R.sup.1, R.sup.2, R.sup.3 are each independently selected from halogenated or unsubstituted C.sub.1-C.sub.24-hydrocarbon radicals; wherein the radical Y is selected from the group consisting of (i) halogen atom, (ii) —OR.sup.x and (iii) —OC(═O)OR.sup.x, wherein R.sup.x is in each case selected from the group consisting of (i) hydrogen and (ii) substituted or unsubstituted C.sub.1-C.sub.24-hydrocarbon radical, wherein substituted is to be understood as meaning that at least one CH.sub.2 group, but not the one bonded to silicon, may be replaced by —O—; and d) 0-5% by weight of other fillers; wherein the proportions are based on the total weight of the composition and the components a) to d) sum to 100% by weight.

18. The composition of claim 17, wherein the CNTs are MWCNTs.

19. The composition of claim 17, wherein the siloxane is a siloxane mixture comprising: a) at least one H-siloxane selected from compounds of general formula (IIa)
(R.sup.x.sub.2SiO.sub.2/2).sub.c(HR.sup.xSiO.sub.2/2).sub.c′(R.sup.xSiO.sub.3/2).sub.d(HR.sup.x.sub.2SiO.sub.1/2).sub.d′  (IIa), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical and wherein the indices c, c′, d and d′ indicate the number of the respective siloxane unit in the compound; wherein c and c′ each represent an integer in the range from 0 to 100 000; wherein d and d′ may each assume the value 0 or 1 or 2; wherein the sum of d and d′ is 2; and b) at least one vinylsiloxane selected from compounds of general formula (IIb)
(R.sup.x.sub.2SiO.sub.2/2).sub.c(ViR.sup.xSiO.sub.2/2).sub.c′(ViR.sup.x.sub.2SiO.sub.1/2).sub.2  (IIb), wherein the radicals Vi each represent a —CH═CH.sub.2 group bonded to the silicon atom; wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; and wherein the indices c and c′ indicate the number of the respective siloxane unit in the compound, and c and c′ each represent an integer in the range from 0 to 100 000.

20. The composition of claim 17, wherein the siloxane is a siloxane mixture comprising: a) 1-10% by weight of at least one H-siloxane of general formula (III) as a crosslinker
(R.sup.x.sub.2SiO.sub.2/2).sub.c(HR.sup.xSiO.sub.2/2).sub.c′(R.sup.x.sub.3SiO.sub.1/2).sub.2  (III), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; wherein the indices c and c′ indicate the number of the respective siloxane unit in the compound; wherein c is an integer in the range from 0 to 100 000; wherein c′ is an integer in the range from 3 to 100 000; and either b1) 90-99% by weight of at least one vinylsiloxane of general formula (IV)
(R.sup.x.sub.2SiO.sub.2/2).sub.c(ViR.sup.x.sub.2SiO.sub.1/2).sub.2  (IV), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; wherein the index c indicates the number of the respective siloxane unit in the compound and c=1001-100 000; or b2) 40-94% by weight of at least one vinylsiloxane of general formula (IV′)
(R.sup.x.sub.2SiO.sub.2/2).sub.c(ViR.sup.x.sub.2SiO.sub.1/2).sub.2  (IIb′), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; wherein the index c indicates the number of the respective siloxane unit in the compound and c=1-1000; and 0-50% by weight of at least one H-siloxane of general formula (IIa′)
(R.sup.x.sub.2SiO.sub.2/2).sub.c(HR.sup.x.sub.2SiO.sub.1/2).sub.2  (IIa′), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; and wherein the index c indicates the number of the respective siloxane unit in the compound and c=1-100 000.

21. The composition of claim 17, wherein the radicals R.sup.1, R.sup.2, R.sup.3 in formulae (IV) and (V) are each independently of one another selected from the group consisting of methyl radical, ethyl radical, propyl radical, 3,3,3-trifluoropropyl radical, octyl radical, phenyl radical and vinyl radical.

22. The composition of claim 17, wherein the organosilicon compound is selected from the group consisting of trimethylchlorosilane, trimethylmethoxysilane, vinyldimethylchlorosilane, vinyldimethylmethoxysilane, hexamethyldisilazane, bisvinyldimethyldisilazane and mixtures thereof.

23. The composition of claim 17, wherein the hydrophobic silica has the following properties a BET surface in the range of 0.1 to 1,000 m.sup.2/g; a residual silanol content of <100%; a methanol number of at least 30; a DBP number of ≤250 g/100 g; a tamped density in the range from 20 to 500 g/l; and a carbon content in the range of ≥0.4% by weight.

24. The composition of claim 23, wherein the hydrophobic silica is based on a pyrogenic silica.

25. The composition of claim 17, wherein the other filler is selected from quartz, diatomaceous earth, metal oxides such as aluminum oxides, zinc oxides, titanium oxides or zirconium oxides, metal silicates such as calcium silicate, carbonates such as calcium carbonate, sulfates such as calcium sulfate, color pigments and carbon blacks.

26. The composition of claim 17, wherein the composition is use as a formative material in 3D printing or screen printing.

27. A process for producing low-viscosity, electrically conductive, CNT-containing siloxane compositions, comprising the steps of: providing a siloxane composition, wherein the siloxane composition comprises a) 0.1-5% by weight of CNTs; b) 70-97.9% by weight of at least one siloxane selected from compounds of general formula (I)
(SiO.sub.4/2).sub.a(R.sup.xSiO.sub.3/2).sub.b(R.sup.x.sub.2SiO.sub.2/2).sub.c(R.sup.x.sub.3SiO.sub.1/2).sub.d  (I), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) hydrogen, (ii) —CH═CH.sub.2, (iii) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical, (iv) phenyl radical and (v) —OH and wherein the indices a, b, c and d indicate the number of the respective siloxane unit in the compound and independently of one another represent an integer in the range from 0 to 100 000, wherein a+b+c+d≥2; c) 1-20% by weight of at least one hydrophobic silica which is surface-silylated with at least one organosilicon compound selected from organosilanes of formula (IV) and organosilazanes of formula (V)
R.sup.1R.sup.2R.sup.3Si—Y  (IV),
R.sup.1R.sup.2R.sup.3Si—NH—SiR.sup.1R.sup.2R.sup.3  (V), wherein the radicals R.sup.1, R.sup.2, R.sup.3 are each independently selected from halogenated or unsubstituted C.sub.1-C.sub.24-hydrocarbon radicals; wherein the radical Y is selected from the group consisting of (i) halogen atom, (ii) —OR.sup.x and (iii) —OC(═O)OR.sup.x, wherein R.sup.x is in each case selected from the group consisting of (i) hydrogen and (ii) substituted or unsubstituted C.sub.1-C.sub.24-hydrocarbon radical, wherein substituted is to be understood as meaning that at least one CH.sub.2 group, but not the one bonded to silicon, may be replaced by —O—; and d) 0-5% by weight of other fillers; wherein the proportions are based on the total weight of the composition and the components a) to d) sum to 100% by weight; and dispersing the siloxane composition using a dissolver having a scraper.

28. The process of claim 27, wherein the dispersing is carried out at the power maximum of the dissolver and at least one dispersing pause in the range from 1 minute to 60 minutes is taken; wherein the power maximum is determined by increasing the dissolver speed by 250 rpm every 5 minutes and evaluating the dispersing power against the speed of the dissolver, thus allowing determination of an optimal rotational speed of the dissolver for the specific power maximum.

29. The process of claim 27, wherein two or more dispersing pauses are taken at regular intervals.

30. The process of claim 27, wherein the duration of the dispersing intervals between the dispersing pauses is in a range from 1 minute to 60 minutes.

31. The process of claim 27, wherein the dissolver is a planetary dissolver.

32. An elastic, electrically conductive shaped article obtainable by a process comprising the steps of: A) producing a siloxane composition, wherein said siloxane composition comprises: a) 0.1-5% by weight of CNTs; b) 70-97.9% by weight of at least one siloxane selected from compounds of general formula (I)
(SiO.sub.4/2).sub.a(R.sup.xSiO.sub.3/2).sub.b(R.sup.x.sub.2SiO.sub.2/2).sub.c(R.sup.x.sub.3SiO.sub.1/2).sub.d  (I), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) hydrogen, (ii) —CH═CH.sub.2, (iii) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical, (iv) phenyl radical and (v) —OH and wherein the indices a, b, c and d indicate the number of the respective siloxane unit in the compound and independently of one another represent an integer in the range from 0 to 100 000, wherein a+b+c+d≥2; c) 1-20% by weight of at least one hydrophobic silica which is surface-silylated with at least one organosilicon compound selected from organosilanes of formula (IV) and organosilazanes of formula (V)
R.sup.1R.sup.2R.sup.3Si—Y  (IV),
R.sup.1R.sup.2R.sup.3Si—NH—SiR.sup.1R.sup.2R.sup.3  (V), wherein the radicals R.sup.1, R.sup.2, R.sup.3 are each independently selected from halogenated or unsubstituted C.sub.1-C.sub.24-hydrocarbon radicals; wherein the radical Y is selected from the group consisting of (i) halogen atom, (ii) —OR.sup.x and (iii) —OC(═O)OR.sup.x, wherein R.sup.x is in each case selected from the group consisting of (i) hydrogen and (ii) substituted or unsubstituted C.sub.1-C.sub.24-hydrocarbon radical, wherein substituted is to be understood as meaning that at least one CH.sub.2 group, but not the one bonded to silicon, may be replaced by —O—; and d) 0-5% by weight of other fillers; wherein the proportions are based on the total weight of the composition and the components a) to d) sum to 100% by weight; B) reacting the siloxane composition with a hydrosilylation catalyst; and c) forming the elastic, electrically conductive shaped article.

33. The process of claim 32, the siloxane composition is a siloxane mixture comprising: a) 1-10% by weight of at least one H-siloxane of general formula (III) as a crosslinker
(R.sup.x.sub.2SiO.sub.2/2).sub.c(HR.sup.xSiO.sub.2/2).sub.c′(R.sup.x.sub.3SiO.sub.1/2).sub.2  (III), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; wherein the indices c and c′ indicate the number of the respective siloxane unit in the compound; wherein c is an integer in the range from 0 to 100 000; wherein c′ is an integer in the range from 3 to 100 000; and either b1) 90-99% by weight of at least one vinylsiloxane of general formula (IV)
(R.sup.x.sub.2SiO.sub.2/2).sub.c(ViR.sup.x.sub.2SiO.sub.1/2).sub.2  (IV), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; wherein the index c indicates the number of the respective siloxane unit in the compound and c=1001-100 000; or b2) 40-94% by weight of at least one vinylsiloxane of general formula (IV′)
(R.sup.x.sub.2SiO.sub.2/2).sub.c(ViR.sup.x.sub.2SiO.sub.1/2).sub.2  (IIb′), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; wherein the index c indicates the number of the respective siloxane unit in the compound and c=1-1000; and 0-50% by weight of at least one H-siloxane of general formula (IIa′)
(R.sup.x.sub.2SiO.sub.2/2).sub.c(HR.sup.x.sub.2SiO.sub.1/2).sub.2  (IIa′), wherein the radicals R.sup.x are independently of one another selected from the group consisting of (i) unsubstituted or fluorinated C.sub.1-C.sub.20-hydrocarbon radical and (ii) phenyl radical; and wherein the index c indicates the number of the respective siloxane unit in the compound and c=1-100 000.

Description

EXAMPLES

[0153] Chemicals:

[0154] CNTs LUCAN BT1001M, LG Chem Ltd., average diameter according to manufacturer specifications: 5 nm

[0155] ViPo 1000: vinyldimethylsiloxy-terminated polydimethylsiloxane having a viscosity of 1000 mPa*s obtainable from Gelest Inc., product designation DMS-V31 (Gelest catalogue)

[0156] ViPo 20000: vinyldimethylsiloxy-terminated polydimethylsiloxane having a viscosity of 20 000 mPa*s obtainable from Gelest Inc., product designation DMS-V42 (Gelest catalogue)

[0157] HPo 1000: hydridodimethylsiloxy-terminated polydimethylsiloxane having a viscosity of 1000 mPa*s obtainable from Gelest Inc., product designation DMS-H31 (Gelest catalogue)

[0158] Hydrophobic silica A: pyrogenic silica having trimethylsiloxy groups, BET surface area: 187 m.sup.2/g, carbon content: 4.5% by weight, methanol number: 72%, residual silanol content: 25%, DBP number: 161 g/100 g, tamped density: 150 g/ml.

[0159] Hydrophobic silica B: pyrogenic silica having trimethylsiloxy groups, BET surface area: 89 m2/g, carbon content: 1.9% by weight, methanol number: 78%, residual silanol content: 30%, DBP number: 153 g/100 g, tamped density: 135 g/ml.

[0160] Hydrophobic silica HDK® 18: pyrogenic silica having dimethylsiloxy groups, BET surface area: 132 m.sup.2/g, carbon content: 4.7% by weight, methanol number: 79%, residual silanol content: 21%, DBP number: 165 g/100 g, tamped density: 52 g/ml (obtainable from WACKER Chemie AG).

[0161] Analytical Methods for Characterization of the Silicas

[0162] Methanol Number:

[0163] Test of wettability with water-methanol mixtures (% by volume MeOH in water): Shake in an equal volume of the silica with an equal volume of a water-methanol mixture [0164] start with 0% by volume of methanol [0165] in case of non-wetting at least part of the silica floats: A mixture having an MeOH content 5% by volume higher is to be used [0166] in case of wetting the entire volume of the silica sinks: Proportion of MeOH (% by volume) in water gives the methanol number.

[0167] Carbon Content (% C):

[0168] The elemental analysis for carbon was carried out according to DIN ISO 10694 using a CS-530 elemental analyzer from Eltra GmbH (D-41469 Neuss).

[0169] Residual Silanol Content:

[0170] Determination of residual silanol content was carried out analogously to G. W. Sears et al. (Analytical Chemistry 1956, 28, 1981ff) by acid-base titration of the silica suspended in a 1:1 mixture of water and methanol. The titration was carried out in the range above the isoelectric point and below the pH range of dissolution of the silicic acid. The residual silanol content in % can then be calculated using the following formula:

% SiOH=SiOH(silyl)/SiOH(phil)*100,

where

[0171] SiOH(phil): titration volume from titration of the untreated silica

[0172] SiOH(silyl): titration volume from titration of the silylated silica

[0173] DBP number:

[0174] The dibutyl phthalate absorption is measured using a RHEOCORD 90 instrument from Haake, Karlsruhe in accordance with DIN 53601. To this end, 12 g±0.001 g of the silicon dioxide powder are charged into a kneading chamber, the latter is sealed with a lid and dibutyl phthalate is metered in at a predetermined metering addition rate of 0.0667 ml/s via a hole in the lid. The kneader is operated at a motor speed of 125 revolutions per minute. After reaching the torque maximum, the kneader and the DBP metered addition are switched off automatically. The consumed amount of DBP and the amount of particles weighed in are used to calculate the DBP absorption according to: DBP number (g/100 g)=(consumption of DBP in g/weight of powder in g)×100.

[0175] Tamped Density:

[0176] Tamped density is measured according to DIN EN ISO 787-11.

[0177] Viscosity Measurement:

[0178] Viscosity measurements were performed in an air-bearing MCR 302 rheometer from Anton Paar at 25° C. A cone and plate system (25 mm, 2°) having a gap width of 105 μm was used. The excess material was removed (trimmed) with a spatula at a gap width of 115 μm. The cone then moved to a gap width of 105 μm to fill the entire gap. Before each measurement, a pre-shear is performed to erase the shear history resulting from sample preparation, application and trimming. The pre-shear is carried out for 60 seconds at a shear rate of 10 s.sup.−1, followed by a rest period of 300 seconds. Shear viscosity is determined using a step profile in which the sample is sheared at a constant shear rate of 1 s.sup.−1, 10 s.sup.−1 and 100 s.sup.−1 for 100 seconds in each case. A reading is recorded every 10 seconds, resulting in 10 data points per shear rate. The average of these 10 data points gives the shear viscosity at the respective shear rate.

[0179] Resistance Measurement:

[0180] A four-conductor measurement does not measure the contact resistance since the current is applied at two contacts and it is the voltage U of the current that has already flowed through the sample I.sub.U that is measured.

[00001]$R=\frac{U}{I_U}\left[\Omega \right]$

[0181] The resistance R of unvulcanized siloxanes is measured with a multimeter model 2110 5% digit from Keithley Instrument and a fabricated measuring apparatus made of pure PP and stainless steel (1.4571) electrodes. The measuring instrument is connected to the electrodes by means of brass contacts and laboratory leads. The measuring apparatus is a mold with defined dimensions of L×W×H of 16 cm×3 cm×0.975 cm, into which the siloxane is poured for measurement. The two outer flat electrodes are attached at a distance of 16 cm, thus ensuring the current flows through the entire sample. The two-point electrodes having a diameter of 1 cm are arranged in the base plate at a distance of 12 cm (1) and measure the voltage. The specific resistance is calculated from the measured resistance R using the following formula.

[00002]$\rho =\frac{R.Math.h.Math.w}{l}\left[\Omega \mathrm{cm}\right],$

[0182] with sample height h [cm], sample width w [cm] and electrode distance l [cm](here: h=0.975 cm, w=3 cm, l=12 cm)

[0183] A sample is described as good if it has a specific resistance of <20 Ω*cm based on 1% by weight of CNT in each case.

[0184] Measurement of Relaxation:

[0185] Oscillation-Rotation-Oscillation (ORO) Test:

[0186] In the first stage the resting structure is measured over 300 seconds (one reading every 10 seconds) at constant deformation and angular frequency (γ=0.1%, ω=10 Hz). This is followed by the loading phase in rotation for 0.5 seconds with a shear rate of γ=100 s.sup.−1, which ends with a 0.05 second pause to stop the cone of the viscometer (air-bearing MCR 302 rheometer from Anton Paar). In the last stage of 19.6 minutes (300 readings recorded logarithmically from 1-10 seconds), the same parameters as in the first stage (γ=0.1%, ω=10 Hz) are used to observe structure formation.

TABLE-US-00001 300 Sec 0.05 Sec 19.6 Min (30 × 10 sec) 0.5 Sec pause (300 × 1-10 sec) γ 0.1% — — 0.1% ω 10 Hz — — 10 Hz {dot over (γ)} — 100 s.sup.−1 — —

[0187] Mixing Method:

[0188] The mixtures were produced in a Labotop 1 LA from PC Laborsystem GmbH of 1 liter in capacity at a vacuum of 300 mbar and room temperature. The tools employed were a dissolver disk (14 teeth, teeth at 90° to disk, diameter 52 cm), a cross-beam stirrer (standard tool) and a scraper with temperature measurement. The mixtures are mixed at the highest possible power and the power can be read off on the device. In the case of this mixing process, the highest power of 1900 watts is achieved in the range from 500 rpm to 1400 rpm. The selected speed of 1250 rpm results in a rotational speed of 3.4 m/s.

[0189] In the case of dissolvers without an integrated power display, the power may be determined using a power meter (wattmeter).

Example 1

[0190] In a laboratory mixer from VMA-Getzmann GmbH fitted with a Zahn dissolver disk (diameter 40 mm), 1% by weight of CNT (1 g) was mixed into a mixture of ViPo 1000 (38% by weight), HPo 1000 (39% by weight) and 22% by weight of silica A for 15 minutes at room temperature and 6000 rpm (12.57 m/s) under vacuum (300 mbar) (total mass: 100 g). A homogeneous, black paste having a specific resistance of 11 Ω*cm was obtained. After 60 seconds of relaxation, the structural relaxation shows 74.9% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 529 000 mPa*s at a shear rate of 1 s.sup.−1 and 97 200 mPa*s at a shear rate of 10 s.sup.−1.

[0191] Good relaxation coupled with good viscosity values and good conductivity is obtained.

Example 2

[0192] In a laboratory mixer from VMA-Getzmann GmbH fitted with a Zahn dissolver disk (diameter 40 mm), 0.5% by weight of CNT (1 g) was mixed into a mixture of ViPo 1000 (38% by weight), HPo 1000 (39% by weight) and 22% by weight of silica A for 6 minutes at room temperature and 6000 rpm (12.57 m/s) under vacuum (300 mbar) (total mass: 100 g). A homogeneous, black paste having a specific resistance of 35 Ω*cm was obtained. After 60 seconds of relaxation, the structural relaxation shows 76.4% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 173 000 mPa*s at a shear rate of 1 s.sup.−1 and 43 400 mPa*s at a shear rate of 10 s.sup.−1.

[0193] Good relaxation coupled with good viscosity values and acceptable conductivity is obtained.

Example 3

[0194] In a laboratory mixer from VMA-Getzmann GmbH fitted with a Zahn dissolver disk (diameter 40 mm), a 100 g mixture of 1% by weight of CNT and 5% by weight of silica A in ViPo 20 000 was produced for 15 minutes at room temperature and 3000 rpm (6.28 m/s) under vacuum (300 mbar). A homogeneous, black paste having a specific resistance of 17 Ω*cm was obtained. The structural relaxation shows a cross-over from G″>G′ to G″<G′ after 2.6 seconds of recovery and after 60 seconds of relaxation achieves 72.2% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 371 000 mPa*s at a shear rate of 1 s.sup.−1 and 94 300 at a shear rate of 10 s.sup.−1.

[0195] Good relaxation coupled with good viscosity values and good conductivity is obtained.

Example 4

[0196] In a laboratory mixer from VMA-Getzmann GmbH fitted with a Zahn dissolver disc (diameter 40 mm), a 100 g mixture of 1% by weight of CNT and 10% by weight of silica A in ViPo 20 000 (38% by weight) was produced for 15 minutes at room temperature and 3000 rpm (6.28 m/s) under vacuum (300 mbar). A homogeneous, black paste having a specific resistance of 24 Ω*cm was obtained. The structural relaxation shows a cross-over from G″>G′ to G″<G′ after 2.5 seconds of recovery and after 60 seconds of relaxation achieves 72.9% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 487 000 mPa*s at a shear rate of 1 s.sup.−1 and 125 000 at a shear rate of 10 s.sup.−1.

[0197] Good relaxation coupled with good viscosity values and acceptable conductivity is obtained.

Example 5

[0198] In a laboratory mixer from VMA-Getzmann GmbH fitted with a Zahn dissolver disc (diameter 40 mm), a 100 g mixture of 1% by weight of CNT and 15% by weight of silica A in ViPo 20 000 (38% by weight) was produced for 15 minutes at room temperature and 3000 rpm (6.28 m/s) under vacuum (300 mbar). A homogeneous, black paste having a specific resistance of 33 Ω*cm was obtained. The structural relaxation shows a cross-over from G″>G′ to G″<G′ after 2.4 seconds of recovery and after 60 seconds of relaxation achieves 70.1% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 598 000 mPa*s at a shear rate of 1 s.sup.−1 and 154 000 at a shear rate of 10 s.sup.−1.

[0199] Good relaxation coupled with good viscosity values and acceptable conductivity is obtained.

Example 6

[0200] In a laboratory mixer from VMA-Getzmann GmbH fitted with a Zahn dissolver disc (diameter 40 mm), a 100 g mixture of 1% by weight of CNT and 20% by weight of silica A in ViPo 20 000 (38% by weight) was produced for 15 minutes at room temperature and 3000 rpm (6.28 m/s) under vacuum (300 mbar). A homogeneous, black paste having a specific resistance of 61 Ω*cm was obtained. The structural relaxation shows a cross-over from G″>G′ to G″<G′ after 2.4 seconds of recovery and after 60 seconds of relaxation achieves 65.5% of the storage modulus based on the plateau value of the storage modulus after 20 min. The viscosity is 758 000 mPa*s at a shear rate of 1 s.sup.−1 and 206 000 at a shear rate of 10 s.sup.−1.

[0201] Good relaxation coupled with good viscosity values and acceptable conductivity is obtained.

Example 7

[0202] In a laboratory mixer from VMA-Getzmann GmbH fitted with a Zahn dissolver disk (diameter 40 mm), a 100 g mixture of 10% by weight of silica A in ViPo 20 000 was produced for 1 hour at room temperature and 6000 rpm (12.57 m/s) under vacuum (300 mbar). Subsequently, 1% by weight of CNT were mixed in for 15 minutes at room temperature and 3000 rpm (6.28 m/s) under vacuum (300 mbar). A homogeneous, black paste having a specific resistance of 19 Ω*cm was obtained. The structural relaxation shows a cross-over from G″>G′ to G″<G′ after 2.4 seconds of recovery and after 60 seconds of relaxation achieves 70.8% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 492 000 mPa*s at a shear rate of 1 s.sup.−1 and 128 000 at a shear rate of 10 s.sup.−1.

[0203] Good relaxation coupled with good viscosity values and acceptable conductivity is obtained.

Example 8 (Noninventive)

[0204] In a laboratory mixer from VMA-Getzmann GmbH fitted with a Zahn dissolver disk (diameter 40 mm), a 100 g mixture of 1% by weight of CNT in ViPo 20 000 was mixed for 15 minutes at room temperature and 6000 rpm (12.57 m/s) under vacuum. A homogeneous, black paste having a specific resistance of 6 Ω*cm was obtained. It shows no cross-over in the structural relaxation since G′ immediately after the loading phase is greater than G″. The structural relaxation achieves 86.3% of the storage modulus after 60 seconds based on the plateau value of the storage modulus after 20 minutes. The viscosity is 456 000 mPa*s at a shear rate of 1 s.sup.−1 and 108 000 mPa*s at a shear rate of 10 s.sup.−1.

[0205] Poor relaxation coupled with good viscosity values and good conductivity are obtained.

Example 9

[0206] In a planetary mixer from PC Laborsystem GmbH fitted with a crossbeam stirrer, dissolver (disk diameter 52 mm) and scraper a 500 g mixture consisting of 1% by weight of CNT and 5% by weight of silica A in ViPo 20 000 was mixed 3 times for 5 minutes at room temperature under vacuum at 1250 rpm with respective 30-minute pauses between the dispersing intervals. After a total dispersing time of 15 minutes (5 minutes of dispersing, 30-minute pause, 5 minutes of dispersing etc.) a homogeneous, black paste having a specific resistance of 11 Ω*cm was obtained. The structural relaxation shows a cross-over from G″>G′ to G″<G′ after 2.9 seconds of recovery and after 60 seconds of relaxation achieves 70.3% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 383 000 mPa*s at a shear rate of 1 s.sup.−1 and 99 600 at a shear rate of 10 s.sup.−1.

[0207] Good relaxation coupled with good viscosity values and good conductivity is obtained.

Example 10

[0208] In a planetary mixer from PC Laborsystem GmbH fitted with a crossbeam stirrer, dissolver (disk diameter 52 mm) and scraper a 500 g mixture consisting of 1% by weight of CNT and 10% by weight of silica A in ViPo 20 000 was mixed 3 times for 5 minutes at room temperature under vacuum at 1250 rpm with respective 30-minute pauses between the dispersing intervals. After a total dispersing time of 15 minutes (5 minutes of dispersing, 30-minute pause, 5 minutes of dispersing etc.) a homogeneous, black paste having a specific resistance of 12 Ω*cm was obtained. The structural relaxation shows a cross-over from G″>G′ to G″<G′ after 2.7 seconds of recovery and after 60 seconds of relaxation achieves 71.0% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 498 000 mPa*s at a shear rate of 1 s.sup.−1 and 133 000 at a shear rate of 10 s.sup.−1.

[0209] Good relaxation coupled with good viscosity values and good conductivity is obtained.

Example 11

[0210] In a planetary mixer from PC Laborsystem GmbH fitted with a crossbeam stirrer, dissolver (disk diameter 52 mm) and scraper a 500 g mixture consisting of 1% by weight of CNT and 10% by weight of silica B in ViPo 1000 was mixed 3 times for 5 minutes at room temperature under vacuum at 250 rpm with respective 30-minute pauses between the dispersing intervals. After a total dispersing time of 15 minutes (5 minutes of dispersing, 30-minute pause, 5 minutes of dispersing etc.) a homogeneous, black paste having a specific resistance of 16 Ω*cm was obtained. After 60 seconds of relaxation, the structural relaxation shows 75.2% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 190 000 mPa*s at a shear rate of 1 s.sup.−1 and 29 012.8 mPa*s at a shear rate of 10 s.sup.−1.

[0211] Good relaxation coupled with good viscosity values and good conductivity is obtained.

Example 12

[0212] In a planetary mixer from PC Laborsystem GmbH fitted with a crossbeam stirrer, dissolver (disk diameter 52 mm) and scraper a 500 g mixture consisting of 1% by weight of CNT and 10% by weight of silica B in ViPo 1000 was mixed in for 10 minutes without interruption at room temperature under vacuum at 1250 rpm. A homogeneous, black paste having a specific resistance of 46 Ω*cm after 15 minutes of pure dispersing time was obtained. After 60 seconds of relaxation, the structural relaxation shows 77.8% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 172 000 mPa*s at a shear rate of 1 s.sup.−1 and 16 988.6 mPa*s at a shear rate of 10 s.sup.−1.

[0213] Good relaxation coupled with good viscosity values and acceptable conductivity is obtained.

Example 13 (Noninventive, Dimethylsiloxy Modification as Comparison to CN107298859)

[0214] In a planetary mixer from PC Laborsystem GmbH fitted with a crossbeam stirrer, dissolver (disk diameter 52 mm) and scraper a 500 g mixture consisting of 1% by weight of CNT and 10% by weight of silica HDK® H18 in ViPo 20 000 was mixed 3 times for 5 minutes at room temperature under vacuum at 1,250 rpm with respective 30-minute pauses between the dispersing intervals. After a total dispersing time of 15 minutes (5 minutes of dispersing, 30-minute pause, 5 minutes of dispersing etc.) a homogeneous, black paste having a specific resistance of 26 Ω*cm was obtained. After 60 seconds of relaxation, the structural relaxation achieves 76.7% of the storage modulus based on the plateau value of the storage modulus after 20 minutes. The viscosity is 1 120 000 mPa*s at a shear rate of 1 s.sup.−1 and 254 000 mPa*s at a shear rate of 10 s.sup.−1.

[0215] Although the relaxation has a good value, undesirable high viscosities (>1 000 000 mPa*s) occur when using the dimethylsiloxy-modified silica. The mixture is also inhomogeneous due to incompatibilities.

TABLE-US-00002 Relaxation CNTs after 60 Shear rate Shear rate [% by Resistance seconds 1 s-1 10 s-1 Example Siloxane(s) wt] Silica [Ω*cm] [%] [mPa*s) [mPa*s]  1 ViPo 1000 1 A, 22% by weight 11 74.9 529 000  97 200 (38% by weight) HPo 1000 (39% by weight)  2 ViPo 1000 0.5 A, 22% by weight 35 76.4 173 000  43 400 (38% by weight) HPo 1000 (39% by weight)  3 ViPo 20 000 1 A, 5% by weight 17 72.2 371 000  94 300  4 ViPo 20 000 1 A, 10% by weight 24 72.9 487 000 125 000  5 ViPo 20 000 1 A, 15% by weight 33 70.1 598 000 154 000  6 ViPo 20 000 1 A, 20% by weight 61 65.5 758 000 205 000  7 ViPo 20 000 1 A, 10% by weight 19 70.8 492 000 128 000  8 (CE) ViPo 20 000 1 none 6 86.3 456 000 108 000  9 ViPo 20 000 1 A, 5% by weight 11 70.3 383 000  99 600 10 ViPo 20 000 1 A, 10% by weight 12 71.0 498 000 133 000 11 ViPo 1000 1 B, 10% by weight 16 75.2 190 000  29 013 12 ViPo 1000 1 B, 10% by weight 46 77.8 172 000  16 989 13 (CE) ViPo 20000 1 HDK ® H18, 26 76.7 1 120 000   254 000 10% by weight