High-speed printable carbon ink

Abstract

The present invention relates to a conductive composition comprising: a) a resin selected from the group consisting of nitrocellulose, chlorinated polyester, chlorinated polyether, chlorinated polyvinyl, chlorinated polyacetate, and mixtures thereof; b) conductive particles containing graphite and carbon black, wherein the ratio of the graphite to the carbon black is 1:1 to 5:1; and c) a solvent, wherein the ratio of the conductive particles to the resin is 0.20:1 to 4:1. The composition of the present invention can be used in high-speed printing techniques such as flexographic printing and rotogravure printing.

Description

[Technical Field]

[0001] The present invention relates to a conductive composition that can be used in high-speed printing technologies such as flexographic printing and rotgravure printing. [Background technology]

[0002] Conventional conductive inks have been applied to substrates by methods such as screen printing, rotary screen printing, and dispensing. These printing methods are considered relatively slow.

[0003] For example, screen printing is a traditional printing method that has been widely used in the printed electronics industry. Screen printing produces solid layers ranging in thickness from 5 to 15 microns, and these layers are conductive enough to carry electric current in many applications. The printing speed of screen printing is approximately 3 to 20 meters per minute.

[0004] These mature high-speed printing technologies are also used in the graphics industry, for example, in packaging creation. Typically, a thin layer of colored ink is applied to a substrate to obtain an image. In this method, the colors are applied as individual dots, but to the naked eye, these individual dots provide a very good color image. For conductive applications, conductive ink cannot be applied as individual dots because dry ink needs to be connected to provide a stable current flow.

[0005] There is a growing demand for new smart consumer goods such as smart diapers, RFID antennas, and medical electrodes. High-speed printing technologies, such as flexographic and rotgravure printing, are necessary to enable mass production of these new smart consumer goods. In this specification, "high-speed printing" refers to speeds of 200 m / min or more. The inks used in these new smart consumer goods require a certain level of conductivity; some inks require high conductivity, while others suffice with low conductivity. For demanding applications where high conductivity is essential, silver is used as the conductive material; however, for less demanding applications where lower resistance levels are sufficient, carbon or graphite can be used as the conductive material. However, not all conductive inks are suitable for high-speed printing processes. In fact, most conductive inks currently available are not suitable for high-speed printing processes.

[0006] One recent trend in the printed electronics industry is the research into cost-effective high-speed printing methods. Currently available carbon-based conductive inks have proven unsuitable for high-speed printing. Current carbon inks primarily fail because they lack sufficient conductivity when printed in thin layers, and the dried coating retains too much solvent after application. Another failure is that current carbon inks lose their functionality when printed at high speeds. [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, there is a need for a cost-effective conductive ink that can be applied by high-speed printing while maintaining good technical properties. [Means for solving the problem]

[0008] The present invention relates to a conductive composition comprising: a) a resin selected from the group consisting of nitrocellulose, chlorinated polyesters, chlorinated polyethers, chlorinated polyvinyls, chlorinated polyacetates and mixtures thereof; b) conductive particles comprising graphite and carbon black, wherein the ratio of said graphite to said carbon black is 1:1 to 5:1; and c) a solvent, wherein the ratio of said conductive particles to said resin is 0.20:1 to 4:1.

[0009] The present invention includes a conductive film comprising the conductive composition of the present invention.

[0010] The present invention relates to use of the conductive composition of the present invention in flexographic printing or rotogravure printing.

[0011] The present invention includes use of the conductive composition or conductive film of the present invention in smart personal hygiene products, heating elements, pressure sensors, smart books, smart labels, and shielding applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] [Figure 1] Figures 1a and 1b show flexographic printing trials on an industrial printer. [Figure 2] Figure 2 shows a microscopic image (magnified 25 times) of a dry coating after rotogravure printing using a backlight in Experimental Example 3. [Figure 3] Figure 3 shows a microscopic image (magnified 25 times) of a dry coating after rotogravure printing using a backlight in Experimental Example 7. MODE FOR CARRYING OUT THE INVENTION

[0013] The present invention will be described in more detail below. Each aspect described herein can be combined with any other aspect unless otherwise expressly stated. In particular, any feature indicated as preferred or advantageous can be combined with any other feature indicated as preferred or advantageous.

[0014] In the context of this invention, terms used should be interpreted according to the following definitions unless the context indicates otherwise.

[0015] As used herein, the singular forms "a," "an," and "the" include both singular and plural forms unless the context explicitly indicates otherwise.

[0016] As used herein, the terms “comprising,” “comprises,” and “comprised of” are synonymous with “including,” “includes,” or “containing,” and are comprehensive or open-ended and do not exclude additional unlisted members, elements, or method steps.

[0017] Numerical endpoints include not only the endpoint itself, but also all numbers and fractions within their respective ranges.

[0018] All percentages, parts, proportions, etc., mentioned herein are based on weight unless otherwise stated.

[0019] If a quantity, concentration, or other value or parameter is expressed in the form of a range, preferred range, or preferred upper and preferred lower limits, any range obtained by combining any upper or preferred value and any lower or preferred value should be understood as specifically disclosed, without regard to whether such range is explicitly mentioned in the context.

[0020] All references cited herein are incorporated herein in their entirety by reference.

[0021] Unless otherwise defined, all terms used in the disclosure of this invention, including technical and scientific terms, have meanings that are generally understood by those skilled in the art to which this invention pertains. Further guidance includes definitions of terms to better understand the teachings of this invention.

[0022] The applicant investigated conductive inks applied by high-speed printing methods. In particular, examining the sheet resistance of conductive ink layers (of various thicknesses) coated on a gravure printing press, it was found that a low sheet resistance of Ohm / sq / 25μm does not always provide the minimum resistance in thin layers. In this regard, thin layers are considered to have a thickness in the range of 1-2μm. Further experiments showed that low sheet resistance can be optimized by selecting an ideal combination of resin and conductive particles. A further advantage of this ideal combination of resin and conductive particles is that it can provide an ink with appropriate viscosity, excellent cost performance, and excellent conductivity in thin layers.

[0023] The present invention relates to a conductive composition comprising: a) a resin selected from the group consisting of nitrocellulose, chlorinated polyester, chlorinated polyether, chlorinated polyvinyl, chlorinated polyacetate, and mixtures thereof; b) conductive particles comprising graphite and carbon black, wherein the ratio of graphite to carbon black is 1:1 to 5:1; and c) a solvent, wherein the ratio of conductive particles to the resin is 0.20:1 to 4:1.

[0024] The conductive composition of the present invention has a combination of conductive particles optimized to provide good conductivity in a thin layer. Furthermore, the solvent and rheology allow the composition to be printed and dried rapidly (after dilution).

[0025] The conductive composition of the present invention comprises a resin. Resins suitable for use in the present invention are selected from nitrocellulose, chlorinated polyester, chlorinated polyether, chlorinated polyvinyl, chlorinated polyacetate, and mixtures thereof, and preferably the resin is nitrocellulose.

[0026] The term chlorinated polyvinyl, as used herein, means a vinyl chloride copolymer comprising a vinyl chloride polymer (homopolymer) and / or two, three, four or more comonomers.

[0027] In this specification, the term chlorinated polyester refers to a copolymer of vinyl chloride and a copolymerizable polyester oligomer.

[0028] In this specification, the term chlorinated polyether means a copolymer of vinyl chloride with a copolymerizable polyether oligomer.

[0029] In this specification, the term chlorinated polyacetate means a copolymer of vinyl chloride and vinyl acetate.

[0030] Preferably, the chlorinated polyvinyl is selected from the group consisting of: vinyl chloride polymers, vinyl chloride vinyl acetate copolymers, vinyl chloride vinyl stearate copolymers, vinyl chloride 1,2-dichloroethene copolymers, vinyl chloride (meth)acrylonitrile copolymers, vinyl chloride methyl (meth)acrylate copolymers, vinyl chloride butyl (meth)acrylate copolymers, vinyl chloride dicarboxylic acid copolymers, vinyl chloride fumarate copolymers, vinyl chloride maleic acid copolymers, vinyl chloride dibutyl fumarate copolymers, vinyl chloride diethyl maleate copolymers, vinyl chloride-vinyl acetate-dicarboxylic acid terpolymers, vinyl chloride-vinyl acetate-vinyl alcohol terpolymers, and mixtures thereof.

[0031] Preferably, the chlorinated polyester is selected from a copolymer of vinyl chloride and polyester acrylate oligomer.

[0032] Preferably, the chlorinated polyether is selected from copolymers of vinyl chloride and polyether acrylate oligomers such as dipropylene glycol diacrylate.

[0033] Preferably, the chlorinated polyacetate is a copolymer of vinyl chloride and vinyl acetate.

[0034] The selected resins readily release solvents, resulting in compositions suitable for consumer use. Furthermore, these resins are preferred because they offer low resistance and high conductivity. Generally, these resins disperse conductive particles well.

[0035] In a very preferred embodiment, nitrocellulose is used as the resin. Nitrocellulose is particularly preferred because it has good solubility and quickly releases the solvent used while providing excellent conductivity.

[0036] In another highly preferred embodiment, a vinyl chloride-vinyl acetate-vinyl alcohol terpolymer is used as the resin.

[0037] Suitable commercially available resins for use in the present invention include, but are not limited to, ShinEtsu's Solbin A and Dow's NC-E560 IPA 30%.

[0038] The resin may be present in the conductive composition of the present invention in an amount of 2 to 25% by weight, preferably 3 to 23%, and more preferably 4 to 21%, of the total weight of the composition.

[0039] If the amount of resin exceeds 25%, the viscosity of the composition may increase, potentially rendering it unsuitable for high-speed printing. On the other hand, if the amount is too low, less than 2%, the coating may be insufficient, the viscosity low, and the resin and conductive particles may settle.

[0040] The conductive composition of the present invention comprises conductive particles containing graphite and carbon black, wherein the ratio of graphite to carbon black is 1:1 to 5:1.

[0041] The applicant discovered that good results could be obtained by using a combination of graphite and carbon black as conductive particles.

[0042] Graphite suitable for use in the present invention preferably has a particle size D90 of 1 μm to 75 μm, more preferably 2 μm to 45 μm, more preferably 3 μm to 25 μm, and even more preferably 3 μm to 10 μm. Here, the particle size is measured by laser diffraction. In this method, a cell containing a sample of graphite suspended in water is illuminated with a laser beam, the generated diffraction pattern is collected by a system and analyzed using light scattering developed by Mie. The particle size distribution is calculated and reported in 90% of the amounts.

[0043] In addition to particle size D90, another characteristic of graphite suitable for use in this invention is its specific surface area, preferably 0.25 m². 2 / g~25m 2 / g, more preferably 4m 2 / g~22m 2 / g, more comfortably 7m 2 / g~21m 2 The specific surface area is calculated per gram, where the specific surface area is measured by BET nitrogen adsorption. The measurement is performed by measuring the nitrogen adsorption / desorption isotherm on the material surface using the Brunauer-Emmet-Teller algorithm, and a fixed amount (accuracy 0.01 mg) of powder is weighed into a sample tube. The sample is then subjected to a series of heating and cooling cycles based on the pressure changes in the sample tube, and the amount of adsorbed nitrogen is calculated in different steps; the specific surface area is calculated from this data, and m 2 It is reported as / g.

[0044] In a preferred embodiment, the graphite has a particle size D90 of 1 μm to 75 μm, preferably 2 μm to 45 μm, more preferably 3 μm to 25 μm, even more preferably 3 μm to 10 μm, and / or 0.25 m 2 / g to 25 m 2 / g, preferably 4 m 2 / g to 22 m 2 / g, more preferably 7 m 2 / g to 21 m 2 / g, wherein the particle size is measured by laser diffraction, and the specific surface area is measured by B.E.T nitrogen adsorption.

[0045] The preferred specific surface area and particle size of graphite, as separate features or in combination, provide low resistance and good electrical conductivity in thin layers, as well as good printability.

[0046] Generally, if the particle size of graphite is too large, the specific surface area will be reduced, and furthermore, it may become difficult to release particles from cells during the printing process. On the other hand, if the particle size of graphite is too small, the manufacturing cost may be too high, the specific surface area will increase, and the viscosity may increase. High viscosity is not ideal for high-speed printing, requires a large amount of dilution before application, and may adversely affect the conductivity of the printed layer.

[0047] If the specific surface area of graphite is less than 0.25 m 2 / g, the conductivity may decrease, and if the specific surface area is higher than 25 m 2 / g, problems may arise with the viscosity of the composition, and furthermore, it is not a cost-effective component.

[0048] Commercially available graphites suitable for use in the present invention include, but are not limited to, Timrex SFG6 from TIMCAL Graphite & Carbon.

[0049] Carbon black suitable for use in the present invention preferably has a lubrication amount of 70 ml / 100g to 500 ml / 100g, more preferably 100 ml / 100g to 300 ml / 100g, and more preferably 150 ml / 100g to 200 ml / 100g, where the above lubrication amount is measured according to ASTM D2414.

[0050] In addition to its oil absorption capacity, or as another characteristic, a carbon black suitable for use in the present invention is preferably 30m 2 / g~1400m 2 / g, comfortable 100m 2 / g~700m 2 / g, comfortable 150m 2 / g~350m 2 The specific surface area is 1 / g, where the specific surface area is measured by BET. This method is based on the description of nitrogen adsorption at 77K. The monolayer volume can be determined according to the model proposed by Brunauer, Emmet, and Teller (BET). The specific surface area can be calculated based on the cross-sectional area of ​​the nitrogen molecule, the monolayer volume, and the sample weight.

[0051] In a preferred embodiment, carbon black is supplied in amounts of 70 ml / 100g to 500 ml / 100g, preferably 100 ml / 100g to 300 ml / 100g, more preferably 150 ml / 100g to 200 ml / 100g, and / or 30 ml 2 / g~1400m 2 / g, preferably 100m 2 / g~700m 2 / g, comfortable 150m 2 / g~350m 2 It has a specific surface area of ​​ / g, where the oil quantity is measured according to ASTM D2414, and the specific surface area is measured by BET.

[0052] The preferred specific surface area and oil absorption, either separately or in combination, provide good printability and low resistance in thin layers.

[0053] If the oil absorption of carbon black is too low, it means there are fewer branches in the carbon black, resulting in fewer contact points in the thin layer and negatively affecting conductivity. On the other hand, if the oil absorption of carbon black is too high (mainly above 500), problems may occur in the printing process.

[0054] If the specific surface area of ​​carbon black is too small (mainly less than 30), its conductivity may decrease, and if the specific surface area of ​​carbon black is too large (mainly more than 1400), the printing process may become difficult.

[0055] Suitable commercially available carbon blacks for use in the present invention include, but are not limited to, Vulcan XC72 from Cabot and Ensaco 250G from Imerys.

[0056] According to the present invention, the ratio of graphite to carbon black is 1:1 to 5:1, preferably 2:1 to 4:1, and more preferably 3:1.

[0057] The applicant found that these graphite:carbon black ratios provide ideal viscosity and conductivity properties for the composition according to the present invention. It was found that if the concentration of carbon black relative to graphite is too high, the printed layer may become too thick. Furthermore, if the amount of carbon black is too high, the viscosity of the composition may become too high, making it impossible to print the composition at high speed.

[0058] Conductive particles may be present in the conductive composition of the present invention in an amount of 3 to 45% by weight, preferably 4 to 43%, and more preferably 4.75 to 41%, of the total weight of the composition.

[0059] If the amount of conductive particles is too low, mainly less than 3%, the amount may not provide the desired conductivity; on the other hand, if the amount is too high, mainly more than 45%, it may become difficult to process the composition in the printing process.

[0060] The applicant has found that particularly good properties can be obtained when the ratio of conductive particles to the resin is 0.20:1 to 4:1, preferably 0.25:1 to 3:1, and that the composition can be used for high-speed printing.

[0061] The applicant found that the ratio of conductive particles to resin provides good viscosity and good conductivity.

[0062] The conductive composition of the present invention comprises a solvent. The composition may comprise one solvent or a mixture of two or more solvents. The solvent preferably has a relatively low boiling point, preferably below 119°C, and more preferably between 80°C and 105°C. Solvents with relatively low boiling points are preferred because they dry quickly, enabling faster printing speeds.

[0063] In preferred embodiments, the solvent is selected from the group consisting of toluene, ethanol, isopropyl alcohol, n-propanol, ethyl acetate, n-propyl acetate, isopropyl acetate, methyl ethyl ketone, methyl isobutyl ketone, water, and mixtures thereof. Preferably, the solvent is selected from ethyl acetate, isopropyl alcohol, n-propyl acetate, and mixtures thereof, and more preferably from isopropyl alcohol, n-propyl acetate, and mixtures thereof.

[0064] These solvents are preferred because they dissolve the resin well and are readily released during the drying process.

[0065] Suitable commercially available solvents for use in the present invention include, but are not limited to, ethyl acetate from Eastman and butyl acetate from Eastman.

[0066] The solvent may be present in the conductive composition of the present invention in an amount of 40 to 92% by weight, preferably 45 to 91%, and more preferably 46 to 90%, of the total weight of the composition.

[0067] If the amount of solvent is less than 40%, the viscosity of the composition may become too high, which may adversely affect the printing properties of the composition. If the amount is too high (more than 90%), it may adversely affect the conductivity of the composition.

[0068] The conductive composition of the present invention is preferably manufactured by the pebble mill method. In the pebble mill method, the conductive particles, resin, and solvent are pulverized in a large mill using pebbles for about 15 hours.

[0069] In one aspect of the present invention, a conductive film containing the conductive composition of the present invention can be formed.

[0070] The conductive film according to the present invention has one or more layers, and the thickness of each layer is 0.5 μm to 3 μm, preferably 0.75 μm to 2 μm, and more preferably 1 to 1.5 μm.

[0071] Thin layers are desirable not only from a cost-effectiveness perspective but also from a process perspective. Thinner layers mean less material accumulates on the rolls used in the printing process, thus improving print quality.

[0072] The conductive composition of the present invention can be used in high-speed printing such as flexographic printing or rotgravure printing.

[0073] In flexographic printing, ink is transferred from a metal cylinder (containing small cells filled with ink) to a polymer sleeve (which holds the image like a stamp), and the sleeve then transfers the ink (stamp) to the substrate. This process is fast, and the viscosity of the ink used must be low to enable it. When ink is applied in flexographic or gravure printing, a thin, dry layer with a thickness ranging from about 1 micron is obtained.

[0074] The conductive composition of the present invention can be printed at speeds of up to 200 m / min or more.

[0075] The conductive composition of the present invention preferably has a viscosity of 600 to 5000 mPas, preferably 650 to 3000, and more preferably 700 to 2000 mPas, where the viscosity is measured at room temperature using a Brookfield (DV-I prime), spindle #2, 20.

[0076] The applicant found that this viscosity range is ideal for the manufacturing process used to produce the conductive compositions of the present invention, and furthermore, that this viscosity range prevents sedimentation of the compositions during storage.

[0077] In flexographic or rotgravure printing, the viscosity of the composition needs to be relatively low in order to obtain good release from the cell. Therefore, in one preferred embodiment, the composition according to the present invention is diluted before application. Thus, the present invention also relates to diluted conductive compositions, in which the conductive composition of the present invention is diluted to a range of 20 to 70% by weight, preferably 40 to 50% by weight.

[0078] A preferred dilution range is approximately 40-50% by weight, which results in a viscosity in the range of 100 mPa·s. Despite the low viscosity, the diluted composition according to the present invention provides good conductivity in thin layers.

[0079] A suitable solvent for dilution is the solvent used in the composition according to the present invention. In a very preferred embodiment, the solvent used for dilution is n-propyl acetate.

[0080] The composition according to the present invention retains its functionality even when printed at high speed.

[0081] The present invention also includes the use of the conductive composition or conductive film of the present invention in smart personal hygiene products, heating elements, pressure sensors, smart books, smart labels, and shielding applications.

[0082] Smart personal hygiene products include smart diapers / absorbent products, etc. [Examples]

[0083] [Table 1]

[0084] The viscosity of the composition is approximately 200 mPa.s.

[0085] The sample was applied to the substrate using a bar coater and dried in air. Before application, the sample was diluted until the solid content reached 23%. The results are summarized in Table 2. Experimental Example 1 provided minimal resistance in a thick, dense layer.

[0086] [Table 2]

[0087] The experimental examples in Tables 1 and 2 were applied using a 90 μm applicator. Next, the coating was air-dried, and the thickness of the layer was measured using a Mitutoyo digital thickness gauge. The film was allowed to stand for 15 minutes, a 10 x 1 cm track was isolated, and the resistance of this track was measured. Resistance measurements were performed using a digital Keithley electrometer with a four-point probe. After measuring the resistance, the sheet resistance was calculated according to the following formula.

number

[0088] The results are shown in Table 2. Experimental Example 2 provided the least resistance. The thinner the thickness, the better the formulation of Experimental Example 2 is compared to the other inks.

[0089] [Table 3]

[0090] Figures 1a and 1b show trials of flexographic printing using an industrial printer. Both Experiment 1 and Experiment 2 were printed on PET under the same conditions using a gravure proofer. After printing, the resistance of a 50 × 2 mm (= 25 square) track was measured and kOhm / sq was calculated.

[0091] Experimental Example 2 provides the minimum resistance (Experimental Example 1: 6.3 kOhm / sq, and Experimental Example 2: 2.0 kOhm / sq).

[0092] Table 4 below illustrates other compositions.

[0093] [Table 4]

[0094] The samples were diluted until the solid content reached 16%. Then, Experimental Examples 3-7 were applied to substrates using a gravure printing press and dried in the air. The results are summarized in Table 5.

[0095] [Table 5]

[0096] Figures 2 and 3 show microscopic images (25x magnification) of the dried coating after rotogravure printing using backlighting in Experimental Example 3 (Figure 2) and Experimental Example 7 (Figure 3).

[0097] The viscosity of experimental examples 3-5 is approximately 200 mPa·s. Experimental example 7 has high viscosity, and due to its high viscosity, it is unsuitable for high-speed printing. This is shown in Figure 3, and the formed film is not a uniform layer but a film full of pinholes, which is not a desired characteristic. The initial disclosures of this specification include at least the following aspects: [1] a) Resins selected from the group consisting of nitrocellulose, chlorinated polyester, chlorinated polyether, chlorinated polyvinyl, chlorinated polyacetate, and mixtures thereof; b) Conductive particles comprising graphite and carbon black, wherein the ratio of graphite to carbon black is 1:1 to 5:1; and, c) Solvent A conductive composition comprising, wherein the ratio of the conductive particles to the resin is 0.20:1 to 4:1. [2] The conductive composition according to [1], wherein the resin is nitrocellulose. [3] The conductive composition according to [1] or [2], wherein the resin is present in an amount of 2 to 25% by weight, preferably 3 to 23%, more preferably 4 to 21%, of the total weight of the composition. [4] Graphite has a particle size D90 of 1 μm to 75 μm, preferably 2 μm to 45 μm, more preferably 3 μm to 25 μm, and even more preferably 3 μm to 10 μm. and / or, 0.25m 2 / g~25m 2 / g, preferably 4m 2 / g~22m 2 / g, more comfortably 7m 2 / g~21m 2 Specific surface area / g A conductive composition according to any one of [1] to [3], wherein the particle size is measured by laser diffraction and the specific surface area is measured by BET nitrogen adsorption. [5] Carbon black has an oil absorption capacity of 70 ml / 100g to 500 ml / 100g, preferably 100 ml / 100g to 300 ml / 100g, more preferably 150 ml / 100g to 200 ml / 100g. and / or, 30m 2 / g~1400m 2 / g, preferably 100m 2 / g~700m 2 / g, comfortable 150m 2 / g~350m 2 Specific surface area / g A conductive composition according to any one of [1] to [4], wherein the oil absorption amount is measured by ASTM D2414 and the specific surface area is measured by BET. [6] The conductive composition according to any one of [1] to [5], wherein the ratio of graphite to carbon black is 2:1 to 4:1, preferably 3:1. [7] The conductive composition according to any one of [1] to [6], wherein the conductive particles are present in an amount of 3 to 45% by weight, preferably 4 to 43%, and more preferably 4.75 to 41% of the total weight of the composition. [8] Conductive particles: The ratio of resin to conductive particles is 0.25:1 to 3:1, the conductive composition according to any one of [1] to [7]. [9] The solvent is selected from the group consisting of toluene, ethanol, isopropyl alcohol, n-propanol, ethyl acetate, n-propyl acetate, isopropyl acetate, methyl ethyl ketone, methyl isobutyl ketone, water, and mixtures thereof, preferably the solvent is selected from ethyl acetate, isopropyl alcohol, n-propyl acetate, and mixtures thereof, and more preferably is selected from isopropyl alcohol, n-propyl acetate, and mixtures thereof, the conductive composition according to any one of [1] to [8].

[10] The conductive composition according to any one of [1] to [9], wherein the solvent is present in an amount of 40 to 92% by weight, preferably 45 to 91%, more preferably 46 to 90%, of the total weight of the composition.

[11] The conductive composition according to any one of [1] to

[10] , having a viscosity of 600 to 5000 mPas, preferably 650 to 3000 mPas, more preferably 700 to 2000 mPas, wherein the viscosity is measured at room temperature using a Brookfield (DV-I prime), spindle #2, 20. A diluted conductive composition obtained by diluting any of the conductive compositions described in

[12] [1] to

[11] in an amount of 20 to 70% by weight, preferably 40 to 50% by weight. A conductive film comprising the conductive composition described in any of

[13] , [1], to

[11] .

[14] The conductive film according to

[13] , wherein the film has one or more layers, each layer having a thickness of 0.5 μm to 3 μm, preferably 0.75 μm to 2 μm, and more preferably 1 to 1.5 μm.

[15] Use of a conductive composition according to any of [1] to

[11] or a diluted conductive composition according to

[12] in flexographic printing or rotgravure printing.

[16] Use of any of the conductive compositions described in [1] to

[11] or the conductive films described in

[12] or

[13] in smart personal hygiene products, heating elements, pressure sensors, smart books, smart labels, and shielding applications.

Claims

1. a) Nitrocellulose resin; b) Conductive particles comprising graphite and carbon black, wherein the ratio of graphite to carbon black is 1:1 to 5:1; and, c) Solvent A conductive ink composition comprising, wherein the ratio of conductive particles to resin is 0.20:1 to 4:1, the resin is present in an amount of 2 to 25% by weight of the total weight of the composition, and the conductive particles are present in an amount of 3 to 45% by weight of the total weight of the composition.

2. Graphite has a particle size of 1 μm to 75 μm, D90. and / or, 0.25m ２ / g to 25m ２ Specific surface area of ​​ / g The conductive ink composition according to claim 1, wherein the particle size is measured by laser diffraction and the specific surface area is measured by BET nitrogen adsorption.

3. Carbon black has an oil absorption capacity of 70 ml / 100 g to 500 ml / 100 g. and / or, 30m ２ / g ~ 1400m ２ Specific surface area of ​​ / g The conductive ink composition according to claim 1 or 2, wherein the oil absorption amount is measured by ASTM D2414 and the specific surface area is measured by BET.

4. The conductive ink composition according to any one of claims 1 to 3, wherein the ratio of graphite to carbon black is 2:1 to 4:

1.

5. The conductive ink composition according to any one of claims 1 to 4, wherein the conductive particles are present in an amount of 3 to 45% by weight of the total weight of the composition.

6. The conductive ink composition according to any one of claims 1 to 5, wherein the ratio of conductive particles to resin is 0.25:1 to 3:

1.

7. The conductive ink composition according to any one of claims 1 to 6, wherein the solvent is selected from the group consisting of toluene, ethanol, isopropyl alcohol, n-propanol, ethyl acetate, n-propyl acetate, isopropyl acetate, methyl ethyl ketone, methyl isobutyl ketone, water, and mixtures thereof.

8. The conductive ink composition according to any one of claims 1 to 7, wherein the solvent is present in an amount of 40 to 92% by weight of the total weight of the composition.

9. The conductive ink composition according to any one of claims 1 to 8, wherein the composition has a viscosity of 600 to 5000 mPas, where the viscosity is measured at room temperature using a Brookfield (DV-I prime), spindle #2, 20.

10. A diluted conductive ink composition obtained by diluting the conductive ink composition according to any one of claims 1 to 9 in an amount ranging from 20 to 70% by weight.

11. A conductive film comprising the conductive ink composition according to any one of claims 1 to 9.

12. The conductive film according to claim 11, wherein the film has one or more layers, each layer having a thickness of 0.5 μm to 3 μm.

13. Use of a conductive ink composition according to any one of claims 1 to 9, or a diluted conductive ink composition according to claim 10, in flexographic printing or rotgravure printing.

14. Use of a conductive ink composition according to any one of claims 1 to 9, or a conductive film according to claim 11 or 12, in smart personal hygiene products, heating elements, pressure sensors, smart books, smart labels, and shielding applications.

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