Carbon nanotube-based conductive ink for fabric
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-04-03
AI Technical Summary
Carbon nanotubes in existing conductive inks are difficult to disperse stably in aqueous systems, resulting in decreased conductivity and mechanical properties, as well as a lack of flame retardant properties, making it difficult to meet the high safety requirements of smart fabrics.
Carbon nanotubes are modified with chitosan, which forms a hydrophilic protective layer on the surface of the carbon nanotubes through π-π conjugation and zwitterionic segments. Combined with an aqueous polyurethane matrix, the carbon nanotubes are uniformly dispersed and reinforced. The P, N and S elements added to the modified chitosan provide a flame retardant effect.
This method achieves long-term stable dispersion of carbon nanotubes in an aqueous system, maintains high conductivity, enhances the mechanical strength and fire safety of the coating, and significantly improves the stability and functionality of the conductive network.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of ink technology, specifically, it relates to a conductive ink for fabrics based on carbon nanotubes. Background Technology
[0002] Currently, conductive inks for fabrics are a research hotspot in the field of smart textiles, and their performance hinges on the selection and dispersion of conductive fillers. Carbon nanotubes are considered ideal conductive fillers due to their excellent conductivity and mechanical properties, but their inherent hydrophobicity and high specific surface area easily lead to severe aggregation in water, making it difficult to disperse stably in aqueous systems, which greatly limits their application in conductive inks.
[0003] In existing technologies, covalent modification methods such as strong acid oxidation are often used to treat the surface of carbon nanotubes. Although this can improve their hydrophilicity, it will destroy their spline properties. 2 Hybrid structures introduce defects, leading to a significant decrease in intrinsic conductivity. Furthermore, conventional dispersants (such as common surfactants or polymers) have weak binding forces with carbon nanotubes, making them prone to desorption during storage or film formation. This causes the carbon nanotubes to re-aggregate, affecting the stability and uniformity of the conductive network, ultimately resulting in poor coating conductivity and decreased mechanical properties. Simultaneously, most existing conductive inks have limited functionality and lack additional properties such as flame retardancy, making it difficult to meet the high-level safety requirements of smart fabrics.
[0004] Therefore, developing a water-based conductive ink that can simultaneously achieve high stability dispersion of carbon nanotubes, maintain their high conductivity, and impart multifunctionality to the coating has become a pressing technical challenge in this field. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a carbon nanotube-based conductive ink for fabrics.
[0006] The objective of this invention can be achieved through the following technical solutions: A conductive ink for fabrics based on carbon nanotubes comprises the following components: by weight, 5-8 parts modified carbon nanotubes, 20-30 parts waterborne polyurethane, 0.1-0.5 parts defoamer, 50-60 parts deionized water, and 2-3 parts film-forming aid.
[0007] In a more optimized manner, the preparation process of the modified carbon nanotubes is as follows: adding modified chitosan to deionized water, raising the temperature to 40-50℃, and stirring continuously for 5-6 hours to obtain a modified chitosan solution; adding carbon nanotube powder to the modified chitosan solution, ultrasonically treating for 1-2 hours, and then stirring continuously for 10-12 hours to obtain modified carbon nanotubes.
[0008] In this scheme, the aromatic rings on the modified chitosan molecular chain can generate π-π conjugation with carbon nanotubes, resulting in overlapping attraction. This allows the modified chitosan to adhere tightly and uniformly to the outer surface of the carbon nanotubes without destroying their original structure. Furthermore, carbon nanotubes are prone to aggregation due to their hydrophobic surface. The zwitterionic chains grafted onto the modified chitosan possess both hydrophilicity and electroneutrality (locally carrying positive and negative charges). They can form a hydrophilic protective layer on the surface of the carbon nanotubes through hydrogen bonding or electrostatic attraction with water molecules, solving the hydrophobic aggregation problem and ensuring uniform dispersion in deionized water. They can also further ensure the stability of the system through steric hindrance (forming a three-dimensional barrier to prevent carbon nanotubes from approaching). Combined with ultrasound and continuous stirring, this ultimately achieves the efficient preparation of modified carbon nanotubes.
[0009] In a more optimized manner, the raw materials for preparing the modified carbon nanotubes include the following components: 5-8 parts by weight of modified chitosan, 80-90 parts by weight of deionized water, and 2-3 parts by weight of carbon nanotube powder.
[0010] The optimized preparation process of the modified chitosan is as follows: S1: Under a protective atmosphere, vanillin, triethylamine and ethyl acetate were mixed and cooled to 0°C. Then, phenylphosphonic dichloride solution was added dropwise. After the addition was complete, the system was slowly raised to room temperature and the reaction was continued for 48 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain intermediate A. S2: Mix 1-(3-aminopropyl)imidazolium, intermediate A, and N,N-dimethylformamide, raise the temperature to 70-80℃, and react for 10-12 h. After the reaction is complete, perform post-treatment to obtain intermediate B. Then, transfer intermediate B to acetonitrile, add 1,3-propanesulfonic acid lactone, stir to dissolve, and reflux at 80℃ for 24 h under a protective atmosphere. After the reaction is complete, cool to room temperature, wash, and dry to obtain the modifier. S3: Add chitosan to a mixed solution of acetic acid and toluene, stir until completely dissolved, then add modifier and piperidine, react at room temperature for 30-40 min, then adjust the pH to 5.5 and continue the reaction for 1-2 h. After the reaction is complete, let it stand to precipitate, filter, wash, and dry to obtain modified chitosan.
[0011] In this scheme, the phenolic hydroxyl group on the vanillin molecule acts as a nucleophile, attacking the electronegative phosphorus atom in the phenylphosphonic dichloride molecule to obtain intermediate A; the specific synthetic process is shown below: In a more optimized manner, the raw materials for preparing intermediate A include the following components: by weight, 10-12 parts vanillin, 7-8 parts triethylamine, 80-100 parts ethyl acetate, and 12-15 parts phenylphosphonic dichloride solution; wherein the concentration of phenylphosphonic dichloride solution is 50 wt%.
[0012] In this process, an aldehyde group of intermediate A undergoes dehydration condensation with the primary amino group of 1-(3-aminopropyl)imidazolium to generate a Schiff base structure containing a carbon-nitrogen double bond. Subsequently, the nitrogen atom on the imidazolium ring of intermediate B acts as a nucleophile, attacking the three-membered ring of 1,3-propanesulfonic acid lactone to induce a ring-opening reaction, yielding the modifier. The specific synthetic process is shown below: More preferably, the raw materials for preparing intermediate B include the following components: by weight, 4-5 parts of 1-(3-aminopropyl)imidazolium, 14-15 parts of intermediate A, and 60-80 parts of N,N-dimethylformamide; the raw materials for preparing the modifier include the following components: by weight, 14-15 parts of intermediate B, 60-80 parts of acetonitrile, and 4-5 parts of 1,3-propanesulfonic acid lactone.
[0013] In this method, the amino groups on the chitosan chain react with the aldehyde groups retained on the modifier molecule again to form stable C=N bonds, thereby obtaining modified chitosan.
[0014] In a more optimized manner, the raw materials for preparing the modified chitosan include the following components: by weight, 100-120 parts of a mixed solution of acetic acid and toluene, 4-5 parts of chitosan, 1-2 parts of modifier, and 0.5-0.8 parts of piperidine.
[0015] Ideally, the defoamer is an organosilicone defoamer SD998.
[0016] More preferably, the film-forming aid is polyether-modified polyorganosiloxane 8030F.
[0017] The beneficial effects of this invention are: This invention modifies carbon nanotubes using chitosan and then combines it with components such as waterborne polyurethane to prepare a conductive ink that exhibits significant advantages in dispersion stability, conductivity, film-forming properties, and functionality. Specifically: Firstly, the aromatic rings on the modified chitosan molecular chain adsorb onto the surface of carbon nanotubes through a strong π-π conjugation effect. This is a non-covalent modification that can adsorb onto the surface of carbon nanotubes without destroying their intrinsic sp. 2The hybrid structure, while maintaining excellent conductivity, achieves complete, uniform, and tight coating of the carbon nanotubes. More importantly, the zwitterionic segments (carrying both positive and negative charges) grafted onto the modified chitosan endow the entire modified system with excellent hydrophilicity and electroneutrality. Through strong hydrogen bonds and electrostatic interactions with water molecules, the zwitterionic chains construct a stable hydrophilic protective layer on the hydrophobic surface of the carbon nanotubes, fundamentally solving the problem of easy aggregation of carbon nanotubes in aqueous phases. Simultaneously, these hydrophilic segments extend spatially, forming an effective three-dimensional barrier, further preventing carbon nanotubes from approaching each other through steric hindrance, thus achieving long-term, uniform, and stable dispersion of carbon nanotubes in aqueous systems.
[0018] Secondly, the modified carbon nanotubes of this invention exhibit a synergistic effect with the waterborne polyurethane matrix. The zwitterionic segments on their surface form numerous hydrogen bonds with the polar groups on the polyurethane molecular chains, enhancing interfacial bonding, improving compatibility, reducing phase separation, and allowing the carbon nanotubes to be uniformly embedded in the polyurethane network. This not only promotes the formation of stable conductive pathways but also significantly improves the mechanical strength, flexibility, and adhesion of the coating film, making it resistant to repeated bending and washing. Simultaneously, the uniformly dispersed carbon nanotube network also strengthens and toughens the polyurethane film.
[0019] Thirdly, in this solution, the P, N, and S elements contained in the modified chitosan can produce a synergistic flame retardant effect during combustion. Through the combined action of the condensed phase and gas phase flame retardant mechanisms, it can effectively delay the spread of flames, inhibit the generation of smoke, and significantly improve the fire safety of the coated fabric. Detailed Implementation
[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0021] Example 1: A conductive ink for fabrics based on carbon nanotubes, comprising the following components by weight: 5 parts modified carbon nanotubes, 20 parts waterborne polyurethane, 0.1 parts defoamer (organosilicone defoamer SD998), 50 parts deionized water, and 2 parts film-forming aid (polyether modified polyorganosiloxane 8030F). The preparation process of modified carbon nanotubes is as follows: 5 parts of modified chitosan are added to 80 parts of deionized water, the temperature is raised to 40℃, and the mixture is stirred continuously for 5 hours to obtain a modified chitosan solution; 2 parts of carbon nanotube powder are added to the modified chitosan solution, ultrasonically treated for 1 hour, and then stirred continuously for 10 hours to obtain modified carbon nanotubes. The preparation process of modified chitosan is as follows: S1: Under a protective atmosphere, 10 parts vanillin, 7 parts triethylamine and 80 parts ethyl acetate were mixed and cooled to 0°C. Then, 12 parts phenylphosphonic dichloride solution (concentration of 50wt%) was added dropwise. After the addition was completed, the system was slowly raised to room temperature and the reaction was continued for 48 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain intermediate A. S2: Mix 4 parts of 1-(3-aminopropyl)imidazole, 14 parts of intermediate A, and 60 parts of N,N-dimethylformamide, raise the temperature to 70°C, and react for 10 h. After the reaction is completed, post-process to obtain intermediate B. Then, transfer 14 parts of intermediate B to 60 parts of acetonitrile, add 4 parts of 1,3-propanesulfonic acid lactone, stir to dissolve, and reflux at 80°C for 24 h under a protective atmosphere. After the reaction is completed, cool to room temperature, wash, and dry to obtain the modifier. S3: Add 4 parts chitosan to 100 parts of a mixed solution of acetic acid and toluene (acetic acid concentration is 28wt%), stir until completely dissolved, then add 1 part modifier and 0.5 parts piperidine, react at room temperature for 30 min, then adjust the pH to 5.5 and continue the reaction for 1 h. After the reaction is complete, let it stand to precipitate, filter, wash, and dry to obtain modified chitosan.
[0022] Example 2: A conductive ink for fabrics based on carbon nanotubes, comprising the following components by weight: 8 parts modified carbon nanotubes, 30 parts waterborne polyurethane, 0.5 parts defoamer (silicone defoamer SD998), 60 parts deionized water, and 3 parts film-forming aid (polyether modified polysiloxane 8030F). The preparation process of modified carbon nanotubes is as follows: 8 parts of modified chitosan are added to 90 parts of deionized water, the temperature is raised to 50℃, and the mixture is stirred continuously for 6 hours to obtain a modified chitosan solution; 3 parts of carbon nanotube powder are added to the modified chitosan solution, ultrasonically treated for 2 hours, and then stirred continuously for 12 hours to obtain modified carbon nanotubes. The preparation process of modified chitosan is as follows: S1: Under a protective atmosphere, 12 parts vanillin, 8 parts triethylamine and 100 parts ethyl acetate were mixed and cooled to 0°C. Then, 15 parts phenylphosphonic dichloride solution (concentration of 50wt%) was added dropwise. After the addition was completed, the system was slowly raised to room temperature and the reaction was continued for 48 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain intermediate A. S2: Mix 5 parts of 1-(3-aminopropyl)imidazolium, 15 parts of intermediate A, and 80 parts of N,N-dimethylformamide, raise the temperature to 80℃, and react for 12 h. After the reaction is completed, post-process to obtain intermediate B. Then, transfer 15 parts of intermediate B to 80 parts of acetonitrile, add 5 parts of 1,3-propanesulfonic acid lactone, stir to dissolve, and reflux at 80℃ for 24 h under a protective atmosphere. After the reaction is completed, cool to room temperature, wash, and dry to obtain the modifier. S3: Add 5 parts chitosan to a mixed solution of 120 parts acetic acid and toluene (acetic acid concentration is 28 wt%), stir until completely dissolved, then add 2 parts modifier and 0.8 parts piperidine, react at room temperature for 40 min, then adjust the pH to 5.5 and continue the reaction for 2 h. After the reaction is complete, let it stand to precipitate, filter, wash, and dry to obtain modified chitosan.
[0023] Example 3: A conductive ink for fabrics based on carbon nanotubes, comprising the following components by weight: 6.5 parts modified carbon nanotubes, 25 parts waterborne polyurethane, 0.3 parts defoamer (silicone defoamer SD998), 55 parts deionized water, and 2.5 parts film-forming aid (polyether modified polysiloxane 8030F). The preparation process of modified carbon nanotubes is as follows: 6.5 parts of modified chitosan are added to 85 parts of deionized water, the temperature is raised to 45℃, and the mixture is stirred continuously for 5.5 hours to obtain a modified chitosan solution; 2.5 parts of carbon nanotube powder are added to the modified chitosan solution, ultrasonically treated for 1.5 hours, and then stirred continuously for 11 hours to obtain modified carbon nanotubes. The preparation process of modified chitosan is as follows: S1: Under a protective atmosphere, 11 parts vanillin, 7.5 parts triethylamine and 90 parts ethyl acetate were mixed and cooled to 0°C. Then, 13.5 parts phenylphosphonic dichloride solution (concentration of 50wt%) was added dropwise. After the addition was completed, the system was allowed to slowly rise to room temperature and the reaction was continued for 48 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain intermediate A. S2: Mix 4.5 parts of 1-(3-aminopropyl)imidazole, 14.5 parts of intermediate A, and 70 parts of N,N-dimethylformamide, raise the temperature to 75°C, and react for 11 h. After the reaction is complete, post-process to obtain intermediate B. Then, transfer 14.5 parts of intermediate B to 70 parts of acetonitrile, add 4.5 parts of 1,3-propanesulfonic acid lactone, stir to dissolve, and reflux at 80°C for 24 h under a protective atmosphere. After the reaction is complete, cool to room temperature, wash, and dry to obtain the modifier. S3: Add 4.5 parts chitosan to a mixed solution of 110 parts acetic acid and toluene (acetic acid concentration is 28 wt%), stir until completely dissolved, then add 1.5 parts modifier and 0.65 parts piperidine, react at room temperature for 35 min, then adjust the pH to 5.5 and continue the reaction for 1.5 h. After the reaction is complete, let it stand to precipitate, filter, wash, and dry to obtain modified chitosan.
[0024] Comparative Example 1: No modification was made to the carbon nanotubes, as follows: A conductive ink for fabrics based on carbon nanotubes comprises the following components: by weight, 6.5 parts carbon nanotubes, 25 parts waterborne polyurethane, 0.3 parts defoamer (silicone defoamer SD998), 55 parts deionized water, and 2.5 parts film-forming aid (polyether modified polysiloxane 8030F).
[0025] Comparative Example 2: No modification was made to chitosan, as follows: A conductive ink for fabrics based on carbon nanotubes comprises the following components: by weight, 6.5 parts modified carbon nanotubes, 25 parts waterborne polyurethane, 0.3 parts defoamer (silicone defoamer SD998), 55 parts deionized water, and 2.5 parts film-forming aid (polyether modified polysiloxane 8030F). The preparation process of modified carbon nanotubes is as follows: 6.5 parts of chitosan are added to 85 parts of deionized water, the temperature is raised to 45℃, and the mixture is stirred continuously for 5.5 hours to obtain a chitosan solution; 2.5 parts of carbon nanotube powder are added to the chitosan solution, ultrasonically treated for 1.5 hours, and then stirred continuously for 11 hours to obtain modified carbon nanotubes.
[0026] Testing experiment: The fabric (polyester) was treated with ink obtained from the examples and comparative examples to form a conductive coating; then, a four-probe resistance meter was used to measure the resistance three times at different locations, and the average value was taken as the final result. Using the GB / T 6753.3-1986 standard, the inks obtained in the examples and comparative examples were placed in a sealed container and stored at 40°C for 7 days to observe whether they separated into layers, precipitated, or clumped. The ink-treated fabrics (polyester) obtained using the examples and comparative examples were tested using the oxygen index method of the textile flammability test as described in GB / T5454-1997 standard. The obtained data is shown in the table below: project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Electrical conductivity (S / m) 345 344 351 58 210 stability No obvious precipitation, stable dispersion No obvious precipitation, stable dispersion No obvious precipitation, stable dispersion Severe precipitation and carbon nanotube aggregation Slight sedimentation Oxygen index (%) 28.5 28.6 29.2 21.3 24.5 Conclusion: The conductive ink based on modified carbon nanotubes prepared in this invention exhibits significant advantages in conductivity, dispersion stability, and flame retardancy. The conductivity of Examples 1 to 3 is all above 340 S / m, far superior to Comparative Example 1 (58 S / m) using unmodified carbon nanotubes and Comparative Example 2 (210 S / m) using only unmodified chitosan. Regarding stability, all examples showed no significant precipitation and good dispersion, while Comparative Example 1 showed severe agglomeration, and Comparative Example 2 also showed slight precipitation. Furthermore, the oxygen index of all examples exceeded 28%, indicating good flame retardancy, significantly higher than Comparative Example 1 (21.3%) and Comparative Example 2 (24.5%). These results fully demonstrate the key role of modified chitosan in improving the dispersibility, conductivity, and functionality of carbon nanotubes, as well as the comprehensive performance advantages of the conductive ink of this invention in textile applications.
[0027] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0028] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.
Claims
1. A conductive ink for fabrics based on carbon nanotubes, characterized in that, It includes the following components by weight: 5-8 parts modified carbon nanotubes, 20-30 parts waterborne polyurethane, 0.1-0.5 parts defoamer, 50-60 parts deionized water, and 2-3 parts film-forming aid.
2. The conductive ink for fabrics based on carbon nanotubes according to claim 1, characterized in that, The preparation process of the modified carbon nanotubes is as follows: add modified chitosan to deionized water, raise the temperature to 40-50℃, and stir continuously for 5-6 hours to obtain a modified chitosan solution; add carbon nanotube powder to the modified chitosan solution, sonicate for 1-2 hours, and then stir continuously for 10-12 hours to obtain modified carbon nanotubes.
3. The conductive ink for fabrics based on carbon nanotubes according to claim 2, characterized in that, The raw materials for preparing the modified carbon nanotubes include the following components: by weight, 5-8 parts modified chitosan, 80-90 parts deionized water, and 2-3 parts carbon nanotube powder.
4. The conductive ink for fabrics based on carbon nanotubes according to claim 2, characterized in that, The preparation process of the modified chitosan is as follows: S1: Under a protective atmosphere, vanillin, triethylamine and ethyl acetate were mixed and cooled to 0°C. Then, phenylphosphonic dichloride solution was added dropwise. After the addition was complete, the system was slowly raised to room temperature and the reaction was continued for 48 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain intermediate A. S2: Mix 1-(3-aminopropyl)imidazolium, intermediate A, and N,N-dimethylformamide, raise the temperature to 70-80℃, and react for 10-12 h. After the reaction is complete, perform post-treatment to obtain intermediate B. Then, transfer intermediate B to acetonitrile, add 1,3-propanesulfonic acid lactone, stir to dissolve, and reflux at 80℃ for 24 h under a protective atmosphere. After the reaction is complete, cool to room temperature, wash, and dry to obtain the modifier. S3: Add chitosan to a mixed solution of acetic acid and toluene, stir until completely dissolved, then add modifier and piperidine, react at room temperature for 30-40 min, then adjust the pH to 5.5 and continue the reaction for 1-2 h. After the reaction is complete, let it stand to precipitate, filter, wash, and dry to obtain modified chitosan.
5. The conductive ink for fabrics based on carbon nanotubes according to claim 4, characterized in that, The raw materials for preparing intermediate A include the following components: by weight, 10-12 parts vanillin, 7-8 parts triethylamine, 80-100 parts ethyl acetate, and 12-15 parts phenylphosphonic dichloride solution; wherein the concentration of phenylphosphonic dichloride solution is 50 wt%.
6. The conductive ink for fabrics based on carbon nanotubes according to claim 4, characterized in that, The raw materials for preparing intermediate B include the following components: by weight, 4-5 parts of 1-(3-aminopropyl)imidazolium, 14-15 parts of intermediate A, and 60-80 parts of N,N-dimethylformamide; the raw materials for preparing the modifier include the following components: by weight, 14-15 parts of intermediate B, 60-80 parts of acetonitrile, and 4-5 parts of 1,3-propanesulfonic acid lactone.
7. The conductive ink for fabrics based on carbon nanotubes according to claim 4, characterized in that, The raw materials for preparing the modified chitosan include the following components: by weight, 100-120 parts of a mixed solution of acetic acid and toluene, 4-5 parts of chitosan, 1-2 parts of modifier, and 0.5-0.8 parts of piperidine.
8. The conductive ink for fabrics based on carbon nanotubes according to claim 1, characterized in that, The defoamer is silicone defoamer SD998.
9. The conductive ink for fabrics based on carbon nanotubes according to claim 1, characterized in that, The film-forming aid is polyether-modified polyorganosiloxane 8030F.