Nanometer carbon black synergistically modified by pei and 1-carboxymethyl-3-methyl imidazolium, its preparation method and application

Abstract

This invention discloses a synergistic dual-modified nano-carbon black of PEI and 1-carboxymethyl-3-methylimidazolium, its preparation method, and its application. The preparation method of the modified nano-carbon black includes the following steps: reacting oxidized nano-carbon black, PEI, and 1-carboxymethyl-3-methylimidazolium compounds in a solvent at a mass ratio of 10:(5~20):(2~10) at 60~120℃ for 5~8 h to obtain nano-carbon black synergistically modified by PEI and 1-carboxymethyl-3-methylimidazolium compounds. This invention, through the dual modification of PEI and ionic liquids, constructs a multilayer structure rich in amino and ionic liquid groups on the surface of nano-carbon black, greatly enhancing its interaction with the polar groups of polymers and solving the problem of easy agglomeration of nano-carbon black in polymers.

Description

Technical Field

[0001] This invention relates to nano-carbon black, specifically to a method for synergistic dual chemical surface modification of nano-carbon black by polyethyleneimine (PEI) and 1-carboxymethyl-3-methylimidazolium, and its preparation and application. Background Technology

[0002] Carbon black is an important nanoscale carbon material, widely used in rubber composites, conductive coatings, lithium-ion battery electrodes, polymer reinforcements, and catalyst supports due to its excellent electrical conductivity, high specific surface area, stable chemical properties, and reinforcing effect. However, untreated raw carbon black has a chemically inert surface and is prone to irreversible agglomeration due to its strong van der Waals forces, resulting in extremely poor dispersibility in polar solvents (such as water) or polymer matrices. This poor compatibility and dispersion uniformity severely restrict the full utilization of carbon black's properties and ultimately affect the overall performance of composite materials.

[0003] To overcome the aforementioned shortcomings, surface modification of carbon black is a key approach to improving its application performance. Traditional modification methods mainly fall into two categories: physical adsorption and chemical modification.

[0004] 1. Physical adsorption method: This method typically uses surfactants or polymeric dispersants to physically adsorb onto the carbon black surface, thereby improving its temporary dispersibility. While simple to operate, this method results in weak adhesion between the modified layer and the carbon black surface, making it prone to desorption in complex chemical environments, at high temperatures, or during long-term use, leading to unstable performance and insufficient durability.

[0005] 2. Chemical Modification: This method primarily involves introducing oxygen-containing functional groups such as carboxyl, hydroxyl, and carbonyl groups onto the carbon black surface through strong oxidation (e.g., concentrated nitric acid, mixed acids, ozone treatment). This method can permanently alter the surface properties of carbon black, enhancing its hydrophilicity and interaction with certain polar matrices. However, strong oxidation processes often disrupt the graphite lattice structure of the carbon black matrix, leading to a significant decrease in its inherent excellent electrical conductivity. Furthermore, the introduced functional groups are relatively limited, resulting in limited improvement in universal compatibility with complex multiphase systems. Summary of the Invention

[0006] To address the problems existing in the above-mentioned carbon black modification methods, this invention provides a nano-carbon black synergistically modified with PEI and 1-carboxymethyl-3-methylimidazolium, its preparation method and application. This dual-modified nano-carbon black significantly improves its dispersibility and interfacial interaction in the polymer matrix through a dual modification strategy, thereby endowing TPU composite materials with excellent comprehensive properties.

[0007] To achieve the above objectives, the present invention provides a method for preparing nano-carbon black synergistically modified with PEI and 1-carboxymethyl-3-methylimidazolium, comprising the following steps: reacting oxidized nano-carbon black, PEI and 1-carboxymethyl-3-methylimidazolium in a solvent at a mass ratio of 10:(5~20):(2~10) at 60~120℃ for 5~8 h to obtain nano-carbon black synergistically modified with PEI and 1-carboxymethyl-3-methylimidazolium.

[0008] Oxidation of nano-carbon black can introduce oxygen-containing functional groups (such as carboxyl-COOH, hydroxyl-OH, carbonyl C=O, etc.) onto its surface, significantly improving its hydrophilicity and surface chemical activity. This transforms it from a hydrophobic material into a platform that is easily dispersed in water or polar solvents and can undergo chemical reactions. This is mainly achieved through the strong steric hindrance generated by the thick polymer brush constructed with PEI, while the interfacial affinity with the polymer is improved by the ionic liquid and the numerous polar groups (amide bonds, amine groups, imidazolium) introduced by PEI.

[0009] PEI reacts with the oxygen-containing functional groups on the surface of carbon black nanoparticles, firmly anchoring itself to the carbon black surface and introducing a high density of primary, secondary, and tertiary amine groups onto the carbon black oxide surface. The carboxyl group on 1-carboxymethyl-3-methylimidazolium reacts with the amine group introduced by PEI, resulting in chemical bonding. This means that the ionic liquid is no longer merely physically attached to the carbon black surface, but is "suspended" on the PEI molecular chain through chemical bonds, forming an extremely stable three-layer structure of "carbon black-PEI-ionic liquid". This structure includes a core layer composed of carbon black nanoparticles, a bridging layer composed of PEI, and an interface layer composed of 1-carboxymethyl-3-methylimidazolium. This structure combines the stability of chemical modification, the steric hindrance of polymer modification, and the functional properties of ionic liquids.

[0010] Preferably, the PEI is a branched polyethyleneimine with a number average molecular weight of 10,000 to 70,000. This allows for the utilization of its branched structure, which provides high reactivity and steric hindrance, and allows for the selection of a molecular weight range that can form a stable, thick modified layer without causing processing difficulties or self-aggregation due to excessively large molecular weight.

[0011] Preferably, the 1-carboxymethyl-3-methylimidazolium compound is 1-carboxymethyl-3-methylimidazolium chloride or its ion exchange product with other anions.

[0012] The second aspect of the present invention provides modified nano-carbon black prepared by the above-described preparation method.

[0013] A third aspect of the present invention provides the application of the above-described modified nano-carbon black in the preparation of thermoplastic polyurethane composite materials.

[0014] Specifically, the preparation method of the thermoplastic polyurethane composite material is as follows: the modified nano carbon black and polyurethane particles or powder are melt-blended at 180~200°C for 6~8 minutes.

[0015] Preferably, the content of the modified nano-carbon black is 0.5~15 wt% of the thermoplastic polyurethane composite material.

[0016] Through the above technical solution, the present invention achieves the following beneficial effects: 1. This invention constructs a multilayer structure rich in amino and ionic liquid groups on the surface of nano-carbon black through dual modification with PEI and ionic liquid, which greatly enhances its interaction with the polar groups of polymers and solves the problem of easy agglomeration of nano-carbon black in polymers.

[0017] 2. The obtained modified nano carbon black is uniformly dispersed in the TPU matrix and has strong interfacial bonding. It can significantly improve the conductivity, electromagnetic shielding effectiveness, mechanical strength and wear resistance of the composite material even with low addition amount.

[0018] 3. The preparation process is simple and environmentally friendly, the conditions are mild, and it is easy to carry out industrial production.

[0019] 4. The resulting TPU composite material has adjustable properties and a wide range of applications, especially suitable for high-end products with high requirements for strength, elasticity, durability and functional properties. Attached Figure Description

[0020] Figure 1 The modified nano-carbon black microstructure is obtained by the method of Example 1 and Comparative Example 2 of this invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to examples. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] Example 1: Preparation of dual-modified nano-carbon black (DCB-1) The double-modified nano-carbon black was obtained by reacting oxidized nano-carbon black (Aladdin), polyethyleneimine (PEI) (Macklin, number average molecular weight of 18000) and 1-carboxymethyl-3-methylimidazolium chloride (Adamas) in ethanol at 80°C for 6 h by mass ratio of 1:1:0.8.

[0023] Examples 2 to 7: The same steps as in Example 1 were used, except that the mass ratio of oxidized nano carbon black, polyethyleneimine, and 1-carboxymethyl-3-methylimidazolium chloride was changed.

[0024]

[0025] Examples 8 to 10: The same steps as in Example 1 were followed, except that the reaction temperature was changed (see table below).

[0026]

[0027] Examples 11 to 13: The same steps as in Example 1 were used, except that the PU prepolymer grafting reaction time was changed (see table below).

[0028]

[0029] Comparative Example 1 Unmodified carbon black nano-oxide.

[0030] Comparative Example 2 Other conditions are the same as in Example 1, except that oxidized nano-carbon black and PEI are reacted in a mass ratio of 1:1.8 to obtain PEI-modified carbon black.

[0031] Comparative Example 3 Other conditions were the same as in Example 1, except that oxidized nano-carbon black and 1-carboxymethyl-3-methylimidazolium chloride were reacted at a mass ratio of 1:1.8 to obtain 1-carboxymethyl-3-methylimidazolium chloride-modified carbon black.

[0032] Comparative Example 4 Other conditions were the same as in Example 1, but the reaction temperature was 40°C (too low).

[0033] Comparative Example 5 Other conditions were the same as in Example 1, but the reaction temperature was 160°C (too high).

[0034] Comparative Example 6 Other conditions were the same as in Example 1, but the reaction time was 2 hours (too short).

[0035] Comparative Example 7 Other conditions were the same as in Example 1, but the reaction time was 12 hours (too long).

[0036] The modified nano-carbon black obtained from the above examples and comparative examples was melt-blended with polyurethane particles at a mass ratio of 1:9 at 180°C for 8 minutes to obtain a thermoplastic polyurethane composite material.

[0037] The comprehensive performance of composite materials was tested in accordance with relevant national standards: Oxygen index: GB / T 2406.2 Heat shrinkage rate: GB / T 18380.3-2001 Smoke density: GB / T 8323.2 Power frequency dielectric strength: GB / T 5019.2 Tensile strength: JB / T 10259 The results are shown in the table below.

[0038]

[0039] As can be seen from the table above: 1) Comprehensive Compliance and Performance Advantages: The composite materials prepared using the modified nano-carbon black from Examples 1-13 all met and significantly exceeded the preset technical indicators in all five key performance indicators. In contrast, all Comparative Examples 1-6 failed to meet one or more indicators, fully demonstrating the effectiveness and necessity of the dual modification strategy of this invention.

[0040] 2) Optimal ratio: Example 1 (ratio 1:1:0.8) exhibits the best overall performance, especially in oxygen index (32.5%), heat shrinkage rate (3.8%) and tensile strength (28.5 MPa).

[0041] 3) The core role of dual modification: Comparative Example 2 (single PEI modification) Comparative Example 3 (single 1-carboxymethyl-3- (Methylimidazolium chloride modification) Although the performance was better than that of Comparative Example 1 (unmodified), it was far inferior to that of Example 1, demonstrating that 1-carboxymethyl-3-methylimidazolium as a second flexible interface layer is crucial for comprehensively improving performance.

[0042] 4) Influence of process parameters: The performance of the comparative examples (low temperature) and (short time) did not fully meet the standards, indicating that sufficient reaction conditions are the basis for achieving perfect modification. Examples 1, 12, and 13 showed the best results at 80°C for 5-7 hours.

[0043] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0044] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0045] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing nano-carbon black synergistically modified with PEI and 1-carboxymethyl-3-methylimidazolium, characterized in that, The process includes the following steps: reacting oxidized nano-carbon black, PEI, and 1-carboxymethyl-3-methylimidazolium compounds in a mass ratio of 10:(5~20):(2~10) in a solvent at 60~120℃ for 5~8 h to obtain nano-carbon black synergistically modified by PEI and 1-carboxymethyl-3-methylimidazolium compounds.

2. The preparation method according to claim 1, characterized in that, PEI is a branched polyethyleneimine with a number average molecular weight of 10,000 to 70,000.

3. The preparation method according to claim 1, characterized in that, The 1-carboxymethyl-3-methylimidazolium compounds are 1-carboxymethyl-3-methylimidazolium chlorides or their ion exchange products with other anions.

4. Modified nano-carbon black prepared by any one of claims 1 to 3.

5. The application of the modified nano-carbon black according to claim 4 in the preparation of thermoplastic polyurethane composite materials.

6. The application according to claim 5, characterized in that, The preparation method of thermoplastic polyurethane composite material is as follows: the modified nano carbon black and polyurethane particles or powder are melt-blended at 180~200°C for 6~8 minutes.

7. The application according to claim 6, characterized in that, The modified nano-carbon black content is 0.5~15 wt% of the thermoplastic polyurethane composite material.

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