Melamine-based multi-arm polymer as well as preparation method and application thereof

Abstract

The invention discloses a melamine-based multi-arm polymer as well as a preparation method and application thereof. The melamine-based multi-arm polymer is obtained by reacting the following components: (a) polyether amine; (b) benzenetricarboxaldehyde; and (c) melamine. The preparation method of the melamine-based multi-arm polymer comprises the following steps: adding polyether amine and 1, 3-benzenetricarboxaldehyde into a flask, then adding an organic solvent, uniformly stirring, then adding melamine, carrying out ultrasonic dispersion, carrying out a reaction, and cooling to room temperature to obtain the melamine-based multi-arm polymer. The melamine-based multi-arm polymer has a good dispersion effect on carbon black, carbon nanotubes and graphene, and can be used for dispersing a carbon material in a new energy battery.

Description

Technical Field

[0001] The invention belongs to the technical field of dispersants, and in particular relates to a melamine-based multi-arm polymer and a preparation method and application thereof. Background Art

[0002] With the development of industry, people's lives have changed dramatically. At the same time, the huge demand for energy and the resulting environmental pollution also trouble people around the world. Therefore, it is very important to find a pollution-free, high-efficiency, sustainable and clean new energy. Lithium batteries as a new type of energy storage device have attracted the attention of many researchers.

[0003] In the process of battery preparation, it is often necessary to add an appropriate amount of conductive agent to improve the conductivity of the positive electrode material. Commonly used conductive agents include conductive graphite, conductive carbon black, carbon nanotubes, etc. The conductive agent has the following main functions: 1) The normal charging and discharging process of lithium batteries requires the participation of lithium ions and electrons. This requires that the electrodes of lithium-ion batteries must be mixed conductors of ions and electrons, and the electrode reaction can only occur at the junction of the electrolyte, conductive agent, and active material; 2) The electrode active materials are mostly transition metal oxides or transition metal phosphates, which are semiconductors or insulators with poor conductivity. Conductive agents must be added to improve the conductivity; 3) The conductivity of negative electrode graphite materials is slightly better, but during multiple charges and discharges, the expansion and contraction of graphite materials reduces the contact between graphite particles, increases the gap, and even some of them are separated from the collector and become dead active materials. They no longer participate in electrode reactions, so conductive agents are also needed to maintain the stability of the conductivity of negative electrode materials during the cycle.

[0004] Since the particles of carbon black conductive agent are tens of nanometers, the particles of conductive graphite are several microns, and the particles of carbon nanotubes and graphene are only a few nanometers, it is difficult to disperse them evenly inside the electrode, making it difficult to meet the growing performance requirements of power batteries.

[0005] At present, there are many studies on the dispersion of conductive agents, mainly using physical dispersion and chemical dispersion. Physical dispersion is mainly divided into mechanical stirring and ultrasonic dispersion. After dispersion, it is easy to re-agglomerate, so its application is limited; chemical dispersion mainly includes sodium polyacrylate (PAANa), maleic acid monopolyethylene glycol monomethyl ether ester and PVP dispersant, all of which have been proven to improve the electrochemical performance of lithium-ion batteries.

[0006] A large number of domestic and foreign literature and patent reports can be used to disperse CNTs by non-covalent treatment, that is, using a dispersant with a special structure to interact with CNTs to achieve directional arrangement and stable distribution, and enhance the dispersibility of CNTs in the dispersion medium. Chinese patent application CN101773801A proposes to disperse carbon nanotubes with biomolecules, which can achieve the dispersion of CNTs without destroying the structure of carbon nanotubes. However, the production process of such bio-based dispersants is complicated, difficult to obtain, and expensive. Chinese patent application CN106587013A designs a switch-type dispersant that can disperse CNTs in an aqueous solution, but the dispersant needs to be introduced with nitrogen, air or heated and decomposed during use. The method of use is complicated, and it can only be dispersed in an aqueous solution, and the application conditions are relatively limited. Chinese patent application CN113248739A discloses a carbon-olefin material dispersion and its application, and the carbon-olefin material dispersion includes: carbon-olefin material, dispersant, and solvent. The olefin-carbon material dispersion can be used for olefin-carbon composite aramid fiber, which is low-cost, green and environmentally friendly, simple in process, and has excellent dispersion effect. It is greatly beneficial to the preparation of olefin-carbon composite aramid fiber, improve the comprehensive performance of aramid fiber, and accelerate the upgrading and innovation of the aramid industry. However, the dispersant has limited dispersion effect on graphene, carbon nanotubes, etc., and there is room for further improvement; and the dispersant is mainly used in the preparation of aramid fiber composite materials, and whether it can be applied to lithium-ion batteries remains to be discussed. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a melamine-based multi-arm polymer and a preparation method and use thereof. The melamine-based multi-arm polymer has a good dispersing effect on carbon black, carbon nanotubes and graphene, and can be used for dispersing carbon materials in new energy batteries.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A melamine-based multi-arm polymer obtained by reacting the following components:

[0010] (a) polyetheramines;

[0011] (b) trimesaldehyde;

[0012] (c) melamine;

[0013] The M of the melamine-based multi-arm polymer n 3000-100000.

[0014] Preferably, the (a) is a single-terminal primary amino polyether, and its structural formula is R-(CH2CH2O) y (CH2CHCH3O) x-NH2; wherein x is an integer from 0 to 100; y is an integer from 0 to 100; x+y≥20, and R is a straight-chain alkyl group having 1 to 18 carbon atoms.

[0015] Preferably, the (a) is a single-terminal primary amino polyether, and its structural formula is R-(CH2CH2O) y (CH2CHCH3O) x -NH2; wherein x is an integer from 20 to 80; y is an integer from 30 to 70; x+y≥20, and R is a straight-chain alkyl group having 1 to 18 carbon atoms.

[0016] Preferably, the molar ratio of (a), (b) and (c) is 6:3:2.

[0017] The present invention also protects a method for preparing the melamine-based multi-arm polymer as described above, comprising the following steps:

[0018] Add polyetheramine and trimesic acid into a flask, then add an organic solvent, stir evenly, then add melamine, disperse by ultrasonic, react, and cool to room temperature to obtain the melamine-based multi-arm polymer.

[0019] In the present invention, through high temperature Schiff base reaction, since the reaction rate of amino groups in polyetheramine is faster than that of amino groups in melamine, polyetheramine reacts with trimesaldehyde first to obtain a macromonomer, and then the macromonomer reacts with melamine to obtain a melamine-based multi-arm polymer.

[0020] Preferably, the organic solution is one or more of N-methylpyrrolidone, dimethyl sulfoxide, and N,N-dimethylacetamide.

[0021] Preferably, the reaction temperature is 180-220° C. and the reaction time is 10-20 h.

[0022] More preferably, the reaction temperature is 180-200°C and the reaction time is 15-20h.

[0023] In the present invention, the reaction temperature can be 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, and the reaction time can be 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h.

[0024] Preferably, the ultrasonic dispersion time is 10-20 min.

[0025] More preferably, the ultrasonic dispersion time is 15-20 min.

[0026] The present invention also protects the use of the melamine-based multi-arm polymer as described above in dispersing carbon black, carbon nanotubes and graphene.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The melamine-based multi-arm polymer provided by the present invention uses polyetheramine, trimesic acid, and melamine as raw materials, and utilizes the Schiff base reaction principle to generate a multi-arm polymer in a one-step process. The multi-arm polymer contains rich aromatic rings, triazine rings, and amide bond structures. Since the benzene rings, amide bonds, triazine rings, etc. have good affinity for carbon, the carbon material can be effectively dispersed evenly. At the same time, the introduced polyether chain segments can provide dispersibility and lithium ion complexing ability, making the melamine-based multi-arm polymer very suitable for the dispersion of carbon materials in new energy batteries.

[0029] (2) The melamine-based multi-arm polymer provided by the present invention has a simple preparation method, and the raw materials used are easily available, which is suitable for industrial production and has good application prospects. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The polyetheramines are Huntsman M1000, Huntsman M2070 and Huntsman M3085, all of which were purchased from Hubei Maidehao Chemical Co., Ltd.

[0032] Example 1

[0033] A method for preparing a melamine-based multi-arm polymer comprises the following steps:

[0034] 100 g of polyetheramine M2070 (molecular weight 2070) and 3.91 g of trimesaldehyde were added to a flask, followed by 500 mL of N-methylpyrrolidone, stirred evenly, and then 2.03 g of melamine was added, ultrasonically dispersed for 15 min, reacted at 200 ° C for 15 h, and cooled to room temperature to obtain the melamine-based multi-arm polymer. The melamine-based multi-arm polymer M n is 10000.

[0035] Example 2

[0036] A method for preparing a melamine-based multi-arm polymer comprises the following steps:

[0037] 100 g of polyetheramine M1000 (molecular weight 1000) and 8.1 g of trimesaldehyde were added to a flask, followed by 500 mL of N-methylpyrrolidone, stirred evenly, and then 4.2 g of melamine was added, ultrasonically dispersed for 15 min, reacted at 200 ° C for 15 h, and cooled to room temperature to obtain the melamine-based multi-arm polymer. The melamine-based multi-arm polymer M n is 5000.

[0038] Example 3

[0039] A method for preparing a melamine-based multi-arm polymer comprises the following steps:

[0040] 90 g of polyetheramine M3085 (molecular weight 3085) and 2.36 g of trimesaldehyde were added to a flask, followed by 500 mL of N,N-dimethylacetamide, stirred evenly, and then 1.23 g of melamine was added, ultrasonically dispersed for 15 min, reacted at 200 ° C for 15 h, and cooled to room temperature to obtain the melamine-based multi-arm polymer. The melamine-based multi-arm polymer M n is 20000.

[0041] Example 4

[0042] A method for preparing a melamine-based multi-arm polymer comprises the following steps:

[0043] 100 g of polyetheramine M2070 (molecular weight 2070) and 3.91 g of trimesaldehyde were added to a flask, followed by 500 mL of N-methylpyrrolidone, stirred evenly, and then 2.03 g of melamine was added, ultrasonically dispersed for 10 min, reacted at 180° C. for 20 h, and cooled to room temperature to obtain the melamine-based multi-arm polymer. n is 7000.

[0044] Example 5

[0045] A method for preparing a melamine-based multi-arm polymer comprises the following steps:

[0046] 100 g of polyetheramine M2070 (molecular weight 2070) and 3.91 g of trimesaldehyde were added to a flask, followed by 500 mL of dimethyl sulfoxide, stirred evenly, and then 2.03 g of melamine was added, ultrasonically dispersed for 20 min, reacted at 220° C. for 10 h, and cooled to room temperature to obtain the melamine-based multi-arm polymer. n is 9000.

[0047] Comparative Example 1

[0048] A method for preparing a multi-arm polymer comprises the following steps:

[0049] 100 g of polyetheramine M2070 (molecular weight 2070) and 3.91 g of trimesaldehyde were added to a flask, followed by 500 mL of N-methylpyrrolidone. After stirring evenly, ultrasonic dispersion was performed for 15 min, the mixture was reacted at 200° C. for 15 h, and cooled to room temperature to obtain the multi-arm polymer.

[0050] Compared with Example 1, no melamine was added in this comparative example.

[0051] Comparative Example 2

[0052] A method for preparing a melamine-based multi-arm polymer comprises the following steps:

[0053] 3.91 g of trimesaldehyde was added to a flask, followed by 500 mL of N-methylpyrrolidone. After stirring evenly, 2.03 g of melamine was added, ultrasonically dispersed for 15 minutes, reacted at 200° C. for 15 hours, and cooled to room temperature to obtain the melamine-based multi-arm polymer.

[0054] Compared with Example 1, no polyetheramine was added in this comparative example.

[0055] The multi-arm polymers prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to a dispersion test on carbon nanotubes. The test conditions were: ambient humidity of 75% and ambient temperature of 25°C. The dispersion method was as follows: 50g carbon nanotubes, 5g multi-arm polymers, and 945g N-methylpyrrolidone were first dispersed uniformly at 2000rpm and then added to a 1000mL desktop nano grinder and ground at 25°C for 3 hours. The prepared slurry was tested for particle size and viscosity using a Malvern particle size analyzer and a viscometer, respectively. The evaluation results are shown in Table 1:

[0056] Table 1 Evaluation results of carbon nanotube dispersion slurry

[0057] Group Carbon nanotube particle size / nm Slurry viscosity / mPas Apparent state after 60 days of static storage Example 1 326 465 Evenly dispersed Example 2 389 537 Evenly dispersed Example 3 352 493 Evenly dispersed Example 4 341 482 Evenly dispersed Example 5 304 426 Evenly dispersed Comparative Example 1 627 881 Layered, with sediment at the bottom Comparative Example 2 913 2745 Layered, with a lot of sediment at the bottom

[0058] As can be seen from Table 1, the melamine-based multi-arm polymer prepared in the present invention can stably and uniformly disperse carbon nanotubes into a high-concentration dispersion, and the particle size of the carbon nanotubes and the viscosity of the slurry are lower than those in the comparative example, indicating that the melamine-based multi-arm polymer in the embodiment of the present invention has a good dispersion effect on carbon nanotubes and excellent performance.

[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A melamine-based multi-arm polymer, characterized in that: Obtained by the reaction of the following components: (a) polyetheramines; (b) trimesaldehyde; (c) Melamine.

2. The melamine-based multi-arm polymer according to claim 1, characterized in that: The M of the melamine-based multi-arm polymer n 3000-100000.

3. The melamine-based multi-arm polymer according to claim 1, characterized in that: The (a) is a single-terminal primary amino polyether, and its structural formula is R-(CH2CH2O) y (CH2CHCH3O) x -NH2; wherein x is an integer from 0 to 100; y is an integer from 0 to 100; x+y≥20, and R is a straight-chain alkyl group having 1 to 18 carbon atoms.

4. The melamine-based multi-arm polymer according to claim 3, characterized in that: The (a) is a single-terminal primary amino polyether, and its structural formula is R-(CH2CH2O) y (CH2CHCH3O) x -NH2; wherein x is an integer from 20 to 80; y is an integer from 0 to 70; x+y≥20, and R is a straight-chain alkyl group having 1 to 18 carbon atoms.

5. The melamine-based multi-arm polymer according to claim 1, characterized in that: The molar ratio of (a), (b) and (c) is 6:3:

2.

6. A method for preparing a melamine-based multi-arm polymer as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: Add polyetheramine and trimesic acid into a flask, then add an organic solvent, stir evenly, then add melamine, disperse by ultrasonic, react, and cool to room temperature to obtain the melamine-based multi-arm polymer.

7. The preparation method according to claim 6, characterized in that: The organic solution is one or more of N-methylpyrrolidone, dimethyl sulfoxide, and N,N-dimethylacetamide.

8. The preparation method according to claim 6, characterized in that: The reaction temperature is 180-220° C. and the reaction time is 10-20 h.

9. The preparation method according to claim 6, characterized in that: The ultrasonic dispersion time is 10-20 min.

10. Use of the melamine-based multi-arm polymer according to any one of claims 1 to 5 in dispersing carbon black, carbon nanotubes and graphene.