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CN-121975083-A - Aqueous polyurethane dispersion and preparation method and application thereof

CN121975083ACN 121975083 ACN121975083 ACN 121975083ACN-121975083-A

Abstract

The invention belongs to the technical field of polymer materials, and discloses a water-based polyurethane dispersion, a preparation method and application thereof. The raw materials of the aqueous polyurethane dispersoid comprise A, polyisocyanate, B, polybutadiene polyol, C, hydrophilic chain extender, D, end capping agent containing furan ring, E, micromolecular chain extender and F, neutralizer. The waterborne polyurethane dispersoid provided by the invention adopts polybutadiene polyol with a specific structure as a soft segment and furfuryl amine containing furan rings as a blocking agent, and the prepared waterborne polyurethane molecular chain segment contains side chain double bonds and conjugated double bonds, so that Diels-Alder reaction can be generated during high-temperature film formation to generate post-crosslinking, thereby providing excellent strength, and meanwhile, the reversibility of DA reaction brings about self-repairing performance for polyurethane, so that the waterborne polyurethane dispersoid has good application prospect in the field of battery negative electrode binders.

Inventors

  • SUN YONGJIAN
  • JI XUESHUN
  • HUA WEIQI

Assignees

  • 万华化学集团股份有限公司

Dates

Publication Date
20260505
Application Date
20260305

Claims (10)

  1. 1. The aqueous polyurethane dispersion is characterized in that raw materials of the aqueous polyurethane dispersion comprise polyisocyanate, polybutadiene polyol, a hydrophilic chain extender, a furan ring-containing end-capping agent, a small molecule chain extender and a neutralizing agent, wherein the furan ring-containing end-capping agent is furfuryl amine.
  2. 2. The aqueous polyurethane dispersion according to claim 1, wherein the polyurethane dispersion, The polybutadiene polyol comprises a structural unit shown in a formula III, and a structural unit shown in a formula I and/or a structural unit shown in a formula II; the molar percentage of the structural unit shown in the formula I of the polybutadiene polyol is denoted as a, the molar percentage of the structural unit shown in the formula II is denoted as b, the molar percentage of the structural unit shown in the formula III is denoted as c, a+b+c=1, a and b are not 0 at the same time, and 50% < c <90%; Preferably, the polybutadiene polyol has a number average molecular weight of 1000-3500g/mol.
  3. 3. The aqueous polyurethane dispersion according to claim 2, wherein the polyisocyanate content is 15 to 35wt%, preferably 16 to 30wt%, the polybutadiene polyol content is 55 to 80wt%, preferably 60 to 76wt%, the hydrophilic chain extender content is 3 to 5wt%, preferably 4 to 4.5wt%, the furan ring-containing capping agent content is 0.5 to 2wt%, preferably 0.8 to 1.5wt%, the small molecule chain extender content is 0.5 to 3wt%, preferably 0.8 to 2.5wt%, and the neutralizing agent content is 0.5 to 2wt%, based on 100% of the total mass of the polyisocyanate, the polybutadiene polyol, the hydrophilic chain extender, the furan ring-containing capping agent, the small molecule chain extender and the neutralizing agent.
  4. 4. The aqueous polyurethane dispersion according to claim 3, wherein said polyisocyanate is one or more of aromatic, cycloaliphatic and aliphatic chain isocyanates, preferably one or more of xylylene diisocyanate, diphenylmethane diisocyanate, 1, 4-phenylene diisocyanate, 1, 3-phenylene diisocyanate, toluene diisocyanate, 1, 5-naphthalene diisocyanate, 4 '-dibenzyl diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, 4' -dicyclohexylmethane diisocyanate, 1, 4-cyclohexane diisocyanate, dodecamethylene diisocyanate, 2-methylpentane-1, 5-diisocyanate, lysine diisocyanate, 3-methylpentane-1, 5-diisocyanate and polymers or modifications thereof.
  5. 5. The aqueous polyurethane dispersion according to claim 3, wherein the hydrophilic chain extender comprises one or more of a compound containing both hydroxyl and carboxyl groups, a compound containing both amino and sulfonic groups, and a compound containing both hydroxyl and ethoxy groups, preferably comprises one or more of 2, 2-dimethylolpropionic acid, 2-dimethylolbutyric acid, 2-dimethylolvaleric acid, 2, 6-dihydroxybenzoic acid, dihydroxymaleic acid, lysine, histidine, phenylalanine, aminobutyric acid, aminocaproic acid, alanine, glycine, aminopentanoic acid, valine, leucine, asparagine, tyrosine, 1, 3-phenylenediamine-4, 6-disulfonic acid, 1, 4-butanediol-2-sulfonic acid, 2- (2-aminoethyl) aminoethanesulfonic acid, 1, 2-dihydroxy-3-propanesulfonic acid, 2, 4-diaminotoluene-5-sulfonic acid, 2- (2-aminoethyl) aminopropanesulfonic acid, polyoxyethylene glycol, polyoxyethylene-polyoxybutylene copolymer glycol, polyoxyethylene-polyoxypropylene copolymer glycol, polyoxyethylene-polyoxyalkylene copolymer glycol, and monoalkyl ether thereof.
  6. 6. The aqueous polyurethane dispersion according to claim 3, wherein the raw materials of the aqueous polyurethane dispersion further satisfy at least one of the following conditions: (1) The small molecular chain extender comprises one or more of aliphatic polyamine chain extender, alicyclic polyamine chain extender and aromatic polyamine chain extender, preferably small molecular diamine chain extender, and further preferably comprises one or more of ethylenediamine, isophorone diamine and 4,4' -diamino dicyclohexylmethane; (2) The neutralizing agent is an inorganic alkaline compound comprising one or more of alkali metal hydroxide, alkali metal carbonate and alkali metal bicarbonate, and more preferably comprises one or more of LiOH, naOH, na CO3 and NaHCO 3.
  7. 7. The aqueous polyurethane dispersion according to any one of claims 1 to 6, characterized in that the aqueous polyurethane dispersion further comprises at least one of the following conditions: (1) The raw materials of the aqueous polyurethane dispersion also comprise a catalyst, wherein the catalyst comprises one or more of stannous octoate, dibutyl tin dilaurate, dibutyl tin diacetate and dimethyl bis [ (neodecanoyl) oxy ] dimethyl tin, and preferably, the mass content of the catalyst is 500-1000ppm based on 100 percent of the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, furan ring-containing end-capping agent, small molecule chain extender and neutralizing agent; (2) The raw materials of the aqueous polyurethane dispersion also comprise an organic solvent, wherein the organic solvent comprises one or more of acetone, methyl ethyl ketone, dimethylacetamide, dimethylformamide, diethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-butyl-2-pyrrolidone, tetrahydrofuran, chlorobenzene, dichlorobenzene, toluene, xylene and trimethylbenzene, and preferably, the mass content of the organic solvent is 100-250 percent based on 100 percent of the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, furan ring-containing end-capping agent, small molecule chain extender and neutralizing agent.
  8. 8. A process for the preparation of an aqueous polyurethane dispersion according to any one of claims 1 to 7, comprising the steps of: step 1), mixing polyisocyanate, polybutadiene polyol, a hydrophilic chain extender and a catalyst to perform polymerization reaction until residual NCO reaches a theoretical value to generate a prepolymer; Step 2), cooling the prepolymer, adding a furan ring-containing end-capping agent for end-capping reaction, adding a neutralizing agent for neutralization, adding water for emulsification and dispersion to obtain emulsion, adding a small molecular chain extender, and continuing the chain extension reaction to obtain the aqueous polyurethane dispersoid.
  9. 9. The method of claim 8, further satisfying at least one of the following conditions: A. the polymerization temperature in the step 1) is 60-90 ℃; B. the mass percentage of residual NCO of the prepolymer in the step 1) is 0.5-2.5%; C. Step 2), the end capping reaction temperature is 30-50 ℃ and the time is 5-20min; D. step 2), the neutralization reaction temperature is 30-50 ℃ and the time is 5-20min; E. Step 2) dispersing at 30-40 ℃ for 3-15min; F. The chain extension reaction temperature is 20-40 ℃ and the time is 5-20min.
  10. 10. Use of an aqueous polyurethane dispersion according to any one of claims 1 to 7 or a aqueous polyurethane dispersion prepared by a method according to any one of claims 8 to 9 in the field of lithium ion battery negative electrode binders.

Description

Aqueous polyurethane dispersion and preparation method and application thereof Technical Field The invention belongs to the technical field of polymer materials, belongs to the field of waterborne polyurethane, and particularly relates to a waterborne polyurethane dispersoid and a preparation method and application thereof. Background Lithium ion batteries have been widely used in the fields of new energy automobiles, portable electronic devices, and the like because of their high energy density, long cycle life, and the like. One of the core paths of the iteration of the lithium ion battery to the high energy density direction is the large-scale application of high-capacity anode materials such as silicon-based, silicon-carbon composite and the like. In the charge-discharge cycle process, the lithium ion intercalation and deintercalation of the negative electrode material can generate violent volume expansion and shrinkage of 300%, and the volume effect can apply continuous dynamic stress impact to the negative electrode adhesive, so that the negative electrode material becomes a core bottleneck for inducing adhesive failure and restricting battery cycle performance improvement. The traditional adhesive lacks self-repairing capability for adapting to working conditions of a battery, and under the effect of repeated expansion and contraction of the volume of a negative electrode, a large number of microcracks are easily grown on the adhesive matrix, and the microcracks can continuously expand along with the increase of the circulation times. As most of the existing adhesive molecular chains are of static cross-linked structures, the active repair of microcracks cannot be realized, and finally the adhesive gradually fails in the bonding action of the adhesive on active substances, conductive agents and current collectors. The aqueous polyurethane dispersion (PUD) becomes one of research hot spots of lithium ion battery anode binders by virtue of the characteristics of excellent flexibility, bonding strength, environmental protection and the like. However, the conventional PUD binder has several disadvantages, namely, low crosslinking density, reduced adhesive strength at high temperature, difficulty in tolerating local temperature rise possibly generated in the battery operation process, and failure in self-repairing performance, and failure in effective repair of microcracks generated by volume expansion/shrinkage of the anode material, thereby resulting in degradation of battery cycle performance. Therefore, the PUD adhesive which has high bonding strength and can realize interface self-repairing under the working condition of the battery (such as moderate heating) is developed, and has great significance for improving the reliability and the service life of the next generation of high-energy-density lithium ion batteries. Chinese patent CN113711383a discloses a binder composition for electrodes, in which an aqueous polyurethane dispersion obtained by reacting a polyisocyanate, a polyol, a compound having a hydrophilic group and 1 or more active hydrogens, and a chain extender is used as a binder, wherein the polyol is an olefin-based polyol having 1.5 or more active hydrogens and/or a carbonate diol having a carbon number between carbonate chains of less than 6. The aqueous polyurethane dispersion has the characteristics of electrolyte stability, cohesiveness and inhibition of expansion rebound of the pole piece active substance coating, but the binder is poor in performance, and the mechanical property of the aqueous polyurethane dispersion is still to be improved. Chinese patent CN115917793a discloses an aqueous polyurethane resin dispersion for a battery binder, which maintains a state in which the binder swells in an electrolyte by controlling a crosslinking density in the aqueous polyurethane resin dispersion while balancing cohesiveness, lithium ion conductivity, discharge retention rate, and resistance. However, the patent fails to provide the self-repairing function to the binder, and when the volume change of the anode material causes microcracks in the binder layer, the repairing cannot be realized, thereby affecting the long-term cycle performance of the battery. Disclosure of Invention Aiming at the technical bottleneck that the existing polyurethane adhesive is difficult to cope with microcrack caused by electrode volume expansion in battery charge-discharge circulation, the Diels-Alder (DA) reaction building block is innovatively and accurately introduced into a polyurethane molecular chain network, a dynamic polyurethane adhesive system with high adhesive strength and in-situ self-repairing function is constructed, the deep adaptation of the adhesive performance and the battery working condition is realized, and a breakthrough technical path is provided for improving the battery circulation stability. Specifically, the invention adopts the following technical scheme: In a first aspect, the