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CN-122011323-A - Water-based polyurethane and preparation method and application thereof

CN122011323ACN 122011323 ACN122011323 ACN 122011323ACN-122011323-A

Abstract

The invention discloses waterborne polyurethane and a preparation method and application thereof, wherein the preparation raw materials comprise a first polyol resin, a second polyol resin, a polyisocyanate curing agent, a chain extender, a cross-linking agent, a neutralizer, a catalyst and a solvent, and the second polyol resin is a polyol resin containing benzene rings. The invention uses hydroxyl-terminated polybutadiene styrene as the second polyol resin, which can remarkably improve the adhesive force. And the balance of the elasticity of the main chain and the anchoring ability of the lateral phenyl is ensured, and good dispersibility and film forming property are maintained while the adhesion is improved. The three-step polymerization process is adopted to synthesize the waterborne polyurethane, so that benzene rings are distributed at two sides of a polymer chain instead of the middle part of the main chain, an effective connection structure of graphite/conductive agent-benzene ring-main chain-benzene ring-graphite/conductive agent is formed, and the problems that the affinity between the main chain and dispersed particles is too high and the main chain and the dispersed particles cannot be effectively stretched due to the fact that the benzene rings are too close to the main chain are avoided.

Inventors

  • XIONG GUIYU
  • Han Chimin
  • FANG ZHENYING

Assignees

  • 有行鲨鱼（上海）科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260303

Claims (10)

  1. 1. The waterborne polyurethane is characterized in that the preparation raw materials comprise a first polyol resin, a second polyol resin, a polyisocyanate curing agent, a chain extender, a cross-linking agent, a neutralizing agent, a catalyst and a solvent, wherein the second polyol resin is a polyol resin containing benzene rings.
  2. 2. The aqueous polyurethane according to claim 1, wherein the preparation raw materials comprise, by weight, 30-50 parts of a first polyol resin, 1-20 parts of a second polyol resin, 5-20 parts of a polyisocyanate curing agent, 1-5 parts of a chain extender, 10-20 parts of a crosslinking agent, 10-20 parts of a neutralizing agent, 0.01-0.1 part of a catalyst and 70-90 parts of a solvent.
  3. 3. The waterborne polyurethane of claim 1, wherein the second polyol resin is a hydroxyl-terminated polybutadiene styrene.
  4. 4. The aqueous polyurethane according to claim 3, wherein the hydroxyl-terminated polybutadiene styrene has a number average molecular weight of >2000, a hydroxyl number of 0.7-0.8mmol/g and a benzene number of 15-20wt%.
  5. 5. The aqueous polyurethane of claim 1, wherein the curing agent comprises at least one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, or dicyclohexylmethane diisocyanate.
  6. 6. The aqueous polyurethane according to claim 1, wherein the preparation raw material further comprises deionized water, the neutralizing agent is an aqueous solution containing an alkaline substance, the mass ratio of the alkaline substance to water in the aqueous solution containing the alkaline substance is 1 (10-30), the crosslinking agent is an aqueous solution containing polyamine, and the mass ratio of the polyamine to water in the aqueous solution containing the polyamine is 1 (10-30).
  7. 7. A process for preparing the aqueous polyurethane according to claim 6, comprising the steps of: Placing first polyol resin, polyisocyanate curing agent and catalyst in inert gas for reaction to obtain a first prepolymer; adding a chain extender and a solvent into the first prepolymer after cooling to continue the reaction to obtain a second prepolymer; adding a second polyol resin into the second prepolymer to continue the reaction to obtain a polymer solution; And cooling the polymer solution, adding a neutralizing agent, stirring and dispersing, adding deionized water, diluting and stirring, adding a cross-linking agent, stirring and dispersing, and distilling the solvent under reduced pressure to obtain the waterborne polyurethane.
  8. 8. The method for producing an aqueous polyurethane according to claim 7, wherein the reaction temperature of the first prepolymer is 80 to 90 ℃, the reaction temperature of the second prepolymer is 65 to 75 ℃, and the reaction temperature of the polymer solution is 68 to 75 ℃.
  9. 9. The method for preparing aqueous polyurethane according to claim 7, wherein deionized water is added to dilute the aqueous polyurethane until the solid content of the polymer is 25-35wt%.
  10. 10. Use of the aqueous polyurethane according to any one of claims 1 to 6 in a negative electrode of a lithium ion secondary battery.

Description

Water-based polyurethane and preparation method and application thereof Technical Field The invention relates to the field of compositions of high molecular compounds, in particular to waterborne polyurethane, a preparation method and application thereof. Background The lithium ion secondary battery can undergo volume expansion during charge and discharge, and the conventional binder is difficult to adapt to the volume change, so that the electrode structure is damaged, and the capacity is attenuated. The existing aqueous polyurethane binder has the problems that the adhesive force with the anode material is insufficient, the main chain rigidity of the aqueous polyurethane is too high to adapt to the high expansion rate in the charge and discharge process, the dispersion coating property of the aqueous polyurethane is poor, and the technical requirement of stable charge and discharge structure of a battery is difficult to meet. Therefore, development of the aqueous polyurethane with strong adhesive force and capability of solving the problem of volume expansion in the process of charging and discharging the battery is important. The Chinese patent application CN120209766A discloses a polyurethane adhesive for a high-cohesive-force lithium ion battery and a preparation method thereof, cyano groups can be introduced by using acrylonitrile modified polyolefin polyol or dihydric alcohol or diamine containing cyano groups, so that the adhesive force of the polyurethane adhesive can be improved, the adhesion of active substances and a current collector is facilitated, but the influence of cohesive force is ignored, and the adhesive force is not remarkably improved. The Chinese patent CN119219889B discloses a water-based polyurethane dispersoid, a preparation method and application thereof, which adopts polybutadiene polyol with a specific structure and molecular weight as a soft segment, and the water-based polyurethane dispersoid has lower polarity and surface energy and excellent solvent resistance, low temperature resistance, hydrolysis resistance and mechanical property through the design and mutual compounding of components. But the effect of solving the problem of volume expansion in the process of charging and discharging the battery is not obvious. Disclosure of Invention In order to develop the aqueous polyurethane with strong adhesive force and capable of solving the problem of volume expansion in the process of charging and discharging the battery, the first aspect of the invention provides the aqueous polyurethane, and the preparation raw materials comprise a first polyol resin, a second polyol resin, a polyisocyanate curing agent, a chain extender, a cross-linking agent, a neutralizing agent, a catalyst and a solvent, wherein the second polyol resin is a polyol resin containing benzene rings. The existing aqueous polyurethane is applied to the bonding of a battery cathode and has the problem of insufficient bonding force, polyol resin containing benzene rings is introduced, the benzene rings are polymerized at two sides of a main chain of the aqueous polyurethane by utilizing the affinity of the benzene rings and a graphite cathode, and side benzene rings are inserted into the graphite cathode to form a graphite/conductive agent-side benzene ring-polyurethane main chain-side benzene ring-another graphite/conductive agent system, so that the connection between particles is enhanced, and the bonding force between the aqueous polyurethane and the graphite cathode is increased. As one embodiment, the preparation raw materials comprise, by weight, 30-50 parts of a first polyol resin, 1-20 parts of a second polyol resin, 5-20 parts of a polyisocyanate curing agent, 1-5 parts of a chain extender, 10-20 parts of a crosslinking agent, 10-20 parts of a neutralizing agent, 0.01-0.1 part of a catalyst and 70-90 parts of a solvent. As one embodiment, the preparation raw materials comprise, by weight, 35-45 parts of a first polyol resin, 5-15 parts of a second polyol resin, 10-15 parts of a polyisocyanate curing agent, 1-3 parts of a chain extender, 10-15 parts of a crosslinking agent, 10-15 parts of a neutralizing agent, 0.03-0.08 part of a catalyst and 70-90 parts of a solvent. When the amount of the second polyol resin added is 5 to 13 parts by weight, the benzene ring gradually approaches the main chain of polyurethane, the affinity of the main chain to the dispersed particles increases sharply, so that effective stretching is not possible, and effective connection of graphite-benzene ring-main chain-benzene ring-another graphite/conductive agent cannot be formed, and the adhesion force decreases as the amount of the second polyol resin used increases. As one embodiment, the second polyol resin is a hydroxyl-terminated polybutadiene styrene. As one embodiment, the hydroxyl-terminated polybutadiene styrene has a number average molecular weight of >2000, a hydroxyl number of 0.7 to 0.8mmol/g and a benzene conten