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CN-121991627-A - High-performance bio-based aqueous polyurethane pressure-sensitive adhesive and preparation method and application thereof

CN121991627ACN 121991627 ACN121991627 ACN 121991627ACN-121991627-A

Abstract

The invention belongs to the technical field of aqueous polyurethane pressure-sensitive adhesives, and discloses a high-performance bio-based aqueous polyurethane pressure-sensitive adhesive, and a preparation method and application thereof. The method comprises the steps of 1) reacting diisocyanate and composite polyol for 1.5-2.5 hours at 75-85 ℃ under the action of a catalyst in a protective atmosphere to obtain a prepolymer, wherein the composite polyol is polytetrahydrofuran and castor oil, 2) reacting the prepolymer with a hydrophilic chain extender, adding an acetone solution of hexamethylenediamine for chain extension reaction, cooling, adding a neutralizer for neutralization reaction, adding water for emulsification, and coating on a substrate to obtain the bio-based aqueous polyurethane pressure-sensitive adhesive. The invention constructs a dynamic-static composite network structure, thereby realizing excellent balance of initial adhesion, holding adhesion and peeling strength. The pressure-sensitive adhesive has better performance. The pressure-sensitive adhesive of the present invention is used for labels, protective films or industrial tapes.

Inventors

  • WANG XIAOHUI
  • HUANG ZHIXING

Assignees

  • 华南理工大学

Dates

Publication Date
20260508
Application Date
20260126

Claims (9)

  1. 1. The preparation method of the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive is characterized by comprising the following steps of: 1) Reacting diisocyanate and composite polyol for 1.5-2.5 hours at 75-85 ℃ under the action of a catalyst in a protective atmosphere to obtain a prepolymer, wherein the composite polyol is polytetrahydrofuran and castor oil, the castor oil consumption in the composite polyol is 15-45% of the total molar amount of the composite polyol, and the molar ratio of the isocyanate to the composite polyol is (2.4-2.6): 1; 2) Mixing the prepolymer with a hydrophilic chain extender, reacting for 0.5-1.5 hours at 75-85 ℃, and then adding an acetone solution of hexamethylenediamine to perform chain extension reaction at 45-55 ℃ to obtain a reaction product, wherein the hydrophilic chain extender is dimethylolbutyric acid; 3) And cooling the reaction product to 20-40 ℃, adding a neutralizing agent for neutralization reaction, adding water for emulsification, and then coating the substrate to obtain the bio-based aqueous polyurethane pressure-sensitive adhesive.
  2. 2. The preparation method of the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive according to claim 1, wherein the amount of castor oil in the composite polyol is 30% -45% of the total molar amount of the composite polyol.
  3. 3. The preparation method of the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive according to claim 1, wherein the isocyanate is more than one of isophorone diisocyanate, hexamethylene diisocyanate and diphenylmethane diisocyanate.
  4. 4. The method for preparing the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive according to claim 1, wherein the neutralizer is triethylamine; The catalyst is dibutyl tin dilaurate.
  5. 5. The method for preparing the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive according to claim 1, which is characterized in that: The mol ratio of the hydrophilic chain extender to the diisocyanate is (0.8-0.9): 1.5-1.6; the mol ratio of the hexamethylenediamine to the composite polyol is (0.13-0.15) 0.6; the molar ratio of hexamethylenediamine to acetone in the hexamethylenediamine acetone solution is 1 (9-11).
  6. 6. The preparation method of the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive according to claim 1, wherein the molar ratio of the neutralizer to the diisocyanate is 0.02 (1.5-1.6); The dosage of the catalyst is 0.04% -0.08% of the molar quantity of diisocyanate.
  7. 7. The preparation method of the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive according to claim 1, wherein the emulsified shear rate is 1000-15000 rpm; In the step 3), water is added for emulsification, and the solid content in the emulsion is 25% -35%.
  8. 8. A high performance bio-based aqueous polyurethane pressure sensitive adhesive obtained by the preparation method of any one of claims 1 to 7.
  9. 9. The application of the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive according to claim 8, wherein the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive is used for preparing labels, protective films or industrial adhesive tapes.

Description

High-performance bio-based aqueous polyurethane pressure-sensitive adhesive and preparation method and application thereof Technical Field The invention belongs to the technical field of pressure-sensitive adhesives, and particularly relates to a high-performance bio-based aqueous polyurethane pressure-sensitive adhesive, and a preparation method and application thereof. Background The pressure sensitive adhesive is an adhesive which can be adhered instantly only by slight pressure and is widely applied to the fields of labels, protective films, medical adhesive tapes, industrial adhesive tapes and the like. Polyurethane pressure-sensitive adhesives are favored for their excellent flexibility, adhesion, and weatherability. However, conventional polyurethane pressure-sensitive adhesives rely heavily on petroleum-based materials and may release volatile organic compounds during production and application, causing environmental and human health hazards. In addition, the "three properties" of the pressure sensitive adhesive, i.e., initial tack, peel strength, and hold-up, are difficult to balance and are a central challenge in the performance control thereof. The aqueous polyurethane takes water as a dispersion medium, has the advantages of no toxicity, no pollution, safety, reliability and the like, and is the development direction of green chemical industry. Meanwhile, development of bio-based polymer materials based on renewable resources to replace increasingly depleted petroleum resources is also an important research direction. According to the invention, a composite structure of castor oil and polytetrahydrofuran soft segment is introduced into the pressure-sensitive adhesive, and the technical problems of balanced three properties, improved bio-based content, water-based green preparation and the like of the pressure-sensitive adhesive are solved by utilizing the synergistic effect of a chemical crosslinking network and dynamic hydrogen bonds. Disclosure of Invention In order to overcome the defects of the prior art, the invention aims to provide a high-performance bio-based aqueous polyurethane pressure-sensitive adhesive and a preparation method and application thereof. According to the invention, castor oil is introduced into the pressure-sensitive adhesive as a covalent crosslinking unit, and is cooperated with a urea bond multiple hydrogen bond physical crosslinking network to construct a unique dynamic-static composite network structure, so that excellent balance of initial adhesion, holding adhesion and peeling strength is realized, and meanwhile, the pressure-sensitive adhesive has high bio-base content and environment-friendly characteristics. The pressure-sensitive adhesive is used for preparing labels, protective films and adhesive tapes. In order to achieve the above purpose, the invention adopts the following technical scheme: The preparation method of the high-performance bio-based aqueous polyurethane pressure-sensitive adhesive comprises the following steps: 1) Reacting diisocyanate and composite polyol for 1.5-2.5 hours at 75-85 ℃ under the action of a catalyst in a protective atmosphere to obtain a prepolymer, wherein the composite polyol is polytetrahydrofuran and castor oil, and the castor oil consumption in the composite polyol is 15% -45% of the total molar amount of the composite polyol; 2) Mixing the prepolymer and a hydrophilic chain extender, reacting for 0.5-1.5 hours at 75-85 ℃, and then adding an acetone solution of hexamethylenediamine for chain extension reaction at 45-55 ℃ to obtain a reaction product; 3) And cooling the reaction product to 20-40 ℃, adding a neutralizing agent for neutralization reaction, adding water for emulsification, and then coating on a substrate to obtain the bio-based aqueous polyurethane pressure-sensitive adhesive. The catalyst is dibutyl tin dilaurate. The diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate and diphenylmethane diisocyanate. The hydrophilic chain extender is dimethylolbutyric acid. The neutralizing agent is triethylamine. The molar ratio of the isocyanate to the composite polyol is (2.4-2.6): 1. The mol ratio of the hydrophilic chain extender to the diisocyanate is (0.8-0.9): 1.5-1.6. The chain extension reaction time is 25-35 min. The molar ratio of the hexamethylenediamine to the composite polyol is (0.13-0.15) to 0.6. The molar ratio of hexamethylenediamine to acetone in the hexamethylenediamine acetone solution is 1 (9-11). The molar ratio of the neutralizer to the diisocyanate is 0.02 (1.5-1.6). The dosage of the catalyst is 0.04-0.08% of the molar quantity of diisocyanate. The neutralization reaction time is 50-65 min. The shear rate of the emulsification is 1000-1500 rpm. Compared with the prior art, the invention has the beneficial effects that: (1) And the method is environment-friendly, takes water as a dispersion medium, and has no VOCs pollution. (2) The adhesive has excellent performan