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CN-122011332-A - Degradable polyurethane wall material system and preparation method thereof

CN122011332ACN 122011332 ACN122011332 ACN 122011332ACN-122011332-A

Abstract

The invention relates to the technical field of material chemistry microcapsules, and provides a degradable polyurethane wall material system and a preparation method thereof, wherein the degradable polyurethane wall material system comprises a solid component, namely isocyanate group-containing blocked degradable polyurethane prepolymer and 2-hydroxyethyl amino oxidized starch, which form a covalent network through urea bonds and urethane bonds, wherein the solid component of the system comprises 25-45 parts by weight of solid component, 200-1500 mPa.s of viscosity, and 80-300nm of volume median diameter D50, and the solid component can be emulsified and solidified with a hydrophobic liquid core material to obtain polyurethane/starch covalent network wall layer microcapsules, and the volume median diameter D50 is 1-20 mu m, so that the problem that both the solid component, the viscosity and the emulsification and solidification are difficult is solved, and the degradable polyurethane wall material system is used for preparing and applying the hydrophobic liquid core material microcapsules.

Inventors

  • CHEN KUN
  • PENG TAO
  • LIU RUNFENG

Assignees

  • 江苏明德立达作物科技有限公司

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. The degradable polyurethane wall material system is characterized by comprising, by weight, 100 parts of total weight, 25-45 parts of solid components and the balance of deionized water, wherein the balance of the solid components is 100 parts of total weight, and the solid components comprise, by weight, 70-85 parts of isocyanate group-terminated degradable polyurethane prepolymer and 15-30 parts of 2-hydroxyethyl amino oxidized starch, and the sum of the two is 100 parts; The isocyanate group-terminated degradable polyurethane prepolymer is prepared by reacting polycaprolactone dihydric alcohol, 2-dimethylolpropionic acid, 2' -dithio-diethyl alcohol and isophorone diisocyanate, the isocyanate group content is 2.0-4.5wt%, the 2-hydroxyethyl amino oxidized starch is prepared by reacting starch, sodium periodate, ethanolamine and sodium borohydride, the amino content is 0.20-0.80mmol/g, the residual aldehyde group content is not higher than 0.10mmol/g, and the isocyanate group-terminated degradable polyurethane prepolymer and the 2-hydroxyethyl amino oxidized starch form a covalent network in the wall material system through urea bonds and urethane bonds.
  2. 2. The degradable polyurethane wall system of claim 1, wherein the isocyanate-terminated degradable polyurethane prepolymer is prepared by: A1. Mixing 100 parts by weight of polycaprolactone diol, 4-12 parts by weight of 2, 2-dimethylolpropionic acid and 2-10 parts by weight of 2,2' -dithiodiethanol; A2. treating at 95-115 deg.c and vacuum degree of-0.08-0.095 MPa for 1-3 hr; A3. Adding isophorone diisocyanate in an inert atmosphere according to a molar ratio of isocyanate groups to hydroxyl groups of 1.20-1.80:1, and reacting for 2-5h at 70-85 ℃; A4. stopping the reaction when the content of the isocyanate groups reaches 2.0-4.5wt percent, and cooling to 25-40 ℃ to obtain the isocyanate group-terminated degradable polyurethane prepolymer.
  3. 3. The degradable polyurethane wall system according to claim 1, wherein the 2-hydroxyethyl aminated oxidized starch is prepared by: C1. dispersing 100 parts by weight of the oxidized starch intermediate in 300-800 parts by weight of deionized water; C2. Adding 10-35 parts by weight of ethanolamine into the system, controlling the pH of the system to be 8.5-10.5, and reacting for 2-6h at 25-45 ℃; C3. 1-8 parts by weight of sodium borohydride is prepared into an alkaline aqueous solution with the concentration of 1-5 wt%, wherein the alkaline aqueous solution is a NaOH solution with the concentration of 0.1-0.5 mol/L, the pH of the solution is controlled to be 10-12, the sodium borohydride is slowly added into the system in batches at intervals of 5-15 and min, the pH of the system is maintained to be 10-12 in the adding process, and the reaction is continued for 1-3 hours at the temperature of 20-35 ℃; C4. filtering, washing with deionized water for 2-4 times, wherein the water consumption for each washing is 3-5 times of the dry weight of the product, the washing end point is that the pH value of the filtrate is stabilized at 5.5-7.5, and the filtrate is dried in vacuum for 8-16h under the condition of absolute pressure of 2-5kPa at 40-60 ℃, and the quality difference of 1h between two continuous weighing intervals is not more than 0.1% of the total quality.
  4. 4. A degradable polyurethane wall system according to claim 3, characterized in that the oxidized starch intermediate used for the preparation of the 2-hydroxyethyl aminated oxidized starch is prepared by the steps of: B1. Dispersing 100 parts by weight of starch in 500-1000 parts by weight of deionized water to obtain starch slurry; B2. Adding 20-80 parts by weight of sodium periodate into the starch slurry, adjusting the pH of the slurry to 3.5-5.5 by using 0.1-1 mol/L hydrochloric acid aqueous solution or 0.1-0.5 mol/L acetic acid-sodium acetate buffer solution, and reacting for 4-8 hours at 15-30 ℃ under the condition of avoiding light; B3. filtering and washing with deionized water until the pH of the filtrate is 5.5-7.5; B4. Vacuum drying at 40-60 deg.C under 2-5 kPa absolute pressure for 6-16 hr, wherein the drying end point is that the mass difference of two continuous weighing intervals 1-h is not more than 0.1% of the total mass, and the oxidized starch intermediate with aldehyde group content of 1.0-3.0mmol/g is obtained. D4. obtaining the degradable polyurethane wall material system with the volume median particle diameter D50 of 80-300 nm.
  5. 5. The degradable polyurethane wall system according to claim 1, wherein the number average molecular weight of the polycaprolactone diol is 530-3000, the pH of the wall system is 6.0-8.5, the viscosity is 200-1500 mPa.s, and the starch is potato starch or corn starch.
  6. 6. A method for preparing a degradable polyurethane wall system according to claims 1-5, comprising the steps of: s1, providing a prepared isocyanate group-terminated degradable polyurethane prepolymer; S2, providing the prepared 2-hydroxyethyl amino oxidized starch; S3, dispersing 15-30 parts by weight of 2-hydroxyethyl aminated oxidized starch in 70-200 parts by weight of deionized water, controlling the pH of a system to be 6.5-8.5, and shearing for 5-20min at 2000-6000rpm to obtain a dispersion liquid; s4, adding 70-85 parts by weight of the isocyanate group-terminated degradable polyurethane prepolymer into the dispersion liquid obtained in the step S3 at 20-35 ℃, pre-reacting for 10-60min, and curing for 0.5-2h at 35-50 ℃; s5, adding deionized water into the system obtained in the step S4, wherein the total 100 weight parts of the system comprise 25-45 weight parts of solid components and the balance of the deionized water, and the balance is 100 weight parts, so that the degradable polyurethane wall material system with the volume median particle diameter D50 of 80-300nm is obtained.
  7. 7. The process according to claim 6, wherein the carboxyl groups introduced from 2, 2-dimethylolpropionic acid in the isocyanate group-terminated degradable polyurethane prepolymer are neutralized with a tertiary amine neutralizer at a neutralization temperature of 25 to 35℃for 15 to 30 minutes before step S4.
  8. 8. The method of claim 6, wherein after step S5, the degradable polyurethane wall system is further mixed with a hydrophobic liquid core material, emulsified at 3000-12000rpm for 3-10min at 20-35 ℃ and then cured at 35-60 ℃ for 1-4h to obtain a microcapsule with polyurethane/starch covalent network wall layer.
  9. 9. The method of claim 8, wherein the weight ratio of the hydrophobic liquid core material to the solid component in the degradable polyurethane wall system is 1:1 to 6:1, and the volume median particle diameter D50 of the microcapsule is 1-20 μm.
  10. 10. The method of claim 7, wherein the tertiary amine neutralizer is at least one of triethylamine, N-methyldiethanolamine, or triethanolamine.

Description

Degradable polyurethane wall material system and preparation method thereof Technical Field The invention relates to the technical field of material chemistry microcapsules, in particular to a degradable polyurethane wall material system and a preparation method thereof. Background In the technology, the water-dispersible wall material system is required to maintain proper viscosity under the condition of higher solid components so as to support processes such as shearing dispersion, emulsification, pre-reaction, curing and the like, and is required to form a stable covalent network in the curing stage so as to ensure the construction and maintenance of a wall layer structure, and meanwhile, the molecular structure design of the degradable polyurethane wall material system is also required to be considered, so that the isocyanate group reactivity and chain segment introduction mode are matched with the water dispersion process, and the volume median particle diameter D50 is controllable, and the whole preparation process is provided with the feasibility and repeatability. However, the existing water-dispersible wall material system is often accompanied by viscosity rise when the solid component is improved, the shearing and emulsifying processes are easy to limit, and if the existing water-dispersible wall material system is only dependent on the polyurethane system, insufficient covalent network construction or uneven distribution of reaction sites easily occurs under the deionized water condition, so that the control of the median particle diameter D50 in the volume and the consistency of the microcapsule forming process are affected, and meanwhile, after the degradable requirement is introduced, the coupling among chain segment design, curing and curing windows can further amplify the process sensitivity. For example, chinese patent publication No. CN101503617B discloses a water-based polyurethane microcapsule phase change energy storage material and a preparation method thereof, but the technical route does not relate to the systematic design of forming a covalent network by isocyanate group-terminated degradable polyurethane prepolymer and 2-hydroxyethyl amino oxidized starch through urea bonds and urethane bonds. For example, chinese patent publication No. CN116322327a discloses a method for preparing microcapsules, but still requires the establishment of more controllable covalent network building paths around the constraints of isocyanate group content, amino group content and residual aldehyde group content. Disclosure of Invention The invention aims to provide a degradable polyurethane wall material system and a preparation method thereof, which solve the problem that the existing solid components, viscosity and emulsification curing process are difficult to take into account. The invention is based on the synergistic reaction site design of isocyanate group-terminated degradable polyurethane prepolymer and 2-hydroxyethyl aminated oxidized starch, and a covalent network is constructed in a water-dispersible wall material system through urea bonds and urethane bonds, so that the dispersion under the condition of solid components and the subsequent emulsification and solidification process are mutually matched, thereby realizing the controllable construction of volume median particle diameter D50 and wall layer structure and the preparation of supporting microcapsules. In order to achieve the above object, the present invention provides the following technical solutions: The degradable polyurethane wall material system is a water-dispersible wall material system, and comprises, by weight, 25-45 parts of solid components and the balance of deionized water, wherein the solid components account for 100 parts by weight, and the balance of the solid components comprises, by weight, 70-85 parts of isocyanate group-terminated degradable polyurethane prepolymer and 15-30 parts of 2-hydroxyethyl aminated oxidized starch, and the sum of the two is 100 parts; The isocyanate group-terminated degradable polyurethane prepolymer is prepared by reacting polycaprolactone dihydric alcohol, 2-dimethylolpropionic acid, 2' -dithio-diethyl alcohol and isophorone diisocyanate, the isocyanate group content is 2.0-4.5wt%, the 2-hydroxyethyl amino oxidized starch is prepared by reacting starch, sodium periodate, ethanolamine and sodium borohydride, the amino content is 0.20-0.80mmol/g, the residual aldehyde group content is not higher than 0.10mmol/g, and the isocyanate group-terminated degradable polyurethane prepolymer and the 2-hydroxyethyl amino oxidized starch form a covalent network in the wall material system through urea bonds and urethane bonds. Further, the isocyanate group-terminated degradable polyurethane prepolymer is prepared by the steps of: A1. Mixing 100 parts by weight of polycaprolactone diol, 4-12 parts by weight of 2, 2-dimethylolpropionic acid and 2-10 parts by weight of 2,2' -dithiodiethanol; A2. trea