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CN-121992683-A - Nanocellulose-based daytime radiation refrigeration coating liquid, preparation method thereof and fresh-keeping application of nanocellulose-based daytime radiation refrigeration coating liquid in paper-based fruit and vegetable packaging

CN121992683ACN 121992683 ACN121992683 ACN 121992683ACN-121992683-A

Abstract

The invention belongs to the technical field of fresh-keeping materials, and relates to a nanocellulose-based daytime radiation refrigeration coating liquid, a preparation method thereof and fresh-keeping application of the nanocellulose-based daytime radiation refrigeration coating liquid in paper-based fruit and vegetable packaging. Aiming at the problems of high viscosity and poor leveling property of the phosphoryl cellulose nanofiber coating liquid, the invention weakens hydrogen bonding action among phosphoryl cellulose nanofibers through cocoanut glucoside to reduce entanglement density, adjusts surface charge and steric hindrance of TiO 2 particles to cooperatively optimize rheological property of a system, on the other hand, the low surface tension of the cocoanut glucoside obviously improves wetting and spreading capacity of the coating liquid on corrugated paper base materials, and the cocoanut glucoside induces a highly communicated micro/nano scale air duct structure in a film forming and drying process, thereby realizing efficient scattering and reflection of solar spectrum by utilizing refractive index difference between air and the phosphoryl cellulose nanofiber base materials, and the porous network simultaneously provides a uniform load platform for TiO 2 to construct an air-phosphoryl cellulose nanofiber-TiO 2 triple light scattering interface so as to further enhance the reflectivity of visible light wave bands.

Inventors

  • LIU HONGZHI
  • Jiang Xiushuang

Assignees

  • 浙大宁波理工学院

Dates

Publication Date
20260508
Application Date
20260323

Claims (10)

  1. 1. A preparation method of a cellulose nanofiber-based daytime radiation refrigeration coating liquid for fruit and vegetable fresh-keeping packaging is characterized by comprising the following steps of uniformly mixing a dispersion liquid containing nano metal oxide particles with high refractive index and high infrared reflectivity, a cocoyl glucoside solution and a dispersion liquid containing phosphoryl cellulose nanofibers, and finally diluting to obtain the coating liquid.
  2. 2. The method for preparing the cellulose nanofiber-based daytime radiation refrigeration coating liquid for fruit and vegetable fresh-keeping packaging according to claim 1, wherein the nano metal oxide particles with high refractive index and high infrared reflectivity comprise at least one of TiO 2 、ZnO、BaSO 4 、CaCO 3 .
  3. 3. The method for preparing the cellulose nanofiber-based daytime radiation refrigeration coating liquid for fruit and vegetable fresh-keeping packaging according to claim 2, which is characterized in that the nano metal oxide particles with high refractive index and high infrared reflectivity are TiO 2 .
  4. 4. The method for preparing the cellulose nanofiber-based daytime radiation refrigeration coating liquid for fruit and vegetable fresh-keeping packaging according to claim 1, wherein the cocoyl glucoside solution is an aqueous solution containing 5-15wt% cocoyl glucoside.
  5. 5. The method for preparing the cellulose nanofiber-based daytime radiation refrigeration coating liquid for fruit and vegetable fresh-keeping packaging according to claim 1, wherein the dispersion liquid containing the phosphoryl cellulose nanofibers is an aqueous dispersion liquid containing 0.5-1.5wt% of the phosphoryl cellulose nanofibers, and the surface charge amount of the phosphoryl cellulose nanofibers is 1.0-1.5mmol/g.
  6. 6. The method for preparing the cellulose nanofiber-based daytime radiation refrigeration coating liquid for fruit and vegetable fresh-keeping packaging according to claim 1, which is characterized by comprising the following steps of: s1, spraying a mixed solution of urea and monoammonium phosphate on the surface of a bamboo pulp board, drying, and performing high-temperature treatment to obtain phosphoryl cellulose; S2, soaking the phosphoryl cellulose in water for dispersion treatment, and then carrying out high-pressure homogenization treatment to obtain a dispersion liquid containing phosphoryl cellulose nano fibers.
  7. 7. The method for preparing the cellulose nanofiber-based daytime radiation refrigeration coating liquid for the fruit and vegetable fresh-keeping package according to claim 1, wherein the cellulose nanofiber-based daytime radiation refrigeration coating liquid for the fruit and vegetable fresh-keeping package is characterized in that: The content of the phosphoryl cellulose nano-fiber is 0.3-0.8wt%; The mass ratio of the phosphoryl cellulose nano-fiber to the radiation-resistant metal oxide is 1 (2-10); the coco glucoside content satisfies the following conditions: 。
  8. 8. The preparation method of the cellulose nanofiber-based daytime radiation refrigeration coating liquid for fruit and vegetable fresh-keeping packaging according to claim 1, wherein the mass ratio of water to organic solvent in the diluted coating liquid is (5-6): 1.
  9. 9. A cellulose nanofiber-based daytime radiation refrigeration coating liquid for fruit and vegetable fresh-keeping packaging, which is characterized by being prepared by the method of any one of claims 1-8.
  10. 10. Use of the coating liquid according to claim 9 in paper-based fruit and vegetable fresh-keeping packaging, wherein the coating liquid according to claim 9 is coated on the surface of the paper-based fruit and vegetable fresh-keeping packaging in a scraping way, and then drying treatment is carried out.

Description

Nanocellulose-based daytime radiation refrigeration coating liquid, preparation method thereof and fresh-keeping application of nanocellulose-based daytime radiation refrigeration coating liquid in paper-based fruit and vegetable packaging Technical Field The invention belongs to the technical field of fresh-keeping materials, and relates to a nanocellulose-based daytime radiation refrigeration coating liquid, a preparation method thereof and fresh-keeping application of the nanocellulose-based daytime radiation refrigeration coating liquid in paper-based fruit and vegetable packaging. Background In recent years, with the rise of living standard, 40% of food in the world needs cold chain storage and transportation, while the cold chain consumes 11% of electricity in the world and generates about 2.5% of greenhouse gases in the world, so that a novel refrigeration technology with zero energy consumption and zero emission is urgently needed to be explored to meet the requirements of national economic development and daily life of people. Passive radiation refrigeration is a strategy to reduce the temperature by radiating excess heat to the cold universe through an atmospheric transparent window (8-13 μm) without any energy consumption. In recent years, the passive radiation refrigerating material has a great application prospect in the fields of energy-saving buildings, personal heat management, farm refrigerating systems, photovoltaic cooling, thermo-optical-electric systems, food preservation and the like. Although passive radiation refrigeration materials have made significant progress in enhancing mid-infrared emissivity and improving refrigeration capacity, the development and use of daytime radiation refrigeration materials still face significant challenges because the absorption of solar radiation by the material during the daytime can offset the refrigeration capacity of its infrared radiation. At present, scholars at home and abroad have developed materials with daytime radiation refrigerating capacity such as inorganic nonmetallic materials, porous polymer materials, polymer-inorganic nonmetallic composite materials, polymer-metal composite materials, polymer-inorganic nonmetallic-metal ternary composite materials and the like, but have the defects of high raw material cost, difficult degradation after use and the like, and cellulose is taken as a natural high polymer material with the most abundant reserves in the nature, and has the advantages of wide raw material sources, reproducibility, biodegradability, easy regulation and control of a multiscale structure and the like, and the molecular structure can vibrate in an atmospheric transparent window band, so that the natural high polymer material has certain radiation refrigerating potential. Although cellulose-based daytime radiation refrigerant materials have great potential in the field of passive cooling by virtue of their renewable and biocompatible properties, their practical use is limited by three key drawbacks. Firstly, the radiation refrigeration performance is insufficient, and the high solar reflectivity and the high middle infrared emissivity are difficult to realize simultaneously in a complex environment, so that the net refrigeration power is limited. Meanwhile, precise process equipment such as directional freezing, electrostatic spinning and the like is expensive, high in energy consumption and low in yield, is difficult to adapt to continuous industrial production, has single material form and difficult integration application, and the current products are mostly rigid blocks or independent films, lack flexibility, cannot be conveniently integrated on the surfaces of various food packaging materials such as paper or plastics in a coating mode, and seriously prevent the large-scale deployment of the products in wide scenes such as cold chain preservation. It can be seen that although the current cellulose-based daytime radiation refrigerating material is excellent in cooling performance, systematic defects still exist in the aspects of green manufacturing path, environment adaptability, long-term service stability, low-cost expandability and the like. The Chinese patent application document (CN 118879131A) discloses an ultraviolet-resistant nanocellulose radiation refrigeration coating and a preparation method thereof, and provides the preparation method of the ultraviolet-resistant nanocellulose radiation refrigeration coating, wherein the preparation method aims at realizing high solar reflectivity, high infrared emissivity and good ultraviolet resistance by Combining Nanocellulose Crystal (CNC), nanocellulose fibril (CNF), titanium dioxide (TiO 2) and a silane coupling agent, the preparation process involves multiple ultrasonic dispersion and high-temperature rotary evaporation, the energy consumption is high, the batch consistency is difficult to ensure in large-scale production, and the used organosilane such as methyltrimet