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CN-121224270-B - Degradable food packaging bag and preparation process thereof

CN121224270BCN 121224270 BCN121224270 BCN 121224270BCN-121224270-B

Abstract

The invention relates to the technical field of food packaging, in particular to a degradable food packaging bag and a preparation process thereof, wherein the packaging bag comprises two layers of base layer films and a functional adhesive layer compounded between the two layers of base layer films, the base layer is prepared from the following raw materials, by mass, 50-70 parts of polybutylene adipate terephthalate, 20-35 parts of polylactic acid, 10-25 parts of corn starch, 2-6 parts of a compatilizer, and the functional adhesive layer is prepared from the following raw materials, by mass, 100 parts of aqueous polyurethane emulsion, 3-15 parts of hydrophobic silica particles, 5-20 parts of chitosan derivative modified micron zinc oxide and 1-5 parts of a plasticizer. The invention provides a method for combining degradability, antibacterial property and mechanical property, and has the effect of being safer and more reliable.

Inventors

  • ZHAO ZHENHUA
  • WANG FENGYU
  • QU XIAOPENG

Assignees

  • 浙江星冠包装材料有限公司

Dates

Publication Date
20260508
Application Date
20251009

Claims (9)

  1. 1. The degradable food packaging bag is characterized by comprising two layers of base films and a functional adhesive layer compounded between the two layers of base films; The base layer is prepared from the following raw materials in parts by mass: 50-70 parts of polybutylene adipate terephthalate; 20-35 parts of polylactic acid; 10-25 parts of corn starch; 2-6 parts of compatilizer; The functional adhesive layer is prepared from the following raw materials in parts by mass: 100 parts of aqueous polyurethane emulsion; 3-15 parts of hydrophobic silica particles; 5-20 parts of chitosan derivative modified micron zinc oxide; 1-5 parts of plasticizer; the raw materials of the functional adhesive layer also comprise 0.5-1.5 parts of wetting dispersant, wherein the wetting dispersant is ammonium polyacrylate salt.
  2. 2. The degradable food packaging bag according to claim 1, wherein the compatilizer is at least one of maleic anhydride grafted polybutylene adipate terephthalate or maleic anhydride grafted polylactic acid, the hydrophobic silica particles are silica modified by hexadecyltrimethoxysilane, and the plasticizer is a mixture of glycerin and sorbitol.
  3. 3. The degradable food packaging bag according to claim 1, characterized in that the preparation method of the chitosan derivative modified micron zinc oxide comprises the following steps: a. 1-5 parts by mass of chitosan derivative is dissolved in 97-99 parts by mass of dilute acetic acid solution with the concentration of 1-3% to prepare chitosan derivative solution; b. Adding 10-30 parts by mass of micron zinc oxide powder into the chitosan derivative solution prepared in the step a, and dispersing for 30-60 minutes by adopting a high-speed shearing dispersing machine at a rotating speed of 3000-5000rpm to form uniform suspension; c. b, regulating the pH value of the suspension obtained in the step b to 8-10 by using an alkaline solution, and promoting the chitosan derivative to deposit and coat on the surface of the micron zinc oxide; d. Filtering the mixture after the reaction in the step c, collecting a filter cake, and washing the filter cake with deionized water to be neutral; e. and (3) drying the washed filter cake in vacuum at 50-70 ℃ for 6-12 hours, and grinding and sieving to obtain the chitosan derivative modified micron zinc oxide.
  4. 4. The degradable food packaging bag according to claim 3, wherein the chitosan derivative is carboxymethyl chitosan or hydroxypropyl chitosan, the particle size of the micron zinc oxide is 1-5 μm, and the alkaline solution is sodium hydroxide solution with mass fraction of 5-10%.
  5. 5. A process for preparing a degradable food package according to any one of claims 1 to 4, comprising the steps of: s1, preparing a base film, namely melting and blending polybutylene adipate, polylactic acid, corn starch and a compatilizer, and then carrying out blow molding or tape casting molding to prepare the base film; S2, preparing a functional adhesive, namely premixing the chitosan derivative modified micron zinc oxide, a wetting dispersant, a plasticizer and part of aqueous polyurethane emulsion, then carrying out high-speed shearing emulsification treatment, adding hydrophobic silica particles, and finally mixing with the residual aqueous polyurethane emulsion to obtain the functional adhesive; S3, coating and compounding, namely coating a functional adhesive on the surface of the base film, drying and then carrying out hot-pressing compounding with another film; and S4, curing, namely curing the compounded film roll.
  6. 6. The process for preparing a degradable food packaging bag according to claim 5, wherein in the step S1, the melt blending is performed in a twin screw extruder, the temperature of each zone of the extruder is set to 155-185 ℃, the blow-molding inflation ratio is 2.5-3.5, and the temperature of a casting cooling roller is 20-40 ℃.
  7. 7. The preparation process of the degradable food packaging bag according to claim 5, wherein in the step S2, the part of the aqueous polyurethane emulsion for premixing accounts for 20-40% of the total mass of the emulsion, the rotating speed of the high-speed shearing emulsification treatment is 1500-3000rpm, and the treatment time is 10-20min.
  8. 8. The process for preparing a degradable food packaging bag according to claim 5, wherein in the step S3, a wire roll with a mesh depth of 60-70 μm is used for coating, and the coating amount is controlled to be 4-6g/m 2 .
  9. 9. The process for preparing the degradable food packaging bag according to claim 5, wherein in the step S3, the drying is specifically three-stage gradient air drying, the temperature of the first stage is 45-60 ℃, the temperature of the second stage is 65-80 ℃, the temperature of the third stage is 80-95 ℃, the temperature of the hot press compounding is 60-80 ℃, the pressure is 0.3-0.6MPa, the temperature of the curing treatment is 40-55 ℃ and the curing time is 24-72 hours.

Description

Degradable food packaging bag and preparation process thereof Technical Field The invention relates to the technical field of food packaging, in particular to a degradable food packaging bag and a preparation process thereof. Background With the enhancement of environmental awareness, the development of degradable food packaging materials has become an industry trend. However, the degradable package in the prior art often has multiple challenges that firstly, the degradability and mechanical property of the material are difficult to be compatible, the interface compatibility is poor and the toughness of the material is insufficient due to simple blending, secondly, the functional expansion faces regulatory bottlenecks, such as nano titanium dioxide and the like, which are widely used in the past, and the development of safe and reliable functional degradable package becomes particularly urgent because the potential safety risk of the degradable package is strictly limited or forbidden in food contact materials, thirdly, the process feasibility of production is also a key difficult problem while the safety and the function are ensured. Therefore, there is a need in the industry for a comprehensive solution that systematically addresses compatibility, functional safety, and process feasibility, thereby achieving an organic unification of high performance and full degradation. CN 120118485A discloses an environment-friendly degradable plastic food packaging bag and a preparation method thereof, wherein the food packaging bag comprises, by weight, 90-100 parts of PBAT, 10-20 parts of PLA, 15-20 parts of antibacterial modified nano calcium carbonate, 1-2 parts of polyethylene wax and 1-2 parts of titanium dioxide, wherein PBAT and PLA which account for a large proportion are used as base materials, when the components are relatively different, the acting force between the PBAT and the PLA is relatively strong, the mixing and the melting are relatively good, the two base materials are firstly mixed and dissolved to prepare base particles, and then the base particles are relatively good in compatibility with other components when the base materials are mixed and melted, so that the prepared degradable plastic food packaging bag is relatively excellent in mechanical property, and the antibacterial modified nano calcium carbonate is relatively good in compatibility with other components of the plastic food packaging bag when melted, and the flowability of the materials is relatively good when melted, and meanwhile, the prepared plastic bag is not easy to separate out silver, and the antibacterial property of the plastic food packaging bag can be kept permanently. Although this solution proposes a method of compromising degradability, antibacterial properties and mechanical properties, titanium dioxide is still selected. Disclosure of Invention In order to solve the problems, the invention provides a degradable food packaging bag and a preparation process thereof, provides a method for combining degradability, antibacterial property and mechanical property, and has the effects of safety and reliability. The degradable food packaging bag comprises two layers of base films and a functional adhesive layer compounded between the two layers of base films; The base layer is prepared from the following raw materials in parts by mass: 50-70 parts of polybutylene adipate terephthalate (PBAT); 20-35 parts of polylactic acid (PLA); 10-25 parts of corn starch; 2-6 parts of compatilizer; The functional adhesive layer is prepared from the following raw materials in parts by mass: 100 parts of aqueous polyurethane emulsion; 3-15 parts of hydrophobic silica particles; 5-20 parts of chitosan derivative modified micron zinc oxide; 1-5 parts of plasticizer. In the basic layer system, polybutylene adipate terephthalate is used as a flexible framework to provide necessary elongation at break and toughness, polylactic acid is used as a rigid chain segment to endow rigidity and strength to the material to form a complementary mechanical support network, however, hydrophilic corn starch is introduced to remarkably improve degradation rate but can generate interface separation with a hydrophobic polymer matrix, at the moment, a compatilizer is respectively bridged with starch and polyester through polar groups and nonpolar segments on a molecular chain of the compatilizer to reconstruct interface compatibility, and if the dosage of the compatilizer is too low, the compatilizer has insufficient compatibility effect, and too high content can form excessive crosslinking to inhibit degradation. In the functional adhesive layer, the aqueous polyurethane emulsion is used as a film forming carrier and provides interfacial adhesion, hydrophobic silica particles delay water vapor permeation by constructing a tortuous blocking path in the film layer, the content of the hydrophobic silica particles needs to be precisely balanced, the blocking effect is