PE composite fresh-keeping bag for preventing and controlling cold-chain temperature loss as well as preparation method and application of PE composite fresh-keeping bag
The PE preservation bag with a three-layer co-extruded composite structure solves the problems of condensation and gas imbalance caused by temperature fluctuations in cold chain transportation, achieving stable packaging of fruits and vegetables and reducing losses.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHONGKAI UNIV OF AGRI & ENG
- Filing Date
- 2025-10-27
- Publication Date
- 2026-05-12
AI Technical Summary
Existing PE preservation bags cannot effectively cope with condensation, gas imbalance and microbial spoilage caused by temperature fluctuations in cold chain transportation. They cannot actively regulate gas composition and humidity, resulting in serious losses of fruits and vegetables.
The PE composite food preservation bag adopts a three-layer co-extrusion composite structure, including a heat insulation layer, a gas conditioning layer and a dehumidification layer, which are respectively composed of LDPE, LLDPE and functional fillers. It is prepared by melt blending and co-extrusion blown film process to achieve physical heat insulation, intelligent gas conditioning and active dehumidification functions.
It effectively alleviates condensation and gas imbalance caused by temperature fluctuations, maintains the stability of the microenvironment of fruits and vegetables, significantly reduces fruit and vegetable losses, and is suitable for cold chain transportation and storage.
Smart Images
Figure CN122009657A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of food packaging materials technology, specifically relating to a PE composite preservation bag for preventing cold chain de-temperature damage, its preparation method, and its application. Background Technology
[0002] Cold chain logistics is a key technology for ensuring the quality of perishable fruits and vegetables and extending their shelf life. However, in actual operation, "temperature absorptive" is difficult to avoid and often occurs during loading and unloading, at sales terminals, or in household refrigerators. Temperature fluctuations caused by temperature absorptive can trigger a series of chain reactions: First, a sudden temperature rise drastically accelerates the respiration of fruits and vegetables (respiratory burst), generating a large amount of respiratory heat (field heat) and CO2, while consuming a significant amount of O2; second, when the temperature drops, the high absolute humidity inside the bag easily reaches supersaturation due to the increased dew point temperature, producing a large amount of condensation. This condensation not only provides a breeding ground for microorganisms, leading to spoilage, but its evaporation process also carries away a large amount of heat, causing secondary chilling injury to the fruits and vegetables.
[0003] Current technologies mostly use ordinary polyethylene (PE) food storage bags or perforated microporous membranes. While ordinary PE bags offer some barrier properties, their poor moisture and air permeability leads to rapid accumulation of CO2 and moisture under de-thermal conditions, creating a high-humidity, high-CO2, and low-O2 adverse environment that exacerbates physiological disorders and microbial spoilage. Microporous membranes regulate gas through physical openings, but their regulatory effect is passive, singular, and uncontrollable. They cannot cope with drastic changes in respiration rates and lack heat insulation and active dehumidification functions, failing to fundamentally solve the three core problems caused by de-thermal processes: condensation, gas imbalance, and temperature shock.
[0004] Therefore, developing a multifunctional smart packaging that can proactively respond to and mitigate heat loss damage, integrating heat insulation, intelligent atmosphere control, and efficient dehumidification, is of great significance for improving cold chain resilience and reducing post-harvest losses of fruits and vegetables. Summary of the Invention
[0005] The purpose of this invention is to provide a PE composite preservation bag for preventing cold chain de-temperature damage.
[0006] The present invention also aims to provide a method for preparing the above-mentioned PE composite preservation bag for preventing cold chain de-temperature damage.
[0007] The final objective of this invention is to provide the application of the above-mentioned PE composite preservation bag in the packaging of perishable fruits and vegetables.
[0008] The first objective of this invention can be achieved through the following technical solution: a PE composite preservation bag for preventing cold chain de-temperature damage, wherein the preservation bag is a three-layer co-extruded composite polyethylene film, consisting of an insulation layer A, a gas conditioning layer B, and a dehumidification layer C from the outside to the inside. The insulation layer A is composed of a blend of low-density polyethylene (LDPE) and a heat-insulating functional filler; the gas conditioning layer B is composed of a blend of linear low-density polyethylene (LLDPE) and a gas adsorption and conditioning functional filler; and the dehumidification layer C is composed of a blend of low-density polyethylene (LDPE) and a moisture-absorbing functional filler.
[0009] In the PE composite preservation bag of the present invention for preventing cold chain de-temperature damage: The physical insulation layer A is composed of low-density polyethylene (LDPE) as the base resin and heat-insulating filler through melt blending. It is used to reflect and block environmental heat radiation and convection, and to slow down the intrusion of external heat and the loss of internal cold.
[0010] The intelligent gas conditioning layer B is composed of linear low-density polyethylene (LLDPE) as the matrix resin and gas adsorption conditioning filler through melt blending. It is used to selectively adsorb excess carbon dioxide (CO2) and ethylene (C2H4) gas, and maintain an appropriate amount of oxygen (O2) transport, dynamically establishing and stabilizing the modified atmosphere (MA).
[0011] The dehumidification layer C is composed of low-density polyethylene (LDPE) as the base resin and moisture-absorbing filler through melt blending. It is used to efficiently adsorb water vapor generated by the transpiration and respiration of fruits and vegetables, reduce the relative humidity of the air inside the bag, and maintain it below the critical saturation humidity, thereby fundamentally inhibiting the generation of condensate.
[0012] Preferably, the heat insulation filler has a mass percentage of 5-20% in the heat insulation layer A; the gas adsorption and regulation filler has a mass percentage of 10-25% in the gas regulation layer B; and the moisture absorption filler has a mass percentage of 5-20% in the dehumidification layer C.
[0013] This filler ratio range ensures the functionality of each layer while guaranteeing the mechanical properties, processing performance, and economy of the film.
[0014] Preferably, the heat-insulating filler is selected from one or a mixture of several of nano-silica aerogel, vacuum glass microspheres, hollow ceramic microspheres, mica powder and cork powder; these fillers can effectively increase thermal resistance and reduce heat conduction and convection through their nanoporous or hollow structures.
[0015] Preferably, the gas adsorption regulating filler is selected from one or a mixture of several of the following: 4A type zeolite molecular sieve, 13X type zeolite molecular sieve, zeolite, carbon molecular sieve, metal-organic framework materials (MOFs), activated alumina, and diatomaceous earth. These materials have specific pore size distributions and extremely high specific surface areas, and preferentially adsorb CO2 and ethylene molecules through physical adsorption mechanisms, thereby intelligently regulating the gas composition inside the bag.
[0016] Preferably, the moisture-absorbing filler is selected from one or a mixture of several of sodium polyacrylate, potassium polyacrylate, sodium polyacrylate grafted starch, sodium carboxymethyl cellulose (CMC), sodium alginate, kaolin, and superabsorbent polymer (SAP); these materials, especially superabsorbent polymer (SAP), have extremely high equilibrium moisture absorption rate and speed, and can quickly control the ambient humidity below its critical value.
[0017] Preferably, to achieve the best synergistic effect of the triple functions, the thickness ratio of the heat insulation layer A, the gas conditioning layer B, and the dehumidification layer C is (15~30):(10~20):(15~30); this ratio ensures that the gas conditioning and dehumidification have sufficient filler capacity, while the outer heat insulation provides sufficient protection, and the overall mechanical properties are balanced.
[0018] The PE composite preservation bag of this invention for preventing cold chain temperature-induced damage uses an innovative three-layer functional composite structure design to simultaneously solve problems such as condensation, deterioration of gas composition, and temperature shock caused by temperature fluctuations, providing full protection for fruits and vegetables.
[0019] The second objective of this invention can be achieved through the following technical solution: the preparation method of the above-mentioned PE composite preservation bag for preventing cold chain de-temperature damage includes the following steps: (1) Preparation of functional masterbatch: The heat insulation functional filler is mixed with LDPE, the gas adsorption and regulation functional filler is mixed with LLDPE, and the moisture absorption functional filler is mixed with LDPE at high speed. Then, the mixture is melt-extruded and granulated to obtain the functional masterbatch of heat insulation layer A, gas regulation layer B and dehumidification layer C respectively. (2) Three-layer co-extrusion blown film: The functional masterbatch in step (1) is added to the three extruders of the three-layer co-extrusion blown film equipment, and after melt co-extrusion, blowing, cooling, corona treatment and winding, a three-layer composite film is obtained; (3) Post-processing: After the rolled film is cured, it is cut and bagged.
[0020] In the above-mentioned preparation method of PE composite preservation bags for preventing cold chain de-temperature damage: Preferably, in step (1), masterbatch technology is used, in which each functional filler and the corresponding matrix resin (LDPE or LLDPE) are placed in a high-speed mixer for pre-dispersion, and then melt-mixed, extruded, air-cooled and pelletized by a twin-screw extruder at a set temperature to obtain high-concentration, highly dispersible heat insulation masterbatch, gas conditioning masterbatch and moisture-absorbing masterbatch respectively.
[0021] Preferably, the die temperature of the three-layer co-extrusion blown film equipment in step (2) is 165~175℃, the blow-up ratio during blowing is 2.5~3.0:1, and the strength during corona treatment is 38~48 dyne / cm.
[0022] Preferably, in some embodiments of the present invention, in step (2), the three types of functional masterbatches obtained in step (1) are diluted online with an appropriate amount of pure resin, and then accurately metered and fed into three single-screw extruders of a three-layer co-extrusion blown film equipment. After the material is plasticized, it is extruded through a co-extrusion die with a concentric annular flow channel to form a preform. The preform is inflated to a predetermined inflation ratio (2.5~3.0:1) by compressed air filled inside, cooled and shaped by an outer air ring, and then traction, thickness measurement, corona treatment (treatment intensity 38~48 dyne / cm to optimize subsequent printing suitability), and winding to obtain a three-layer composite film. The die temperature is precisely controlled in the range of 165~175℃ to ensure the matching of melt flowability and interfacial composite strength of each layer.
[0023] High-concentration functional masterbatches can be prepared first, and then diluted with a suitable resin to make the heat insulation filler in the heat insulation layer A have a mass percentage of 5-20%, the gas adsorption and regulation filler in the gas regulation layer B have a mass percentage of 10-25%, and the moisture absorption filler in the dehumidification layer C have a mass percentage of 5-20%.
[0024] More preferably, in step (3), the rolled film is aged at a constant temperature for 24 to 48 hours to relax the stress, improve the crystallization, and make the interface between the functional filler and the matrix more stable; finally, the finished food preservation bag is obtained through processes such as slitting and heat sealing.
[0025] The preparation method of this invention is based on a mature three-layer co-extrusion blown film process, which can achieve efficient, stable and environmentally friendly industrial production.
[0026] The last objective of the present invention can be achieved by the following technical solution: the application of the above-mentioned PE composite preservation bag in the packaging of perishable fruits and vegetables.
[0027] More preferably, the PE composite food preservation bag of the present invention can be used in cold chain scenarios where there is a risk of temperature deterioration.
[0028] In some embodiments of the present invention, the PE composite preservation bag of the present invention is preferably used in the packaging of perishable fruits and vegetables in cold chain transportation, sales and home storage.
[0029] Preferably, the perishable fruit or vegetable is corn.
[0030] The PE composite preservation bag of this invention is made of functional polymer composite material and can be used as a multi-layer co-extruded composite preservation bag for cold chain logistics of fresh fruits and vegetables, which actively prevents damage caused by "temperature drop".
[0031] Compared with the prior art, the present invention has the following advantages: (1) Active prevention and control and multi-functional synergy: This invention first clearly proposes the design concept of "preventing de-thermal damage" and innovatively realizes the synergy and integration of three functions of "physical insulation, intelligent atmosphere regulation and active dehumidification" through a three-layer structure. The outer insulation layer A effectively buffers external temperature fluctuations, the middle gas regulation layer B quickly adsorbs excess CO2 and ethylene during respiratory bursts to prevent gas adversity, and the inner dehumidification layer C actively reduces humidity to below the dew point, fundamentally eliminating condensation. The three work together to systematically address all the core problems caused by de-thermal damage. (2) Intelligent regulation: Utilizing the physicochemical properties of functional fillers (such as molecular sieves, MOFs, SAP) to achieve active and adaptive regulation of gas and humidity, rather than traditional passive blocking or fixed pore size regulation, the response is more sensitive and the protection is more comprehensive. (3) Advanced and reliable processing technology: The process route of “masterbatch preparation + three-layer co-extrusion blown film” is adopted, which realizes the high dispersion and precise positioning of functional fillers in the polymer matrix. Co-extrusion molding enables the interlayer to be bonded by melt entanglement, resulting in high interface strength, no risk of delamination, good product consistency, and suitability for large-scale industrial production. (4) Safety and environmental protection: All materials are recognized as safe (GRAS), no solvents are added, the production process is environmentally friendly, and the functional fillers are firmly encapsulated in the polymer matrix, with no risk of migration or shedding, and meet the safety standards for food contact materials. Attached Figure Description
[0032] Figure 1 This is a diagram showing the effect of packaging corn with the PE composite preservation bag from Example 1 in Example 4 of the present invention and the ordinary packaging film from Comparative Example 1. Figure 2 This is a comparison diagram of the interior of corn packaged in Example 4 of the present invention using the PE composite preservation bag from Example 1 and the ordinary packaging film from Comparative Example 1. Figure 3 This is a graph showing the soluble solids content of corn packaged in Example 4 of the present invention using the PE composite preservation bag from Example 1 and the ordinary packaging film from Comparative Example 1. Detailed Implementation
[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.
[0034] Unless otherwise specified, all reagents and materials used in the following examples are commercially available products. Example 1
[0035] The PE composite preservation bag provided in this embodiment for preventing cold chain de-temperature damage is a three-layer co-extruded polyethylene film, consisting of an insulation layer A, a gas conditioning layer B, and a dehumidification layer C from the outside to the inside. The insulation layer A is composed of a blend of low-density polyethylene (LDPE) and heat-insulating filler; the gas conditioning layer B is composed of a blend of linear low-density polyethylene (LLDPE) and gas adsorption and conditioning filler; and the dehumidification layer C is composed of a blend of low-density polyethylene (LDPE) and moisture-absorbing filler.
[0036] The heat insulation filler has a mass percentage of 18% in the heat insulation layer A; the gas adsorption and regulation filler has a mass percentage of 22% in the gas regulation layer B; and the moisture absorption filler has a mass percentage of 12% in the dehumidification layer C.
[0037] The heat insulation filler is nano-silica aerogel.
[0038] The gas adsorption regulating packing material is a 13X type zeolite molecular sieve.
[0039] The moisture-absorbing filler is sodium polyacrylate.
[0040] The thickness ratio of the insulation layer A, the gas conditioning layer B, and the dehumidification layer C is 20:10:20.
[0041] The preparation method of the PE composite preservation bag for preventing cold chain de-temperature damage includes the following steps: (1) Preparation of functional masterbatch: Insulation layer A (physical insulation layer): Take 18 parts of nano-silica aerogel and 82 parts of LDPE (2426K), place them in a high-speed mixer (3000r / min) according to the design ratio for pre-dispersion, and then melt granulate (including melt mixing, extrusion, air cooling and pelletizing) through a twin-screw extruder (temperature range: 140~180℃) to obtain a high-concentration and highly dispersible insulation functional masterbatch; Gas conditioning layer B (intelligent gas conditioning layer): Take 22 parts of 13X type zeolite molecular sieve and 78 parts of LLDPE (7042), and granulate them using the same process to obtain a high-concentration and highly dispersible gas conditioning functional masterbatch; Dehumidification layer C (active dehumidification layer): Take 12 parts of sodium polyacrylate and 88 parts of LDPE (2426K), and granulate them using the same process to obtain a high-concentration, highly dispersible moisture-absorbing masterbatch; (2) Three-layer co-extrusion blown film: The three types of functional masterbatches obtained in step (1) are diluted online with an appropriate amount of pure resin (added as needed), and then accurately measured and fed into the three single-screw extruders of the three-layer co-extrusion blown film equipment. After plasticization, the material is extruded through a co-extrusion die with a concentric annular flow channel to form a tube blank. The tube blank is blown up to a predetermined blow-up ratio (2.8:1) by the internal compressed air, cooled and shaped by the outer air ring, and then traction, thickness measurement, corona treatment (treatment strength 42 dyne / cm, to optimize subsequent printing suitability), and winding to obtain a three-layer composite film. The die temperature is precisely controlled at 170℃ to ensure the matching of melt flowability and interfacial composite strength of each layer. (3) Post-processing: The rolled-up film is aged at 25°C for 36 hours to relax stress, improve crystallization, and stabilize the interface between the functional filler and the matrix. Finally, the finished food preservation bag is obtained through processes such as slitting and heat sealing. Example 2
[0042] Unlike Example 1: Insulation layer A: 8 parts vacuum glass microspheres, 7 parts hollow ceramic microspheres, 85 parts LDPE; Gas conditioning layer B: 15 parts of type 4A zeolite molecular sieve, 5 parts of activated alumina and 80 parts of LLDPE; Dehumidification layer C: 10 parts sodium polyacrylate grafted starch, 5 parts kaolin and 85 parts LDPE; The thickness ratio of the three layers—insulation layer A, gas conditioning layer B, and dehumidification layer C—is 15:15:20. Blow-up ratio 3.0:1, die head temperature 168℃.
[0043] The subsequent process is the same as in Example 1. Example 3
[0044] Unlike Example 1: Insulation layer A: 10 parts nano-silica aerogel, 90 parts LDPE; Gas conditioning layer B: 10 parts zeolite, 10 parts diatomaceous earth and 80 parts LLDPE; Dehumidifier layer C: 10 parts superabsorbent polymer (SAP), 5 parts kaolin, and 85 parts LDPE; The thickness ratio of the three layers—insulation layer A, gas conditioning layer B, and dehumidification layer C—is 20:15:15. Blow-up ratio 3.0:1, die head temperature 168℃.
[0045] The subsequent process is the same as in Example 1. Example 4
[0046] The core challenge in the logistics of sweet corn lies in its extremely high post-harvest respiration rate, which easily leads to heat accumulation, sugar loss, and accelerated spoilage. Furthermore, condensation caused by temperature fluctuations further exacerbates microbial growth. This invention develops a PE composite preservation bag for preventing cold chain de-temperature damage. Through a synergistic mechanism of "heat insulation, gas regulation, and dehumidification," it precisely addresses these issues: the outer layer provides heat insulation to buffer sudden temperature changes, the middle layer actively adsorbs CO2 to inhibit respiration heat generation, and the inner layer efficiently dehumidifies to prevent condensation. This creates a stable microenvironment within the packaging, significantly delaying quality deterioration and effectively reducing de-temperature damage.
[0047] The PE composite preservation bag prepared in Example 1, which prevents cold chain de-temperature damage, was used to package fruit corn. The fruit corn was transported by cold chain logistics from Hainan to Beijing, and the whole process took 9 days.
[0048] The results are as follows Figure 1 , Figure 2 As shown, the corn packaged in this invention has no mold on the outer husk, the husk is moist, the kernels inside have small gaps, and the color is light yellow, bright, and glossy. The blank control (packaged in ordinary PE bags originally used in the corn base) has severely moldy outer husk, large gaps between kernels inside, and is dark and yellow, thus losing its commercial value.
[0049] The soluble solids content was determined using a handheld saccharimeter. The soluble solids content of the fruit corn in the preservation packaging of this invention was 15.8%, while the soluble solids content of the blank control fruit corn was only 13.1%. The results are as follows... Figure 3 As shown.
[0050] The above examples illustrate specific embodiments of the present invention. It is important to note that these specific embodiments are only for further explanation and do not constitute a limitation on the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the present invention still fall within the scope of protection of the present invention.
Claims
1. A PE composite preservation bag for preventing cold chain de-temperature damage, characterized in that, The food preservation bag is a three-layer co-extruded composite polyethylene film, consisting of a heat insulation layer A, a gas conditioning layer B, and a dehumidification layer C from the outside to the inside. The heat insulation layer A is composed of a blend of low-density polyethylene (LDPE) and heat-insulating filler; the gas conditioning layer B is composed of a blend of linear low-density polyethylene (LLDPE) and gas adsorption and conditioning filler; and the dehumidification layer C is composed of a blend of low-density polyethylene (LDPE) and moisture-absorbing filler.
2. The PE composite preservation bag for preventing cold chain de-temperature damage according to claim 1, characterized in that, The heat insulation filler has a mass percentage of 5-20% in the heat insulation layer A; the gas adsorption and regulation filler has a mass percentage of 10-25% in the gas regulation layer B; and the moisture absorption filler has a mass percentage of 5-20% in the dehumidification layer C.
3. The PE composite preservation bag for preventing cold chain de-temperature damage according to claim 1, characterized in that, The heat-insulating filler is selected from one or a mixture of several of the following: nano-silica aerogel, vacuum glass microspheres, hollow ceramic microspheres, mica powder, and cork powder.
4. The PE composite preservation bag for preventing cold chain de-temperature damage according to claim 1, characterized in that, The gas adsorption regulating filler is selected from one or a mixture of several of the following: 4A type zeolite molecular sieve, 13X type zeolite molecular sieve, zeolite, carbon molecular sieve, metal-organic framework materials (MOFs), activated alumina, and diatomaceous earth.
5. The PE composite preservation bag for preventing cold chain de-temperature damage according to claim 1, characterized in that, The moisture-absorbing filler is selected from one or a mixture of several of sodium polyacrylate, potassium polyacrylate, sodium polyacrylate grafted starch, sodium carboxymethyl cellulose (CMC), sodium alginate, kaolin, and superabsorbent polymer (SAP).
6. The PE composite preservation bag for preventing cold chain de-temperature damage according to claim 1, characterized in that, The thickness ratio of the heat insulation layer A, the gas conditioning layer B, and the dehumidification layer C is (15~30):(10~20):(15~30).
7. The method for preparing the PE composite preservation bag for preventing cold chain de-temperature damage according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of functional masterbatch: The heat insulation functional filler is mixed with LDPE, the gas adsorption and regulation functional filler is mixed with LLDPE, and the moisture absorption functional filler is mixed with LDPE at high speed. Then, the mixture is melt-extruded and granulated to obtain the functional masterbatch of heat insulation layer A, gas regulation layer B and dehumidification layer C respectively. (2) Three-layer co-extrusion blown film: The functional masterbatch in step (1) is added to the three extruders of the three-layer co-extrusion blown film equipment, and after melt co-extrusion, blowing, cooling, corona treatment and winding, a three-layer composite film is obtained; (3) Post-processing: After the rolled film is cured, it is cut and bagged.
8. The method according to claim 7, characterized in that, The die head temperature of the three-layer co-extrusion blown film equipment in step (2) is 165~175℃, the blow-up ratio during blowing is 2.5~3.0:1, and the strength during corona treatment is 38~48 dyne / cm.
9. The application of the PE composite preservation bag according to any one of claims 1-6 in the packaging of perishable fruits and vegetables.
10. The application of the PE composite preservation bag according to any one of claims 1-6 in the packaging of perishable fruits and vegetables in cold chain transportation, sales and home storage.