Views: 0 Author: Eva Publish Time: 2025-06-20 Origin: GUANGDONG YINGHUI NEW MATERIAL TECHNOLOGY CO., LTD.
The molecular structure and physical properties of PE labels make them inherently suitable for the harsh conditions of the cold chain. Through molecular chain design, density regulation, and additive modification, they can maintain excellent flexibility and bonding stability at low temperatures, resolving the industry pain points of traditional labels cracking and falling off in the cold chain.
The non-polar molecular chain structure of PE materials endows it with unique low-temperature properties:
Precise control of crystallinity: By adjusting the polymerization process, the crystallinity of low-density polyethylene (LDPE) is controlled at 30%-40%, allowing it to maintain the flexibility of the molecular chain at -60°C (glass transition temperature Tg = -120°C), with a tensile elongation rate of over 600%, which is more suitable for ultra-low temperature environments than BOPP labels (-40°C tensile elongation rate drops to 80%). Tests on a biological sample library showed that PE labels remained undamaged after being frozen in liquid nitrogen at -80°C and repeatedly bent 50 times.
Optimization of Branch Structure: Introducing α-olefin copolymer monomers (such as 1-butene) during ethylene polymerization forms a moderate long branch structure, enabling the PE film to maintain an impact resistance strength of > 20 kJ/m², which is three times that of PVC labels, and can withstand mechanical collisions and compressions during cold chain transportation. A logistics test by a frozen food enterprise showed that the breakage rate of PE labels was only 0.3%, much lower than the 15% of paper labels.
Molecular Weight Distribution Regulation: Using metallocene catalyst technology, the molecular weight distribution (MWD) of PE is controlled within a narrow range of 2-3, ensuring uniform and stable mechanical properties of the material at low temperatures, avoiding local brittleness caused by molecular weight differences, and with a strength fluctuation of < 5% in the tensile test at -40°C.
By adjusting the density of PE, precise adaptation to different cold chain scenarios can be achieved:
Low-density PE (LDPE) labels: Density 0.910-0.925g/cm³, with excellent flexibility and low-temperature resistance, maintaining good extensibility at -60°C, suitable for packaging with small curvature radii (such as frozen food packaging bags), with no wrinkles after labeling and a 99% adhesion rate.
Linear low-density PE (LLDPE) labels: Density 0.915-0.925g/cm³, achieving a balance between strength and toughness through the uniform distribution of short branches, with a tensile strength of 12 MPa, maintaining a peel force retention rate of > 85% with paper boxes in -30°C cold storage, suitable for logistics turnover boxes identification.
Medium-density PE (MDPE) labels： Density 0.926-0.940g/cm³， with a 40% increase in stiffness compared to LDPE， while maintaining low-temperature toughness at -40°C， suitable for automated labeling production lines (speed up to 300 bottles/minute)， and after application by a pharmaceutical cold chain enterprise， the labeling efficiency was increased by 25%.
Through the scientific addition of functional additives， PE labels can achieve targeted performance improvements：
Antioxidant Composite System： Using a 1：2 ratio of hindered phenolic main antioxidants (such as 1010) and phosphite ester auxiliary antioxidants (such as 168)， with an addition amount of 0.1%-0.3%， effectively inhibiting the oxidation degradation of PE at low temperatures， ensuring the mechanical properties of the labels remain > 90% after storage at -20°C for 5 years. Fog inhibitor migration control: By adding glycerol monostearate (GMS) as a fog inhibitor to the PE film, the migration rate of the inhibitor can be controlled (2-5mg/m²·h), ensuring that the label maintains a transmittance of > 85% in a 95% humidity refrigerated environment. This solves the problem of barcode unreadability caused by fogging in traditional labels, and the scanning success rate of a certain fresh food e-commerce platform has increased to 99.8%.
Antibacterial agent long-term release: 0.5% nano-zinc oxide (ZnO) antibacterial agent is introduced, and through slow-release technology, it forms an antibacterial layer on the PE label surface, with an antibacterial rate against Escherichia coli and Staphylococcus aureus > 99%. The validity period is 6 months, and it is suitable for hygiene protection in cold chain pharmaceutical packaging.
The core advantage of PE labels in the cold chain environment lies in their tolerance to temperature fluctuations, high humidity, and repeated freeze-thaw. Through innovations in material science and process technology, information integrity and adhesive reliability are ensured under various extreme conditions.
The adhesive system of PE labels is specifically designed for the cold chain temperature difference environment, achieving stable adhesion from ultra-low temperature to normal temperature:
Low-temperature specific pressure-sensitive adhesive: A butyl rubber and polyisobutylene (PIB) composite system is used, maintaining a 180° peel force of 5N/25mm at -60℃, which is more suitable for ultra-low temperature scenarios than acrylic adhesive (-40℃ peel force drops to 1N/25mm), and after application by a blood product enterprise, the label detachment rate from -80℃ stored blood bags decreased from 8% to 0.1%.
Temperature-responsive adhesive layer: By adding thermal expansion microspheres (particle size 10-20μm), the adhesive layer undergoes moderate volume changes with temperature variations, compensating for the thermal expansion and contraction differences between the PE label and the substrate, with a label warpage of < 0.5mm in temperature cycles from -30℃ to 25℃. The reliability of a cold chain test for a frozen food company was verified.
Adhesive bonding on damp surfaces: A hydrophilic modified pressure-sensitive adhesive was developed, maintaining 80% initial adhesion on a surface with a relative humidity of 90%, solving the problem of label detachment caused by condensation water in the cold chain. The label retention rate of a dairy enterprise in the refrigerated warehouse increased to 98%.
The molecular structure of PE labels makes them a natural moisture barrier, effectively resisting water vapor erosion in the cold chain:
Extremely low water vapor transmission rate: The water vapor transmission rate (WVTR) of PE film is < 5g/m²·24h (40℃/90% RH), combined with the hot melt adhesive sealing process, the entire label forms a sealed moisture-proof system, and after being placed in the refrigerated warehouse for 6 months, the ink does not smudge, and the clarity of the information remains 100%, the test data of a seafood enterprise is 3 times better than industry standards.
Resistance to ice water immersion: After being immersed in a 0℃ ice water mixture for 72 hours, the peel force retention rate of the PE label is > 90%, and the substrate shows no delamination phenomenon, suitable for ice storage environments in aquatic cold chain, after application by an ocean fishing company, the intact rate of fishing catch identification reached 97%.
Anti-condensation design: Through double-sided corona treatment (surface tension > 38mN/m), a micro-nano scale uneven structure is formed on the PE film surface, enhancing the contact angle (>100°), and condensate water forms spherical rolling on the surface, not affecting barcode recognition, the scanning efficiency of labels in a supermarket freezer cabinet increased by 30%.
For frequent temperature fluctuations in the cold chain, PE labels achieve stable performance through structural design: Thermal cycling tolerance: In the cycle test where the sample is frozen at -20℃ for 4 hours and then thawed at 25℃ for 2 hours, after 100 cycles, the tensile strength retention rate of the PE label remained > 85%, and the adhesive did not peel off. The simulation test of a vaccine cold chain enterprise verified its long-term reliability.
Adaptability to temperature conversion: After the label is taken out from -80℃, it will not curl due to water vapor condensation in the normal temperature environment. By adding absorbent resin (5% content) to absorb surface water vapor, it maintains flatness. The sample labels of a biological laboratory remained intact after repeated loading and unloading.
Resistance to low-temperature creep: In the -30℃ environment, with a constant load of 5N, the creep amount of the PE label was < 0.1mm/24h, which was much lower than that of the PET label (0.5mm/24h), ensuring that the label position remained unchanged during long-term cold chain storage. The shelf identification of a pharmaceutical cold storage achieved an accuracy rate of 100%.
PE labels build a safety protection network for cold chain products through three mechanisms: material compliance, information durability, and anti-counterfeiting traceability, ensuring the traceability of information throughout the production-to-consumption chain and providing key support for food and drug safety.
The raw materials and processing techniques of PE labels fully comply with food and medicine contact standards, ensuring safety from the source:
Food contact certification: Using food-grade PE resin (in compliance with GB 4806.6-2016), the volatile organic compounds (VOC) content is < 10mg/m², and the heavy metals (lead, cadmium) content is < 0.01mg/kg. It has passed FDA 21 CFR 177.1520 certification and can directly contact liquid food (such as milk, juice). The migration test of a dairy enterprise showed that no harmful substances were detected.
Pharmaceutical cleanroom standards: Produced in a 100,000-level clean workshop, the particle pollution (≥0.5μm) of the PE label is < 10 per cm², and the total bacterial count is < 10CFU/100cm². It has passed ISO 13485 medical device quality management system certification and is suitable for cold chain packaging of sterile medical devices. A vaccine enterprise applied it and passed the WHO pre-certification.
Extractable substance control: Through optimizing the formula, the extractable substances of the PE label in simulated body fluids (pH 7.4) are < 0.1mg/dm², avoiding any impact on the stability of the drugs, and meeting the USP <661> packaging material biocompatibility requirements. The compatibility test of a biologic company achieved a 100% pass rate.
PE labels ensure the long-term clarity and readability of information in the cold chain environment through innovations in ink and printing techniques:
Low-temperature scratch-resistant ink: Using UV-cured ink (containing 20% nano-aluminum oxide for wear resistance), it reaches 3H in the pencil hardness test at -40℃, and the abrasion resistance (500g load) is > 500 times. The label of a frozen food still retains the information intact after transportation friction.
Low-temperature drying printing: Using electron beam curing (EB) printing technology, it achieves ink curing at room temperature, avoiding damage to PE materials from high temperatures. The printing resolution is 1200dpi, ensuring that small characters (0.5mm) remain clear at -80℃. The label of a genetic test sample had an identification accuracy rate of 100%. Barcode low-temperature reading performance: Through a special dot pattern design (300 lpi), the QR code on the PE label has a reading rate of over 99.5% at -20℃. Even if there is a slight frost layer on the surface, it can still be recognized by a dedicated scanning gun. The traceability efficiency of a certain pharmaceutical cold chain has increased by 40%.
PE labels can integrate multiple anti-counterfeiting technologies to prevent products in the cold chain from being tampered with or replaced, ensuring the security of the supply chain:
Low-temperature RFID integration: Embed an ultra-low-temperature RFID tag (operating temperature -40℃ to 85℃) into the PE label, with a storage capacity of 512 bits and an identification distance of over 3 meters. It can achieve batch inventory in the frozen state. The inventory efficiency of a large cold storage has increased by 80%, and the error rate has decreased by 90%.
Irreversible temperature change marking: Print irreversible temperature change ink on the PE label. When the temperature exceeds 8℃ (the upper limit for vaccine storage), the marking changes from blue to white and cannot be restored, providing an intuitive warning of the interruption of the cold chain. After being applied by a disease control center, the identification rate of vaccine cold chain breakage reached 100%.
Laser micro-hole anti-counterfeiting: Use femtosecond laser to create a micro-hole array with a diameter of 5-10 μm on the PE film, forming a unique "fingerprint" pattern that can be identified under a microscope. The cost of counterfeiting is extremely high, and this brand of high-end seafood has used it to investigate multiple cases of cold chain counterfeiting.
