Three layers laminated foil for package PET+AL+HDPE

The three-layer composite foil packaging material PET+AL+HDPE exhibits various characteristics in the packaging field, mainly due to the properties of its individual layers and the synergistic effects between them. The ingenuity of this material lies not only in the functional advantages of each layer but also in the performance leap achieved through scientific proportioning and technological integration, making it excel in stringent packaging scenarios.

The PET (polyester) layer, as the surface layer with a thickness typically ranging from 12-25μm, is produced using a biaxial stretching process. This process arranges its molecules more regularly, resulting in over 90% transparency, far exceeding the 85% of ordinary plastic films. This high transparency makes it an ideal substrate for printing, accurately presenting product information and exquisite patterns, especially suitable for brand display in high-end cosmetics and pharmaceutical packaging. Its excellent high-temperature resistance allows it to withstand 120-150℃, maintaining shape stability during the 121℃ high-pressure sterilization of retort food packaging without generating odors or deformation due to high temperatures. Meanwhile, the tensile strength of the PET layer can reach 200-250MPa, and its rigidity endows the packaging with good stiffness, capable of withstanding pressures above 30kg during stacking and transportation without easy damage, preventing contents from being squeezed.

The AL (aluminum foil) layer, usually 7-12μm thick, achieves a thickness deviation within ±0.5μm through high-precision rolling technology, serving as the core guarantee for barrier performance. It controls the oxygen transmission rate below 0.1 cm³/(m²·24h) and water vapor transmission rate under 0.5 g/(m²·24h), improving barrier properties nearly a hundred times compared to single-layer plastic packaging. This superior performance effectively blocks the intrusion of external gases and moisture, delaying oxidative deterioration of contents. In addition, the aluminum foil has a light-shielding rate of 99.9%, completely blocking ultraviolet and infrared rays, forming perfect protection for light-sensitive products such as vitamin medicines and essential oil cosmetics, preventing component decomposition due to light exposure. Experimental data shows that vitamin C tablets protected by the aluminum foil layer retain over 95% of active ingredients after 3 months of light testing, while ordinary packaging only retains 60%.

The HDPE (high-density polyethylene) layer, as the inner layer with a thickness of approximately 20-50μm, is blow-molded to achieve higher molecular density. It features a wide heat-sealing temperature range (120-160℃) and heat-seal strength over 30N/15mm, without embrittlement or cracking even at -20℃. Compliant with standards like FDA 21 CFR 177.1520 and EU 10/2011 for food contact materials, its heavy metal content is below 0.01mg/kg, and volatile organic compound residues are below 5mg/m², allowing direct contact with pharmaceuticals and food. Meanwhile, HDPE has excellent acid and alkali resistance, remaining stable within the pH range of 2-12, suitable for packaging acidic sauces like ketchup and lemon juice, as well as alcohol-containing oral liquid preparations.

The three layers are bonded via a solvent-free lamination process using polyurethane-based adhesives with a coating weight controlled at 2-3g/m². After curing in an 80-90℃ oven, the interlayer peel strength exceeds 5N/15mm, without delamination during repeated rubbing tests. This composite structure combines PET's printability, aluminum foil's high barrier properties, and HDPE's heat-sealing reliability, forming a 1+1+1＞3 synergistic effect—its overall puncture resistance reaches over 80N, far exceeding the sum of individual layers.

In pharmaceutical packaging, this material can be made into 0.3-0.5mm thick medicinal aluminum-plastic blisters, combined with PVC hard sheets to form double-aluminum packaging, creating a moisture-proof and oxygen-proof sealed environment for tablets and capsules, extending their shelf life to 2-3 years. For traditional Chinese medicine granules, its oxygen resistance can control the loss rate of volatile oil components within 5%; for temperature-sensitive suppositories, HDPE's low-temperature resistance (-40℃ without embrittlement) ensures storage stability during cold chain transportation. In lyophilized preparation packaging, its water vapor transmission rate below 0.1g/(m²·24h) can maintain the vacuum inside the packaging for over 12 months.

In food packaging, it suits long-preserved products like nuts and tea. The aluminum foil layer blocks oil oxidation, slowing the acid value increase of nuts by 60%; the PET layer's puncture resistance can withstand the impact of sharp particles under 5kg pressure, effectively preventing packaging damage. In the fast-food industry, it can withstand 121℃ high-temperature sterilization for condiment packets without releasing harmful substances; in coffee capsule packaging, its good formability can accurately match the capsule shape, ensuring no leakage during extraction.

In cosmetics packaging, used as outer hoses for creams and serums, the thickness can be reduced to below 40μm, reducing weight while maintaining stiffness. The PET layer can achieve exquisite patterns with over 8 colors through gravure printing, while the aluminum foil layer blocks 99% of ultraviolet rays, extending the retention period of active ingredients in vitamin C serums to 18 months. In perfume sample packaging, its gas barrier properties prevent fragrance volatilization, ensuring stable scent concentration.

In terms of performance testing, it must comply with multiple international standards: oxygen transmission rate is tested by the differential pressure method according to ASTM D3985, water vapor transmission rate by the infrared sensor method according to ISO 15106-3, heat-seal strength by T-peel test according to ISO 11339, and interlayer adhesion strength according to GB/T 8808. Different regions have special requirements: Chinese pharmaceutical packaging must comply with YBB 00132002, the EU market requires CE PED certification, and the US market needs to meet FDA's DMF file requirements.

With rising environmental demands, lightweight PET+AL+HDPE composite foils (total thickness below 50μm) are becoming popular, reducing raw material consumption by 30% compared to traditional materials while maintaining performance. Recycling technology is also constantly breaking through—aluminum foil and plastic layers can be separated by alkali immersion, with aluminum foil recovery rate over 95%, and PET and HDPE can be used for recycled packaging materials after cleaning and granulation. In the future, applications of HDPE inner layers with silver ion antibacterial agents (antibacterial rate 99%) or bio-based PET substrates (50% plant-sourced) will further expand its potential in high-end packaging markets.