Material Selection Guide for Thermal Bag Foil: AL/PE Heat Sealable Laminate vs. Metalized Film Bag Material

The rapid growth of cold chain logistics and food delivery services has driven sustained demand for thermal insulated bags. As the core insulation material inside these bags, the choice of aluminum foil laminate directly impacts thermal retention, seal integrity, and production cost. This article provides a systematic comparison of two mainstream raw materials — AL/PE heat sealable foil laminate and metalized film bag material — covering structure, heat sealing performance, insulation efficiency, production compatibility, and supply chain considerations, offering practical guidance for thermal bag manufacturers.

1. Structural Analysis of Thermal Bag Foil Materials

The two primary foil materials differ significantly in layer construction:

AL/PE Heat Sealable Foil Laminate combines pure aluminum foil (AL) with a polyethylene (PE) heat-seal layer in a two-layer AL/PE or three-layer PET/AL/PE structure. The pure aluminum foil provides exceptional reflective insulation with a reflectivity exceeding 95%, while the PE layer serves dual purposes — as both the heat-seal interface and a moisture barrier. The three-layer variant adds a PET support layer that increases film stiffness, making it suitable for reusable thermal bags that require structural durability.

Metalized Film Bag Material uses PET or BOPP as the base substrate, with a vacuum-deposited aluminum layer on the surface, laminated with a PE heat-seal layer. The metalized layer achieves approximately 85%-90% reflectivity — slightly below pure foil — but at a lower material cost and with a lighter overall gauge. The silver appearance closely resembles pure aluminum foil, making it a common choice for mid-range and single-use thermal delivery bags.

2. Heat Sealing Performance and Production Compatibility

Heat sealability is a critical selection factor. AL/PE heat sealable foil laminate typically features a PE layer thickness of 15-30μm, with a sealing temperature range of 120-150°C and seal strength exceeding 8N/15mm. The extrusion lamination process creates a strong AL-PE interface bond, minimizing delamination risk during heat sealing.

Metalized film bag material also uses PE as the heat-seal layer, but the metalized coating sits on the PET substrate surface rather than as an independent foil layer. During high-temperature sealing, aluminum migration into the PE layer can occur, causing darkened seal areas. This makes metalized film better suited for low-temperature rapid sealing (130-140°C) with seal times of 0.5-1 second.

For production lines, AL/PE heat sealable laminate is recommended for wide-format sealing machines (600-1200mm web width), while metalized film bag material pairs better with narrow-width rapid sealing equipment. Always match the material's sealing temperature window to your existing equipment parameters.

3. Insulation Performance Comparison

Under standard test conditions (ambient 25°C, 500ml water at 60°C inside the bag):

• AL/PE Heat Sealable Foil Laminate thermal bag: Internal temperature approximately 48°C after 2 hours, 38°C after 4 hours. The high reflectivity of pure foil effectively blocks radiative heat loss, while PE blocks convective transfer.
• Metalized Film Bag Material thermal bag: Approximately 45°C after 2 hours, 35°C after 4 hours. The slightly lower reflectivity shows a modest performance gap, but when combined with a bubble layer, insulation can approach pure foil levels.

In practice, thermal bags use multi-layer constructions. The foil layer typically pairs with bubble insulation or foam padding. AL/PE laminate combined with a bubble layer (foil bubble insulation material) delivers the best thermal performance, while metalized film paired with foam offers a cost-effective alternative.

4. Cost and Supply Chain Considerations

AL/PE heat sealable foil laminate costs approximately 20%-30% more than metalized film due to the use of pure aluminum foil. However, for volume purchases (over 5 tons/month), Hongcheng Technology offers custom width and thickness combinations that reduce unit costs effectively. Available foil gauges include 7μm, 9μm, and 12μm; PE thickness ranges from 15-50μm, accommodating different product positioning needs.

Metalized film bag material offers cost advantages through lower substrate pricing and simpler processing, ideal for price-sensitive customers and mid-range thermal bag mass production. Hongcheng supplies metalized film in widths from 500-1500mm with adjustable metalized layer thickness, supporting both small-batch trials and large-scale continuous supply.

From a supply chain stability perspective, AL/PE foil laminate is more sensitive to aluminum ingot price fluctuations — quarterly price-lock contracts are recommended. Metalized film pricing is relatively stable, suitable for on-demand purchasing.

5. Selection Recommendations by Application

Based on product positioning and target markets:

Premium Thermal Bags (cold chain, medical transport): AL/PE heat sealable foil laminate or PET/AL/PE three-layer composite is the first choice for optimal insulation and seal reliability. Recommended specification: 12μm foil + 25-30μm PE, combined with bubble insulation layer.

Mid-Range Thermal Bags (food delivery, fresh produce): Metalized film bag material offers the best cost-performance ratio. The metalized layer meets basic insulation needs while PE ensures efficient bag production. Foam inner lining can enhance thermal retention.

Single-Use Thermal Bags (fast food delivery, short-distance): Thin-gauge metalized film (total thickness 40-60μm) is the most economical option — fast sealing speed, low material cost, suitable for disposable applications at scale.

6. Hongcheng Technology Supply Capabilities

Hangzhou Hongcheng Technology Co., Ltd. specializes in aluminum foil composite materials and PE laminated films, offering comprehensive material solutions for thermal bag insulation:

• AL/PE heat sealable foil laminate: 7/9/12μm foil + 15-50μm PE, bubble layer lamination available
• Metalized film bag material: PET metalized + PE heat-seal layer, widths 500-1500mm
• PET/AL/PE three-layer composite: High-strength thermal bag grade, puncture-resistant, fold-durable

All products support custom widths, thicknesses, and interlayer structure combinations. Monthly production capacity is stable, fulfilling needs from trial batches to continuous high-volume supply.

For material selection consultation or sample testing, contact the Hongcheng Technology technical team.

Phone/WeChat: +86 13758223270 Email: wendy@hcdxcl.com.cn