Vacuum Aluminum Metallized 4.5 Micron BOPET polyester Film

Vacuum Aluminum Metallized 4.5 Micron BOPET polyester Film
Vacuum aluminum metallized 4.5-micron (4.5um) BOPET (VMPET) is a high-performance, ultra-thin specialty material. 
In this configuration, the 4.5µm polyester base provides the structural carrier, while a nanometer-scale layer of vaporized aluminum provides high-reflectivity and barrier properties.
Here is a detailed breakdown of its properties, applications, and technical significance.
1. Key Technical PropertiesUltra-Thin Gauge: At 4.5 microns, it is one of the thinnest commercially available metallized films. 
This allows for maximum "yield" (more square meters per kilogram of material).
High Barrier Performance: The aluminum layer significantly reduces the Oxygen Transmission Rate (OTR) and Water Vapor Transmission Rate (WVTR) compared to clear film.
Thermal Stability: As a BOPET-based material, it maintains dimensional stability at highertemperatures (melting point ≈ 260° C), which is critical for heat-sealing and high-speedlamination.
Optical Density (OD): Typically ranges from 1.8 to 2.5. This determines the "brightness"and opacity of the silver finish.
High Tensile Strength: Despite its thinness, the biaxial orientation gives it the mechanicalstrength to be processed on industrial coating and slitting machines without stretching orsnapping
2. Primary Applications
A. Thermal Transfer Ribbons (TTR) - Premium Grade
The Role: Metallized 4.5um BOPET is often used as the base for high-end resin or wax-resin ribbons.
The Benefit: The metallization can act as a "heat-shield" or a primer layer that improvesthe release of the ink and protects the print head from overheating.
B. High-Performance Lamination (Flexible Packaging)
The Role: It acts as the middle barrier layer in a multi-layer structure (e.g.,BOPP /VMPET 4.5m / PE).
The Benefit: It provides the barrier of a much thicker film while keeping the totalpackaging weight extremely low. This is ideal for snack food pouches and "lightweighting"initiatives.
C. Insulation & Electronics
The Role: Used in Cryogenic Insulation (multi-layer insulation or MLI) and radiantbarriers.
The Benefit: The silver surface reflects up to 98% of radiant heat. Its ultra-thin natureallows for many layers to be wrapped in a small space (crucial for aerospace and LNG tankinsulation).
Capacitors: Some ultra-thin metallized BOPET is used in the manufacturing of filmcapacitors.
D. Decorative & Yarn Applications
The Role: Slit into tiny strips to create Metallic Yarn (Lurex) for textiles.
The Benefit: Provides high shine and metallic luster while remaining soft enough to bewoven into fabrics.
3. Comparison: Metallized vs. Aluminum Foil
4. Technical Keywords for Sourcing
When communicating with suppliers (like Shuangxing, Toray, or CloudFilm), use thesespecific terms:
VMPET 4.5mic: Short for Vacuum Metallized PET.
Metal Bond Strength: The force required to peel the aluminum from the PET (crucial forlamination).
 Dyne Level: Usually needs to be > 42 dyne for lamination adhesive to stick.
 Yield (m2/kg): For 4.5uum, the yield is approximately 158 m2/kg.
Pro-Tip for Purchasing:
If you are buying 4.5um Metallized Off-grade (Substandard), it is excellent for paper-to-cardboard lamination (like luxury cigarette or liquor boxes). The paper provides the strength,and the "substandard" metallization still provides 100% of the required metallic aesthetic for amuch lower price.