BOPP vs. BOPET vs. BOPA: Decoding the Differences and Applications in Flexible P

Mar 12, 2025

In the fast-evolving world of flexible packaging, BOPP, BOPET, and BOPA films stand out as key players. But what sets them apart, and how do they serve diverse industries?

Plastic films typically refer to flat, glossy or matte, transparent or opaque, relatively rigid or flexible plastic film products made from materials such as polypropylene, polyethylene, polyester, or polystyrene, with a thickness of 0.25 mm (250 µm) or less. These films are widely used across various industries, including electronics, consumer goods, labeling, protective printing, pharmaceuticals, chemicals, optical imaging, and new energy applications. In recent years, guided by national economic development policies, plastic film companies in China have actively adjusted their product structures, developed new technologies, and introduced innovative products, achieving sustained and stable growth. China has become one of the world’s largest producers of plastic packaging, with its annual plastic film output ranking among the global leaders.

Based on the raw materials used, plastic film products can be categorized into types such as polyethylene film, polypropylene film, polyester film, nylon film, polyvinyl chloride film, and polystyrene film. Among these, biaxially oriented films—namely BOPP (Biaxially Oriented Polypropylene), BOPET (Biaxially Oriented Polyethylene Terephthalate), and BOPA (Biaxially Oriented Polyamide)—are the three primary substrates for plastic film packaging and are the most widely applied in the packaging sector.

While there is some overlap in their application fields, these three films serve distinct purposes. BOPP is extensively used in food and beverage packaging, adhesive tapes, apparel, consumer electronics, daily chemicals, and tobacco industries. BOPET finds broad applications in packaging, printing, magnetic recording, photosensitive materials, insulation, construction, and decorative industries. BOPA is predominantly utilized in flexible food packaging, daily chemical packaging, pharmaceutical packaging, and soft-pack battery applications.

So, what are the key differences between BOPP, BOPET, and BOPA films?

Chemical Structure and Raw Materials

• BOPP Film: Made from polypropylene (PP) through the polymerization of propylene, its molecular structure consists mainly of hydrocarbon chains, classifying it as a non-polar polymer.
• BOPET Film: Produced from polyethylene terephthalate (PET), its molecular backbone contains ester groups, formed by the polymerization of terephthalic acid and ethylene glycol via transesterification or direct esterification methods.
• BOPA Film: Derived from polyamide 6 (nylon 6), its molecular structure includes polar amide groups (-CO-NH-), where the -NH- group can form hydrogen bonds with the -C=O group.

Performance Characteristics

• Mechanical Properties: BOPP film’s tensile strength and Young’s modulus increase significantly with higher stretching ratios, though its elongation at break decreases notably. BOPET film offers excellent mechanical properties, with high rigidity and hardness. BOPA film excels in toughness, tensile strength, tear strength, impact resistance, and burst strength, making it one of the top-performing plastic materials.
• Barrier Properties: BOPP film serves as an effective moisture barrier. BOPET film provides strong resistance to water, gases, and odor retention. BOPA film offers excellent barrier properties against oxygen, nitrogen, carbon dioxide, and odors, preserving flavors and aromas effectively.
• Heat and Cold Resistance: BOPP film maintains good performance across a wide temperature range but has relatively weaker heat resistance compared to BOPET and BOPA. BOPET film is suitable for temperatures ranging from -70°C to 150°C. BOPA film can be used long-term between -60°C and 150°C.
• Chemical Stability: BOPP film exhibits high chemical stability. BOPET film resists oils, most solvents, and weak acidic or alkaline liquids. BOPA film offers superior resistance to oils, greases, and chemical solvents.
• Printability: As a non-polar polymer, BOPP film has low surface tension and is difficult to wet with most inks and solvents, resulting in the poorest printability. BOPET film, after corona treatment, achieves a surface tension of up to 52 mN/m, making it highly suitable for printing and lamination. BOPA film, with its polar structure, requires no surface treatment prior to printing and offers the best printability.

Manufacturing Processes

• BOPP Film: Produced by extruding molten polypropylene through a narrow die to form a sheet or thick film, which is then stretched in a specialized machine at specific temperatures and speeds—either simultaneously or sequentially—in two perpendicular directions (longitudinal and transverse). The film is finalized through cooling, heat treatment, or additional processes like corona treatment or coating.
• BOPET Film: Made by drying polyester resin, followed by melt extrusion, casting, biaxial stretching, traction, and winding.
• BOPA Film: Manufactured either by simultaneous biaxial stretching via blown film processes or stepwise biaxial stretching using a T-die extrusion method. Production techniques include flat film and tubular film methods, with the synchronous biaxial stretching process in flat film production effectively mitigating the bowing effect.

Application Fields

• BOPP Film: Widely used in packaging for food, daily necessities, and pharmaceuticals—such as food and sealant packaging, general-purpose printed bags, cable overwraps, and cough syrup strip packaging—as well as substrates for adhesive and pressure-sensitive tapes.
• BOPET Film: Commonly applied in packaging requiring high barrier properties, mechanical strength, and heat resistance, such as food, daily chemical, and electronic product packaging. It is also used in vacuum metallized films and coated films.
• BOPA Film: As a premium flexible packaging material, it is widely adopted in food processing, pharmaceutical, and chemical product packaging. It is especially suited for frozen, vacuum, and retort packaging, offering excellent preservation of freshness and aroma, and is also used in soft-pack battery applications.