BOPP plastic film, or Biaxially Oriented Polypropylene film, is a versatile and widely used material in various industries. From food packaging to product labeling, BOPP film is valued for its strength, transparency, and durability. In this article, we will examine the concept of BOPP film, its characteristics, and the manufacturing process.

1. What is BOPP Film?

1.1 Definition

What is BOPP film?

BOPP (Biaxially-Oriented Polypropylene) film is a type of plastic film with a wide range of applications in the packaging, labeling, and laminating industries. It is produced by extruding polypropylene resin into a thin film and then stretching it in two perpendicular directions, a process known as biaxial orientation. This technique improves the strength and durability of the film, making it resistant to tearing, puncturing, and other forms of damage.

BOPP plastic films are the preferred substrate for food packaging worldwide due to their inherent moisture barrier properties, sealability, high clarity, excellent graphic reproduction, and strong shelf appeal. They also offer the advantage of achieving a monolayer or homogeneous structure.

BOPP film is most commonly used as a co-extruded, heat-sealable, reverse-printed film for food packaging. In the labeling industry, it is highly valued because of its yield benefits (with the lowest density of 0.55 for the IML orange peel effect), as well as its recyclability with PP containers and other materials.

The demand for BOPP films continues to grow globally, largely driven by the expansion of the flexible packaging sector.

1.2 Benefits of Using BOPP Plastic Film

BOPP plastic film has become one of the most widely used materials in packaging, labeling, and laminating applications thanks to its numerous advantages. Below are the key benefits of BOPP film:

Shelf Life Extension

BOPP film provides the best moisture barrier among commonly used plastic films, while its metallized version offers excellent oxygen barrier properties. These features are particularly important in food packaging, as they help extend product shelf life and reduce food waste.

High Clarity

The outstanding transparency of BOPP film makes it ideal for packaging where product visibility is essential. Clear packaging enhances customer confidence, increases sales, and improves the overall shelf appeal of the product.

Product Quality

With limited gauge variation, BOPP film ensures consistent and reliable sealing performance. It also offers strong heat-seal strength, a lower seal initiation temperature, a wide sealing range, and excellent machinability, all of which are critical in food packaging applications.

Aesthetic and Graphics

Clear BOPP films deliver high visual appeal, supporting high-quality halftone and multicolor printing. White opaque BOPP films provide excellent opacity, whiteness, and gloss, further enhancing the packaging’s attractiveness. Metallized BOPP films offer a premium metallic finish that helps products stand out on shelves. In addition, the high surface tension of BOPP film allows for post-lamination treatments such as foil stamping, UV spot coating, and embossing.

Versatility

BOPP film can be easily converted into bags, pouches, laminates, and other packaging formats, offering manufacturers flexible and cost-effective solutions. This adaptability ensures that packaging can be tailored to meet both protective and aesthetic requirements.

Density Advantage

Compared with other flexible packaging films, BOPP film has a lower density, which increases yield during conversion and reduces plastic consumption per product. Lighter rolls are also easier to handle and transport, providing additional efficiency benefits.

Sustainability

BOPP film is recyclable and has a relatively low carbon footprint compared with alternatives like polyester. Its lower melting point requires less energy for processing, and reprocessed BOPP granules can be reused in injection-molded products such as furniture and household items. For these reasons, BOPP is considered one of the most eco-friendly choices in flexible food packaging.

Cost-Effectiveness

BOPP film is widely available, easy to process, and cost-efficient on a per-square-foot basis compared to many other packaging materials. This makes it a practical choice for businesses aiming to reduce costs without compromising on packaging quality.

2. What is BOPP film used for?

BOPP film is a highly versatile material that finds applications across many industries. Its strength, durability, and clarity make it a preferred choice for a wide range of products. Key applications include:

Food & Beverage Packaging

BOPP film is widely applied in food and beverage packaging because of its high strength, durability, and moisture resistance. It is commonly used to produce stand-up pouches, vacuum pouches, and side gusseted bags. These formats protect products from damage during transportation and storage, while maintaining product quality.

Labeling and Branding

Thanks to its high transparency and smooth surface, BOPP film is ideal for labeling. It allows high-quality printing, which makes it possible to create attractive and informative labels. This contributes to stronger brand recognition and improved customer loyalty.

Laminating

BOPP film is used to laminate paper, cardboard, aluminum foil, and printed materials. Laminating with BOPP enhances strength and durability, making it suitable for brochures, posters, and other printed products that need both protection and visual appeal.

Tamper Evident Films

BOPP film plays a role in producing tamper-evident films, used to secure products and prevent unauthorized access. Typical applications include packaging for pharmaceuticals, electronic components, and other sensitive products. This ensures safety, integrity, and consumer confidence.

Personal Care Product Packaging

BOPP film is used in packaging cosmetics, shampoos, and other personal care products. Its durability and moisture resistance protect product quality, while its clarity allows for eye-catching packaging designs that enhance brand image.

Medical Packaging

In the medical sector, BOPP film is used for packaging devices and supplies. It can be formed into bags, pouches, and blister packs, providing protection and allowing clear visibility of the contents for easy identification.

Adhesive Tape

BOPP film is a common material in adhesive tape production, including packaging tape and Scotch tape. Its strength and tear resistance make it reliable in applications where secure sealing is required.

Agricultural Films

BOPP film is also applied in agriculture for greenhouse covers and mulch films. Its transparency ensures light penetration, while its weather resistance protects crops from environmental stress.

3. How is BOPP Plastic Film Made?

In the flexible packaging sector, BOPP (Biaxially-Oriented Polypropylene) film has been utilized for many years. It is well regarded for its affordable price, superior optical and mechanical features, and exceptional gas barrier qualities, particularly water vapor.

Below is a detailed demonstration of the BOPP film manufacturing process:

Step 1. Raw Material Feeding System

Isotactic Polypropylene, a semi-crystalline, thermoplastic polymer, serves as the primary raw material in the center layer. Ethylene-propylene copolymers and/or ethylene-butane-propylene copolymers are used for the outer layers. A hopper system introduces these ingredients into the extruders.

Step 2. Extrusion

The materials are melted and heated to 200–230°C within the extruders before being fed into the extrusion head, where they emerge as a foil.

Step 3. Foil Cooling

The foil comes into direct contact with a chilled cylinder and is then submerged in a water bath to cool the melt.

Step 4. Machine Direction Orientation (MDO)

The film passes over rollers that raise the temperature and prepare it for longitudinal stretching (machine direction). Stretching is achieved by moving the foil between rollers that spin at increasing rates. At this stage, the polymer chains align, and the foil is stretched up to five times its original length. This improves the film’s mechanical qualities and reduces thickness.
After stretching, the film is reheated in an annealing phase to remove tension created during stretching.

Step 5. Transverse Direction Orientation (TDO)

After longitudinal stretching, a chain of metal jaws grabs the film on both edges. The film is heated in an oven and stretched transversely (up to nine times its original width). The macromolecules align transversely, further improving mechanical properties and reducing thickness.
Following this, the chain and film converge, allowing the tension to balance out (annealing phase).

Step 6. Thickness Measurement and Flame Treatment

At this stage, the film’s thickness is automatically measured across its full width. One side of the film undergoes flame or corona treatment to prepare the surface for conversion processes such as printing, laminating, or metallization.

Step 7. Reel Winding

The finished film is wound onto reels and then slit to specific dimensions.

Step 8. Film Measurements

The final product is tested against several performance metrics, including:

• ·  Density, grammage, and thickness

• ·  Elastic modulus, elongation at break, and tensile strength

• ·  Haze (opacity) and gloss (appearance)

• ·  Friction coefficient between films and metals

• ·  Sealing strength and sealing temperature threshold

• ·  Temperature stability (heat shrinkage)

Typically, BOPP film has at least three layers with a thickness between 15 and 60 microns. The center layer provides most of the mechanical strength, while the outer layers deliver properties such as heat-sealing. Additives may also be included depending on the intended end-use application.

4. BOPP Film Raw Material

BOPP (Biaxially-Oriented Polypropylene) film is produced from PP (Polypropylene) plastic resins. This type of plastic is harder than PE and is recognized for its good tensile strength and higher transparency compared to many other plastics.

BOPP film is typically manufactured as a thin film, with a thickness ranging from 10 to 40 microns. This characteristic is largely due to the low density of PP particles, which is only 0.90 g/m³.