What Is Bopp

BOPP film, also known as biaxially oriented polypropylene film, is a versatile material. From food packaging to product labels, BOPP film is known for its durability and transparency. In this article, let’s take a look at the concept of BOPP film, the characteristics of BOPP plastic film, and the production process.

BOPP Film Definition

BOPP film is a type of plastic film widely used in the packaging, labeling, and laminating industries. It is made by extruding polypropylene plastic into a thin film, which is then stretched in two perpendicular directions. This process enhances the strength and durability of the film, making it resistant to tearing, punctures, and other forms of damage.

BOPP film has moisture barrier properties, sealing capabilities, high clarity, and formability, making it a top choice for food packaging around the world.

BOPP Material Properties

Extended Shelf Life
BOPP films offer the best moisture barrier, and its metallized version provides the best oxygen barrier for goods.

High Clarity
BOPP films offer excellent clarity.

High Product Quality
BOPP films are heat sealable and machinable in addition to their barrier properties.

High Appearance
BOPP films are opaque white films with excellent gloss and opacity, giving product packaging an attractive appearance.
The appearance of metallized films makes your products stand out on the shelf. The material’s high surface tension enables post-lamination processes such as stamping, UV spot coating, and embossing.

Flexibility
BOPP films can be easily converted into bags, pouches, laminates, and other forms of packaging.

Densité
BOPP films have a low density and are lighter than all other commonly used flexible packaging films.

Environmental Sustainability
Can BOPP films be recycled? Recycled BOPP resins are often used to make injection-molded parts, furniture such as tables and chairs, and other household products such as carpets.

Bopp Film Manufacturing Process

The following is a detailed description of the BOPP film manufacturing process:

​Step 1: Providing the raw materials
Isotactic polypropylene is the main raw material for the center layer. The outer layers are made of ethylene-propylene copolymer and/or ethylene-butane-propylene copolymer. A hopper system is used to feed these ingredients into the extruder.

Step 2: Extrusion
The raw materials are melted and heated to 200-230°C in the extruder and then fed into the machine to form a film.

Step 3: Cooling
The film is immersed in water to cool.

Step 4: Machine Direction (MDO)
The film passes through rollers to increase the temperature and prepare for longitudinal stretching, and the film is moved between rollers to perform the stretching process. After the film is stretched to five times its original length, the polymer chains are aligned at this time. This step can improve the mechanical quality of the film, and the thickness can be reduced by up to five times. The film is reheated after stretching to eliminate the tension caused by the stretching process.

Step 5: Transverse Direction (TDO)
After the film leaves the longitudinal stretching area, metal clamps grab the film on both sides. After the film is heated in the middle furnace, it is stretched horizontally (i.e., horizontally stretched to 9 times its original width) through diverging tracks. At this point, the mechanical properties of the BOPP film are improved, and its thickness is reduced by up to 9 times. After stretching, the film is brought into equilibrium with the tension formed during the stretching process.

Step 6: Measuring Thickness And Heat Treatment
The BOPP film enters the automatic thickness measurement. One of the faces is then heat-treated or corona-treated to prepare the film for further processing treatments, in particular to modify the surface as an anchor point for materials such as inks (printing), glues (lamination), or metals (printing).

Step 7: Rolling
Once wound on a roll of film, the film is cut to specific dimensions.

Step 8: Measuring Data
The following data are measured for the final BOPP film:

• Density and thickness
• Elastic modulus, elongation at break and tensile strength
• Haze (opacity) and gloss (shiny appearance)
• Coefficient of friction between films and between film and metal
• Seal strength and °C value
• Temperature stability (heat shrinkage)

The film has at least three layers with a thickness of 15 to 60 microns; the middle layer is the thickest and is mainly responsible for the mechanical properties, while the two outer layers give the film different properties (i.e., heat-sealing properties).

Bopp Film Applications

BOPP film is mainly used in the packaging and lamination industries, as follows:

BOPP film is a very important flexible packaging material. BOPP film is colorless, odorless, tasteless, non-toxic, and has high tensile strength, impact strength, rigidity, toughness, and good transparency. BOPP film has low surface energy and needs corona treatment before gluing or printing. However, after corona treatment, BOPP film has good printing adaptability and can be printed in multiple colors to obtain an exquisite appearance, so it is often used as the surface material of composite film.

Emballage

BOPP film is durable and moisture-resistant and can be used to make many different types of packaging, including stand-up pouches, vacuum bags and side-seam bags.

Label

The high transparency and clarity of BOPP film allows this film to be used for labels. The smooth surface is suitable for printing, and labels can be created.

Laminated Materials

BOPP can be used for laminating materials, including paper, aluminum foil, and other materials. BOPP film improves the strength and durability of laminated materials.

Pharmaceutical Packaging

BOPP can be used to package medical products and devices, as well as sachets and blister packs.

Adhesive Tape

BOPP is commonly used to produce many different types of tape, including packaging tape and scotch tape, which are both transparent and durable.

Agricultural Mulch Film

BOPP film is used to produce agricultural films, such as greenhouse mulch films. Its high transparency allows light to penetrate, while its weather resistance helps protect plants from the effects of harsh weather.

BOPP Material

What is bopp film? BOPP film is produced from PP resin (polypropylene). This type of plastic is harder than PE and is considered to have better tensile resistance and higher transparency than plastic. In addition, BOPP film is also called thin film, with a thickness of 10 to 40 microns. The reason is that the density of PP particles is low, only 0.90 g/m3.

Bopp holographic film: It is a transparent BOPP film with a moldable functional layer. It can be molded without a pre-coated moldable layer. Bopp holographic film is used for anti-counterfeiting packaging after aluminum plating or vapor deposition or combined with cardboard or non-abrasive materials to be used as packaging boxes for cigarettes, medicines, foods, etc. Holographic bopp film is relatively rare in China and is generally used for high-end commodity anti-counterfeiting and decorative packaging, which has certain requirements for production technology.

Bopp thermal lamination film: mainly used for printing and bag making. BOPP single/double thermal lamination film is used for independent packaging of small products after partial printing, suitable for vertical or horizontal packaging; the product is simply printed on the surface and then heat-sealed (lap-joined) to package CDs, snow cakes, cakes, etc.; Bopp thermal lamination film is laminated with BOPP and BOPET films with back printing and then self-sealed to package various daily electrical appliances, and is used for high-speed independent packaging after printing.