Understanding the Differences Between CPP, OPP, BOPP, and MOPP Films in One Article

As the packaging industry rapidly evolves, CPP film, OPP film, BOPP film, and MOPP film have become the preferred materials for many businesses due to their unique properties. But what are the essential differences between these seemingly similar films? How do distinct stretching processes give them their unique characteristics? This article will explore these details.

1. CPP, OPP, BOPP, MOPP Films: Name Origins and Detailed Explanation of Stretching Processes

PP film is the general term for polypropylene film. Different production methods yield PP films with varying characteristics for diverse applications, leading to different names. The most common are CPP, OPP, BOPP, and MOPP films. All four refer to PP films produced from polypropylene plastic raw materials via an extruder, each undergoing a distinct “film stretching” process.

Differences in Film Stretching Methods

1. CPP Film: Abbreviation for Cast Polypropylene, this refers to an unstretched, unoriented flat extruded film.
2. OPP Film: Abbreviation for Uniaxially Oriented Polypropylene, this film is stretched unidirectionally in the TD (Transverse Direction)
3. BOPP Film: Abbreviation for Biaxially Oriented Polypropylene, i.e., “biaxially oriented polypropylene film,” stretched in both MD (Machine Direction) and TD directions.
4. MOPP Film: Abbreviation for Uniaxially Oriented Polypropylene, this film is stretched unidirectionally along the MD (Machine Direction).

▶ MD Direction: Refers to the Machine Direction, i.e., the longitudinal direction of the film.

▶ TD Direction: Refers to the Transverse Direction, i.e., the transverse direction of the film.

For those who want to learn about CPP and MOPP extrusion production lines, please check the links below and contact us:

🔗 Webpage link for CPP cast film extrusion production line

🔗 Webpage link for MOPP uniaxial stretching production line

2. The Core Value of Film Stretching: The Key to Performance Enhancement

Generally, plastic films are “stretched” for the following purposes:

1. To improve dimensional stability.
2. To enhance mechanical properties.
3. To increase gloss and transparency.
4. To enhance gas barrier properties.

The above four points are the reasons for film stretching. Stretching polymers causes macromolecules to align regularly in the stretching direction. This alignment leads to higher coordination, improved material density and film strength, enhanced gas barrier properties, better mechanical properties, and increased surface gloss and transparency.

This section mainly discusses the differences in characteristics among CPP, OPP, BOPP, and MOPP films. The following are some sorted FAQs:

FAQ

• Can CPP film be heat-sealed? Yes. CPP has excellent heat-sealing properties and is often used as the inner layer of composite films.
• Is BOPP more expensive than OPP? Generally, BOPP has a more complex process, so the cost is slightly higher than OPP at the same thickness.
• Is MOPP easy to tear? It has high longitudinal strength but weak transverse strength, making it prone to cracking and tearing in specific directions.
• Is OPP suitable for food packaging? It can be used as the outer layer of food packaging, usually compounded with CPP.
• Which is better, CPP or PE film? It depends on the application. CPP has higher stiffness, while PE is softer with better sealing properties.
• Can these films be recycled? Most PP-based films are recyclable but require proper sorting to avoid mixing with other materials.

3. What is the Difference Between PP Film and OPP Film?

PP film refers to polypropylene film. The “PP film” we commonly mention can be CPP film, BOPP film, or other functional PP films (e.g., PP protective film, PP pearlescent film, PP heat-sealing film, PP composite film). Therefore, “PP film” is simply a general term.

In fact, PP films can have various functions and undergo different stretching processes.

OPP film is a product created by applying the “uniaxial stretching method” to PP film, extending it in the TD direction. This process enhances its tensile strength, gloss, and gas barrier properties, making it ideal for product packaging bags or transparent tape.

Conclusion:

• Both PP film and OPP film are made of polypropylene.
• PP film is just the general term for polypropylene film.
• Stretching PP film with a TDO stretcher produces OPP film.
• OPP film boasts enhanced mechanical properties, making it suitable for packaging bags and tapes

4. What is the Difference Between CPP Film and OPP Film?

CPP film, also known as cast polypropylene or unstretched polypropylene film, is produced by plasticizing and melting PP raw materials in an extruder. The molten material is then extruded through a T-shaped die, cast onto a cooling roller for rapid cooling, and finally drawn, trimmed, and calendered into a sheet.

This process gives CPP film the following characteristics:

• Higher stiffness than PE film.
• Excellent moisture and odor resistance.
• Customizable to produce various functional films.
• Environmentally friendly, as no solvents are used in its production process.
• Lightweight, high-strength, high-toughness, and excellent impact resistance, making it a primary choice for composite materials.

Conclusion:

The most significant difference between CPP film and OPP film lies in whether the film is stretched.OPP utilizes stretching technology to enhance film performance. Although CPP film is unstretched, its formulation can be adjusted to customer needs, broadening its application range and versatility.

For example, by altering the film’s color, finish (matte/glossy), anti-fogging properties, or printability, various functional PP films can be produced through different formulations.

5. What are the Differences Between OPP, BOPP, and MOPP Films?

• BOPP film: Biaxially oriented polypropylene film.
• OPP film: Transversely oriented polypropylene film.
• MOPP film: Longitudinally oriented polypropylene film.

a. What is the Difference Between OPP Film and BOPP Film?

The physical properties and characteristics of OPP and BOPP films show no significant differences under actual use conditions; they can even be regarded as the same film. OPP film is produced by an extruder, undergoing longitudinal stretching (MD direction) during production, followed by transverse stretching (TD direction) via a stretcher. This entire process constitutes “biaxial stretching,” resulting in a film similar to BOPP film produced by a biaxial stretcher. Therefore, there is no significant difference in the properties of OPP and BOPP films.

For materials like PET or PC, uniaxial and biaxial stretching methods yield distinct characteristics. For example, PET and BOPET exhibit clear differences in optical properties or refractive index, but the distinctions between BOPP and OPP films are relatively minor.

b. What is the Difference Between OPP Film and MOPP Film?

• OPP film is stretched transversely.
• MOPP film is stretched longitudinally.

When MOPP film is stretched longitudinally, it aligns the molecular chains in the forward direction. This results in very high longitudinal tensile strength, but its transverse tensile strength remains very weak, making it easy to break.

As mentioned, OPP film has properties similar to BOPP film, exhibiting good tensile strength in both longitudinal and transverse directions, making it not easy to break.

Conclusion:

• OPP vs. BOPP Films: While produced by different manufacturing processes, their property differences are minimal, so from an application perspective, they are often considered the same product.
• OPP vs. MOPP Films: MOPP film boasts significantly greater longitudinal tensile strength than OPP film. Therefore, MOPP film is ideal for applications requiring high uniaxial tensile strength, whereas OPP film offers balanced tensile strength in both longitudinal and transverse directions.

6. A Table to Understand the Differences Between CPP, OPP, BOPP, and MOPP Films at a Glance

🔸 CPP Film: Cast film, unstretched, can be further adjusted in formulation to produce various functional PP films, such as anti-fog film, antistatic film, anti-puncture film, matte film, etc.

🔸 OPP Film: Transversely oriented PP film, similar in properties to BOPP film, used in products like tapes, labels, and packaging.

🔸 BOPP Film: A biaxially oriented PP film with excellent gas barrier properties, widely applied to packaging bags for daily necessities such as food, clothing, and cigarettes.

🔸 MOPP Film: A longitudinally oriented PP film with high uniaxial tensile strength, primarily used in strapping tapes, item labels, and tire linings.

The table below summarizes the characteristic differences among CPP, OPP, BOPP, and MOPP films:

1. CPP film has better extensibility and formability and can be customized with various properties.
2. In terms of gas barrier properties, PP films themselves have good gas barrier effects, so extended OPP or BOPP films are even better.
3. Regarding MOQ (Minimum Order Quantity), since MDO and TDO stretching mechanisms require a certain quantity for production, the MOQ for stretched films is generally not low.

In summary, while CPP, OPP, BOPP, and MOPP films all belong to the polypropylene film family, their distinct stretching processes lead to unique characteristics in performance and application. CPP film, with its unstretched structure and flexible formulation advantages, holds an important position in customized functional films. OPP and BOPP films, with their excellent gas barrier properties, are widely used in diverse product packaging; MOPP film, with its high uniaxial tensile strength, plays an irreplaceable role in specific packaging and strapping applications. A deeper understanding of the differences between these films provides a scientific basis for selecting appropriate packaging materials, thus meeting diverse production and application needs.