A co-extrusion casting film machine is a highly versatile system designed for producing multi-layer functional films used in packaging, industrial protection, medical applications, and high-performance films. One of the defining advantages of co-extrusion technology is its ability to combine different polymers into a unified structure, each layer fulfilling a specific mechanical, optical, or barrier requirement. Because modern manufacturing demands films with stronger durability, better stretch behavior, precise optical clarity, or superior adhesion, understanding which materials can be processed is essential for building an efficient production workflow. Advanced systems such as SAIBANG’s Casting Machine support a wide range of polymer materials, giving manufacturers flexibility in customizing film properties based on end-use requirements.

This article explores the key material categories commonly processed on co-extrusion casting lines, their characteristics, and how they contribute to multi-layer casting film performance.

1. Polyethylene-Based Materials (LDPE, LLDPE, HDPE)

Polyethylene (PE) is one of the most widely used polymers in casting film production. Its excellent processability, balanced mechanical strength, and broad compatibility with other polymers make it suitable for both monolayer and multi-layer structures. In co-extrusion casting lines, different grades of PE are selected based on their performance in flexibility, clarity, and mechanical properties.

How PE Performs in Co-Extrusion

• LDPE (Low-Density Polyethylene)
  Offers good clarity, softness, and sealing performance. Often used as an outer layer for flexibility and shine.

• LLDPE (Linear Low-Density Polyethylene)
  Provides excellent mechanical strength and stretchability. Commonly used in stretch film and protective film cores.

• HDPE (High-Density Polyethylene)
  Delivers higher rigidity and barrier performance. Can serve as a structural layer when greater stiffness is required.

PE’s thermal stability makes it easy to process with multi-extruder configurations. SAIBANG’s Casting Machine supports temperature control systems tailored to PE-based film production, maintaining melt uniformity and thickness accuracy.

PE Material Comparison Table

PE materials remain a fundamental choice for many casting film structures due to their adaptability and cost-efficiency.

2. Polypropylene-Based Materials (PP, CPP, BOPP Feedstock)

Polypropylene (PP) is another essential casting film material due to its balance of heat resistance, rigidity, and clarity. Its crystalline nature allows it to achieve high transparency when cast, making PP-based casting films ideal for protective films, lamination layers, and food packaging.

PP Grades Used in Casting Film

• PP Homopolymer (PP-H)
  Known for rigidity and high temperature resistance. Suitable for structural layers.

• PP Random Copolymer
  Provides good optical clarity and flexibility.

• CPP (Cast Polypropylene)
  Specifically designed for casting processes; highly clear with exceptional heat sealing properties.

Why PP Works Well in Co-Extrusion

• High melt strength, ideal for stable casting flow

• Excellent clarity for display or lamination films

• Good stiffness and dimensional stability

• Works well as middle or surface layers in multi-layer films

SAIBANG’s Casting Machine is engineered with precise temperature zoning, allowing PP to maintain stable melt flow across multi-layer dies without crystallization defects.

PP Performance Table

3. EVA, EAA, and Other Copolymers Used for Adhesion and Flexibility

Ethylene-Vinyl Acetate (EVA) and Ethylene Acrylic Acid (EAA) are widely used for specialized functions such as flexibility, adhesion, and impact strength. These materials act as “functional layers” in multi-layer casting films.

EVA in Casting Film

EVA improves softness, transparency, and sealing strength. Because of its elasticity, EVA is commonly used in:

• Protective films

• Footwear film

• Solar encapsulation layers

• Stretchable packaging films

Its lower crystallinity makes it easy to process and bond with other materials.

EAA and Functional Copolymers

EAA is especially useful when strong adhesion between dissimilar polymers is needed. For example:

• Bonding polyolefins to barrier resins

• Improving hot tack strength

• Enhancing chemical resistance

Other functional resins such as EMA, EBA, and specialized tie-layers are also frequently used.

Functional Copolymer Table

Machines like SAIBANG’s Casting Machine support wide temperature processing windows, ensuring EVA and functional copolymers maintain stable flow characteristics.

4. PA (Nylon), PETG, and Specialized Engineering Polymers

High-performance casting films sometimes require engineering-grade materials to enhance barrier properties, mechanical strength, or temperature resistance. These materials are typically used in multi-layer structures where they play a specialized role.

Nylon (PA6, PA66)

Nylon provides:

• Excellent puncture resistance

• High tensile strength

• Good barrier properties

• Superior toughness

Nylon layers are commonly used in food packaging, vacuum packaging, and industrial protection films. However, nylon requires careful moisture control and pre-drying, which modern casting lines accommodate.

PETG and PET Variations

PETG, known for clarity and rigidity, is often used for:

• Release liners

• Medical packaging

• Thermoformable films

PET-type materials require precise temperature control. SAIBANG’s Casting Machine is engineered with multi-zone heating for these materials.

Engineering Polymer Table

Engineering polymers allow co-extruded films to reach specialized performance levels required in niche industries.

5. Adhesive Resins, Tackifiers, and Specialty Additives

Multi-layer casting film structures often require adhesives or specialty materials that improve inter-layer bonding or enhance surface performance. These materials are not typically used as primary layers but act as essential functional components.

Adhesive Resins

Tie-layer adhesives bond incompatible materials such as:

• Polyolefins with nylon

• PE with EVOH

• PP with PET

Adhesive layers ensure no delamination occurs and maintain the mechanical integrity of the film.

Tackifiers and Additives

Tackifiers improve cling performance in stretch films, while additives provide properties such as:

• Anti-static

• Anti-block

• UV protection

• Anti-slip

• Optical brightness

Functional Additive Table

SAIBANG’s Casting Machine supports precise metering of additives through gravimetric dosing systems to maintain consistent formulation.

Summary

Co-extrusion casting film machines are capable of processing an extensive range of materials, from basic polyolefins like LDPE, LLDPE, and PP to advanced engineering polymers like PA and PETG. Functional layers—including EVA, EAA, adhesives, and specialized additives—further expand the diversity of film types that can be manufactured.

This material flexibility allows manufacturers to produce films tailored for packaging, protection, stretch applications, lamination structures, industrial coatings, and specialty products. Modern systems such as SAIBANG’s Casting Machine are built with advanced control systems, high-efficiency screws, and multi-zone temperature settings to handle these materials with precision and stability.

By understanding the characteristics and processing requirements of each polymer category, manufacturers can maximize film performance, reduce waste, and improve production efficiency—unlocking the full potential of co-extrusion casting technology.