IBC, OBC, and Water Quench Blown Film Extrusion: Key Differences and Applications

Introduction

Blown Film Extrusion

Blown film extrusion is a process where molten plastic is extruded through a circular die to form a tube. This tube is blown into a bubble, cooled down, and then pressed flat to create a film. The option of a cooling method directly affects the efficiency, film properties, and production quality.

IBC (Internal Bubble Cooling)

Internal Bubble Cooling (IBC) is a method where air is introduced inside the bubble to maintain its shape and size. The internal airflow, combined with external cooling, controls the bubble’s stability and temperature.
Cooling Method: Air is introduced into the bubble to cool the molten polymer from the inside out.

Key Features of IBC

• Accurate
  control of bubble diameter.
• Minimized
  film variation.
• Suitable
  for high-output production.

Applications of IBC

IBC is commonly used in the production of:

• High-clarity
  films for food packaging.
• Industrial
  bags and printable film.

Film Properties:

• Good balance of strength and flexibility.
• Moderate gloss and clarity.
• Suitable for a wide range of applications, including general-purpose packaging, agriculture film, and industrial liners.

Outer Bubble Cooling (OBC)

Outer Bubble Cooling (OBC) involves the use of external cooling rings that direct airflow onto the bubble’s surface. This method provides efficient cooling from the outside.

Key Features of OBC

• Enhanced cooling efficiency.
• Lower production costs compared to IBC.
• Requires less setup and maintenance

Applications of OBC

• OBC is ideal for producing:
• Agricultural films.
• General-purpose packaging films.

Film Properties:

• Lower cost compared to IBC.
• Lower gloss and clarity

 

 

OBC

Water Quench Blowing Film Extrusion:

Using the water quench technique, the extruded molten film is rapidly cooled by submerging it in a water bath. The film is rapidly solidified through immediate cooling, leading to exceptional clarity.

Film Properties:

• High clarity and gloss
• Excellent optical properties
• Improved puncher and tear resistance
• Enhanced thermoformability
• Suitable for high-end packaging applications, such as food packaging and medical packaging.

Key Differences:

FEATURE	IBC	OBC	WATER QUENCH
Cooling Method	Internal air cooling	External air cooling	Water cooling
Film Properties	Balanced strength and flexibility, moderate gloss and clarity	Lower cost, lower gloss and clarity	High clarity and gloss, improved puncher and tear resistance, enhanced thermoformability
Applications	General-purpose packaging, agricultural film, industrial liners	Less demanding applications, such as trash bags and liners	High-quality packaging applications, particularly within the food and medical domains.

Conclusion:

Recognizing the unique characteristics of IBC, OBC, and Water Quench is essential for achieving maximum efficiency in blown film production. By selecting the right cooling technique, manufacturers can enhance product quality, efficiency, and overall performance.

Water quench technology offers significant advantages in terms of film quality and performance, but it also requires more complex equipment and careful process control.

Do you have questions about blown film extrusion or specific cooling methods? 

Note:

• Read more about the blown film extrusion process.

Multiple-choice question and answer 

Question: In a comparative analysis, which cooling method offers the highest cooling efficiency?
a) Internal Bubble Cooling (IBC)
b) Outer Bubble Cooling (OBC)
c) Water Quench
d) External Air Cooling

Answer: c) Water Quench

Que: Which material is commonly processed using the water quench method?
a) Polyethylene Terephthalate (PET)
b) Low-Density Polyethylene (LDPE)
c) Polypropylene (PP)
d) Polystyrene (PS)

Answer: b) Low-Density Polyethylene (LDPE)

Que: What is a key advantage of outer bubble cooling (OBC) compared to IBC?
a) Precise control of bubble thickness
b) Faster cooling through water immersion
c) Lower production costs and simpler maintenance
d) Superior optical properties for transparent films

Answer: c) Lower production costs and simpler maintenance

Question: Which cooling method is most suitable for producing shrink films with exceptional clarity?
a) Internal Bubble Cooling (IBC)
b) Outer Bubble Cooling (OBC)
c) Water Quench
d) Dual cooling (IBC and OBC combined)

Answer: c) Water Quench

Question: What is the principal role of internal bubble cooling (IBC) during blown film extrusion?
a) Enhancing optical properties through water immersion
b) Controlling bubble diameter and stability with internal airflow
c) Directing external airflow onto the bubble’s surface
d) Submerging the film in water for rapid cooling

Answer: b) Controlling bubble diameter and stability with internal airflow