Cling film is made from a type of plastic called polyvinyl chloride, or PVC for short.
The raw materials used to make PVC are petroleum-based, including naphtha and salt.
PVC is a versatile plastic that's also used in pipes, vinyl records, and even credit cards.
The manufacturing process involves combining PVC with other chemicals, such as plasticizers and stabilizers, to make it flexible and durable.
Raw Materials
Cling film is made from a variety of raw materials, including PVC, PVDC, and low-density polyethylene. These polymers are derived from simple hydrocarbons like methane and ethylene, which come from natural gases.
Most household plastic wraps are made from polyethylene, PVC, or PVDC. These materials are commonly used in cling film production due to their flexibility and durability.
Polyethylene is made directly from ethylene, which is a byproduct of natural gas or petroleum. PVC, on the other hand, is made from vinyl chloride, derived from ethylene or acetylene.
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Some plastic films, including cellophane, are derived from cellulose, which is obtained from wood pulp or from linters, tiny fibers that cling to cotton seeds after the longer cotton fibers have been removed by a cotton gin.
Here's a breakdown of the common raw materials used in cling film production:
These raw materials are transformed into cling film through a process that involves heating, shaping, and stretching the plastic to create a flexible and durable film.
How It's Made
Cling film is made through a process called extrusion, where plastic granules are heated until they melt at around 212°F (100°C) for polyethylene. This liquid plastic is then forced through a die to form a tube of warm, stretchable plastic.
The plastic is stretched to the desired thinness by blowing compressed air into the tube at regular intervals, creating large bubbles. This stretching process helps to create a film that's perfect for wrapping food or covering surfaces.
The bubble is then collapsed between metal rollers to form a film, which is rapidly cooled. The film is then wound around a large metal roller to form a roll that can hold several kilometers of plastic wrap.
The plastic film on these rolls is then unrolled, cut to the proper length (usually about 49 feet [15 m]) and width (about 1 foot [0.33 m]), and rerolled onto small cardboard tubes. This rolling, unrolling, and rerolling process gives the plastic wrap a slight negative charge of static electricity, which helps it cling to surfaces.
Here are the key steps involved in making cling film:
- Heating plastic granules until they melt
- Forcing the liquid plastic through a die to form a tube of warm, stretchable plastic
- Blowing compressed air into the tube to create large bubbles and stretch the plastic
- Collapsing the bubble between metal rollers to form a film
- Winding the film around a large metal roller
- Unrolling, cutting, and rerolling the film onto small cardboard tubes
Frequently Asked Questions
What is the difference between cling film and saran wrap?
Cling film and Saran Wrap are often used interchangeably, but Saran Wrap was originally made with PVDC, while most cling films are made of polyethylene or PVC. Today, modern Saran Wrap is also made of polyethylene, similar to generic cling films.
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