What are the stretching methods for stretch film?

Stretch film is a commonly used plastic film for packaging, which increases the strength and ductility of the film through stretching processes. The stretching methods of stretch film mainly include the following:

Uniaxial Stretching

Unidirectional stretching refers to the stretching of a stretch film in one direction, usually longitudinal. By uniaxial stretching, the tensile strength and ductility of the film are improved, and this type of film is generally used for packaging products that require high strength.

Biaxial Stretching

Bi directional stretching refers to the stretching of a stretch film in both directions, which can be longitudinal and transverse. Bidirectional stretching can provide more uniform mechanical properties, making the membrane more tough and stretchable. This type of film is commonly referred to as biaxially oriented polypropylene film (BOPP) and is widely used, such as for packaging food or other lightweight goods.

Mechanical Stretching

Mechanical stretching is the process of stretching a film using mechanical equipment, primarily by physically stretching it using rollers and pulleys. In this way, the film will be stretched between the rollers, usually used for producing film packaging.

Thermal Stretching

Hot stretching is the process of heating a film material to a certain temperature to soften it, and then stretching the film using a stretching machine. The heated material is easier to stretch, and after stretching, it will have better strength and elasticity. Hot stretch film is commonly used in the packaging field to achieve higher strength and thickness.

Gas Stretching

Gas stretching is commonly used in the production process of thin films, where gas is used to inflate and stretch the film. Gas stretching is suitable for some special films, such as gas films and certain types of bubble films.