Polyvinylidene chloride Films

Properties

Polyvinylidene chloride or PVDC is a clear and flexible synthetic thermoplastic produced by the polymerization of vinylindene chloride. It is optically clear with a high degree of gloss and has outstanding oxygen and moisture barrier properties comparable to metallized films. This makes PVDC ideal for household wrap and food, medical and pharmaceutical packaging to extend shelf life. PVDC also is highly resistant to many chemicals including grease and oil.

PVDC can be easily extruded and laminated. It is also microwavable and printable using common ink systems.

The most common type is biaxial oriented PVDC film.1 It has low stretch and provides excellent bond strength and low water absorption. It also has good cling properties, making it ideal for food wrap applications.

Vinylidene chloride is sometimes copolymerized with other monomers such as acrylonitrile (AN), vinyl chloride (VC) and various alkyl (meth)acrylates. A common copolymer consists of about 85 percent vinylidene chloride and 15 percent vinyl chloride.2 This polymer film is known under the trade name Saran™. It has a lower melting point, less cristallinity and noticeably higher CO2 and O2 permeability than PVDC.2 Some other commercial grades are copolymers of three or more monomers. For example, some PVDC copolymers contain varying amounts of acrylates, methacrylates and acrylonitrile as well as small amounts of vinvyl carboxylic acid such as acrylic acid, methacrylic acid or itaconic acid. The latter monomers enhance adhesion to polar substrates. However, in all Saran films, PVDC is the main component.

Because of its higher cost, PVDC is typically combined with other cheaper plastics like polypropylene, polyethylene and nylon. It is usually applied as a thin coating or laminate or it is coextruded with other resins to produce a multilayer film or sheet to improve the barrier properties of the cheaper base film.

Due to the low odor, high chemical resistance and inertness, PVDC is suitable for many packaging applications.2

Although PVDC is recyclable, most PVDC film is not recycled, mainly because PVDC is often used as a very thin coating which cannot be easily extracted.

Applications

Polyvinylidene chloride film is an attractive see-through packaging film. PVDC (coated) film is mainly used in packaging of food, drugs, cosmetics, and other perishable or delicate products to extend shelf life. In comparison with many common films, PVDC coated films have superior gas and moisture barrier properties, and excellent heat sealability. PVDC coated films often compete with acrylic, PVOH and EVOH coated films.

  • 1”Biaxially oriented" means that the PVDC film is stretched in two different directions to increase strength and modulus (lower elongation and higher stiffness).
  • 2Dow Saran Resins & Films brochure: Vinylidene Chloride Monomer and Polymers, Dow Chemical Company 2000
  • 3Saran and PVDC are often used interchangeably in the literature. However, commercial grades of Saran are copolymers of PVDC. Three common comonomers are vinyl chloride, (meth)acrylates, and acrylonitrile.2