Polyvinylidene chloride

• PVDC
• CLF
• Poly (1,1- dichloroethylene )
• Saran

Thermoplastic

Fixed

1.63 g · cm -3

About 200 ° C.

720-670 N · mm -2 (longitudinal - transverse)

Polyvinylidene chloride ( PVDC ) is composed of vinylidene dichloride (1,1- dichloroethene, H2C = CCl 2 ) formed analogously to the PVC thermoplastic that easily decomposes near the melting point of about 200 ° C. Technical importance for this reason in particular, the copolymers of vinylidene chloride, e.g. vinyl chloride.

History

PVDC in 1933 accidentally discovered by Ralph Wiley at Dow Chemical as a residue in a template, which could be removed only with great difficulty. The fabric was further developed by Dow and first used for a seawater- resistant protective film of the aircraft of the U.S. Armed Forces. The strong unpleasant odor and the greenish color initially prevented other applications. Once these properties have been removed, the product could be even used for sheets in the food industry. Trademark of Dow Chemical for PVDC Saran is.

Properties

Use

PVDC is available as a barrier film, as granules for extrusion and as a solution for coating. PVDC is an excellent barrier material for oxygen and water vapor.

As a paint / coating, film or barrier layer in or on a protective / support film

Food packaging (bottle seals, foil and laminated cardboard, sausage skin, etc. ) PVDC is approved in the U.S. for food applications in accordance with FDA regulation 21 CFR, and corresponds to the application in the EU by EU Directive 2002/72/EU. The approval for the particular application is to be inquired at the source of supply.

Other applications:

• Vapor barrier
• Oxygen barrier
• Corrosion protection (eg Liner in tubes for hydrochloric acid and chlorinated hydrocarbons)

The PVDC film is generally extruded in a two-stage blow molding and is therefore stretched. Maximum application temperature is 80 ° C. Therefore, Co-extruded multilayer film with PVdC contributes Dow Chemical Saranex the tradename ™. Further possible components of a multi-layer film, for example PE, EVA.