The strongest point about polyvinylidene chloride is its excellent barrier property (gas non-permeable property) against both oxygen and moisture, and its oxygen barrier property is maintained even at a high humidity. These are advantages that are not found with other resins. Taking advantage of such an excellent barrier property, polyvinylidene chloride has been used for a wide range of usual products, like packaging film for ham, sausage, cheese and other preserved food, as well as household-use cling wrap. It has also been used as a coating agent to provide a barrier property to paper or other types of plastic film. (See the coated film section of coating agents.)
Vinylidene chloride is first made from chlorine obtained by electrolysis of salt (sodium chloride) and ethylene obtained by pyrolysis of petroleum.
CH2=CH2（ethylene）＋ Cl2（chlorine） → CH2Cl-CH2Cl（1,2-dichloroethane）
CH2=CH2（ethylene）＋ 2HCl（hydrogen chloride）＋ 1/2O2（oxygen）
→ CH2Cl-CH2Cl（1,2-dichloroethane）＋ H2O（water）
CH2Cl-CH2Cl（1,2-dichloroethane）→ CH2=CHCl（vinyl chloride）＋ HCl（hydrogen chloride）
CH2=CHCl（vinyl chloride）＋ Cl2（chlorine）→ CH2Cl-CHCl2（1,1,2-trichloroethane）
CH2Cl-CHCl2（1,1,2-trichloroethane）＋ NaOH（sodium hydroxide） or Ca（OH)2（calcium hydroxide）
→ CH2=CCl2（vinylidene chloride）＋ NaCl（sodium chloride） or CaCl2（calcium chloride）
Under the Japanese Food Sanitation Act, general standards and standards for individual materials have been set for plastic utensils, containers and packages for food. For polyvinylidene chloride, the Ministry of Health and Welfare Notification No. 20 of 1982 established the standards for material tests and elution tests. Cadmium, lead, barium, and vinylidene chloride monomer are specified as material tests, and heavy metals, evaporation residues (total migration amount), and potassium permanganate consumption are specified as elution tests.
In addition, the revised Food Sanitation Act came into effect on June 1, 2020, polymers and additives that can be used in products are also controlled by the national positive list system. It is necessary for polyvinylidene chloride to comply with the positive list, general standards and individual standards.
For cling wrap for home use that is made from polyvinylidene chloride, softening and stabilizing agents are used as additives. Additives registered by the national positive list system and certified by the European Union (EU) or U.S. Food and Drug Administration (FDA) for food packaging plastics are used.
If oily, deep-fried or other cooked food that is in direct contact with cling wrap is microwaved, the heatproof temperature limit of the film may be exceeded and the film may break. In such a case, place food in a deep, heatproof container and cover it with cling wrap so that it is not in direct contact with food.