Polyvinylidene chloride

Structural formula
General
Surname	Polyvinylidene chloride
other names	PVDC; CLF; Poly (1,1-dichloroethylene); Saran; Ixan (Solvay);
CAS number	9002-85-1
Monomer	1,1-dichloroethene
Molecular formula of the repeating unit	C 2 H 2 Cl 2
Molar mass of the repeating unit	96.94 g mol −1
PubChem	6366
Type of polymer	Thermoplastic
properties
Physical state	firmly
density	1.63 g cm −3
Melting point	approx. 200 ° C (decomposition)
safety instructions
GHS labeling of hazardous substances	no classification available
	no classification available
H and P phrases	H: see above
	P: see above
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Polyvinylidene chloride ( abbreviation PVDC ) is the thermoplastic formed from vinylidene dichloride ( 1,1-dichloroethene , H ₂ C = CCl ₂ ) analogous to PVC , which easily decomposes near the melting point of approx. 200 ° C. For this reason, the copolymers of vinylidene chloride, eg. B. with vinyl chloride .

history

PVDC was accidentally discovered by Ralph Wiley at Dow Chemical in 1933 as a residue in a template that was very difficult to remove. The fabric was further developed by Dow and initially used for a seawater-resistant protective film for aircraft used by the US armed forces. The very unpleasant odor and the greenish color initially prevented other applications. After these properties were eliminated, the product could also be used for films even in the food sector. Dow Chemical's trademark for PVDC is Saran .

properties

Other properties of polyvinylidene chloride
Decomposition temperature	approx. 200 ° C
Glass transition temperature	−11 ° C to −19 ° C
Surface tension	40 mN / m ( dyn / cm) film 25 µm
Oxygen permeability	1.5 cm ³ / (m ² 24 h bar)
CO ₂ permeability	5.0 cm ³ / (m ² 24 h bar)

use

PVDC is available as a (barrier) film, as a granulate for extrusion , as a solution for coating and as a dispersion for coating.

PVDC is an excellent barrier material for oxygen , carbon dioxide and water vapor . It can be co-polymerized with other monomers to improve solubility, but this reduces the barrier effect. If the co-monomer content exceeds 20%, the corresponding polymers are soluble in esters and ketones .

PVDC films can be stretched to three to four times their original length. When the temperature rises, the film shrinks back to its original size, which is why shrink packs and shrink tubing can be made from PVDC.

As food packaging (bottle seals , foil and laminated cardboard, sausage skin, etc.), PVDC is approved in the USA according to FDA regulation 21 CFR for food applications and corresponds to EU Directive 2002/72 / EU for use in the EU. The approval for the respective application is to be requested from the source of supply.

PVDC is also used as a corrosion protection layer (e.g. liner in pipes for hydrochloric acid and chlorinated hydrocarbons).

The PVDC film is usually extruded in a two-stage blow molding process and is therefore stretched. The maximum application temperature is therefore 80 ° C. Coextruded multilayer film with PVDC bears the trade name Saranex ™ at Dow Chemical. Further possible components of a multilayer film are, for. B. PE or EVA .

literature

Ullmann's Encyclopedia of Industrial Chemistry: Electronic Release 2006. 1st ed. Wiley-VCH, Weinheim 2006, ISBN 3-527-31318-4 .

Individual evidence

↑ ^a ^b ^c ^d ^e Ulrich Poth: Synthetic binders for coating systems . Vincentz Network, Hannover 2016, ISBN 978-3-86630-611-0 , p. 377-378 .
↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
↑ Data sheet Saran ™ 19E from Dow Chemical.
^ ^A ^b Elsner, Peter, Eyerer, Peter, Hirth, Thomas: Kunststoffe: Properties and applications . 8th, revised and expanded edition. Springer, Heidelberg 2012, ISBN 978-3-642-16173-5 , pp. 480 .
↑ Elsner, Peter, Eyerer, Peter, Hirth, Thomas: Kunststoffe: Properties and Applications . 8th, revised and expanded edition. Springer, Heidelberg 2012, ISBN 978-3-642-16173-5 , pp. 354 .
^ Jan Hoinkis: Chemistry for Engineers . 14., completely revised. and updated edition Wiley-VCH, Weinheim 2016, ISBN 978-3-527-33752-1 .

[:1-1] Ulrich Poth: Synthetic binders for coating systems . Vincentz Network, Hannover 2016, ISBN 978-3-86630-611-0 , p. 377-378 .

[NV-2] This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.

[3] Data sheet Saran ™ 19E from Dow Chemical.

[:0-4] A ^b Elsner, Peter, Eyerer, Peter, Hirth, Thomas: Kunststoffe: Properties and applications . 8th, revised and expanded edition. Springer, Heidelberg 2012, ISBN 978-3-642-16173-5 , pp. 480 .

[5] Elsner, Peter, Eyerer, Peter, Hirth, Thomas: Kunststoffe: Properties and Applications . 8th, revised and expanded edition. Springer, Heidelberg 2012, ISBN 978-3-642-16173-5 , pp. 354 .

[6] Jan Hoinkis: Chemistry for Engineers . 14., completely revised. and updated edition Wiley-VCH, Weinheim 2016, ISBN 978-3-527-33752-1 .