Polyvinyl fluoride

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Structural formula
Structure of polyvinyl fluoride
General
Surname Polyvinyl fluoride
other names

PVF

CAS number 95508-16-0
Monomer Vinyl fluoride
Molecular formula of the repeating unit C 2 H 3 F
Molar mass of the repeating unit 46.04 g mol −1
Type of polymer

Thermoplastic

properties
Physical state

firmly

density

1.77 g cm −3

Melting point

200 ° C

Glass temperature

−20 ° C

Crystallinity

partially crystalline

Water absorption

0.04

solubility

soluble in dimethylformamide

Chemical resistance

Resistant to acids, alkalis, many solvents at room temperature, cooking in carbon tetrachloride , benzene, acetone and MEK does not damage.

safety instructions
GHS labeling of hazardous substances
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 .

Polyvinyl fluoride ( abbreviation PVF ) is a fluorine-containing polymer . PVF heard as a thermoplastic plastic to the class of fluoro-plastics . A well-known trade name is Tedlar from DuPont .

structure

Polyvinyl fluoride with the empirical formula - [- CH 2 –CHF–] n - has a chain structure . Only every second atom on the carbon chain has exactly one fluorine atom, the remaining bonds are saturated with hydrogen .

In the more widely used polyvinylidene fluoride (PVDF) (- [- CH 2 –CF 2 -] n -), one atom of the carbon chain alternates between two fluorine atoms, the next two hydrogen atoms, etc.

Polyvinyl chloride (PVC) has the same bond structure as polyvinyl fluoride , but instead of fluorine, the heavier halogen chlorine is built into it. The monomer for production by polymerization is correspondingly in one case vinyl fluoride in the other vinyl chloride .

properties

The bond between fluorine and carbon is much stronger than that between chlorine and carbon in PVC, which is why polyvinyl fluoride is more chemically and physically stable than polyvinyl chloride. It can be used over a temperature range from −70 ° C to approx. 110 ° C, although higher temperatures (short-term) are also possible. Due to the lack of temperature resistance, it is not suitable for injection molding , which is why it is typically processed as a film. It is dirt-repellent and easy to clean. It is resistant to many chemicals and plasticizers, but not to ketones and esters. It is impermeable to fats and oils and very diffusion-resistant to gases. In addition, it has good weather resistance and is transparent.

From a wavelength of around 300–400 nm, polyvinyl fluoride is permeable to light well into the infrared range. Refractive index n D 20 = 1.45. Flammability: slowly burning.

Applications

Polyvinyl fluoride was introduced onto the market by DuPont in the early 1960s as a film-shaped semi-finished product. In addition to clear foils, there is also thicker board material.

Polyvinyl fluoride is used for weatherproof foils (among other things in construction and in electrical engineering), bags, lamination of metal sheets in the vehicle sector , for coatings as tool protection or for whiteboards . In vehicle construction, PVF is used in so-called decorative foils for surface coating in aircraft interiors and in the railway sector. In pneumatics, PVF is used as a filter material for vacuum filters. Because of its low gas permeability, polyvinyl fluoride is used for bags for gaseous samples .

PVF films are often used as composite films. The backside coating of standard solar modules is usually made with a film made of a PVF- polyester- PVF composite. The film structure of decorative films is also multilayered and usually consists of a PVF top layer, embossing resin layer, PVF base layer and adhesive coating. To increase the resistance to scratches and damage, glass fiber fabrics are often added to the composite.

The envelope of the Zeppelin NT airship has a layer of PVF on the inside for gas tightness against the diffusion-free carrier gas helium , followed by polyester fabric for tensile strength and polyurethane on the outside so that the laminate can be joined by welding.

Web links

Individual evidence

  1. ↑ a b Johannes Kunz, Kunststoffpraxis: Properties , WEKA Media, ISBN 3-8111-5972-0 .
  2. ↑ a b c d Hans Domininghaus, The plastics and their properties , Springer, 2004, ISBN 3-540-21410-0 . P. 889.
  3. ^ A b Karl Winnacker, Leopold Küchler: Chemical Technology: Organic Technology III . Hanser, 1972, ISBN 3-446-10354-6 , pp. 83 .
  4. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  5. ↑ Ortner; Hensler: Assessment of plastic fires lfu.bayern.de, November 7, 1995, accessed April 23, 2020, p. 12. - "Melting point 300 ° C, decomposition approx. 350 ° C."
  6. ↑ Entry on polyvinyl fluoride. In: Römpp Online . Georg Thieme Verlag, accessed on April 16, 2014.