Polybutylene terephthalate

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Structural formula
Structure of polybutylene terephthalate
General
Surname Polybutylene terephthalate
other names

Polytetramethylene terephthalate

CAS number 24968-12-5
Monomer Terephthalic acid and 1,4-butanediol
Molecular formula of the repeating unit C 12 H 12 O 4
Molar mass of the repeating unit 220.22 g mol −1
properties
Physical state

firmly

density
  • 1.403 g cm −3 (crystalline)
  • 1.280 g cm −3 (amorphous)
Melting point

220 ° C (crystalline α-form)

Glass temperature

47 ° C

modulus of elasticity

1700-2700 MPa

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 .

Polybutylene terephthalate ( abbreviated PBT also PTMT ) is a first time around 1941 made of thermoplastic plastic . It belongs to the polyesters and has similar properties to semi-crystalline polyethylene terephthalate (PET), but is better suited for injection molding due to its more favorable cooling and process behavior.

Due to the expensive raw materials, however, it has not yet been able to establish itself on a broad basis. In 2012 the worldwide consumption was 830,000 t.

synthesis

Polybutylene terephthalate is formed by polycondensation of the intermediate product bis (4-hydroxybutyl) terephthalic acid ester . This can be prepared by esterification of 1,4-butanediol and terephthalic acid or by catalytic transesterification of dimethyl terephthalate , such as with 1,4-butanediol in the presence of transesterification catalysts tetraisopropyl titanate can be produced.

Reaction scheme for PBT production ...
PBT by Polycondensation V1.svg
 ... through polycondensation.
PBT by Transesterification V1.svg
 ... through transesterification.

In order to increase the molar mass, PBT can be post- condensed .

properties

Polybutylene terephthalate is valued for its high strength and rigidity , very high dimensional stability (significantly better than that of POM or PA ) and good friction and wear properties. Typical operating temperatures are in the range -50 to 150 ° C.

PBT has good chemical resistance to many solvents . It cannot be dissolved at room temperature, for example with mixtures of ortho- dichlorobenzene and phenol at higher temperatures . It is sensitive to the degradation of molecular weight through hydrolysis , but it can also be brought into contact with hot water for a short time and is therefore used in steam irons or coffee machines , for example .

use

Polybutylene terephthalate is used for housings in electrical engineering, but also in vehicle construction as a connector and in the household, for example, as a shower head or in an iron. When processed into fibers, it is used, among other things, in toothbrushes , for sheathing optical fibers and as a chemical fiber .

For keycaps on keyboards , polybutylene terephthalate is a material that is mainly used for high-quality products. Compared to acrylonitrile-butadiene-styrene (ABS), it is characterized by lower wear and thus longer service life.

Trade names

Bottle with closure made of Celanex®
  • Anjacom (almaak international GmbH)
  • Arnite ( DSM )
  • Celanex ( Ticona )
  • Crastin ( DuPont )
  • DURANEX®PBT (Polyplastics)
  • DYLOX (Hoffmann + Voss GmbH)
  • Kebater (BARLOG plastics GmbH)
  • Later (LATI)
  • Pocan ( Lanxess )
  • PRECITE® (AKRO)
  • RIALOX (RIA-Polymers GmbH)
  • Schuladur ( A. Schulman )
  • Ultradur ( BASF )
  • Valox ( Sabic Innovative Plastics )
  • VESTODUR ( Evonik Industries AG )
  • Badadur PBT ( Bada AG )
  • Bergadur (PolyOne Th. Bergmann GmbH)
  • Longlite (Chang Chun Plastics Co Ltd)

Web links

Individual evidence

  1. ↑ Jürgen Falbe, Manfred Reglitz: RÖMPP Lexikon Chemie. Volume 5: Pl – S , 10th edition, Thieme, 1998, ISBN 978-3-13-735010-1 .
  2. ↑ a b c Konrad Huber: Pervaporation of pure liquids and binary mixtures through membranes of polybutylene terephthalate in the glass transition area. Herbert Utz Verlag, 1998, ISBN 3-89675-298-7 , pp. 21-23.
  3. ↑ Gerhard W. Becker, Ludwig Bottenbruch (ed.), Dietrich Braun: Technical thermoplastics: polycarbonates, polyacetates, polyesters, cellulose esters., Volume 3/1. Hanser Verlag, 1992, ISBN 3-446-16368-9 , p. 51.
  4. ↑ Bergadur - polybutylene terephthalate (PBT) ( Memento from December 26, 2011 in the Internet Archive ) (PDF; 1.1 MB).
  5. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  6. ↑ Gerhard W. Becker, Ludwig Bottenbruch (ed.), Dietrich Braun: Technical thermoplastics: polycarbonates, polyacetates, polyesters, cellulose esters. Volume 3/1. Hanser Verlag, 1992, ISBN 3-446-16368-9 , p. 2.
  7. ↑ Konrad Huber: Pervaporation of pure liquids and binary mixtures through membranes of polybutylene terephthalate in the glass transition area. Herbert Utz Verlag, 1998, ISBN 3-89675-298-7 , p. 21.
  8. ↑ a b Abdulakh K Mikitaev, TA Borukaev, Gennadi Efremovich Zaikov (ed.): Poly (butylene terephthalate), synthesis and properties. CRC Press, Boca Raton 2006, ISBN 90-474-1866-2 , p. 8.
  9. ↑ Article (PDF) in Kunststoffe 10/2013, accessed on February 22, 2015.
  10. ↑ a b Entry on polybutylene terephthalate. In: Römpp Online . Georg Thieme Verlag, accessed on February 17, 2015.
  11. ↑ a b Dietrich Braun: plastics technology for beginners. Hanser Verlag, 2003, ISBN 3-446-22273-1 , pp. 52-53.
  12. ↑ Current problems with the TKG - Technical Information Library (TIB). Accessed on September 17, 2018 : "In the meantime there are also polyester fibers based on modified raw materials such as polytrimethylene terephthalate (PTT) and polybutylene terephthalate (PBT) with modified fiber properties and modified processing (e.g. in dyeing)"
  13. ↑ "PBT keycap upgrade set". Retrieved August 2, 2020 .
  14. ↑ "ErgoDox - Our Keycaps". Retrieved August 2, 2020 .
  15. ↑ Jake Harrington: ABS vs PBT Keycaps: What's the Difference? Retrieved August 2, 2020 .