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Working group PET neck finishes
The PCO 1881 plastic screw finish
Situation at January 15, 2008
In 2006, a liaison was established between ISBT - International Society of Beverage Technologists in North America – and our working group PET finishes about the project, managed by ISBT, for the development and validation of a lightweight 28 mm PCO voluntary finish standard. The development of suitable plastic closures was also needed for such a reduced height finish.
Works carried on actively in 2007 and it was considered useful to do a situation between the European stakeholders; this has been done during a meeting held on December 14, 2007 in CETIE premises.
This finish will be referenced PCO 1881. At end 2007, the last drawing was version 12 in which some minor details still need to be finalised.
Main differences with PCO 1810 finish are as follow :
- a height between top of finish and neck support ring at 17 mm versus 21 mm
- a height between top of finish and tamper evident bead at 11.2 mm versus 14.1 mm
- a thread pitch at 2.7 mm resulting in a 650° turn of depth thread. For the 1810 finish these characteristics are respectively 3.18 mm and 810°. The pitch has been reduced to keep a sufficient turn of depth thread.
- a trapezoidal thread profile versus a rounded one
- a threat root diameter at 24.2 versus 24.51 (diameter E)
- a restriction on the external diameter between the tamper evident bead and the neck support ring (diameter B2)
- a finish weight decrease of around 1.2 grams
The outstanding points are concerning the following items :
- the maximum capacity of the bottle. At the origin, this finish was intended for single serve bottles, i.e. those having a maximum capacity around 20 oz (0.6 litre). Now bottlers wish to use this finish for bottles with a capacity of at least 2 litres and even up to 3 litres.
- the maximum carbonation rate. At origin it was at 5 volumes. Presently it is advised to limit it at 4.7 volumes because of the risk of finish deformation under extreme conditions (high temperature and carbonation rate)
- the flash specification which is limited at 0.13 mm on 1810 finish. The aim by widening flash tolerance is to decrease the maintenance cost of moulds.
Drawing version 13 disclosed in January 2008 gives an answer to this point
- the profile of the crest thread
- possible adaptations of some blowing and capping equipments
This finish cannot be considered as a revolution but rather as an evolution. In the future this finish should represent an important share of the market but it will not be the sole finish in use. 1810 finish will likely be always in use.
It is expected that this finish will be on the market from 2008, mainly in Europe because of the important pressure to get such a finish available to decrease the global cost of the container. As a consequence there is a risk of drawing multiplication based on this project.
CETIE strongly advices to refer to the ISBT’ drawing as this finish is the result of a consensus obtained by the main professionals of the sector through a common effort and technical analysis.
It will be possible to download this drawing from Specifications - Threadspecs.com on the web site www.closuremanufacturers.com
If you are interested to participate, contact us.
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Working group PET neck finishes
