PET finish and open innovation at Cetie

Par Nicholas Harris
Le 01/03/2016

A quest for the innovation

The quest for innovation enables companies to keep and grow their markets by standing out from the competition. Innovation is easily associated with a culture of secrecy and the protection of intellectual property by patents or brands. But the speed at which markets are changing can make it useful for companies to share some of their knowledge of a given subject in order to shorten the time-to-market through a collaborative approach.
This is what “open innovation” means.

"Cetie can be thought of as an open innovation platform that brings together experts from companies operating in the same sector, and their customers, to facilitate the effective development of solutions to the problems they face"

Some of the work done by Cetie’s PET finish working group illustrates this point. This working group is made up of representatives of the various stakeholders: manufacturers of presses, dies and blowers, closure suppliers and their end customers, the alcohol-free refreshment drink brands. As a general rule, it is assumed to be advantageous if the specifications of the bottle finish are harmonised for new closure systems, allowing the closure suppliers to propose cap models adapted to the common finish, according to their own technology.
In one example, certain test results were shared in order to fine-tune the specifications in a project to develop a new lightweight closure for moderately carbonated drinks, a need identified by the brands present. Through its contacts with the ISBT (International Society of Beverage Technologists), the group could also take comments on the project from a broader panel of experts into consideration. The Cetie GME 30.37 finish produced by the working group has just been published in its "experimental" form, providing the basis for the pilot tests and industrialisation. According to Cetie’s internal rules, experimental specifications must be validated on the basis of industrial results after a period of one year, which is renewable once.
According to the identification nomenclature drawn up by the group (diameter on thread/inner diameter - height - number of threads/pitch), this 26/22-13-1/2.17 finish is intended for levels of carbonation of up to 7 g CO2/litre and for bottles containing a maximum of two litres. The qualification tests were obliged to cover the aspects of consumer safety. By way of example, the risk of rejection of the closure must be controlled under normal opening conditions, with a verification of the effective release of the pressure, as soon as the closure starts to be unscrewed, through the slits in the threads, before the cap is released from the thread of the finish. Accidental exposure to high temperatures must also be simulated, for example when a bottle is left in the sun on the rear shelf of a car, in repeated cycles at between 32°C and 60°C, the temperature at which the bottle starts to become deformed by the pressure generated. To pass this test, the closure must remain engaged on the finish despite any deformation.

A specific Cetie working group harmonises the qualification test methods of PET closures,

such as the examples described above. This group revises and updates an existing ISBT document. A common reference framework for this type of test is clearly in the best interests of all the players, even if certain compliance criteria may be established directly between the supplier and the filler/brand. In this case, the involvement of the fillers/brands and the open sharing of some of their internal procedures make the work done on the subject at the Cetie worthwhile. The revised document will be published in the course of 2016 in collaboration with the ISBT.
In particular, this project raised the question of adapting certain tests to technical developments, and especially to lighter caps and the optimisation of certain dimensional parameters that this demands. One example is the way in which the cap is held in reverse torque tests. This test simulates a consumer who tries to open the closure by turning it in the wrong direction, to the point where the thread is deformed and the closure is ejected in an untimely manner. Currently, in automatic tests, the closure is held by a metal mandrel, marked with the imprint of the closure and its ridges. But rigid mandrels do not simulate the distribution of the forces of human fingers very well, and some time ago, it was decided that these mandrels should only hold the upper half of the height of the cap. This empirical rule still applies and still seems to be quite valid. But the height of lightweight caps can almost match the width of human fingers. Therefore, if we are to simulate a human hand, the tightening force, which affects any possible deformation, must obviously increase with the torque. So recently, the results achieved in the first tests of a new type of self-tightening mandrel were presented to the group. Another example of open innovation that looks set to become part of the test methods in a future issue!
Other recent Cetie publications in the realm of PET finishes include the GME 30.38 (26/22-12-1/2.5), with dimensions close to the above-mentioned GME 30.37, and also for levels of carbonation of up to 7 g CO2/l. But this finish is still specifically intended to provide compatible settings on bottling lines for both sparkling water (with this finish) and still water, with the EN 16594 finish (formerly GME 30.28 (26/22-12-3/6.5).

By N. Harris Cetie General Secretary
Published in Liquides & Conditionnement N°382 (April-March 2016)
PDF (FR) :
- Liquides & Conditionnement N°382 (FR)
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