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Supporting environmental pledges while keeping feet on the ground!

When colours and additives come to the rescue

That customers want more and more the maximum percentage of r-pet in their bottles is a fact, and if some of them are not yet on the market with a 100% recycled packaging, they are anyway already planning it.  
We normally discuss it in detail before offering our solution, highlighting the various issues involved, especially for what the look is concerned, but also from a mechanical point of view.

The colour of r-pet may vary a lot both from supplier to supplier (and even from one batch to the other) and depending on the material mix virgin/recycled. The natural colour of the outcoming bottle can be greyish, yellowish, blue and greenish; also, the more recycled content the bottle has, the “darker” it will appear. Considering Lab values, in fact the first one dropping significantly is the “L” related to the “lightness”, which is hard to regain.

As for mechanical challenges, when talking of a 100% R-pet bottle, two are the most common: IV drop and wall thickness distribution, one being basically the cause of the other. This happens because PET has already passed through several production processes, which impact on its chemical composition, namely shortening its molecular chain. A drop in the Intrinsic viscosity is responsible for inconstances in the moulding machine pressure, this leading to uneven wall thickness and therefor to a fragile packaging.

Customers know the above threats by themselves, but the requests to use as much as 100% recycled material come anyway from the Marketing and from their need to meet a growing consumer consciousness towards our environment. No worries, we are here to help!

How can we support the pledges toward the environment while keeping our feet on the ground?

From the left: 100% R-PET - same with AY 00015 @0.03% - same with AY 00201 with optical brightener @0.03%

REPI has been studying and specialising on additives for PET recycling for many years, since the first “recycle wave” appeared and is today in the position of offering a broad spectrum support made by a range of “Anti Yellow additives and IV-enhancers”, by its expertise and by offering the support of a prototyping lab where preforms and bottles are moulded by “playing” with colours and additives in application with r-PET pellets and flakes mixed in different percentages. 

The Anti Yellow additives range (AY) is  composed by different liquid additives able to balance the appearance of uneven incoming material. So, it is possible to regain brightness, as well as to correct the greenish or the greyish tone. 

IV Enhancer additive helps the mechanical performance of a R-PET bottle increasing IV level from 0,05 dl/g to over 0,10 dl/g depending on the LDR

REPI’s IV Enhancer, instead attracts and binds to itself the free oligomers of recycled PET extending its molecular chain and therefore increasing the IV to the level of a virgin material. 

Customers and brand owners, who are invited to perform with us the prototyping phase, normally come with a “shade idea”; this needs to be evaluated and assessed considering the starting point of the raw material (percentage of r-PET used and its shade).

One single shade starting from two different R-PET

Besides additives, colours also can be of help. We know that the trend is to reduce colours, or even to go clear, but… many brands are not ready to sacrifice aesthetics of their packaging and their brand recognition. When a very dark r-PET is used, the sole Anti Yellow additive may not be enough. For this, REPI has developed the  “Smoky or Fumè” colour range, some proposals of different shades which would be able to even give the packaging a “premium and elegant look”, masking a bit the R-pet visual influence and at the same time adding value to it. Those shades have in common a “dirty” effect and are dosed at so low dosages (as low as 0,05%) that do not impact in the recycling stream, since they are detected as transparent light colours. The range goes from a light amber to light blues, greys, aqua-marine shades and even antique rose, which often are chosen after an evaluation of the starting r-PET look. We are receiving real interest from Brand Owners, since the Smoky-range represents the answer to their concerns related to aesthetics when adding recycled material and also, they get the opportunity to reduce the amount of colour, but without removing it out completely.

Walking towards a circular economy is not easy, but solutions are already in place to help as much as possible to find how to be sustainable from a branding and aesthetic point of view as well as from a technical perspective.   

Colorants and dedicated additives are available to make r-PET look and work even better, let us take advantage of this opportunity, because after all… how would the world look without colour?

Contact Information

Lucia Buffoni - Marketing Manager REPI S.p.A.


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