PP Fabric and Sling Pinking / Yellowing issue caused by HALS?


  Good day, everyone. As we all know, China is one of the biggest FIBC production country.

   As the request of international and localmarket, most of producer add UV masterbatch to their product to keep a goodlight stabilizer property. But in the past decades (we worked in this fieldaround 4 years), PP Fabric and Sling Pinking / Yellowing problem come to aheadache, and most of us think it’s caused by HALS of UV masterbatch and everyMasterbatch producer got similar complaint from customers.

First of all, this discolouration issue is fully reversible - when you put the Fabric or Sling under the sunshine the colour disappears. 

And this Pinking / Yellowing issue happens irregularly.

To solve this problem, we have to make clear,why this discolouration happens. We discussed it with our co-operator who is from ARGUS PLASTIC ADDITLIVES GMBH. We also got in touch with experts from BASF Antioxidant group to analyse the phenomenon and get some test data (actually in international market, they all called Gas-fading issue). Gas-fading issue caused by the Hindered phenol in polypropylene met the high polluted air with Nitrogen oxide or Sulphur oxide, under the alkalescent HALS system, which lead to a benzoquinone intermediate, the root cause for the Pinking / Yellowing.

   Theoryof Gas Fading (as NOx react, for example AO1010 PP)


The H on secondary carbon bonded with anelectron-withdrawing ester, is easier to be attacked by the NOx, reacts to an inter-conjugated benzoquinone ring, as follows:


Above is the mechanism of H of beta-secondary carbon are attacked by the NOx of air, and the inter-conjugated benzoquinone ring is in the circle, which lead to the pink. But the conjugated system is quite weak, when put the fabric or sling under sunshine or even elevated temperature, it gets back, and the antioxidant keep to work.

Sorry to talk so much about the influence of antioxidant on the gas-fading of articles. So what’s the influence of UV-Masterbatch, exactly said, HALS on this issue during the period?

We tested most of UV Masterbatch produced by Chinese producers, the ingredient is HALS-1,seldom partly is HALS-2, both are alkalescent. Under the alkalescent system,the weak acidic phenol at hindered phenol antioxidant (Marked by the pink heartat above graph) will be abstracted and further help the benzoquinone formation. It’s an accelerator!

So how should we solve the problem?

1) don't use phenolic AO like 1010, 1076. We got data from BASF expert:


BASF did the Hindered phenol antioxidant gas-fading test according to AATCC 164. Finally the phenomenon and mechanism are proved by the test.

2) don't pollute the air with exhaustive gases. Please save power, and riding aspossible as you can, and protect our atmosphere.

We are sorry, we can’t use some easier words to explain everything, to make it easier understanding. But we insisted on sharing it with all our customers. You may find some chemist on university to re-check if it’s correct, accurate and reasonable.

Sorry we don’t have some more facts to make it specify, because it’s occasionally happened and depends on the air-pollution degree and the articles exposure degree.

Here we suggested you may send this letter to your customers too, not only local but international, to decide if gas-fading issue has an high impact on your application, if yes, if they would like to add some cost on anti-gas fading PP.

Our UV masterbatch, already considered the gas-fading possibility, and our choice made by anti-gas-fading Polyolefin.

We promise:

Be together with you, we will be there forever❤  





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