Pigments for biodegradable plastic

[polymer2006]

I am looking for pigments for biodegradable plastic. Actually I am confused about which kind of standard I need to follow to pick up the pigment.

Thanks.

 

[patprimmer]

Have you tried the major pigment suppliers in your area.

Regards

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[Demon3]

Luckily a friend of mine is an expert on biodegradable plastics so I asked him. In Europe at least biodegradability is not well-defined in any standard and so people use the standard for compostability instead because that's well defined. In practise people often use these words interchangeably and they are not in fact the same.

So, to be compostible the total residue can be no more than 1 weight %. That means adding a little bit of inorganic pigment could mean that your compostible plastic no longer meets the requirement. So any pigment choice should be made very carefully. As Pat mentioned, good pigment suppliers should be able to help.

 

[polymer2006]

Thanks, Pat and Demon3.

Actually I talked to some big suppliers of pigment, such as Clariant and Ciba. They are also not sure for this issue. In my understanding, first, the pigment should not affect the degradation behavior of biodegradable plastic, second, it would not introduce the hazard materials to the enviroment. Like Demon3 said, the inorganic pigment maybe not a good candidate. The possibility is some organic pigments that can decompose with the biodegradation of the plastic and there is no release of hazard chemicals.

From what I know, Polyone is the only one that claims they have special masterbatch for biodegradable plastics. But I really don't know what's the special for their product.

I expect more discussion in this field.

 

[patprimmer]

Organic pigments that actually dissolve to the mono molecular level in the polymer should be better than inorganic pigments that are suspended as microscopic, but not mono molecular particles.

Certain dyes or organic pigments are toxic to some organisms and that should be considered.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.