P.E.T flakes

[omar]

hi to all.

i`m using 10% of p.e.t flakes to make a preform wight 34g, the problem that i`m facing now is when the bottle which made by our preform is storage for 3 days, the taste of the water becomes so bad with a bad smell.

but the preform smell is good and after blow it also good, the problem happen when the bottle of mineral water storage for at least 3 days.

barrel temperature of the injection machine is 285.

charge pressure is 75, charge speed is 70.

waiting for your kind support.

best regards,

Omar

[greg]

Are you saying that the bottle is starting to smell bad after sitting full of mineral water for three days?

Source and cleanliness of PET Flake? Although I can't imagine what contaminant on the flake would not be cleaned by the temperature.

[Dr. Dick]

Omar said "the taste of the water becomes so bad with a bad smell."

Can you describe the taste or smell. Such as bitter taste, spoiled food taste, rotten eggs smell, putrefied meat smell, sweet smell, or ????

Greg
Organic contaminants probably, Inorganic contaminates no.
There are some contaminates that will catalyze the decomposition of PET especially if wet.

Omar
Are you drying your PET? How and where is the incoming resin stored?
Are you processing any other resins in your plant and if so what ones?

[Louis]

Does the bottle smell when stored EMPTY for three days?

Sounds like an interaction with the bottle and water.

[PDF]

Does it smell if you were to run virgin material? It might eliminate the water as the source of the smell.

[Dr. Dick]

Omar said "i`m using 10% of p.e.t flakes to make a preform wight 34g, ..."

What's the other 90%?

Sorry I forgot to include this in my previous post.

[omar]

thank you for your kind response.

Mr.greg,
yes, after the bottle is sitting full of mineral water for three days.
the flakes which we use are from our industry, i meant that we did not buy the bottles from out side,coz we have blowing section.
therefore, we don`t have to wash.

Dr. Dick,
i can not describe the smill and the taste of the water, it`s a wondered smill and taste.
yes, we drying the p.e.t ( dew point -40 ). P.E.T resin IV 0.80 from RELIANCE CO.,and it`s stored in a good place which is away from humidity and sun light.
we are manufacturing of P.E.T preforms and P.E.T bottles.
we use 10% of p.e.t flakes, the other 90% is virgin p.e.t resin.

Mr.Louis,
No, just when it`s sitting full of mineral water for three days.

Dear PDF,
we tried other preforms from other industries and there is no smell and bad taste in the water.

waiting for your kind replies.

[Will Call]

This may sound absurd but how well is the air filtered that you use in your blow molding dept? Is it possible there is moisture in the bottle from this? Moisture in compressed air really stinks and if you are sending them straight from the molding machine to the fill line without washing, you could be contaminating the water.

[omar]

Mr. Will Call, and everybody,
this problem sounds more likely from the Injection dept., coz as i clarified above that when we did a test by blowing other preforms from another industry, and we filled them of a mineral water and left for 1 month,the result is, nothing changed in the taste and the smell of the water.

moreover, we don`t have any problems of the other preforms ( 80g , 100g , and 150g).

this problem happen on preforms 34g and 22g.

waiting for your kind replies.

[Louis]

OK,

Let's ask some more questions to clear things up.

First, the other preforms were made by another supplier on another machine - is it possible they used a different resin?

You said that other preforms ( 80g , 100g , and 150g) work OK. Are the preforms made in your plant using the same machines and material lots?

I cannot imagine that the same material run on the same machine in a smaller would cause problems.

[Richie D]

As PDF said, do you get the same problem when using 100% virgin material? Is it one batch of material or several batches? Have you tried other suppliers material?

This may enable you to decide if it's a process or material related problem.

Richie D

[Len]

The smell is related to degradation. PET + heat/shear/time (processing) = Odor? I'm not sure what of the chemical nature of the odor causing material.

Flake PET represents a more processed/high heat history material compared to virgin. Virgin material + processing = no odor. Virgin and flake mix + processing = odor.

Len

[Louis]

So is the PET Flake subjected to a remelt prior to mixing with the virgin materail?

"A simple recycle method popular is to only crush mold PET products, then mix crushed PET granules into virgin PET resins, but the percentage should be no more than 20%. High regrind proportion will cause variance on melt's viscosity, color and odor."

Pulled from a quick search on the subject.

http://www.kenplas.com/project/pet/

[omar]

Mr.Louis,
first : the other supplier used same resin. RELPET from RELIANCE INDIA.
second : yes, we use the same machines and material lots.

I cannot imagine that the same material run on the same machine in a smaller would cause problems.

but, that`s what happened.

Mr.Richie D,
we made the preforms by 100% virgin, but it did not work, we still face the same problem.
today we tried TEXPET, another p.e.t resin supplier, nothing changed.

Mr.Len, and Mr.Louis,

thank you for the informations which will contribute of increasing our knowledge.

please be informed that even with the virgin mateial the problem still standing in the same case ( smell and bad taste ).

i could not imagine what makes the smaller preforms have this problem.

dryer dew piont = -40
melt termpreture = 285 each zone, except feeding zone 280.
mould tempreture = 270 - 280
charge pressure = 75, speed 70
shot cycle = 10sec
cooling time = 10sec ( the preform comes out warm )

waiting for your kind replies.
[/quote]

[PDF]

please be informed that even with the virgin mateial the problem still standing in the same case ( smell and bad taste ).

I would start to look at things other than processing conditions. Will Call's "smelly air theory" doesn't sound as absurd as he proclaims. And it's super easy to check... just fill up a garbage bag with air from that line, and take a whiff.

Maybe do something similar for your water lines.

Also, what can contaminate the water between molding and filling?

-Pete