Source for Lexan resin?

[bassnut]

Where can I get a small quantity of black pre-dyed Lexan 141?
The company doing some injection molding for me is having a hard time getting a good finish on the parts. There are tiny specks of what looks like splay on the face. He's having a hard tome getting a clean black finish mixing black dye with clear pellets. I was wondering if using pre-dyed pellets would work better but the minumum order seems to be 100 pounds of the stuff.
Is it possible to get just 5 or 10 pounds somewhere?

 

[patprimmer]

No
50 lb is the pack size

Lexan is a brand name for polycarbonate. there are other manufacturers, depending on where you are.

Even if the granules are dry, the colour might be wet.

Even if the material is supplied dry which is unlikely when you consider just how dry it needs to be, and how quickly it can absorb that much moisture, it needs to be kept dry between the time the pack is opened and when the material is melted.

You need black compound.

You need proper drying equipment, especially in tropical climates or hot humid weather.

Suppliers are GE, Marthogg, Plastral Trading, Marplex, Orica, PIA, Secured Trading, Amtrade

Regards

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

 

[injectionmolder]

Hi bassnut

On your previous question you were talking about some craters kind of like orange peel on your parts, or at least that’s the way I understood. Splay now, I am assuming is a different issue right? Now just like patprimmer said, get some good drying equipment so that you can dry your PC once the dye color is being mixed with. Even if you get completely pre dried resin, pigment sure is going to be wet, by the time you mix it, put it in your hopper, and process it into the mold, you can be sure moisture is going to be present. Depending on the weather in some cases 15 minutes are enough for your PC to suck some moisture in. If what you have its in fact splay, don’t just look at the drying, make sure you are not shutting (injecting) over a cold slug, excessive decompression, wrong temperatures on nozzle and length.

My best regards

 

[dwightdixon]

The OEM should not have to be doing troubleshooting for a plastic molder. Your situation tells me you are working with the wrong molder or your business is so small it is not worth it to him to keep it. Find a competent molder in the US, there are alot of them looking for business since many jobs have migrated to lower labor costs Asia.

 

[patprimmer]

Dwight

He does not say he is US based. That is why my recommendations for suppliers was a list of suppliers from Australia. Just my own subtle little protest against the arrogance of those who presume they are the centre of the universe, and therefore we can just presume where they are located.

This is a site that is on the World Wide Web. I would expect that a little over half the membership is non US based.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[CoryPad]

pat,

Looks like non-US is about 66% of Eng-Tips membership:

http://www.eng-tips.com/geography.cfm

Regards,

Cory

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

 

[Pud]

Pat,

Surely the incorrect spelling of "moulding" is a clue to poster's whereabouts? (or perhaps not!)

Hi Bassnut,

Your moulder should also be using polymer-specific masterbatch (or dry powder) to make it black - PC does not mix well with the carrier used for general purpose colour systems. Polymer specific colour will also need drying with the bulk material.

Rgds

Harry

 

[patprimmer]

Pud

Quite possibly, but many who still use english as specified by the inventors, just use the default spell checker which is American english.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[bassnut]

We're using pre-dyed, jet-black Lexan. I was able to get 50lbs of it.
The dryers are pretty good I'm told with dewpoint control etc.
The molding machine has more than enough pressure available and the die is preheated.
Location is Los Angeles, California.

I found this interesting from Injectionmolder:

"..make sure you are not shutting (injecting) over a cold slug, excessive decompression, wrong temperatures on nozzle and length."

 

[toolman801]

I don't know if anyone thinks about this, but if the mold was polished with "SemiChrome" which is used for alot of polishing jobs, you will get an tiny specs that could look like splay on the surface of your polycarbonate. You will want to ask the molder to use just powder after the diamond polishing of the mold.