Suggestion for Opaque ABS material

[paresh95037]

Dear Forum Members,

We are developing a product that requires no light to enter into an optical cavity except for the designated openings. Unfortunately, we started the project without any plastics knowledge and let the plastics manufacturer choose the material. The color we specified is white and it does need to be white. They chose PA-757. The thickness of our design at it's thinnest point is 1mm. Needless to say, we are getting a lot of "light leakage" into our cavity causing a number of measurement problems. Is there an opaque ABS material that I could use that would help us? My current test is to take my cell phone (Samsung Galaxy Note II), turn on it's light, and see if I get light through the plastic. With PA-757, I get loads!

Regards,
Paresh

 

[MikeHalloran]

If the exterior has to be white, paint the inside flat black.
If the interior has to be white, paint the outside black then white.


Mike Halloran
Pembroke Pines, FL, USA

 

[MacGyverS2000]

Opaque to what wavelengths, visible only?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[paresh95037]

Hi Guys,

Thanks for the info. We already tried the white and black/white paint combo but that didn't work too well. We tried a metallic based paint which worked much better. Still the issue is on flat surfaces, it works great but the corners...not so much.

We are trying to minimally block 400-700nm wavelengths.

Regards,
Paresh

 

[Demon3]

You can buy ABS pigmented with TiO2 to make it white or with carbon black to make it black. Both are high volume standard, inexpensive products from Dow, Styrolution etc.. Normally there may be 1-3% pigment but I've seen formulations with up to 10% to give better light blocking. For those you may need to order from RTP or other compounder. This approach will work better than applying a coating because coatings are too thin to reflect or absorb all the light. When you have the pigment inside the plastic, there is a greater depth of material to work with. Also note that even if you've already bought the ABS and are stuck with it, you can apply the color during the molding process using a color concentrate.

Chris DeArmitt - PhD FRSC

Plastics & Materials Consulting

http://www.phantomplastics.com

Plastic Training Seminars

http://www.plastictraining.com

 

[Pud]

FR ABS has a lot of filler in it. I'll have a look at some parts when at work tomorrow and see how opaque it is. Gets a bit problematic when colouring white though as it's a yellowish base. Requires a custom masterbatch with optical brighteners in.

Stand by...

H

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.

 

[paresh95037]

Thank you Dr. DeArmitt. I will ask about adding extra TiO2. Also eagerly standing by H. Hopefully you have something that is opaque enough.

Regards,
Paresh

 

[Pud]

Bad news I'm afraid - just checked a part 1mm thick and it is still translucent to a single LED pen torch. Less than non-fr ABS but nowhere near opaque.
H

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.

 

[cowski]

I've seen parts where another material, such as TPE, is overmolded to create "windows" for LED's to shine through. The TPE "frame" greatly helps to reduce the light from one LED from leaking through a neighboring "window". Perhaps you could use a similar design?

 

[paresh95037]

Okay no issues, I really appreciate the effort and the help that everybody has offered.
The plastics company I am working with did offer one solution...and that is plating the inside with the same material used to make auto door handles look like chrome (maybe it is chrome?), and then painting white. Anyway, I'll also explore this option.

Regards,
Paresh

 

[CoryPad]

Plastic automotive trim does use chromium plating, usually a triple layer of copper, nickel, then chromium. The final chromium layer is unlikely to be suitable for a traditional polymeric paint.