Infrared transmission of common polymers? 1

[JBDEX]

I am having major trouble finding IR transmission data for polymers commonly used in injection mouldings.
We require an ABS or Polycarbonate matl which not only blocks visible light (~400-700nm) but also effectively blocks all transmission from 700nm>1300nm too.
Are there any resources available for optical transmission characteristics of polymers available on the web or on paper?
thanks for any help on this.
JB

 

[Demon3]

Add some carbon black to it. That should adsorb everything.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[JBDEX]

Many thanks for the fast response. Our problem is that we need white coloured ABS and/or PC. Wouldn't the carbon black darken the colour appearance or is the amount required to block IR so small as not to affect colour?
We can indeed use black polymers for some parts, but some visible parts will have to be white.
Regards,
JB

 

[patprimmer]

Ummm

Carbon black is pretty black. Kinda like soot or coal.

If you need white it might have been good to say so.

Titanium dioxide gives some protection from UV light and is white in colour. You need to contact suppliers for info on suitable grades and level of transmission or otherwise.

Regards
Pat
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[Demon3]

I know a guy who has all kinds of pigments to block specific IR bands so it can be done. I'm not an expert in that though.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[JBDEX]

Thanks for the info Chris. I'm unaware of how to specify these blocking pigments, apart from wavelength range and percentage attenuation and this seems of no help to our moulders.
Does your contact have these pigments produced specifically for his own requirements or are they commercially available so I can get our moulders to use them?
Your help is much appreciated; The big manufacturers have been of little help so far.
thanks.
JB

 

[unclesyd]

How about the old fashioned TiO2 or in some cases Kaolin.

http://download-book.net/tio2-DuPont-ppt-pdf.html

 

[Demon3]

Yes, he has his own pigments ready to go. I've seen some data and it looks good.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[MikeHalloran]

I'm guessing you're molding a fin or tang that's intended to block the optical path of an opto-interrupter.

I've been down that road many times. Even the blackest of black parts can be transparent to IR. White; forget it.

Worse, if you find a compound that works with this year's lot of interrupters, next year's sources will be stronger and the sensors will be more sensitive, and you'll be back in the same boat.
Been down that road also.

One pigment that I've found that works consistently for this purpose is brass, in sheet form. It can be mechanically or adhesively retained. Aluminum or steel could also work, but none of them will be effective in powder form in thin sections; you need sheet or foil.



Mike Halloran
Pembroke Pines, FL, USA

 

[patprimmer]

Along Mikes line, could the part be metallised or does it really need to be white.

For some reason I was thinking UV not IR.

Ciba makes (or made) a range of IR absorbers. I don't know if they cover the full range you require nor if they will make the moulding an unacceptable colour, but they did make IR absorbers.

Regards
Pat
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http://eng-tips.com/market.cfm

for site rules

 

[JBDEX]

Thanks for the extra info. The moulded parts where I need to block VIS&IR (typically 400-1100nm), are housings for lighting control sensors. One of the components, an ambient light detector, is sensitive to wavelengths outside of the visible spectrum which we need to block. Also visible light coming in through the back housing affects the readings of the sensor too. We can, and do, metallise some parts, but as some of these sensors have 240V on the pcbs inside, it gets troublesome to maintain creepage/clearance paramaters.
We do have samples of a white polymer from a competitor's product which blocks all VIS and >95% of the IR. We've just got to match it!
Thaks again for all of the help and advice.
JB

 

[Demon3]

You could send the competitor sample to a lab and have that analyzed. I have no lab so I can't do it, but if you contact me, I will suggest someone who can do it. He's the same guy with the expertise in IR blocking pigments.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[JBDEX]

Many thanks again Chris. I've emailed you directly on this matter.
JB