UV Blocking clear material or coatings

[GuyFromDenver]

I am working on a medical application where I need to block wavelengths of light from 500 nm and lower. The photoinitiators in medical composites typically cure at 470 nm, so I can't have any of the blue and UV light. Most of the methacrylates (Lexan and the like) don't cut off until about 400 nm. Another option would be to use a film or coating on the Lexanish plate. The final size of the lens needs to be about 12" x 12". Does anybody know of a cost effective solution other then telling my customer I can't do it?

 

[berkshire]

Try talking to Mark Livesay at Sunrez corp

http://www.sunrez.com.

He has been selling photo initiated resins since the 1990s
And can tell you what works and what does not.
B.E.

 

[cpretty]

I was working on UV cure adhesive bonding of Radel R. We couldn't cure the UV adhesive due to inability to get the UV light through. I think that the Blue Light spectrum worked for us though, so would be a problem for you

Attached link shows optical properties of the Solvay sulphone medical polymers, which is a usefull document as a reference for this type of work.

Craig

 

[patprimmer]

Lexan is a brand name for Polycarbonate. The other popular brand is Makrolon.

Methacrylate is acrylic, typical brand names Perspex, Oroglass, Plexiglass Shinkolite.

Sheet manufacturers may be able to supply UV filter grades. They may do this by adding UV absorbing pigments. Museum grade has UV filters, but I don't know if it filters in the range you specify. By museum grade, I mean the grade used to protect displays like old documents where they might otherwise be subject to UV degradation. Perspex certainly had one such grade in years gone by.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[tygerdawg]

Investigate

http://www.exatec.biz

, they are in the business of putting an anti-UV coating + an anti-abrasion coating on Lexan polycarbonate for automotive glazing applications. The result of this development work is opening doors to many other applications.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[GuyFromDenver]

Thanks for the help. My biggest concern is that the light will not be white anymore after it passes through the filter. Is anybody out there able to do a notch band reject filter that will squelch out only the wavelengths between say 450 and 490 nm?

 

[lumenharold]

This company came through for us on a recent project:

http://www.evaporatedcoatings.com/

Harold
SW2009 SP4.0 OPW2009 SP2 Win XP Pro 2002 SP3
Dell 690, Xeon 5160 @3.00GHz, 3.25GB RAM
nVidia Quadro FX4600

http://www.lumenflow.com

 

[GuyFromDenver]

Funny! I just got off the phone when I received your message Harold! they can all do it, but the color of the light is so warm that it appears to look like a high pressure sodium lamp, and that is what i am retying to replace. They have low color rendering and are energy hogs. LEDs have a much higher color rendering, but they also have a lot of UV, and it, the lowere wavelengths, below 500 nm, that I am trying to cut out yet still keep a white color.

 

[lumenharold]

Cutting out the blue and having the light look white will be a neat trick with LEDs. It's the blue content that makes it white to the eye. Most phosphor LEDs have diode chip sources that put out 450 - 465nm blue. More blue light that is not converted by the phosphor will make the color temperture higher and make the light "whiter". A few LEDs use 405nm but the trend is higher wavelengths for the high brightness types.

A couple questions to answer might be how white does it need to be (degrees K) and how much blue is too much?

Harold
SW2009 SP4.0 OPW2009 SP2 Win XP Pro 2002 SP3
Dell 690, Xeon 5160 @3.00GHz, 3.25GB RAM
nVidia Quadro FX4600

http://www.lumenflow.com

 

[moltenmetal]

Light missing 450-490 nm will very likely not appear white. So unless you can alter the initiators so that they're only sensitive to UV light, you're going to have to accept light which has a tinge of colour to it.

How much of a tinge will depend on how much you want to spend. A notch filter will be more expensive than a sheet of transparent yellow or orange acrylic (which will block below ~ 500 nm).