Cr39

**beejay** · 02-16-2015, 07:45 AM

Hello Optiboarders,

Is there any other manufacturer/supplier of columbia resin apart from PPG?

Google failed me and leads me to CR39 lens manufacturers.

Benny

**Mauro.Airoldi** · 02-16-2015, 09:38 AM

try Google with allyl diglycol carbonate (ADC) , Cr 39 is a PPG trade mark.

**Chris Ryser** · 02-16-2015, 11:27 AM

Some historic facts :

CR-39, or allyl diglycol carbonate (ADC), is a plastic polymer commonly used in the manufacture of eyeglass lenses. The abbreviation stands for "Columbia Resin #39," because it was the 39th formula of a thermosetting plastic developed by the Columbia Resins project in 1940.^[1]
The first commercial use of CR-39 monomer was to help create glass-reinforced plastic fuel tanks for the B-17 bomber aircraft in World War II, reducing weight and increasing range of the bomber. After the War, the Armorlite Lens Company in California is credited with manufacturing the first CR-39 eyeglass lenses in 1947. CR-39 plastic has an index of refraction of 1.498 and an Abbe number of 58. CR-39 is now a trade marked product of PPG Industries.^[2]
An alternative use includes a purified version that is used to measure neutron radiation, a type of ionizing radiation, in neutron dosimetry.
CR-39 should not be confused with polycarbonate, a tough homopolymer usually made from bisphenol A.^{[3]

See all of It : http://en.wikipedia.org/wiki/CR-39}