1. Field of the Invention
The present invention relates to photosensitive compounds, more particularly, derivatives of halomethyl-1,3,5-triazines.
2. Discussion of the Prior Art
Compounds that decompose to generate free radicals (free radical generating agents) upon exposure to light are well known in the graphic arts. Organic halogen compounds, which are capable of generating free radicals such as a chlorine free radical or a bromine free radical upon exposure to light, have been widely used as photoinitiators in photopolymerizable compositions, as photoactivators in free radical photographic compositions, and as photoinitiators for reactions catalyzed by acids formed by light. The spectral sensitivity of these compositions may be broadened by the addition of sensitizers, which, in essence, transfer their absorbed energy to the organic halogen compound. The use of such halogen compounds in photopolymerization processes and free radical photographic processes have been described in Kosar, Light-Sensitive Systems, J. Wiley & Sons (New York, 1965), pp. 180-181, 361-370.
Halomethyl-1,3,5-triazines are known to be initiators for a number of photochemical reactions. They are employed to produce free radicals for initiating polymerization or color changes and for initiating secondary reactions upon liberation of acid by the interaction of the free-radicals when hydrogen donors are present.
Examples of the use of halomethyl-1,3,5-triazines in the free radical polymerization of acrylate monomers are described in U.S. Pat. No. 3,905,815; U.S. Pat. No. 3,617,288; U.S. Pat. No. 4,181,752; U.S. Pat. No. 4,391,687; U.S. Pat. No. 4,476,215; and DE 3,517,440. U.S. Pat. No. 3,779,778 discloses the photoinitiated acid catalyzed decomposition of pyranyl ether derivatives to produce photosolubilizable compositions useful as positive printing plates. Chromophore substituted styryl-1,3,5-triazines and their uses are disclosed in U.S. Pat. No. 3,987,037 and U.S. Pat. No. 3,394,475.
Radiation sensitive compositions containing bi- and polyaromatic substituted triazines are disclosed in U.S. Pat. No. 4,189,323.