Industrial antimicrobial agents are chemical compositions that are used to prevent microbiological contamination and deterioration of commercial products, materials and systems. The following chemical classes of antimicrobial agents are recognized in industry applications: phenolics; halogen compounds, quaternary ammonium compounds; metal derivatives; amines; alkanolamines and nitro derivatives; anilides; and organo-sulfur and sulfur-nitrogen compounds.
A given antimicrobial agent may either destroy all of the microbes present or just prevent their further proliferation to numbers that would be significantly destructive to the substrate or system being protected. The terms, microbes and microorganisms, refer primarily to bacteria and fungi. Each of these groups is subdivided into two general subclasses: gram-positive and gram-negative bacteria, and among the fungi, molds and yeasts.
Areas of application for antimicrobial agents include cosmetics, disinfectants and sanitizers, wood preservatives, food and animal feeds, paint, cooling water, metalworking fluids, hospital and medical uses.
Of the numerous antimicrobial compounds which are available for use, the phenolic compound dihydric phenol 2,4,4'-trichloro-2'-hydroxydiphenyl ether (a.k.a. triclosan), is perceived as being the most desirable. This antimicrobial agent, however, when incorporated into surfactant compositions containing surfactants whether anionic, cationic, nonionic, amphoteric, zwitterionic, and the like, has a tendency to undergo color degradation when exposed to UV light (either sunlight or indoor light) over prolonged periods of time due to the oxidative formation of free radicals within the system. Thus, an antimicrobial hand soap composition containing triclosan as an antimicrobial agent will, over time, turn dark in color due to the penetration of UV rays through the container, causing it to appear dirty in color.
It is therefore an object of the present invention to enhance the color stability of surfactant compositions containing triclosan as an antimicrobial agent by inhibiting free radical formation.