UV-C sensitive composition and dosimeter

Abstract

The invention is a UV sensitive composition that undergoes a color change upon exposure to a predetermined dosage of UV-C radiation. The UV-C sensitive composition comprises a halogenated polymer, such as polyvinylidene chloride, that produces an acid upon exposure to UV radiation, and a pH sensitive dye. Upon exposure to UV-C radiation, the halogenated polymer undergoes degradation and produces HCl. The pH sensitive dye changes color as a result in an increase in HCl in the system. The composition may also include an acid scavenging composition and/or a diluent to control the amount of HCl produced in the system. The amount of HCl liberated from UV-C exposure may be selectively controlled so that a color change may be produced at a desired UV-C dosage. In some embodiments, the composition may be used to indicate a UV-C dosage from about 100 to 1600 mJ/cm 2 .

1 . A composition for monitoring the amount of UV dosage to which an object has been exposed, said composition comprising: 
 a) a halogenated polymer that produces an acid upon exposure to UV-C radiation; and    b) a pH sensitive dye which changes color in response to a change in acid levels, wherein the amounts of said halogenated polymer and said pH sensitive dye are selected to indicate a UV-C dosage up to about 200 mJ/cm 2 , and wherein said halogenated polymer and said pH sensitive dye are soluble in a lacquer based solution.    
   
   
       2 . The composition according to  claim 1 , wherein said halogenated polymer includes halogenated polymers selected from the group consisting of polyvinyl chloride and copolymers thereof, polyvinylidene chloride and copolymers thereof, ethylene-chlorotrifluoroethylene copolymer, and combinations thereof.  
   
   
       3 . The composition according to  claim 1 , wherein said pH sensitive dye is selected from the group consisting of bromophenol blue, phenol red, thymol blue, ethyl orange, m-Cresol purple, New Fuchsin, p-methyl red, lissamine green, aniline blue, methyl violet, crystal violet, ethyl violet, brilliant green, oralochite green oxalate, methyl green, cresol red, quinaldine red, para methyl red, metanil yellow, orange IV, phenylazoaniline, erythrosin B, benzopurpurin 4B, congo red, methyl orange, bromocresol green, resazurin, ethyl red, methyl red, alizarin red, bromocresol purple, chlorophenol red, and combinations thereof.  
   
   
       4 . A composition for monitoring the amount of WV dosage to which an object has been exposed, said composition comprising: 
 a) a halogenated polymer that produces an acid upon exposure to UV-C radiation;    b) an acid scavenger; and    c) a pH sensitive dye which changes color in response to a change in acid levels, wherein the amounts of said halogenated polymer, acid scavenger, and said pH sensitive dye are selected to indicate a UV-C dosage in the range from about 100 to 1600 mJ/cm 2 , and wherein said halogenated polymer, acid scavenger, and said pH sensitive dye are soluble in a lacquer based solution.    
   
   
       5 . The composition according to  claim 4 , wherein said halogenated polymer includes halogenated polymers selected from the group consisting of polyvinyl chloride and copolymers thereof, polyvinylidene chloride and copolymers thereof, ethylene-chlorotrifluoroethylene copolymer, and combinations thereof.  
   
   
       6 . The composition according to  claim 4 , wherein said pH sensitive dye is selected from the group consisting of bromophenol blue, phenol red, thymol blue, ethyl orange, m-Cresol purple, New Fuchsin, p-methyl red, lissamine green, aniline blue, methyl violet, crystal violet, ethyl violet, brilliant green, oralochite green oxalate, methyl green, cresol red, quinaldine red, para methyl red, metanil yellow, orange IV, phenylazoaniline, erythrosin B, benzopurpurin 4B, congo red, methyl orange, bromocresol green, resazurin, methyl red, alizarin red, bromocresol purple, chlorophenol red, and combinations thereof.  
   
   
       7 . The composition according to  claim 4 , wherein said acid scavenger is selected from the group consisting of,4-diazabicyclo[2.2.2]octane; 2,6-di-tert-butylpyridine; dibutyl 2,6-pyridinedicarboxylate; diphenylamine; 2,4-dihydroxybenzophenone; 1,8-diazabichclo[5.4.0]undec-7-ene (1,5-5); 1,5-diazabicyclo[4.3.0]non-5-ene; 4-(dimethylamino)pyridine; hexamethylenetetramine; and combinations thereof.  
   
   
       8 . The composition according to  claim 4 , wherein said composition is disposed on a substrate in the form of a film.  
   
   
       9 . The composition according to  claim 8 , further comprising a screen layer disposed on a surface of said film.  
   
   
       10 . The composition according to  claim 4 , wherein the amounts of said halogenated polymer, said acid scavenger, and said pH sensitive dye are selected to indicate a UV dosage of at least about 200 mJ/cm 2 .  
   
   
       11 . The composition according to  claim 4 , wherein the amounts of said halogenated polymer, said acid scavenger, and said pH sensitive dye are selected to indicate a UV dosage of at least about 400 mJ/cm 2 .  
   
   
       12 . The composition according to  claim 4 , wherein the amounts of said halogenated polymer, said acid scavenger, and said pH sensitive dye are selected to indicate a UV dosage of at least about 800 mJ/cm 2 .  
   
   
       13 . A composition for monitoring the amount of UV-C dosage to which an object has been exposed, said composition comprising: 
 a) a halogenated polymer that undergoes dehalogenation to produce an acid upon exposure to UV radiation;    b) an acid scavenger having a pKa in the range from about 4 to 8, and wherein the amount of said acid scavenger in said composition is from about 0.5 to 20 percent based on the total weight of the solids in the composition;    c) a diluent, wherein the amount of said diluent in said composition is from about 0 to 50 percent based on the total weight of the solids in the composition; and    d) a pH sensitive color indicator having a pKa in the range from about 2 to 6, wherein the amounts of said halogenated polymer, acid scavenger, diluent and pH sensitive color indicator are selected to indicate a UV-C dosage in the range from about 200 to 800 mJ/cm 2 .    
   
   
       14 . The composition according to  claim 13 , wherein said halogenated polymer comprises polyvinylidene chloride.  
   
   
       15 . The composition according to  claim 13 , wherein the amount of said halogenated polymer is from about 0.10 to 50 percent, based on the total weight of the solids in the composition.  
   
   
       16 . The composition according to  claim 13 , wherein said diluent is selected from the group consisting of cellulose acetate propionate, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, styrene-maleic anhydride copolymers, ethylene acrylate copolymers, styrene-butadiene copolymers, acrylonitrilebutadiene copolymers, poly(ethylenevinyl acetate), and combinations thereof.  
   
   
       17 . The composition according to  claim 13 , wherein the composition is present in a non-aqueous solvent, said solvent selected from the group consisting of toluene, ethyl acetate, tetrahydrofuran, and combinations thereof.  
   
   
       18 . A UV-C dosimeter for measuring the dosage of UV-C radiation to which an article has been exposed, said UV-C dosimeter comprising: 
 a substrate having a plurality of UV-C sensitive compositions coated thereon and wherein said plurality of UV-C sensitive compositions includes one or more of: 
 a first UV-C sensitive composition that undergoes a color change in response a UV-C dosage of 200 mJ/cm 2  or greater;  
 a second UV-C sensitive composition that undergoes a color change in response a UV-C dosage of 400 mJ/cm 2  or greater; and  
 a third UV-C sensitive composition that undergoes a color change in response a UV-C dosage of 800 mJ/cm 2  or greater.  
   
   
   
       19 . The UV-C dosimeter according to  claim 18 , wherein said plurality of UV-C sensitive compositions comprise a halogenated polymer that undergoes dehalogenation to produce an acid upon exposure to UV radiation, an acid scavenger, and a pH sensitive dye which changes color in response to a change in proton levels, wherein the amounts of said halogenated polymer, acid scavenger, and said pH sensitive dye are selected to indicate a UV-C dosage in the range from about 200 to 800 mJ/cm 2 .  
   
   
       20 . The UV-C dosimeter according to  claim 19 , wherein said halogenated polymer, said acid scavenger, and said pH sensitive dye are soluble in a lacquer based solution.  
   
   
       21 . The UV-C dosimeter according to  claim 18 , wherein said halogenated polymer comprises polyvinylidene chloride.  
   
   
       22 . The UV-C dosimeter according to  claim 18 , wherein said reference card further comprises at least one reference color that corresponds to a UV-C dosage of about 0 mJ/cm 2 .  
   
   
       23 . The UV-C dosimeter according to  claim 18 , wherein said halogenated polymer comprises polyvinylidene chloride.  
   
   
       24 . The UV-C dosimeter according to  claim 18 , wherein the UV-C sensitive composition further comprises a diluent selected from the group consisting of cellulose acetate propionate, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, styrene-maleic anhydride copolymers, ethylene-acrylate copolymers, styrene-butadiene copolymers, acrylonitrilebutadiene copolymers, poly(ethylenevinyl acetate), and combinations thereof.  
   
   
       25 . The UV-C dosimeter according to  claim 18 , wherein the first UV-C sensitive composition changes from a yellow to red color upon exposure of a UV-C dosage of about 200 mJ/cm 2  or greater, and said second UV-C sensitive composition changes from a yellow to red color upon exposure of a UV-C dosage of about 400 mJ/cm 2  or greater.  
   
   
       26 . The UV-C dosimeter according to  claim 18 , wherein the third UV-C sensitive composition changes from a green to purple color upon exposure of a UV-C dosage of about 800 mJ/cm 2  or greater.  
   
   
       27 . A kit for measuring the dosage of UV-C radiation to which an article has been exposed, said kit comprising: 
 a. the UV-C dosimeter according to  claim 18;  and    b. a UV-C dosage reference card having one or more reference patterns that are each associated with a different dosage of UV-C radiation, and wherein said reference card includes a corresponding reference pattern for each UV-C sensitive composition on said substrate.    
   
   
       28 . The kit according to  claim 26 , wherein said reference card further comprises at least one reference pattern that corresponds to a UV-C dosage of about 0 mJ/cm 2 .