as used herein , the term &# 34 ; sensitizer moiety &# 34 ; means a moiety containing at least one group that is not a part of the triazine chromophore and is capable of absorbing actinic radiation and enhancing spectral sensitivity . halomethyl substituted , 1 , 3 , 5 - triazine compounds of this invention can be represented by the general formula i : ## str1 ## wherein a represent a member selected from the group consisting of mono -, di - and trihalo methyl groups , y represent a member selected from the group consisting of a , l - s , nh 2 , nhr , nr 2 , or , and r &# 39 ;, where r independently represents a substituted or unsubstituted alkyl group , preferably having 1 to 6 carbon atoms , or a substituted or unsubstituted aryl group , and r &# 39 ; represents a substituted or unsubstituted alkyl group , preferably having 1 to 6 carbon atoms , a substituted or unsubstituted aryl group , a substituted or unsubstituted alkenyl group , preferably having 2 to 6 carbon atoms , or a substituted or unsubstituted heterocyclic aromatic group , s represents a sensitizer moiety that is not part of the triazine chromophore and is capable of absorbing actinic radiation , s having a λmax of at least 330 nm , and l represents a group linking the sensitizer moiety to the triazine nucleus . halomethyl groups that are suitable for the present invention include chloro -, bromo -, and iodomethyl groups , with chloro - and bromomethyl groups being preferred . trihalomethyl groups are preferred ; most preferred are trichloromethyl and tribromomethyl groups . y represents any of a variety of substituents that are useful in modifying the physical , e . g ., solubility , or chemical properties of the molecule , and preferably represents a , l - s , or r &# 39 ;. when y represents a , the maximum number of halomethyl groups per triazine nucleus can be made available for radical generation . when y represents l - s , the chemical composition for both l - s groups can be the same , or it can be different , depending on the composition of linking group l , sensitizer group s , or both . when y represents r &# 39 ;, and in particular when r &# 39 ; represents an aryl , aralkenyl , or heteroaromatic group , the spectral sensitivity of the triazine chromophore portion of the molecule can be varied , based on the photochemical response of r , to actinic radiation . when r or r &# 39 ; represents an aryl group it is preferred that the group have a maximum of five rings , more preferably three rings , and most preferably one ring . when r or r &# 39 ; represents a substituted group , the particular identity of the substituent is not critical . however , the substituents should not adversely affect the photoinitiation characteristics of the compounds of this invention . s represents a sensitizer - containing group which , by itself , would not initiate photopolymerization upon exposure to actinic energy , but is nevertheless capable of absorbing actinic radiation , and transferring energy to the halomethyl - 1 , 3 , 5 - triazine moiety , thereby effectively increasing the spectral sensitivity of the halomethyl - 1 , 3 , 5 - triazine moiety . the sensitizer moiety has a λmax ( i . e ., absorption maximum ) of at least 330 nm , preferably 350 nm up to 900 nm . s preferably comprises at least one member selected from the group consisting of cyanine group , carbocyanine group , merocyanine group , aromatic hydrocarbon group , polyarylamine group , and amino - substituted chalcone group . there is no upper limit on the number of sensitizer moieties per triazine nucleus ; there is no upper limit on the number of triazine nuclei per sensitizer moiety ; however , there must be at least one sensitizer moiety and at least one triazine nucleus . preferably , the number of sensitizer moieties per triazine nucleus ranges from one to two or two to one ; more preferably , there is one sensitizer moiety per triazine nucleus . if more than one sensitizer moiety is present per triazine nucleus , they can be from different generic classes or can be different species from the same generic class . if there is more than one triazine nucleus per sensitizer moiety , they can be of the same or of different species . l represents a group that links the sensitizer moiety or moieties to the triazine nucleus . the precise identity of l is not critical , but it should be selected so that it does not interfere with or adversely affect the light sensitivity of the compound . furthermore , l should be chosen so that it does not connect the chromophore of the halomethyl - 1 , 3 , 5 - triazine nucleus and the chromophore of the sensitizer moiety either directly by a covalent bond or by a conjugated linkage . however , any through space intramolecular complexation between the chromophores is not precluded . l can be a single group or can be formed from a combination of groups . groups that are suitable for linking groups include carbamator (-- nhco 2 --), urea (-- nhconh --), amino (-- nh --), amido (-- conh 2 --), aliphatic e . g ., having up to 10 carbon atoms , alkyl , e . g ., having up to 10 carbon atoms , alkenyl , e . g ., having up to 10 carbon atoms , aryl , e . g ., having one ring , styryl , ester (-- co 2 --), ether (-- o --), and combinations thereof . based on ease of synthesis , the most preferred groups for attachment directly to the triazine nucleus are carbamato , urea , amino , alkenyl , aryl , and ether . whenever the group directly attached to the triazine nucleus is either alkenyl group or aryl group , another group must be interposed between the alkenyl group or aryl group and the sensitizer moiety to prevent the sensitizer moiety from forming a conjugate bond with the triazine nucleus . one method of preparing the compounds of this invention is by the addition reaction of isocyanato - substituted halomethyl - 1 , 3 , 5 - triazines with sensitizers having groups reactive with the isocyanate group . the isocyanato substituted triazines may be prepared from the corresponding amino derivative according to the procedure of u . von gizycki , angew , chem . int . ed . eng ., 1971 , 10 , 403 . isocyanato - 1 , 3 , 5 - triazines suitable for this reaction include : examples of sensitizers that will combine with the isocyanto group include 4 -( 2 &# 39 ;- hydroxyethyl ) amino - n - 2 &# 34 ;- hydroxyethyl )- 1 , 8 - naphthalimide , 3 , 5 - bis ( dimethylaminobenzal )- 4 - piperidone , hydroxyethylrhodanine - n &# 34 ;- methylbenzothiazole , 1 - aminopyrene , and 6 - aminochrysene . the isocyanate addition reaction can be carried out in the presence of solvents , such as , for example , toluene , pyridine , benzene , xylene , dioxane , tetrahydrofuran , etc ., and mixtures of solvents . the duration and temperature of the reaction is dependent on the particular compounds and the catalyst employed . generally , temperatures of about 25 ° to 150 ° for from one to seventy - two hours are sufficient to provide for the reaction . preferably , the reaction is carried out at room temperature from three to seventy - two hours . the preferred catalyst is di - n - butyltin dilaurate . another method of preparing the compounds of this invention is the cotrimerization of organic nitriles having a sensitizer substituent with haloacetonitriles in accordance with the teachings of wakabayashi et al , bulletin of the chemical society of japan , 1969 , 42 , 2924 - 30 ; still another method of preparing the compounds of this invention is the condensation reaction of an aldehyde compound having a photoinitiator functionality in accordance with the teachings of u . s pat . no . 3 , 987 , 037 ; still another method of preparing the compound of this invention is the nucleophilic displacement reactions on halomethyl - 1 , 3 , 5 - triazines using sensitizers having free hydroxy or amino groups . the natural sensitivity of halomethyl - 1 , 3 , 5 - triazines to actinic radiation is well known . simple derivatives , such as 2 - methyl - 4 , 6 - bistrichloromethyl - 1 , 3 , 5 - triazine , absorb actinic radiation in the lower ultraviolet region , e . g . below 300 nm . photosensitizers have been added to compositions containing halomethyl - 1 , 3 , 5 - triazines as separate materials to , in effect , broaden their natural range of sensitivity . this phenomenon is complex , and is believed to involve various types of energy transfer mechanisms from the excited states of the sensitizer . moreover , the efficiency of physical combinations of sensitizing dye and photoinitiator is limited due to concentration , solubility , and light filtration factors . the compounds of this invention in which the sensitizer moiety and the halomethyl - 1 , 3 , 5 - triazine moiety are in the same molecule are more efficient for several reasons . they eliminate the need to add each material separately . they assure that the sensitizer moiety is very close to the triazine nucleus , thereby allowing lower concentrations and increased energy transfer efficiency . a halomethyl - 1 , 3 , 5 - triazine compound having a chromophore substituted directly to the triazine nucleus has a broader sensitivity range than the unsubstituted halomethyl - 1 , 3 , 5 - triazine compound . see , for example , u . s . pat . no . 3 , 954 , 475 , u . s . pat . no . 4 , 189 , 323 , u . s . pat . no . 4 , 391 , 687 , and de 3517440 . however , the nature of the compounds in these patents is limited in that preparation thereof requires formation of a covalent bond or a conjugated linkage between the triazine nucleus and the chromophore substituent , typically by either an aryl group or a vinyl group . because the triazine nucleus is not insulated from the chromophore substituent , it is difficult to predict , a priori , the absorption characteristics , i . e ., absorption maxima , of the resulting chromophore - triazine combination because they will differ from those of both the chromophore and the triazine . the compounds of this invention provide a wide variety of structures in that dye and triazine precursors can be prepared independently and then synthetically combined by simple reactions and without having to form a conjugated linkage . also , the spectral sensitivity can be predicted , a priori , to correspond to the spectral sensitivity of the sensitizer moiety . by utilizing a sensitizer moiety having a λmax ( i . e ., absorption maximum ) of at least 330 nm , the range of sensitivity of a halomethyl - 1 , 3 , 5 - triazine compound can be broadened . photopolymerizable compositions wherein the compounds of this invention can be used typically comprise ( 1 ) an unsaturated , free radical initiated , chain propagating addition polymerizable compound , ( 2 ) a compound of this invention , and ( 3 ) optionally , one or more fillers , binders , dyes , polymerization inhibitors , color precursors , oxygen scavengers , etc . the compounds of this invention should be present in an amount sufficient to initiate polymerization of said polymerizable compound . suitable ratios of ingredients are as follows : for every 100 parts of polymerizable compound there can be from 0 . 005 to 10 parts of photoinitiator , from 0 to 200 parts of filler , from 0 to 200 parts of binder , and from 0 to 10 or more parts of dyes , polymerization inhibitors , color precursors , oxygen scavengers , etc , as may be needed for a particular use of the photopolymerizable compositions . preferably , from 1 to 7 . 5 parts of the compound of this invention and from 25 to 150 parts of binder are used per 100 parts of polymerizable compound . unsaturated , free - radical initiated , chain - propagating addition polymerizable compounds suitable for the compositions of this invention include alkylene or polyalkylene glycol diacrylates , e . g ., ethylene glycol diacrylate , diethylene glycol diacrylate , glycerol diacrylate , glycerol triacrylate , ethylene glycol dimethacrylate , 1 , 3 - propanediol dimethacrylate , 1 , 2 , 4 - butanetriol trimethacrylate , 1 , 4 - cyclohexanediol diacrylate , pentaerythritol tetramethacrylate , pentaerythritol triacrylate , sorbitol hexacrylate ; bis [ 1 -( 3 - acryloxy - 2 - hydroxy )]- p - propoxyphenyl dimethylmethane , bis [ 1 -( 2 - acryloxy )]- p - ethoxyphenyldimethylmethane , tris hydroxyethyl - isocyanurate trimethacrylate , the bis - acrylate and the bis - methacrylates of polyethylene glycols of molecular weight 200 - 500 and the like ; unsaturated amides , e . g ., methylene bis - acrylamide , methylene bis - methacrylamide , 1 , 6 - hexamethylene bis - acrylamide , diethylene triamine trisacrylamide , beta - metha - crylaminoethyl methacrylate ; vinyl esters such as divinyl succinate , divinyl adipate , divinyl phthalate , the preferred unsaturated compounds being pentaerythritol tetracrylate , bis [ p -( 3 - acryloxy - 2 - hydroxypropoxy ) phenyl ] dimethylmethane , and bis [ p -( 2 - acryloxyethoxy ) phenyl ] dimethylmethane . mixtures of these esters can also be used as can mixtures of these esters with alkyl esters of acrylic acid and methacrylic acid , including such esters as methyl acrylate , methyl methacrylate , ethyl acrylate , isopropyl methacrylate , n - hexyl acrylate , stearyl acrylate , allyl acrylate , diallyl phthalate , and the like . to prepare the photosensitive compositions of this invention , the components can be admixed in any order and stirred or milled to form a solution or uniform dispersion . photosensitive elements can be made by coating a photosensitive composition on a suitable base or support and drying the coating . the dry thickness typically ranges from about 0 . 00005 to about 0 . 075 inch . suitable bases or supports for the photosensitive compositions include metals , e . g ., steel and aluminum plates , sheets and foils , and films or plates composed of various film - forming synthetic or high polymers including addition polymers , e . g . vinylidene chloride , vinyl chloride , vinyl acetate , styrene , isobutylene polymers and copolymers and linear condensation polymers e . g ., polyethylene terephthalate , polyhexamethylene adipate , polyhexamethylene adipamide / adipate . the invention will be more specifically illustrated by the following examples . the value of λmax was measured in methanol , unless otherwise indicated . this example illustrates preparation of 4 - amino -[ 2 &# 39 ;- ethyl - n &# 39 ;-( 4 , 6 - bistrichloromethyl )- 1 , 3 , 5 - triazin - 2 - yl )- carbamate ]- n -[ 2 &# 39 ;- ethyl - n &# 34 ;-( 4 , 6 - bis ( trichloromethyl )- 1 , 3 , 5 - triazin - 2 - yl )- carbamate ]- 1 , 8 - naphthalimide . to a solution containing 345 mg ( 1 . 1 mmol )- 4 -( 2 &# 39 ;- hydroxyethyl ) amino - n -( 2 &# 34 ;- hydroxyethyl )- 1 , 8 - napthalimide in 50 ml dry toluene was added a solution of 1 . 17 g ( 3 . 4 mmol ) 2 , 4 - bis ( trichloromethyl )- 6 - isocyanato1 , 3 , 5 - triazine in 8 ml dry toluene . the reaction mixture was stirred under n 2 at 25 ° c . for six days . the solvent was removed by means of a rotary evaporator under reduced pressure and the residue was loaded upon a silica gel column ( 100 g packed in dichloromethane ) and eluted with dichloromethane . the fractions containing the bright yellow compound were collected and the solvent was removed to yield 320 mg product ( 29 % yield ). the product had a melting point in excess of 260 ° c . and a λmax of 433 nm . the structure of this product is shown below . ## str3 ## this example illustrates preparation of n -[ 3 , 5 - bis ( dimethylaminobenzal )- 4 - piperidone ]-[ 4 , 6 - bis ) trichloromethyl )- 1 , 3 , 5 - triazin - 2 - yl ] carbamate . to a solution containing 2 . 20 g ( 5 . 6 mmol ) 3 , 5 - bis ( dimethylaminobenzal )- 4 - piperidone and 20 drops di - n - butyltin dilaurate in 200 ml dry dichloromethane was added 2 . 0 g ( 5 . 6 mmol ) 2 , 4 - bis ( trichloromethyl )- 6 - isocyanato - 1 , 3 , 5 - triazine . the reaction mixture was stirred at room temperature under a nitrogen atmosphere for 24 hours . the solvent was removed by means of a rotary evaporator under reduced pressure at room temperature . the residue was treated with 20 ml dichloromethane and the precipitate was filtered and dried to yield a 3 . 38 g product ( 84 % yield ). the product had a melting point in excess of 260 ° c . and a λmax of 460 nm . the structure of this product is shown below . ## str4 ## this example illustrates preparation of 2 -[ 3 &# 39 ;, 5 &# 39 ;- bis ( dimethylaminobenzal )- 4 &# 39 ;- piperidone ]- 4 , 6 - bis ( trichloromethyl )- 1 , 3 , 5 - triazine . a solution containing 414 mg ( 1 . 2 mmol ) 3 , 5 - bis ( dimethylaminobenzal )- 4 - piperidone and 500 mg ( 1 . 2 mmol ) 2 , 4 , 5 - tris ( trichloromethyl )- 1 , 3 , 5 - triazine in 150 ml methanol was heated to reflux for 62 hours . the reaction mixture was cooled to room temperature , and the precipitate was filtered and dried to yield 385 . 4 mg product ( 53 % yield ). the product had a melting point in excess of 260 ° c . and λmax of 455 nm . the structure of this product is shown below . ## str5 ## this example illustrates preparation of 2 -( hydroxyethylrodanine - n &# 34 ;- methylbenzothiazole )- n &# 39 ;[ 4 , 6 - bis ( trichloromethyl )- 1 , 3 , 5 - triazin - 2 - yl ]- carbamate . to a solution containing 90 . 8 mg ( 2 . 8 mmol ) hydroxyethylrhodanine - n &# 34 ;- methylbenzothiazole in 50 ml dry toluene was added 158 . 3 mg ( 5 . 0 mmol ) 2 , 4 - bis ( trichloromethyl )- 6 - isocyanato - 1 , 3 , 5 - triazine . the reaction mixture was stirred at room temperature under a nitrogen atmosphere for 45 hours . the solvent was removed by means of a rotary evaporator under reduced pressure at room temperature . the residue was treated with a small amount of dichloromethane and the resulting precipitate was filtered to yield 118 . 8 mg product ( 62 % yield ). the product had a melting point of 185 °- 189 ° c . and a λmax of 428 nm . the structure of this product is shown below . ## str6 ## this example illustrates preparation of n -[ 1 &# 39 ;- pyrene ]- n &# 39 ;-[ 4 , 6 - bis ( trichloromethyl )- 1 , 3 , 5 - triazin - 2 - yl ]- urea . to a solution containing 500 mg ( 2 . 3 mmol ) 1 - aminopyrene and 20 drops di - n - butyltin dilaurate in 50 ml dry toluene was added 815 mg ( 2 . 3 mmol ) 2 , 4 - bis ( trichloromethyl )- 6 - isocyanato - 1 , 3 , 5 - triazine . the reaction mixture was stirred at room temperature under a nitrogen atmosphere for 17 . 5 hours . the precipitate was filtered and dried to yield 1 . 11 gm product ( 84 % yield ). the product had a melting point of 244 °- 246 ° c . and a λmax of 340 nm . the structure of this product is shown below . ## str7 ## this example illustrates preparation of n -[ 6 &# 39 ;- chrysene ]- n &# 39 ;-[ 4 , 6 - bis ( trichloromethyl )- 1 , 3 , 5 - triazin - 2 - yl ]- urea . to a solution containing 250 mg ( 1 . 0 mmol ) 6 - aminochrysene and 20 drops of di n - butyltin dilaurate in 50 ml dry toluene was added 365 mg ( 1 . 0 mmol ) 2 , 4 - bis ( trichloromethyl )- 6 - isocyanto - 1 , 3 , 5 - triazine . the reaction mixture was stirred at room temperature under a nitrogen atmosphere for 17 . 5 hours . the precipitate was filtered and dried to yield 354 mg product ( 60 % yield ). the product had a melting point of 238 °- 241 ° c . and a λmax of 330 nm . the structure of this product is shown below . ## str8 ## this example illustrates the preparation of photosensitive elements using the halomethyl - 1 , 3 , 5 - triazines of this invention and the spectral response of the compounds in such elements . a solution was prepared from 74 . 24 g azeotrope of 1 - propanol and water ( 71 . 8 % 1 - propanol / 28 . 2 % water ), 4 . 32 g pentaerythritol tetraacrylate (&# 34 ; sartomer &# 34 ; monomer sr - 295 , arco chemical company ), 5 . 64 g oligomer ( prepared according to u . s . pat . no . 4 , 228 , 232 and 60 . 9 % in methyl ethyl ketone ), 0 . 30 g triethylamine , and 14 . 88 g a 1 : 1 mixture of polyvinyl acetate - methylal resin (&# 34 ; formvar &# 34 ; 12 / 85t , union carbide corp .) and red pigment ( pigment red 48 , c . i . 15865 ) ( 9 . 4 % by weight solution of the azeotrope ). to 2 . 5 g of this solution was added 10 - 15 mg initiator , and the resulting solution shaken in the dark for 15 minutes . the solution was filtered through glass wool and coated onto a grained , anodized aluminum plate with a # 12 mayer bar . the plate was dried at 66 ° c . for 2 min and cooled to room temperature . to this coating was applied a topcoat formulation ( prepared from 5 . 00 g carboxymethyl cellulose ether ( cmc - 7l ), 0 . 26 g surfactant (&# 34 ; triton &# 34 ; x - 100 ( 10 % in water )), and 95 . 00 g water ) with a # 14 mayer bar , and the topcoat carefully dried with a heat gun . the plates were exposed for 5 sec in air on top of a draw - down glass in a 3m seventy unit equipped with a 2 kw photopolymer bulb through a √ 2 , 21 step stouffer step tablet . the plates were soaked in a developer solution prepared from 784 . 4 g deionized water , 16 . 7 g sodium metasilicate pentahydrate , 33 . 4 g 1 - propanol , and 0 . 5 surfactant (&# 34 ; dowfax - 2al &# 34 ;, dow chemical company ( 45 % solution in water )) for 15 sec and rubbed 10 times with a 4 in .× 4 in . cotton pad . the relative sensitivities for triazines are shown in table 2 . table 2______________________________________initiator solid step______________________________________example 1 5example 2 9example 3 5example 4 3example 5 3example 6 3______________________________________ various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention , and it should be understood that this invention is not to be unduly limited to the illustrated embodiments set forth herein .