Method of imaging and developing negative-working elements

Abstract

Negative-working imagable elements can be imaged and then developed using a lower pH organic-based single-phase developer that is less toxic and corrosive and that can be more readily disposed of after use. This developer has a pH less than 12 and comprises a) an amphoteric surfactant comprising a nitrogen-containing heterocycle, b) an amphoteric surfactant having two or more nitrogen atoms, or c) an amphoteric surfactant of a) and an amphoteric surfactant of b).

1 .- 22 . (canceled)  
     
     
         23 . A method of providing an imaged and developed element comprising: 
 A) using a laser, imagewise exposing a negative-working imagable element using imaging radiation having a λ max  of from about 250 to about 450 nm, said imagable element comprising a substrate having thereon an imagable layer to provide exposed and non-exposed regions, said imagable layer comprising: 
 a free radically polymerizable component,  
 an initiator composition capable of generating radicals sufficient to initiate polymerization of said radically polymerizable component upon exposure to imaging radiation, said initiator composition comprising a hexaarylbiimidazole,  
 a radiation absorbing compound that is represented by: 
 G-(Ar 1 ) 3  wherein G is a furan or oxazole ring, and Ar 1  represents the same or different substituted or unsubstituted carbocyclic aryl group, or  
 Ar 1 -G-Ar 2  wherein G is a furan, oxazole, or oxadiazole ring, and Ar 1  and Ar 2  represent the same or different substituted or unsubstituted carbocyclic aryl group, or Ar 2  represents an arylene-G-Ar 1  or an arylene-G-Ar 2  group, and  
 
 a polymeric binder, and  
   B) contacting said imagewise exposed element with a single-phase developer to remove only said non-exposed regions to provide a developed element, 
 wherein said developer has a pH from about 6 to about 10 and comprises:  
 a) an amphoteric surfactant comprising a nitrogen-containing heterocycle,  
 b) an amphoteric surfactant having two or more nitrogen atoms, or  
 c) an amphoteric surfactant of a) and an amphoteric surfactant of b).  
   
     
     
         24 . The method of  claim 23  wherein said amphoteric surfactant has a nitrogen-containing heterocycle and said developer further comprises at least 0.5 weight % of benzyl alcohol.  
     
     
         25 . The method of  claim 23  wherein said developer has a pH of at from about 6.5 to about 9.5.  
     
     
         26 . The method of  claim 23  wherein said developer is free of silicates, hydroxides, or both.  
     
     
         27 . The method of  claim 23  wherein said developer is also free of: (a) reaction products of phenol with ethylene oxide or propylene oxide, (b) esters and ethers of alkylene glycols having 6 or fewer carbon atoms, and (c) mono- and diethanolamines.  
     
     
         28 . The method of  claim 23  wherein said developer further comprises a benzene or naphthalene sulfonate surfactant in an amount of at least 5 weight %.  
     
     
         29 . The method of  claim 23  wherein said amphoteric surfactant of a) comprises two basic nitrogen atoms in a heterocyclic ring and is present in said developer in an amount of at least 2 weight %.  
     
     
         30 . The method of  claim 23  wherein said amphoteric surfactant comprises both carboxy groups and nitrogen atoms wherein the number of nitrogen atoms is greater than the number of carboxy groups.  
     
     
         31 . The method of  claim 23  wherein said developer has a pH of from about 6.5 to about 9.5, said amphoteric surfactant is present in an amount of at from about 2 to about 10 weight %, said developer further comprises benzyl alcohol in an amount of from about 0.5 to about 15 weight % and a benzene or naphthalene sulfonate surfactant in an amount of from about 5 to about 15 weight %, and the weight ratio of all of said amphoteric and benzene or naphthalene sulfonate surfactants to benzyl alcohol in said developer is at least 2.5:1.  
     
     
         32 . The method of  claim 23  wherein said amphoteric surfactant of a) has a carboxylate attached to a nitrogen-containing heterocycle.  
     
     
         33 . The method of  claim 23  wherein said imaged element can be treated overall with heat before step B.  
     
     
         34 . The method of  claim 23  wherein said imagable element further comprises an oxygen-impermeable topcoat disposed over said imagable layer.  
     
     
         35 . The method of  claim 23  further comprising using said imagewise exposed and developed element to print an impression on a receiving material.  
     
     
         36 . The method of  claim 23  wherein said amphoteric surfactant has a nitrogen-containing heterocycle, said developer further comprises at least 0.5 weight % of benzyl alcohol, and said developer has a pH of at from about 6.5 to about 9.5.  
     
     
         37 . The method of  claim 23  wherein said developer has a pH of from about 6.5 to about 9.5, said amphoteric surfactant is present in an amount of at from about 2 to about 10 weight %, said developer further comprises benzyl alcohol in an amount of from about 2 to about 5 weight % and a benzene or naphthalene sulfonate surfactant in an amount of from about 5 to about 15 weight %, and the weight ratio of all of said amphoteric and benzene or naphthalene sulfonate surfactants to benzyl alcohol in said developer is at least 2.5:1.  
     
     
         38 . The method of  claim 23  wherein said imagable element is imaged using imaging radiation having a λ max  of from about 375 to about 450 nm.  
     
     
         39 . The method of  claim 23  wherein said radiation absorbing compound is a 2,4,5-triaryloxazole derivative that is used alone or in combination with a co-initiator that is a 1,3,5-triazine or thiol compound.  
     
     
         40 . The method of  claim 23  wherein said substrate is an aluminum-containing sulfuric acid-anodized substrate that has been treated with a monosodium phosphate solution containing sodium fluoride.  
     
     
         41 . A method of providing an imaged and developed element comprising: 
 A) using a laser, imagewise exposing a negative-working imagable element using imaging radiation having a λ max  of from about 250 to about 450 nm, said imagable element comprising a substrate having thereon an imagable layer to provide exposed and non-exposed regions, said imagable layer comprising: 
 a free radically polymerizable component,  
 an initiator composition capable of generating radicals sufficient to initiate polymerization of said radically polymerizable component upon exposure to imaging radiation, said initiator composition comprising a polycarboxylic acid free radical generating compound,  
 a radiation absorbing compound that is a pyrylium or thiopyrylium dye or 3-ketocoumarin, and  
 a polymeric binder, and  
   B) contacting said imagewise exposed element with a single-phase developer to remove only said non-exposed regions to provide a developed element, 
 wherein said developer has a pH from about 6 to about 10 and comprises:  
 a) an amphoteric surfactant comprising a nitrogen-containing heterocycle,  
 b) an amphoteric surfactant having two or more nitrogen atoms, or  
 c) an amphoteric surfactant of a) and an amphoteric surfactant of b).  
   
     
     
         42 . An imaged element obtained from the method of  claim 23 .  
     
     
         43 . The imaged element of  claim 42  that is a lithographic printing plate.