Flexographic processing solution and use

Abstract

A flexographic printing plate can be prepared with relief images using a processing solution. This processing solution includes one or more esters of monobasic carboxylic acids represented by one or both of the following Structures (I) and (II): R 1 —C(═O)O—(CH 2 ) n —Ar 1   (I) wherein R 1 is an alkyl group having 1 to 5 carbon atoms, Ar 1 is a substituted or unsubstituted phenyl or naphthyl group, and n is 1 to 3, and H—C(═O)OR  (II) wherein R is a hydrocarbon having 6 to 15 carbon atoms, and b. one or more aliphatic alcohols, or a combination of one or more aliphatic alcohols and one or more aromatic alcohols.

1 . A method of providing a flexographic printing plate with a relief image comprising
 imagewise exposing a flexographic printing plate precursor comprising an imageable photopolymer layer to provide exposed and non-exposed regions in an imaged flexographic printing plate precursor,   developing the imaged flexographic printing plate precursor with a processing solution to remove non-imaged photopolymer from the imageable photopolymer layer to provide a relief image having an average depth that is from 2% to 100% of the original thickness of the imageable photopolymer layer, to form a flexographic printing plate,   wherein the processing solution comprise:   a. one or more esters of monobasic carboxylic acids represented by one or both of the following Structures (I) and (II):
   R 1 —C(═O)O—(CH 2 ) n —Ar 1   (I)
 
   
       wherein R 1  is an alkyl group having 1 to 5 carbon atoms, Ar 1  is a substituted or unsubstituted phenyl or naphthyl group, and n is 1 to 3, and
   H—C(═O)OR  (II)
 
 
       wherein R is a hydrocarbon having 6 to 15 carbon atoms, and
 b. one or more aliphatic alcohols, or a combination of one or more aliphatic alcohols and one or more aromatic alcohols. 
 
     
     
         2 . The method of  claim 1 , further comprising drying the flexographic printing plate. 
     
     
         3 . The method of  claim 1 , wherein the imageable photopolymer layer comprises a photopolymerizable elastomeric layer comprising an elastomeric binder, a photoinitiator, at least one monomer, and optionally a plasticizer, and the precursor is imagewise exposed using actinic radiation. 
     
     
         4 . The method of  claim 1 , wherein the one or more esters of monobasic carboxylic acids are present in an amount of at least 5 weight % and up to and including 70 weight %, and the one or more aliphatic alcohols, or combination of one or more aliphatic alcohols and one or more aromatic alcohols, are present in an amount of at least 5 weight % and up to and including 40 weight %. 
     
     
         5 . The method of  claim 1 , wherein the one or more esters of monobasic carboxylic acids are present in an amount of from about 20 weight % to about 60 weight %, and the one or more aliphatic alcohols, or combination of one or more aliphatic alcohols and one or more aromatic alcohols, are present in an amount of from about 10 weight % to about 30 weight %. 
     
     
         6 . The method of  claim 1 , wherein R 1  is an alkyl having 1 to 3 carbon atoms, n is 1 or 2, and R is benzyl or citronellyl. 
     
     
         7 . The method of  claim 1 , wherein the one or more esters of monobasic carboxylic acids includes one of the more of benzyl acetate, 2-phenylethyl acetate, 2-phenylethyl phenyl acetate, 2-phenylethyl isobutyrate, isobutyl phenyl acetate, benzyl propionate, benzyl butyrate, benzyl pentanoate, benzyl formate, and citronellyl formate. 
     
     
         8 . The method of  claim 1 , wherein one or more aliphatic alcohols includes one or more of n-butanol, 2-ethoxyethanol, a hexyl alcohol, a heptyl alcohol, an octyl alcohol, a nonyl alcohol, a decyl alcohol, alpha-terpineol, dipropylene glycol methyl ether, 2-butoxyethanol, isopropyl alcohol, and 2-(2-butoxyethoxy)ethanol, substituted or unsubstituted cyclopentanol, substituted or unsubstituted cyclohexanol, substituted or unsubstituted cycloheptanol, cyclopentyl substituted alcohol, cyclohexyl substituted alcohol, cycloheptyl substituted alcohol, and citronellol, and
 the one or more aromatic alcohols include one or more of benzyl alcohol, phenylethyl alcohol, isopropylbenzyl alcohol, and phenylpropyl alcohol.   
     
     
         9 . The method of  claim 1 , wherein the processing solution further comprises an aliphatic hydrocarbon in an amount of from about 10 to about 50 weight % of one or more hydrocarbon paraffins, isoparaffins, naphthenic hydrocarbons, petroleum distillates, de-aromatized petroleum distillates, terpene hydrocarbons, mixed aromatic solvents, and halogenated hydrocarbon solvents. 
     
     
         10 . The method of  claim 9 , wherein the processing solution further comprises an aliphatic hydrocarbon that is one or more of de-aromatized petroleum distillates, hydrocarbon paraffins and iso-paraffins. 
     
     
         11 . The method of  claim 1 , wherein the processing solution further comprises one or more esters of monobasic carboxylic acids represented by the following Structure (III):
   Ar 1 —C(═O)O—R 2   (III)
   
       wherein R 2  is a saturated hydrocarbon group having 1 to 10 carbon atoms and Ar 1  is a substituted or unsubstituted phenyl or naphthyl group. 
     
     
         12 . The method of  claim 11  wherein Ar 1  in Structure (III) is a substituted or unsubstituted phenyl group, and R 2  is an alkyl group having 1 to 3 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms in the carbocyclic ring.