Development enhancement of radiation-sensitive elements
A positive-working radiation-sensitive composition for use with a radiation source comprises one or more polivinyl acetal polymers capable of being dissolved in an alkaline aqueous solution and a development-enhancing compound. The sensitivity of a radiation-sensitive coating based on the composition of this invention is increased without compromising the handling characteristics. Radiation-sensitive elements based on the composition of the invention have good development latitude. A positive-working lithographic printing precursor is based on the radiation-sensitive composition coated on a hydrophilic surface. The precursor is developable using an alkaline aqueous solution, and may be used with a radiation source in lithographic applications, such as conventional imaging systems, computer-to-plate systems or other direct imaging applications. The precursor is stable in its state before exposure and has an excellent handling property.
1 . A radiation-sensitive composition comprising
a. an acetal resin derived from polyvinyl alcohol by condensation with aldehydes and
b. a developability-enhancing compound.
2 . The composition of claim 1 , further comprising a radiation-to-heat converting compound.
3 . The composition of claim 2 , in which the radiation-to-heat converting compound is an infrared light-to-heat converting compound.
4 . The composition of claim 3 , further comprising a dissolution inhibitor.
5 . A composition according to claim 1 , wherein the developability-enhancing compound is at least one of
a. an alcohol having at least one of an alkyl radical of 12-60 carbon atoms, a fluoroalkyl radical of 4-60 carbon atoms and a fluoroalkylaryl radical of 7-60 carbon atoms;
b. a polyol;
c. a monohydric phenol;
d. a polyhydric phenol;
e. a compound containing thiol functionality;
f. an anionic lithium salt that is one of a carboxylate, thiocarboxylate, sulfate, sulfonate, phosphate, phosphite, nitrate and nitrite;
g. an ester of a phosphorous-containing acid;
h. an amide of a phosphorus containing acid;
i. a polysiloxane;
j. a quaternary ammonium salt having a free hydroxyl group.
k. an azo compound;
l. a compound containing —NH—NH— functionality;
m. a compound containing —NH—N═C functionality;
n. a compound containing the structure
where X is one of —S—, S═O, C═O or CO 2 and where R 13 can be a C 1 to C 12 alkyl, benzyl or structure E, where E is given by
and where R 14 , R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , R 21 can be one of H and OH.
o. a substituted aromatic acid;
p. a substituted aromatic ester;
q. a substituted aromatic amide and
r. a compound containing sulfone functionality.
6 . A composition according to claim 5 , wherein the polyol is dimethicone copolyol.
7 . A composition according to claim 5 , wherein the polyhydric phenol is at least one of resorcinol, 4-hexylresorcinol, n-dodecylresorcinol and 1-naphthole.
8 . A composition according to claim 5 , wherein the polyhydric phenol is one of pyrogallol, phloroglucinol, 1,2,4-benzenetriol and their alkyl and fluoroalkyl derivatives.
9 . A composition according to claim 5 , wherein the anionic lithium salt is one of lithium 3-(1H,1H,2H,2H-fluoroalkyl) propionate and 3-[(1H,1H,2H,2H -fluoroalkyl)thio]propionate, lithium trifluoromethane sulfonate and lithium perfluorooctylethylsulfonate.
10 . A composition according to claim 5 , wherein the ester of a phosphorous-containing acid is one of P(OH)(OR) 2 , P(OH) 2 (OR), P(OH) 2 [O—R—N(CH 2 —CH 2 —OH) 2 ], P(OR) 2 [O—R—NH(CH 2 —CH 2 —OH) 2 ], where R is an alkyl, aryl, alkylaryl, polyethylene oxide, polypropyleneoxide or combination thereof.
11 . A composition according to claim 5 , wherein the ester of a phosphorus containing acid is a nonylphenol phosphate ester.
12 . A composition according to claim 5 , wherein the amide of a phosphorous-containing acid is one of P(OH)(ONHR) 2 , P(OH) 2 (ONHR), P(OR) 2 [O—NH(CH 2 —CH 2 —OH) 2 ], P(OR)[O—NH(CH 2 —CH 2 —OH) 2 ] 2 , where R is an alkyl, aryl, polyethylene oxide, polypropyleneoxide or combination thereof.
13 . A composition according to claim 5 , wherein the polysiloxane is R[OSi(OCH 3 ) 2 ] n —Si(OCH 3 )(OH) 2 where R is an alky, aryl, polyethyleneoxide, polypropyleneoxide group or combination thereof and n=2-1000.
14 . A composition according to claim 5 , wherein the substituted aromatic acid is at least one of 2-nitrobenzoic acid, 3-Nitrobenzoic acid, 4-Nitrobenzoic acid, 2,4-Dinitrobenzoic acid, 2,4-Dichlorobenzoic acid, 2-Hydroxy-1-napthoic acid and 3-Hydroxy-2-napthoic acid.
15 . A composition according to claim 5 , wherein the substituted aromatic ester is methyl salicylate, phenyl salicylate, benzyl-4-hydroxybenzoate, Butyl-4-hydroxybenzoate and methyl-4-hydroxy benzoate.
16 . A composition according to claim 5 , wherein the substituted aromatic amide is 3-nitrobenzamide and (2′-Hydroxyethyl)-2,4-dihydroxybenzamide.
17 . The composition of claim 1 , wherein the acetal resin has the structure
in which R 1 is —C n H 2n+ 1 where n=1 to 12, and R 2 is
wherein R 4 ═—OH;
R 5 ═—OH or —OCH 3 or Br— or —O—CH 2 —C≡CH and
B 6 ═Br— or NO 2
R 3 ═—(CH 2 ) t —COOH, —C≡CH, or
where R 7 ═COOH, —(CH 2 ) t —COOH, —O—(CH 2 ) t —COOH
and in which t=1 to 4, and where b=5 to 40 mole %, preferably 15 to 35 mole %
c=10 to 60 mole %, preferably 20 to 40 mole %
d=0 to 20 mole %, preferably 0 to 10 mole %
e=2 to 20 mole %, preferably 1 to 10 mole %
and f=5 to 50 mole %, preferably 15 to 40 mole %.
18 . A composition according to claim 17 , wherein the developability-enhancing compound is at least one of
a. an alcohol having at least one of an alkyl radical of 12-60 carbon atoms, a fluoroalkyl radical of 4-60 carbon atoms and a fluoroalkylaryl radical of 7-60 carbon atoms;
b. a polyol;
c. a monohydric phenol;
d. a polyhydric phenol;
e. a compound containing thiol functionality;
f. an anionic lithium salt that is one of a carboxylate, thiocarboxylate, sulfate, sulfonate, phosphate, phosphite, nitrate and nitrite;
g. an ester of a phosphorous-containing acid;
h. an amide of a phosphorus containing acid;
i. a polysiloxane;
j. a quaternary ammonium salt having a free hydroxyl group
k. an azo compound;
l. a compound containing —NH—NH— functionality;
m. a compound containing —NH—N═C functionality;
n. a compound containing the structure
where X is one of —S—, S═O , C═O or CO 2 and where R 13 can be a C 1 to C 12 alkyl, benzyl or structure E, where E is given by
and where R 14 , R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , R 21 can be one of H and OH.
o. a substituted aromatic acid;
p. a substituted aromatic ester;
q. a substituted aromatic amide and
r. a compound containing sulfone functionality.
19 . A composition according to claim 18 , wherein the polyhydric phenol is at least one of resorcinol, 4-hexylresorcinol, n-dodecylresorcinol and 1-naphthole.
20 . A radiation-sensitive composition comprising:
a. at least one of resorcinol, n-dodecyl resorcinol, 4-hexyl resorcinol and 1-naphthole,
b. an acetal resin formed by the condensation of polyvinyl alcohol with aldehydes,
c. a dissolution inhibitor and
d. an infrared light-to-heat converting compound.
21 . An imageable element comprising,
a. a substrate and
b. a coated and dried layer of the composition of claim 2 on a surface of the substrate.
22 . An imageable element comprising,
a. a substrate and
b. a coated and dried layer of the composition of claim 5 on a surface of the substrate.
23 . An imageable element comprising,
a. a substrate and
b. a coated and dried layer of the composition of claim 18 on a surface of the substrate.
24 . An imageable element comprising,
a. a substrate and
b. a coated and dried layer of the composition of claim 20 on a surface of the substrate.
25 . A positive-working lithographic printing precursor comprising a layer of a radiation-sensitive composition on a hydrophilic lithographic printing surface, the composition comprising
a. an acetal resin derived from polyvinyl alcohol by condensation with aldehydes and
b. a developability-enhancing compound.
26 . The precursor of claim 25 , wherein the composition further comprises an infrared light-to-heat converting compound.
27 . The precursor of claim 26 , wherein the composition further comprises a dissolution inhibitor.
28 . The precursor of claim 25 , wherein the developability-enhancing compound is at least one of
a. an alcohol having at least one of an alkyl radical of 12-60 carbon atoms, a fluoroalkyl radical of 4-60 carbon atoms and a fluoroalkylaryl radical of 7-60 carbon atoms;
b. a polyol;
c. a monohydric phenol;
d. a polyhydric phenol;
e. a compound containing thiol functionality;
f. an anionic lithium salt that is one of a carboxylate, thiocarboxylate, sulfate, sulfonate, phosphate, phosphite, nitrate and nitrite;
g. an ester of a phosphorous-containing acid;
h. an amide of a phosphorus containing acid;
i. a polysiloxane;
j. a quaternary ammonium salt having a free hydroxyl group.
k. an azo compound;
l. a compound containing —NH—NH— functionality;
m. a compound containing —NH—N═C functionality;
n. a compound containing the structure
where X is one of —S—, S═O, C═O or CO 2 and where R 13 can be a C 1 to C 12 alkyl, benzyl or structure E, where E is given by
and where R 14 , R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , R 21 can be one of H and OH.
o. a substituted aromatic acid;
p. a substituted aromatic ester;
q. a substituted aromatic amide and
r. a compound containing sulfone functionality.
29 . The precursor of claim 28 , wherein the polyol is dimethicone copolyol.
30 . The precursor of claim 28 , wherein the polyhydric phenol is at least one of resorcinol, 4-hexylresorcinol, n-dodecylresorcinol and 1-naphthole.
31 . The precursor of claim 28 , wherein the polyhydric phenol is one of pyrogallol, phloroglucinol, 1,2,4-benzenetriol and their alkyl and fluoroalkyl derivatives.
32 . The precursor of claim 28 , wherein the anionic lithium salt is one of lithium 3-(1H,1H,2H,2H-fluoroalkyl) propionate and 3-[(1H,1H,2H,2H-fluoroalkyl)thio]propionate, lithium trifluoromethane sulfonate and lithium perfluorooctylethylsulfonate.
33 . The precursor of claim 28 , wherein the ester of a phosphorus containing acid is one of P(OH)(OR) 2 , P(OH) 2 (OR), P(OH) 2 [O—R—N(CH 2 —CH 2 —OH) 2 ], P(OR) 2 [O—R—NH(CH 2 —CH 2 —OH) 2 ], where R is an alkyl, aryl, alkylaryl, polyethylene oxide, polypropyleneoxide or combination thereof.
34 . The precursor of claim 28 , wherein the ester of a phosphorus containing acid is a nonylphenol phosphate ester.
35 . The precursor of claim 28 , wherein the amide of a phosphorus containing acid is one of P(OH)(ONHR) 2 , P(OH) 2 (ONHR), P(OR) 2 [O—NH(CH 2 —CH 2 —OH) 2 ], P(OR)[O—NH(CH 2 —CH 2 —OH) 2 ] 2 , where R is an alkyl, aryl, polyethylene oxide, polypropyleneoxide or combination thereof.
36 . The precursor of claim 28 , wherein the polysiloxane is R[OSi(OCH 3 ) 2 ] n —Si(OCH 3 )(OH) 2 where R is an alky, aryl, polyethyleneoxide, polypropyleneoxide group or combination thereof and n=2-1000.
37 . A composition according to claim 28 , wherein the substituted aromatic acid is at least one of 2-nitrobenzoic acid, 3-Nitrobenzoic acid, 4-Nitrobenzoic acid, 2,4-Dinitrobenzoic acid, 2,4-Dichlorobenzoic acid, 2-Hydroxy-1-napthoic acid and 3-Hydroxy-2-napthoic acid.
38 . A composition according to claim 28 , wherein the substituted aromatic ester is methyl salicylate, phenyl salicylate, benzyl-4-hydroxybenzoate, Butyl-4-hydroxybenzoate and methyl-4-hydroxy benzoate.
39 . A composition according to claim 28 , wherein the substituted aromatic amide is 3-nitrobenzamide and (2′-Hydroxyethyl)-2,4-dihydroxybenzamide.
40 . A positive-working lithographic printing precursor comprising a layer of a radiation-sensitive composition on a hydrophilic lithographic printing surface, the composition comprising
a. an acetal resin derived from polyvinyl alcohol by condensation with aldehydes and
b. a developability-enhancing compound,
wherein the acetal resin has the structure
in which R 1 is —C n H 2n+1 where n=1 to 12, and R 2 is
wherein R 4 ═—OH;
R 5 ═—OH or —OCH 3 or Br— or —O—CH 2 —C≡CH and
B 6 ═Br— or NO 2
R 3 ═—(CH 2 ) t —COOH, —C≡CH, or
where R 7 ═COOH, —(CH 2 ) t —COOH, —O—(CH 2 ) t —COOH
and in which t=1 to 4, and where b=5 to 40 mole %, preferably 15 to 35 mole %
c=10 to 60 mole %, preferably 20 to 40 mole %
d=0 to 20 mole %, preferably 0 to 10 mole %
e=2 to 20 mole %, preferably 1 to 10 mole %
and f=5 to 50 mole %, preferably 15 to 40 mole %.
41 . The precursor of claim 40 , wherein the developability-enhancing compound is at least one of
a. an alcohol having at least one of an alkyl radical of 12-60 carbon atoms, a fluoroalkyl radical of 4-60 carbon atoms and a fluoroalkylaryl radical of 7-60 carbon atoms;
b. a polyol;
c. a monohydric phenol;
d. a polyhydric phenol;
e. a compound containing thiol functionality;
f. an anionic lithium salt that is one of a carboxylate, thiocarboxylate, sulfate, sulfonate, phosphate, phosphite, nitrate and nitrite;
g. an ester of a phosphorous-containing acid;
h. an amide of a phosphorus containing acid;
i. a polysiloxane;
j. a quaternary ammonium salt having a free hydroxyl group.
k. an azo compound;
l. a compound containing —NH—NH— functionality;
m. a compound containing —NH—N═C functionality;
n. a compound containing the structure
where X is one of —S—, S═O, C═O or CO 2 and where R 13 can be a C 1 to C 12 alkyl, benzyl or structure E, where E is given by
and where R 14 , R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , R 21 can be one of H and OH.
o. a substituted aromatic acid;
p. a substituted aromatic ester;
q. a substituted aromatic amide and
r. a compound containing sulfone functionality.
42 . The precursor of claim 41 , wherein the polyhydric phenol is at least one of resorcinol, 4-hexylresorcinol, n-dodecylresorcinol and 1-naphthole.
43 . A positive-working lithographic printing precursor comprising a layer of a radiation-sensitive composition on a hydrophilic lithographic printing surface, the composition comprising:
a. at least one of resorcinol, n-dodecyl resorcinol, 4-hexyl resorcinol and 1-naphthole,
b. an acetal resin formed by the condensation of polyvinyl alcohol with aldehydes,
c. a dissolution inhibitor and
d. an infrared light-to-heat converting compound.
44 . A method for making a positive-working lithographic printing precursor, the method comprising the steps of coating a hydrophilic lithographic printing surface with a layer of a radiation-sensitive composition and drying the layer, wherein the composition comprises
a. an acetal resin derived from polyvinyl alcohol by condensation with aldehydes and
b. a developability-enhancing compound.
45 . The method of claim 44 , wherein the composition further comprises an infrared light-to-heat converting compound.
46 . The method of claim 45 , wherein the composition further comprises a dissolution inhibitor.
47 . The method of claim 45 , wherein the developability-enhancing compound is at least one of
a. an alcohol having at least one of an alkyl radical of 12-60 carbon atoms, a fluoroalkyl radical of 4-60 carbon atoms and a fluoroalkylaryl radical of 7-60 carbon atoms;
b. a polyol;
c. a monohydric phenol;
d. a polyhydric phenol;
e. a compound containing thiol functionality;
f. an anionic lithium salt that is one of a carboxylate, thiocarboxylate, sulfate, sulfonate, phosphate, phosphite, nitrate and nitrite;
g. an ester of a phosphorous-containing acid;
h. an amide of a phosphorus containing acid;
i. a polysiloxane;
j. a quaternary ammonium salt having a free hydroxyl group.
k. an azo compound;
l. a compound containing —NH—NH— functionality;
m. a compound containing —NH—N═C functionality;
n. a compound containing the structure
where X is one of —S—, S═O, C═O or CO 2 and where R 13 can be a C 1 to C 12 alkyl, benzyl or structure E, where E is given by
and where R 14 R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , R 21 can be one of H and OH.
o. a substituted aromatic acid;
p. a substituted aromatic ester;
q. a substituted aromatic amide and
r. a compound containing sulfone functionality.
48 . The method of claim 47 , wherein the polyol is dimethicone copolyol.
49 . The method of claim 47 , wherein the polyhydric phenol is at least one of resorcinol, 4-hexylresorcinol, n-dodecylresorcinol and 1-naphthole.
50 . The method of claim 47 , wherein the polyhydric phenol is one of pyrogallol, phloroglucinol, 1,2,4-benzenetriol and their alkyl and fluoroalkyl derivatives.
51 . The method of claim 47 , wherein the anionic lithium salt is one of lithium 3-(1H,1H,2H,2H-fluoroalkyl) propionate and 3-[(1H,1H,2H,2H-fluoroalkyl)thio]propionate, lithium trifluoromethane sulfonate and lithium perfluorooctylethylsulfonate.
52 . The method of claim 47 , wherein the ester of a phosphorus containing acid is one of P(OH)(OR) 2 , P(OH) 2 (OR), P(OH) 2 [O—R—N(CH 2 —CH 2 —OH) 2 ], P(OR) 2 [O—R—NH(CH 2 —CH 2 —OH) 2 ], where R is an alkyl, aryl, alkylaryl, polyethylene oxide, polypropyleneoxide or combination thereof.
53 . The method of claim 47 , wherein the ester of a phosphorus containing acid is a nonylphenol phosphate ester.
54 . The method of claim 47 , wherein the amide of a phosphorus containing acid is one of P(OH)(ONHR) 2 , P(OH) 2 (ONHR), P(OR) 2 [O—NH(CH 2 —CH 2 —OH) 2 ], P(OR)[O—NH(CH 2 —CH 2 —OH) 2 ] 2 , where R is an alkyl, aryl, polyethylene oxide, polypropyleneoxide or combination thereof.
55 . The method of claim 47 , wherein the polysiloxane is R[OSi(OCH 3 ) 2 ] n —Si(OCH 3 )(OH) 2 where R is an alky, aryl, polyethyleneoxide, polypropyleneoxide group or combination thereof and n=2-1000.
56 . A composition according to claim 47 , wherein the substituted aromatic acid is at least one of 2-nitrobenzoic acid, 3-Nitrobenzoic acid, 4-Nitrobenzoic acid, 2,4-Dinitrobenzoic acid, 2,4-Dichlorobenzoic acid, 2-Hydroxy-1-napthoic acid and 3-Hydroxy-2-napthoic acid.
57 . A composition according to claim 47 , wherein the substituted aromatic ester is methyl salicylate, phenyl salicylate, benzyl-4-hydroxybenzoate, Butyl-4-hydroxybenzoate and methyl-4-hydroxy benzoate.
58 . A composition according to claim 47 , wherein the substituted aromatic amide is 3-nitrobenzamide and (2′-Hydroxyethyl)-2,4-dihydroxybenzamide.
59 . A method for making a positive-working lithographic printing precursor, the method comprising the steps of coating a hydrophilic lithographic printing surface with a layer of a radiation-sensitive composition and drying the layer, wherein the composition comprises
a. an acetal resin derived from polyvinyl alcohol by condensation with aldehydes and
b. a developability-enhancing compound,
wherein the acetal resin has the structure
in which R 1 is —C n H 2n+1 where n=1 to 12, and R 2 is
wherein R 4 ═—OH;
R 5 ═—OH or —OCH 3 or Br— or —O—CH 2 —C≡CH and
B 6 ═Br— or NO 2
R 3 ═—(CH 2 ) t —COOH, —C≡CH, or
where R 7 ═COOH, —(CH 2 ) t —COOH, —O—(CH 2 ) t —COOH
and in which t=1 to 4, and where b=5 to 40 mole %, preferably 15 to 35 mole %
c=10 to 60 mole %, preferably 20 to 40 mole %
d=0 to 20 mole %, preferably 0 to 10 mole %
e=2 to 20 mole %, preferably 1 to 10 mole %
and f=5 to 50 mole %, preferably 15 to 40 mole %.
60 . The method of claim 59 , wherein the developability-enhancing compound is at least one of
a. an alcohol having at least one of an alkyl radical of 12-60 carbon atoms, a fluoroalkyl radical of 4-60 carbon atoms and a fluoroalkylaryl radical of 7-60 carbon atoms;
b. a polyol;
c. a monohydric phenol;
d. a polyhydric phenol;
e. a compound containing thiol functionality;
f. an anionic lithium salt that is one of a carboxylate, thiocarboxylate, sulfate, sulfonate, phosphate, phosphite, nitrate and nitrite;
g. an ester of a phosphorous-containing acid;
h. an amide of a phosphorus containing acid;
i. a polysiloxane;
j. a quaternary ammonium salt having a free hydroxyl group.
k. an azo compound;
l. a compound containing —NH—NH— functionality;
m. a compound containing —NH—N═C functionality;
n. a compound containing the structure
where X is one of —S—, S═O , C═O or CO 2 and where R 13 can be a C 1 to C 12 alkyl, benzyl or structure E, where E is given by
and where R 14 R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , R 21 can be one of H and OH.
o. a substituted aromatic acid;
p. a substituted aromatic ester;
q. a substituted aromatic amide and
r. a compound containing sulfone functionality.
61 . The method of claim 60 , wherein the polyhydric phenol is at least one of resorcinol, 4-hexylresorcinol, n-dodecylresorcinol and 1-naphthole.
62 . A method for making a positive-working lithographic printing precursor, the method comprising the steps of coating a hydrophilic lithographic printing surface with a layer of a radiation-sensitive composition and drying the layer, wherein the composition comprises
a. at least one of resorcinol, n-dodecyl resorcinol, 4-hexyl resorcinol and 1-naphthole,
b. an acetal resin formed by the condensation of polyvinyl alcohol with aldehydes,
c. a dissolution inhibitor and
d. an infrared light-to-heat converting compound.
63 . A method for making a lithographic printing master, the method comprising the steps of
a. providing a lithographic printing precursor comprising a layer of a radiation-sensitive composition on a hydrophilic lithographic printing surface, the composition comprising
i. an acetal resin derived from polyvinyl alcohol by condensation with aldehydes and
ii. a developability-enhancing compound,
b. imagewise irradiating areas of the layer with imaging radiation to render the layer more soluble in an aqueous alkaline solution in the areas irradiated.
64 . The method of claim 63 , wherein the composition further comprises an infrared light-to-heat converting compound.
65 . The method of claim 64 , wherein the composition further comprises a dissolution inhibitor.
66 . The method of claim 64 , wherein the developability-enhancing compound is at least one of
a. an alcohol having at least one of an alkyl radical of 12-60 carbon atoms, a fluoroalkyl radical of 4-60 carbon atoms and a fluoroalkylaryl radical of 7-60 carbon atoms;
b. a polyol;
c. a monohydric phenol;
d. a polyhydric phenol;
e. a compound containing thiol functionality;
f. an anionic lithium salt that is one of a carboxylate, thiocarboxylate, sulfate, sulfonate, phosphate, phosphite, nitrate and nitrite;
g. an ester of a phosphorous-containing acid;
h. an amide of a phosphorus containing acid;
i. a polysiloxane;
j. a quaternary ammonium salt having a free hydroxyl group.
k. an azo compound;
l. a compound containing —NH—NH— functionality;
m. a compound containing —NH—N═C functionality;
n. a compound containing the structure
where X is one of —S—, S═O , C═O or CO 2 and where R 13 can be a C 1 to C 12 alkyl, benzyl or structure E, where E is given by
and where R 14 , R 15 , R 16 , R 17 , R 18 , R 19 , R 20 , R 21 can be one of H and OH.
o. a substituted aromatic acid;
p. a substituted aromatic ester;
q. a substituted aromatic amide and
r. a compound containing sulfone functionality.
67 . The precursor of claim 66 , wherein the polyhydric phenol is at least one of resorcinol, 4-hexylresorcinol, n-dodecylresorcinol and 1-naphthole.
68 . A method for making a lithographic printing master, the method comprising the steps of
a. providing a lithographic printing precursor comprising a layer of a radiation-sensitive composition on a hydrophilic lithographic printing surface, the composition comprising
i. an acetal resin formed by the condensation of polyvinyl alcohol with aldehydes,
ii. at least one of resorcinol, n-dodecyl resorcinol, 4-hexyl resorcinol and 1-naphthole,
iii. a dissolution inhibitor and
iv. an infrared light-to-heat converting compound.
b. imagewise irradiating areas of the layer with imaging radiation to render the layer more soluble in an aqueous alkaline solution in the areas irradiated.