# US 8,148,042 B2 · Heat-sensitive imaging element

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- Number: US 8,148,042 B2
- Document ID: US8148042B2
- Status: Granted
- Kind: B2
- Application number: 11/993,105
- Filed: 2006-06-19
- Published: 2010-09-02
- Granted: 2012-04-03
- Earliest claimed: 2005-06-21
- Assignees: Agfa Graphics NV
- Inventors: Paul Callant; Hieronymus Andriessen; Alex Williamson; Christel Geukens; Jos Louwet
- Web page: https://patentgrep.com/patent/US8148042B2

## CPC

- B41C 1/1008: {by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials}
- B41C 1/10: for lithographic printing; Master sheets for transferring a lithographic image to the forme {(chemical or electrical pretreatment B41N3/03)}(neutralising or similar differentiation treatments of lithographic printing formes B41N3/08)
- B41C 1/1025: {using materials comprising a polymeric matrix containing a polymeric particulate material, e.g. hydrophobic heat coalescing particles}
- B41C 1/1041: {by modification of the lithographic properties without removal or addition of material, e.g. by the mere generation of a lithographic pattern}
- B41M 5/465: {Infrared radiation-absorbing materials, e.g. dyes, metals, silicates, C black}
- C09B 23/0066: {the polymethine chain being part of a carbocyclic ring,(e.g. benzene, naphtalene, cyclohexene, cyclobutenene-quadratic acid)}
- C09B 23/0091: {having only one heterocyclic ring at one end of the methine chain, e.g. hemicyamines, hemioxonol (styryl dyes see C09B23/14)}
- C09B 23/083: {five >CH- groups}
- C09B 23/086: {more than five >CH- groups}
- C09B 23/10: The polymethine chain containing an even number of >CH- groups {(styryl dyes C09B23/14, C09B23/14 takes precedence)}
- B41C 2210/04: Negative working, i.e. the non-exposed (non-imaged) areas are removed
- B41C 2210/06: Developable by an alkaline solution
- B41C 2210/08: Developable by water or the fountain solution
- B41C 2210/22: characterised by organic non-macromolecular additives, e.g. dyes, UV-absorbers, plasticisers
- B41C 2210/24: characterised by a macromolecular compound or binder obtained by reactions involving carbon-to-carbon unsaturated bonds, e.g. acrylics, vinyl polymers
- B41C: PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES (photomechanical processes for producing printing surfaces G03F; photoelectrical processes for producing printing surfaces G03G)
- B41M: PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING, (correction of typographical errors B41J; processes for applying transfer pictures or the like B44C1/16; fluid media for correction of typographical errors by coating C09D10/00; printing textiles D06P)
- C09B: ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES {, e.g. PIGMENTS}; MORDANTS; LAKES (fermentation or enzyme using processes to synthesise a desired chemical compound C12P)

## Abstract

A heat-sensitive imaging element includes an IR dye having a structure according to Formula I, wherein at least one of the Rd groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-donor than the Rd; or wherein at least one of the Ra groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-acceptor than the Ra. The imaging element is able to form a visible print-out image with a high contrast directly after image-wise exposure by IR-radiation or heating.

## Claims

### Claim 1

A heat-sensitive lithographic printing plate precursor comprising:
a support having a hydrophilic surface or which is provided with a hydrophilic layer; and
on the support, a coating which includes a photopolymerizable composition and an IR dye having a structure according to Formula I:
wherein
+Y1═ is represented by one of the following structures:
Y2— is represented by one of the following structures:
n is 0, 1, 2, or 3;
each of p and q is 0, 1, or 2;
R1 and R2 are independently an optionally substituted hydrocarbon group, or wherein two of the R1, R2, Rd, or Ra groups together include the necessary atoms to form a cyclic structure;
at least one of the Rd groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-donor than the Rd; or
at least one of the Ra groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-acceptor than the Ra;
the other Rd and Ra groups are independently represented by a group selected from the list consisting of a hydrogen atom, a halogen atom, —Re, —ORf, —SRg, and —NRuRv;
wherein Re, Rf, Rg, Ru, and Rv independently are an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group; and
the transformation provides an increase of the integrated light absorption of the dye between 400 nm and 700 nm.

### Claim 2 (depends on 1)

A heat-sensitive lithographic printing plate precursor according to claim 1, wherein the Rd group, which is transformed by a chemical reaction, is selected from the list consisting of:
—(N═CR17)a—NR3—CO—R4;
—(N═CR17)b—NR5—SO2—R6;
—(N═CR17)c—NR11—SO—R12;
—SO2—NR15R16; and
—S-L-CR7(H)1-d(R8)d—NR9—COOR18;
wherein
a, b, c, and d independently are 0 or 1;
-L- is a linking group;
R17 is a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, or an optionally substituted (hetero)aryl group; or wherein R17 and R3, R17 and R5, or R17 and R11 together include the necessary atoms to form a cyclic structure;
R4 is —OR10, —NR13R14, or —CF3; wherein
R10 is an optionally substituted (hetero)aryl group or an alpha-branched aliphatic hydrocarbon group;
R13 and R14 independently are a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, or an optionally substituted (hetero)aryl group; or R13 and R14 together include the necessary atoms to form a cyclic structure;
R3 is a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, or an optionally substituted (hetero)aryl group; or R3 together with at least one of R10, R13, and R14 include the necessary atoms to form a cyclic structure;
R6 is an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group, —OR10, —NR13R14, or —CF3; wherein R10, R13, and R14 have the same meaning as in R4;
R5 is a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, or an optionally substituted (hetero)aryl group; or wherein R5 together with at least one of R10, R13, and R14 include the necessary atoms to form a cyclic structure;
R11, R15 and R16 are independently a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, or an optionally substituted (hetero)aryl group; or wherein R15 and R16 together include the necessary atoms to form a cyclic structure;
R12 is an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group;
R7 and R9 independently are a hydrogen atom or an optionally substituted aliphatic hydrocarbon group;
R8 is —COO− or —COOR8′, wherein R8′ is a hydrogen atom, an alkali metal cation, an ammonium ion, or a mono-, di-, tri- or tetra-alkyl ammonium ion; and
R18 is an optionally substituted (hetero)aryl group or an alpha-branched aliphatic hydrocarbon group.

### Claim 3 (depends on 2)

A heat-sensitive lithographic printing plate precursor according to claim 2, wherein the IR dye has the structure of formula II, III or IV:
wherein
Ar1, Ar2, and Ar3 are independently an optionally substituted aromatic hydrocarbon group or an aromatic hydrocarbon group with an annulated benzene ring which is optionally substituted;
W1 and W2 are independently a sulfur atom or a —CM10M11 group, wherein M10 and M11 are independently an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group, or wherein M10 and M11 together include the necessary atoms to form a cyclic structure;
M1 and M2 are independently an optionally substituted aliphatic hydrocarbon group, or wherein M1 and M2 together include the necessary atoms to form an optionally substituted cyclic structure;
M3 and M4 are independently an optionally substituted aliphatic hydrocarbon group;
M5, M6, M7, M8, M16, and M17 are independently a hydrogen atom, a halogen atom, or an optionally substituted aliphatic hydrocarbon group;
W3 is a sulfur atom or a —C(A3)=C(A4)- group;
M12 and M13 are independently an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group, or wherein two of the M12, M13, A2, or A4 together include the necessary atoms to form at least one cyclic structure;
W4 is a sulfur atom or a —C(A7)=C(A8)- group;
A1 to A8 are independently a hydrogen atom, a halogen atom, an optionally substituted aliphatic hydrocarbon group, or an optionally substituted (hetero)aryl group; or wherein
each of A1 and A2, A3 and A4, A5 and A6, or A7 and A8 together include the necessary atoms to form a cyclic structure;
M14 and M15 are independently an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group, or wherein two of the M14, M15, A5, or A7 together include the necessary atoms to form at least one cyclic structure; and
M9 is the Rd group which is transformed by a chemical reaction.

### Claim 4 (depends on 3)

A heat-sensitive lithographic printing plate precursor according to claim 3, wherein M1 and M2 together include the necessary atoms to form an optionally substituted 5-membered ring.

### Claim 5 (depends on 3)

A heat-sensitive lithographic printing plate precursor according to claim 3, wherein the IR dye of formula II, III, or IV has at least one anionic group or an acid group selected from the list consisting of —CO2H, —CONHSO2Rh, —SO2NHCORi, —SO2NHSO2Rj, —PO3H2, —OPO3H2, —OSO3H, or —SO3H groups or their corresponding salts; wherein Rh, Ri, and Rj are independently an aryl or an alkyl group.

### Claim 6 (depends on 4)

A heat-sensitive lithographic printing plate precursor according to claim 4, wherein the IR dye of formula II, III, or IV has at least one anionic group or an acid group selected from the list consisting of —CO2H, —CONHSO2Rh, —SO2NHCORi, —SO2NHSO2Rj, —PO3H2, —OPO3H2, —OSO3H, or —SO3H groups or their corresponding salts; wherein Rh, Ri, and Rj are independently an aryl or an alkyl group.

### Claim 7 (depends on 5)

A heat-sensitive lithographic printing plate precursor according to claim 5, wherein each of the aliphatic hydrocarbon groups of M3, M4, or M12 to M15 of the IR dye is terminally substituted with at least one of the anionic groups or acid groups.

### Claim 8 (depends on 6)

A heat-sensitive lithographic printing plate precursor according to claim 6, wherein each of the aliphatic hydrocarbon groups of M3, M4, or M12 to M15 of the IR dye is terminally substituted with at least one of the anionic groups or acid groups.

### Claim 9

A heat-sensitive lithographic printing plate precursor comprising:
a support having a hydrophilic surface or which is provided with a hydrophilic layer; and
on the support, a coating which includes thermoplastic polymer particles dispersed in a hydrophilic binder and an IR dye having a structure according to Formula I:
wherein
+Y1═ is represented by one of the following structures:
Y2— is represented by one of the following structures:
n is 0, 1, 2, or 3;
each of p and q is 0, 1, or 2;
R1 and R2 are independently an optionally substituted hydrocarbon group, or wherein two of the R1, R2, Rd, or Ra groups together include the necessary atoms to form a cyclic structure:
at least one of the Rd groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-donor than the Rd; or
at least one of the Ra groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-acceptor than the Ra;
the other Rd and Ra groups are independently represented by a group selected from the list consisting of a hydrogen atom, a halogen atom, —Re, —ORf, —SRg, and —NRuRv;
wherein Re, Rf, Rg, Ru, and Rv independently are an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group; and
the transformation provides an increase of the integrated light absorption of the dye between 400 nm and 700 nm.

### Claim 10

A heat-sensitive lithographic printing plate precursor comprising:
a support having a hydrophilic surface or which is provided with a hydrophilic layer; and
on the support, a coating which includes a switchable polymer which is capable of changing a polarity of a surface of the coating upon IR-radiation or heating from hydrophilic to hydrophobic or from hydrophobic to hydrophilic and an IR dye having a structure according to Formula I:
wherein
+Y1═ is represented by one of the following structures:
Y2— is represented by one of the following structures:
n is 0, 1, 2, or 3;
each of p and q is 0, 1, or 2;
R1 and R2 are independently an optionally substituted hydrocarbon group, or wherein two of the R1, R2, Rd, or Ra groups together include the necessary atoms to form a cyclic structure:
at least one of the Rd groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-donor than the Rd; or
at least one of the Ra groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-acceptor than the Ra;
the other Rd and Ra groups are independently represented by a group selected from the list consisting of a hydrogen atom, a halogen atom, —Re, —ORf, —SRg, and —NRuRv;
wherein Re, Rf, Rg, Ru, and Rv independently are an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group; and
the transformation provides an increase of the integrated light absorption of the dye between 400 nm and 700 nm.

### Claim 11

A heat-sensitive lithographic printing plate precursor comprising:
a support having a hydrophilic surface or which is provided with a hydrophilic layer; and
on the support, a coating which includes a polymer soluble in an alkaline solution, a solubility inhibiting compound which reduces the solubility of the coating in the alkaline solution, and wherein, upon IR-radiation or heating, the coating has an increased solubility in the alkaline solution, and an IR dye having a structure according to Formula I:
wherein
+Y═ is represented by one of the following structures:
Y2— is represented by one of the following structures:
n is 0, 1, 2, or 3;
each of p and q is 0, 1, or 2;
R1 and R2 are independently an optionally substituted hydrocarbon group, or wherein two of the R1, R2, Rd, or Ra groups together include the necessary atoms to form a cyclic structure:
at least one of the Rd groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-donor than the Rd; or
at least one of the Ra groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-acceptor than the Ra;
the other Rd and Ra groups are independently represented by a group selected from the list consisting of a hydrogen atom, a halogen atom, —Re, —ORf, —SRg, and —NRuRv;
wherein Re, Rf, Rg, Ru, and Rv independently are an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group; and
the transformation provides an increase of the integrated light absorption of the dye between 400 nm and 700 nm.

### Claim 12

A method for making a lithographic printing plate comprising the steps of:
(i) providing a heat-sensitive lithographic printing plate precursor including a support having a hydrophilic surface or which is provided with a hydrophilic layer and on the support, a coating which includes an IR dye having a structure according to Formula I:
wherein
+Y1═ is represented by one of the following structures:
Y2— is represented by one of the following structures:
n is 0, 1, 2, or 3;
each of p and g is 0, 1, or 2;
R1 and R2 are independently an optionally substituted hydrocarbon group, or wherein two of the R1, R2, Rd, or Ra groups together include the necessary atoms to form a cyclic structure;
at least one of the Rd groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-donor than the Rd; or
at least one of the Ra groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-acceptor than the Ra;
the other Rd and Ra groups are independently represented by a group selected from the list consisting of a hydrogen atom, a halogen atom, —Re, —ORf, —SRg, and —NRuRv;
wherein Re, Rf, Rg, Ru, and Rv independently are an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group; and
the transformation provides an increase of the integrated light absorption of the dye between 400 nm and 700 nm;
(ii) image-wise exposing the coating of the precursor to IR-radiation or heat thereby inducing the transformation of the IR dye and forming a print-out image; and
(iii) optionally developing the image-wise exposed precursor.

### Claim 13 (depends on 12)

A method for making a lithographic printing plate according to claim 12, wherein:
the coating includes a photopolymerizable composition.

### Claim 14 (depends on 12)

A method for making a lithographic printing plate according to claim 12, wherein:
the coating includes thermoplastic polymer particles dispersed in a hydrophilic binder.

### Claim 15 (depends on 12)

A method for making a lithographic printing plate according to claim 12, wherein:
the coating includes a switchable polymer which is capable of changing a polarity of the surface of the coating upon IR-radiation or heating from hydrophilic to hydrophobic or from hydrophobic to hydrophilic.

### Claim 16 (depends on 12)

A method for making a lithographic printing plate according to claim 12, wherein:
the coating includes a polymer soluble in an alkaline solution, a solubility inhibiting compound which reduces the solubility of the coating in the alkaline solution, and wherein, upon IR-radiation or heating, the coating has an increased solubility in the alkaline solution.

### Claim 17 (depends on 12)

A method for making a lithographic printing plate according to claim 12, further comprising the step of
developing the image-wise exposed precursor by mounting the image-wise exposed precursor on a printing press and developing the precursor in an on-press developing step.

### Claim 18 (depends on 12)

A method for making a lithographic printing plate according to claim 12, wherein the
the coating which includes a photopolymerizable composition; and further comprising the step of:
developing the image-wise exposed precursor by mounting the image-wise exposed precursor on a printing press and developing the precursor in an on-press developing step.

### Claim 19 (depends on 12)

A method for making a lithographic printing plate according to claim 12, wherein the
the coating which includes thermoplastic polymer particles dispersed in a hydrophilic binder; and further comprising the step of:
developing the image-wise exposed precursor by mounting the image-wise exposed precursor on a printing press and developing the precursor in an on-press developing step.

### Claim 20

A method for obtaining a print-out image by exposing a lithographic printing plate precursor comprising an IR dye having a structure according to Formula I to IR-radiation or heat:
wherein
+Y1═ is represented by one of the following structures:
Y2— is represented by one of the following structures:
n is 0, 1, 2, or 3;
each of p and g is 0, 1, or 2;
R1 and R2 are independently an optionally substituted hydrocarbon group, or wherein two of the R1, R2, Rd, or Ra groups together include the necessary atoms to form a cyclic structure;
at least one of the Rd groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-donor than the Rd; or
at least one of the Ra groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-acceptor than the Ra;
the other Rd and Ra groups are independently represented by a group selected from the list consisting of a hydrogen atom, a halogen atom, —Re, —ORf, —SRg, and —NRuRv;
wherein Re, Rf, Rg, Ru, and Rv independently are an optionally substituted aliphatic hydrocarbon group or an optionally substituted (hetero)aryl group; and
the transformation provides an increase of the integrated light absorption of the dye between 400 nm and 700 nm.