Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2001-02-26
2003-07-15
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S159000, C430S161000, C430S302000, C430S270100
Reexamination Certificate
active
06593054
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a negative-working presensitized plate useful for preparing a lithographic printing plate and more specifically to that comprising diazo resin, photo-polymerizable resin, or photo-crosslinkable resin.
A photosensitive layer comprising diazo resin, photo-polymerizable resin, or photo-crosslinkable resin is known as a negative-working photosensitive layer in a presensitized plate usable for preparing a lithographic printing plate.
Examples of such photosensitive layer comprising diazo resin include a photosensitive layer comprising a binder polymer and diazo resin such as a reaction product of diazonium salt with organic condensation reagent comprising reactive carbonyl salt such as aldol and acetal, e.g., condensation product of diphenylamine-p-diazonium salt and formaldehyde, as described in U.S. Pat. Nos. 2,063,631 and 2,667,415.
Examples of photo-polymerizable composition include a basic composition comprised of a polymer as a binder, a monomer and initiator for photopolymerization as described in Japanese Patent Publication for Opposition Purpose (hereinafter referred to as “J.P.KOKOKU”) No. 46-32174, a composition comprising a binder polymer in which unsaturated double bond has been introduced to improve efficiency of hardening of the binder as described in J.P.KOKOKU No. 49-34041, and a composition comprising a novel initiator for photopolymerization as described in J.P.KOKOKU No. 48-38403, J.P.KOKOKU No. 53-27605 and British Patent No.1388492.
In addition, polymers capable of crosslinking through cycloaddition reaction are well known as the photo-crosslinkable composition. As such photo-crosslinkable polymers, useful are polymers carrying maleimide group on the side chain, or polymers carrying a photo-dimerizable group having unsaturated double bond adjacent to aromatic ring such as cinnamyl group, cinnamoyl group, cinnamylidene group, and cinnamylideneacetyl group on the side chain or main chain. Especially, polymers having maleimide group on the side chain and polyesters having cinnamic acid skeleton in the molecule prepared by condensation of phenylenediacrylic acid or alkyl ester thereof with glycol are highly sensitive and some of them have already been practically used.
However, adhesiveness of such negative-working photosensitive layer to aluminum substrate is not sufficient. As a result, images are easily peeled off from the substrate or damaged when the plate is rubbed with a brush during development, and thus, the strength of image is not sufficient. Especially, in case of low exposure, this tendency becomes dominant and as a result, sensitivity of the photosensitive layer is decreased. In order to improve the low adhesiveness of the image to a substrate, many attempts have been made. For example, for a system in which photo-polymerizable composition is used, Japanese Unexamined Patent Publication (hereinafter referred to as “J.P. KOKAI”) No. 54-72104 and U.S. Pat. No. 3,905,815 disclose that negative-working diazo resin is used as an undercoat layer, J.P. KOKAI No. 61-38943, J.P. KOKAI No. 2-111948, J.P. KOKAI No. 1-137890 disclose that diazo resin is incorporated into photosensitive composition. For a system in which photo-crosslinkable composition is used, J.P.KOKOKU No. 50-7481, J.P. KOKAI No. 62-78544, Japanese Patent Application (hereinafter referred to as “J.P.A.”) No. 1-137891, and J.P.A. No. 2-37786 disclose use of diazo resins.
However, when the above diazo resin is used in an undercoat (intermediate) layer of photosensitive layer comprising diazo resin, photo-polymerizable resin or photo-crosslinkable resin, background contamination is seen in non-imaging areas. This problem is due to decomposition of diazonium group which chronologically decomposes to become adherent to the substrate that cannot be removed by developer. Thus, when a compound having many diazonium groups in its molecule is used as an intermediate layer, contamination during printing operation would be increased in accordance with the increase of the total number of diazonium groups.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a negative-working presensitized plate useful for preparing a lithographic printing plate which has excellent adhesiveness between a substrate and a photosensitive layer and does not cause contamination in non-imaging areas during printing operation, while maintaining high sensitivity, sensitive range and performance of the photosensitive layer.
It is found that the above object is achieved by a negative-working presensitized plate useful for preparing a lithographic printing plate having a negative-working photosensitive layer on an aluminum substrate, which comprises an intermediate layer comprising a compound having at least one diazonium group and molecular weight of 1000 or less formed between said photosensitive layer and said aluminum substrate.
That is, although an intermediate layer comprising diazo resin is conventionally used in a negative-working presensitized plate having a negative-working photosensitive layer comprising diazo resin, photo-crosslinkable resin or photo polymerization resin on an aluminum substrate, the inventors of the present invention found that when a diazonium compound having at least one diazonium group and molecular weight of 1000 or less is used in place of conventional diazo resin in the intermediate layer, background contamination of non-imaging area does not occur and the adhesiveness between the photosensitive layer and the substrate is increased.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Intermediate Layer
Hereinafter, the intermediate layer usable in the presensitized plate that is useful for preparing a lithographic printing plate of the present invention will be described. The intermediate layer comprising diazonium compound of the present invention can be formed by applying a solution comprising diazonium compounds dissolved in a solvent onto after-mentioned aluminum substrate which is optionally treated to obtain hydrophilicity or grained.
The diazonium compound in the intermediate layer of the present invention includes a compound comprising at least one diazonium group in a molecule and having molecular weight of about 1000 or less. The diazonium compound comprising at least one diazonium group can be used in the present invention. But polyfunctional diazonium compound comprising plural diazonium groups can also be used. The diazonium compound of the present invention preferably comprises one or two diazonium groups and more preferably, one diazonium group.
In the present invention, preferable compound comprising one diazonium group includes, for example, compounds represented by the following general formula (I).
wherein, R
1
and R
2
, which may be the same or different, are hydrogen atom, C
1-10
alkyl, C
1-10
alkoxy or halogen atom. More specifically, R
1
and R
2
each represents hydrogen atom, methyl, ethyl, propyl, butyl, methoxy, ethoxy, i-propyloxy, n-propyloxy, n-butyloxy, i-butyloxy, t-butyloxy, Cl, F, Br, I or the like; and Y represents —NR
3
R
4
or —SR
5
. R
3
and R
4
, which may be the same or different, are hydrogen atom, hydroxy, C
1-10
alkyl, aryl or 5- or 6-membered aliphatic or aromatic heterocyclic ring. Alternatively, nitrogen atom, R
3
and R
4
may be linked together to form a 5- or 6-membered aliphatic or aromatic heterocyclic ring. The above groups, (i.e., C
1-10
alkyl, aryl and 5- or 6-membered aliphatic or aromatic heterocyclic ring) may have at least one substitutent selected from the group consisting of hydroxy, C
1-10
alkyl, C
1-10
alkoxy, C
1-10
alkylcarbonyl, aryl, aryloxy, arylcarbonyl, and 5- or 6-membered aliphatic or aromatic heterocyclic ring.
The “aryl” group includes alkylaryl, arylalkyl and alkylarylalkyl.
Further, R
3
and R
4
may represent —R
6
G. R
6
represents C
1-10
alkylene, arylene, or bivalent group comprising C
1-10
alkylene bonded to arylene. G represents at least one of —OR, —CO—R, —CO—NRR′, —NRR′, —NR—CO—R′, wherein, R and R′ may be the same or
Burns Doane , Swecker, Mathis LLP
Chu John S.
Fuji Photo Film Co. , Ltd.
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