Desensitizing solution for offset printing

Abstract

An amine compound-containing, but cyanogen-free, desensitizing solution for offset printing, characterized by containing phytic acid (inositol hexaphosphate) and/or a metal and/or ammonium salts of phytic acid, and at least one selected from the group consisting of amine compounds represented by the following general formulae (1) and (2); a carboxylic acid or carboxylate containing (3); an urea (5) and/or an urethane (6) containing (4); an amide compound represented by (8) and/or an imide compound (9), each containing an amino group (7); and a heterocyclic compound at least one nitrogen atom and having an inorganic/organic value of 0.1 to 4.0 inclusive. ##STR1##

Description

BACKGROUND OF THE INVENTION

The present invention relates to a solution for making lithographic plates such as electrophotographic offset or direct-image masters hydrophilic or, in other words, an etching or dampening solution, which is mainly composed of a metal oxide, a metal sulfide and a binder resin.

The present invention relates generally to a solution for making electrophotographic offset printing plates hydrophilic and, more specifically, to a cyanogen-free desensitizing solution for offset printing, which does not contain cyanide compounds at all.

An electrophotographic offset printing plate precursor (hereinafter called the printing master) includes a photosensitive layer in which photoconductive fine powders of material such as zinc oxide is dispersed in a resin binder, and is obtained by applying ordinary electrophotographic operations to this layer to form a lipophilic image.

Generally used for offset printing is a form plate made up of a non-image area likely to be wetted by water (the hydrophilic area) and a printing area unlikely to be wetted (the lipophilic area). However, the electrographic offset printing master is made up of a hydrophobic photoconductive layer so that when it is used by itself, normal printing cannot be made, because printing ink is deposited on the non-image area as well.

Therefore, prior to printing it is required to desensitize the non-image area of the printing master to make it hydrophilic. So far, cyanogen compound-containing treating solutions containing ferrocyanides and ferricyanides as the main component and cyanogen-free treating solutions containing an ammine-cobalt complex, phytic acid (inositol hexaphosphate) and its derivative and a guanidine derivative as the main component have been proposed as such desensitizing solutions.

However, these treating solutions are still less than satisfactory. That is, the former ferrocyanide and ferricyanide-containing treating solutions have some advantages of having strong desensitizing power, being capable of forming a firm, hydrophilic film and being high in the film forming rate, but have various problems in that ferrocyanide and ferricyanide ions are so unstable to heat and light that upon exposed to light, they are colored to form precipitates which makes the desensitizing power weak, and in the process of cyanogen analysis treated with strong acids, non-toxic cyanogen complexes are detected as free cyanogen, thus offering waste water disposal and pollution problems.

In view of these considerations, on the other hand, the cyanogen-free treating solutions containing the latter desensitizing agents as the main component have been proposed in the art. However, these treating solutions are still insufficient to obtain satisfactory lithographic masters. More specifically, the latter are slower in the film forming rate than the former, and so have the disadvantage that a hydrophilic film having a physical strength high enough for immediate printing cannot be formed only by passing a plating precursor once in the processor etching manner, giving rise to scumming or degradation of dot gradation.

So far, it has been known that phytic acid and its metal derivative form metal chelate compounds, and various desensitizing agents for offset masters have been proposed in the art. However, they are all slow in the film forming rate, so that any printable, hydrophilic film cannot be formed by a single processor treatment; that is, they have the disadvantage that there is scumming or degradation of dot gradation due to unsatisfactory separability.

In order to solve the problems mentioned above, investigation has been made as to the addition of various additives to the treating solutions based on phytic acid. Specifically, there are available treating solutions to which lower amines, alkanolamines and polyamines (see, for instance, Japanese Provisional Patent Publication Nos. 54-117201, 53-109701 and 1-25994). These solutions maintain good water retention in the initial stage of use, but gets worse in terms of etching and water retention, as they are continuously used. In addition, when they are used after long-term storage, the water retention drops, making scumming likely to occur.

Furthermore, there are available treating solutions to which cation polymers are added (see, for instance, Japanese Provisional Patent Publication No. 60-23099). Like the phytic acid solutions, these solutions degrade after continued use and long-term storage and gives rise to rust as well.

In view of energy saving, on the other hand, automatic printing machines of small size with built-in desensitizing systems have been particularly spread in recent years, and the plate-making with offset masters by electrophotography have been achieved within a more reduced time than ever before. For this reason, it is now required that the desensitizing time be reduced and the life of the desensitizing solution be increased. However, these are difficult to achieve by conventional treating solutions.

A primary object of this invention is to provide a desensitizing or dampening solution for offset printing plate precursors which poses no pollution problem, can be stably used after long-term storage and continued use, and can reduce the etching time or is excellent in the desensitizing capability.

SUMMARY OF THE INVENTION

According to this invention, the problems mentioned above can be solved by using the following treating solution for etching.

More specifically, the cyanogen-free desensitizing solution for offset printing is characterized by containing:

(a) phytic acid (inositol hexaphosphate) and/or a metal salt and/or an ammonium salt of phytic acid, and at least one selected from the group consisting of (b)-(f): (b) secondary and tertiary amine compounds represented by the following general formula (1): ##STR2## wherein R.sub.1, and R.sub.2 and R.sub.3 have at least 9 carbon atoms in all, and R.sub.1 denotes an aliphatic group having at least 6 carbon atoms and R.sub.2 and R.sub.3 each stand for a hydrogen atom and an aliphatic group or may optionally form together a cyclic structure, and/or a primary amine compound represented by the following general formula (2): R.sub.4 -NH.sub.2 ( 2) wherein R.sub.4 denotes an aliphatic group having at least 6 carbon atoms, (c) a carboxylic acid (--COOH) and/or a carboxylate (--COOH--) containing at least an amino group represented by the following general formula (3): ##STR3## wherein R.sub.5 and R.sub.6 each denote a hydrogen atom and/or an organic residue or may combined with each other to form a cyclic structure, and having an inorganic/organic value lying in the range of 0.1 to 4.0 inclusive wherein, by definition, the term "inorganic/organic value" is a value representing the degree of the electrostatic (or polar) nature of an organic compound (for instance, see Yoshio Koda et al "Organic Conception Diagram", Sankyo Shuppan (May 10, 1985), (d) a urea compound represented by the following general formula (5) and/or a urethane compound represented by the following general formula (6), each containing at least an amino group represented by the following general formula (4) and having an inorganic/organic value lying in the range of 0.1 to 4.0 inclusive: ##STR4## wherein a.sub.1, a.sub.2 and a.sub.3 each stand for a hydrogen atom and/or an organic residue, R.sub.7 and R.sub.8 each denote a hydrogen atom and/or an organic residue or may optionally be combined with each other to form a cyclic structure, and X refers to an oxygen or sulfur atom, (e) an amide compound represented by the following general formula (8) and/or an imide compound having the following general formula (9), each containing at least an amino group represented by the following general formula (7): ##STR5## wherein R.sub.9 and R.sub.10 each stand for a hydrogen atom and/or an organic residue or may optionally be combined with each other to form a cyclic structure, and a.sub.4 and a.sub.5 each denote a hydrogen atom and/or an organic residue and/or a substituent such as a halogen atom or a cyano or nitro group, and (f) a heterocyclic compound containing at least one nitrogen atom and having an inorganic/organic value lying in the range of 0.1 to 4.0 inclusive, preferably a nitrogen-containing aromatic and/or aliphatic heterocyclic compound which may have a 3 to 10-membered substituent that may be condensed together.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the secondary or tertiary amines of this invention represented by Formulae (1) and (2), it is preferred that R.sub.1 stands for a C.sub.8-18 alkyl, cycloalkyl, alkenyl or aralkyl group which may have a subsitituent, for instance, an alkoxy (--OR.sub.1), sulfide (--SR.sub.1), amino ##STR6## halogen, cyano, nitro or other group.

R.sub.2 and R.sub.3 each denote a hydrogen atom and a C.sub.1-18 aliphatic group mentioned for R.sub.1, or they may be aliphatic rings which can be combined with each other. R.sub.4 denotes an aliphatic group having at least 8 carbon atoms, mentioned for R.sub.1. R.sub.12 and R.sub.13 each denote a hydrogen atom and a C.sub.1-18 aliphatic group mentioned for R.sub.1, or they may be aliphatic rings which can be combined with each other.

More preferably, R.sub.1 represents:

a C.sub.8-18 alkyl group which may have a substituent (for instance, 2-ethylhexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 2-hydroxyoctyl, 2-hydroxyoctadecyl, 2,4-dihydroxyoctyl, 2-methoxyoctyl, 2-chlorooctyl, 2-bromooctyl, 2-cyanooctyl, etc.), a cycloalkyl group which Fay have a substituent (for instance, 2-ethylcyclohexyl, 2-methylcycloheptyl, 2,4-dimethylcyclohexyl, decalino, etc.), and. an alkenyl group which may have a substituent (for instance, 3-ethyl-hexenyl, 3-ethyl-hexenyl, 3,7-dimethyl-6-octenyl, 1-octenyl, 4-methyl-2-octenyl, etc.).

R.sub.2 and R.sub.3 each represent:

a hydrogen atom, a C.sub.1-14 alkyl group which may have a substituent (for instance, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, heptyl, hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-hydroxybutyl, 2-methoxyethyl, 2-butoxyethyl, 2-ethoxyethyl, 4-methoxybutyl, methylthioethyl, methylthiobutyl, 2-aminoethyl, N,N'-dimethylaminoethyl, piperidinoethyl, pyrrolidinoethyl, 2-chloroethyl, 2-chlorobutyl, 2-bromoethyl, 2-cyanoethyl, 4-cyanobutyl, etc.), an alkenyl group which may have a substituent (for instance, 2-methyl-1-propenyl, 2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, 4-methyl-2-hexenyl, vinyl, 2-propenyl, 3-butenyl, etc.), an aralkyl group which may have a subsitituent (for instance, benzyl, phenethyl, 3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, dimethoxybenzyl, cyanobenzyl, nitrobenzyl, etc.), and a cycloalkyl group which may have a substituent (for instance, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, 4-methylcyclohexyl, 4-chlorocyclohexyl, 4-methoxycyclohexyl, 4-cyanocyclohexyl, etc.)

Optionally, R.sub.2 and R.sub.3 may be combined with each other to form an ethyleneimine, pyrrolidine or piperidine ring.

R.sub.4 represents:

a C.sub.8-18 alkyl group which may have a substituent (for instance, 2-ethylhexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 2-hydroxyoctyl, 2-hydroxyoctadecyl, 2,4-dihydroxyoctyl, 2-methoxyoctyl, 2-chlorooctyl, 2-bromooctyl, 2-cyanooctyl, etc. ), a cycloalkyl group which may have a substituent (for instance, 2-ethylcyclohexyl, 2-methylcylcoheptyl, 2,4-dimethylcyclohexyl, decalino, etc. ), and an alkenyl group which may have a substituent (for instance, 3-ethyl-2-hexenyl, 3-ethyl-3-hexenyl, 3,7-dimethyl-6-octenyl, 1-octenyl, 4-methyl-2-octenyl, etc.).

Specific, but not exclusive, examples of the compounds represented by Formulae (1) and (2) are set out below.

Throughout the following compounds 1-99, ".alpha.2EH" refers to ##STR7## (2-ethylhexyl group), "nBu" to --nC.sub.4 H.sub.9 (butyl group), "nHx" to --nC.sub.6 H.sub.13 (hexyl group), "nOct" to --nC.sub.8 H.sub.17 (octyl group), "nDode" to --nC.sub.12 H.sub.25 (dodecyl group) and "nOctdec" to --nC.sub.18 H.sub.37 (octadecyl group). ##STR8##

Referring to the carboxylic acid (--COOH) and/or carboxylate (--COOH--) compounds containing an amino group represented by Formula (3) and having an inorganic/organic value lying in the range of 0.1 to 4.0 inclusive, it is preferred that R.sub.5 and R.sub.6 each denote a hydrogen atom and/or a C.sub.1-22 alkyl, cycloalkyl, alkenyl, aralkyl or aryl group which may have a substituent, or they may be combined with each other to form a cyclic structure. The above-mentioned substituent, for instance, may be hydroxide, alkoxy, sulfide, amino, cyano and nitro groups and halogen atoms.

More preferably, R.sub.5 and R.sub.6 each denote:

C.sub.1-18 alkyl group which may have a substituent which may have a substituent (for instance, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, heptyl, hexyl, 2-ethylhexyl octyl, decyl, dodecyl, hexadecyl octadecyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-hydroxybutyl, 2-methoxyethyl, 2-butoxyethyl, 2-ethoxyethyl, 4-methoxybutyl, methylthioethyl, methylthiobutyl, 2-aminoethyl, N,N'-dimethylaminoethyl, piperidinoethyl, pyrrolidinoethyl, 2-chloroethyl, 2-chlorobutyl, 2-bromoethyl, 2-cyanoethyl, 4-cyanobutyl, etc.), an alkenyl group which may have a substituent (for instance, 2-methyl-1-propenyl, 2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, 4-methyl-2-hexenyl, vinyl, 2-propenyl, 3-butenyl, etc.), an aralkyl group which may have a subsitituent (for instance, benzyl, phenethyl, 3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, dimethoxybenzyl, cyanobenzyl, nitrobenzyl, etc.), a cycloalkyl group which may have a substituent (for instance, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, 4-methylcyclohexyl, 4-chlorocyclohexyl, 4-methoxycyclohexyl, 4-cyanocyclohexyl, etc.), and an aryl group which may have a substituent (for instance, phenyl, tolyl, ethylphenyl, propylphenyl, chlorophenyl, fluorophenyl, bromophenyl, chloro-methyl-phenyl, dichlorophenyl, methoxyphenyl, cyanophenyl, acetamidephenyl, acetylphenyl, butoxyphenyl, etc.).

Optionally, R.sub.5 and R.sub.6 may be combined with each other to form a ring such as an aziridine, pyrrolidine, piperidine, morpholine or other ring.

It is noted that these compounds contain per molecule preferably 1 to 10, more preferably 1 to 6 amino groups, and per molecule preferably 1 to 10, more preferably 1 to 6 carboxyl groups and/or ester bonds.

Specific, but not exclusive, examples of the carboxylic acid or carboxylate compounds containing an amino group represented by Formula (3) are enumerated below. ##STR9##

Referring to the urea compounds represented by Formula (5) and/or the urethane compounds represented by Formula (6), each containing an amino group represented by Formula (4) and having an inorganic/organic value lying in the range of 0.1 to 4.0 inclusive, it is preferred that R.sub.7 and R.sub.8 each denote a hydrogen atom and/or a C.sub.1-22 alkyl, cycloalkyl, alkenyl, aralkyl or aryl group which may have a substituent. Optionally, they may be combined with each other to form a ring. The above-mentioned substituent, for instance, may be hydroxide, carboxyl, alkoxy, ester, sulfide, amino, cyano or nitro groups and halogen atoms.

a.sub.1, a.sub.2 and a.sub.3 each stand for a hydrogen atom and/or a C.sub.1-18 organic residue, mentioned for R.sub.7 and R.sub.8, and X denotes an oxygen or sulfur atom.

More preferably, R.sub.7 and R.sub.8 each denote:

a C.sub.1-18 alkyl group which may have a substituent which may have a substituent (for instance, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, heptyl, hexyl, 2-ethylhexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-hydroxybutyl, 2-methoxyethyl, 2-butoxyethyl, 2-ethoxyethyl, 4-methoxybutyl, methylthioethyl, methylthiobutyl, 2-aminoethyl, N,N'-dimethylaminoethyl, piperidinoethyl, pyrrolidinoethyl, 2-chloroethyl, 2-chlorobutyl, 2-bromoethyl, 2-cyanoethyl, 4-cyanobutyl, etc.), an alkenyl group which may have a substituent (for instance, 2-methyl-1-propenyl, 2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, 4-methyl-2-hexenyl, vinyl, 2-propenyl, 3-butenyl, etc.), an aralkyl group which may have a subsitituent (for instance, benzyl, phenethyl, 3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, dimethoxybenzyl, cyanobenzyl, nitrobenzyl, etc.), a cycloalkyl group which may have a substituent (for instance, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, 4-methylcyclohexyl, 4-chlorocyclohexyl, 4-methoxycyclohexyl, 4-cyanocyclohexyl, etc.), and an aryl group which may have a substituent (for instance, phenyl, tolyl, ethylphenyl, propylphenyl, chlorophenyl, fluorophenyl, bromophenyl, chloro-methyl-phenyl, dichlorophenyl, methoxyphenyl, cyanophenyl, acetamidophenyl, acetylphenyl, butoxyphenyl, etc.).

Optionally, R.sub.7 and R.sub.8 may be combined with each other to form a ring such as an aziridine, pyrrolidine, piperidine, morpholine or other ring.

a.sub.1, a.sub.2 and a.sub.3 each denote:

a hydrogen atom and/or a C.sub.1-14 alkyl group which may have a substituent which may have a substituent (for instance, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, heptyl, hexyl, 2-ethylhexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-hydroxybutyl, 2-methoxyethyl, 2-butoxyethyl, 2-ethoxyethyl, 4-methoxybutyl, methylthioethyl, methylthiobutyl, 2-aminoethyl, N,N'-dimethylaminoethyl, piperidinoethyl, pyrrolidinoethyl, 2-chloroethyl, 2-chlorobutyl, 2-bromoethyl, 2-cyanoethyl, 4-cyanobutyl, etc.), an alkenyl group which may have a substituent (for instance, 2-methyl-1-property, 2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, 4-methyl, 2-hexenyl, vinyl, 2-propenyl, 3-butenyl, etc.), an aralkyl group which may have a subsitituent (for instance, benzyl, phenethyl, 3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, dimethoxybenzyl, cyanobenzyl, nitrobenzyl, etc.), a cycloalkyl group which may have a substituent (for instance, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, 4-methylcyclohexyl, 4-chlorocyclohexyl, 4-methoxycyclohexyl, 4-cyanocyclohexyl, etc.), and an aryl group which may have a substituent (for instance, phenyl, tolyl, ethylphenyl, propylphenyl, chlorophenyl, fluorophenyl, bromophenyl, chloro-methyl-phenyl, dichlorophenyl, methoxyphenyl, cyanophenyl, acetamidephenyl, acetylphenyl, butoxyphenyl, etc.).

It is noted that these compounds contain per molecule preferably 1 to 10, more preferably 1 to 6 amino groups, and per molecule preferably 1 to 10, more preferably 1 to 6 carboxyl groups and/or ester bonds.

Specific, but not exclusive, examples of the compounds used in this invention are enumerated below. ##STR10##

Referring to the amide and/or imide compounds represented by Formulae (8) and (9), respectively, each containing an amino Group represented by Formula (7) and having an inorganic/organic value lying in the range of 0.1 to 4.0 inclusive, it is preferred that R.sub.9 and R.sub.10 each denote a hydrogen atom and/or a C.sub.1-22 alkyl, cycloalkyl, alkenyl, aralkyl or aryl group which may have a substituent. Optionally, they may be combined with each other to form a ring. The above-mentioned substituent, for instance, may be hydroxide, carboxyl, alkoxy, sulfide, amino, cyano, nitro or ester groups and halogen atoms.

a.sub.4 and a.sub.5 each stand for a hydrogen atom and/or a C.sub.1-18 organic residue, mentioned for R.sub.9 and R.sub.10.

More preferably, R.sub.9 and R.sub.10 each denote:

a C.sub.1-18 alkyl group which may have a substituent which may have a substituent (for instance, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, heptyl, hexyl, 2-ethylhexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-hydroxybutyl, 2-methoxyethyl, 2-butoxyethyl, 2-ethoxyethyl, 4-methoxybutyl, methylthioethyl, methylthiobutyl, 2-aminoethyl, N,N'-dimethylaminoethyl, piperidinoethyl, pyrrolidinoethyl, 2-chloroethyl, 2-chlorobutyl, 2-bromoethyl, 2-cyanoethyl, 4-cyanobutyl, etc.),

an alkenyl group which may have a substituent (for instance, 2-methyl-1-propenyl, 2-butenyl-2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, 4-methyl-2-hexenyl, vinyl, 1-propenyl,3-butenyl, etc.),

an aralkyl group which may have a subsitituent (for instance, benzyl, phenethyl, 3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, dimethoxybenzyl, cyanobenzyl, nitrobenzyl, etc.), a cycloalkyl group which may have a substituent (for instance, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, 4-methylcyclohexyl, 4-chlorocyclohexyl, 4-methoxycyclohexyl, 4-cyanocyclohexyl, etc.), and an aryl group which may have a substituent (for instance, phenyl, tolyl, ethylphenyl, propylphenyl, chlorophenyl, fluorophenyl, bromophenyl, chloro-methyl-phenyl, dichlorophenyl, methoxyphenyl, cyanophenyl, acetamidophenyl, acetylphenyl, butoxyphenyl, etc.).

Optionally, R.sub.9 and R.sub.10 may be combined with each other to form a ring such as an aziridine, pyrrolidine, piperidine, morpholine or other ring.

a.sub.4 and a.sub.5 each denote:

a hydrogen atom and/or a C.sub.1-18 alkyl group which may have a substituent which may have a substituent (for instance, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, heptyl, hexyl, 2-ethylhexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-hydroxybutyl, 2-methoxyethyl, 2-butoxyethyl, 2-ethoxyethyl, 4-methoxybutyl, methylthioethyl, methylthiobutyl, 2-aminoethyl, N,N'-dimethylaminoethyl, piperidinoethyl, pyrrolidinoethyl, 2-chloroethyl, 2-chlorobutyl, 2-bromoethyl, 2-cyanoethyl, 4-cyanobutyl, N,N'-dimethylaminopropyl, N,N'-diethylaminopropyl, N,N'-di-n-propylaminopropyl, N,N'-diisopropylaminopropyl, N,N'-di-n-butylaminopropyl, N,N'-di-n-hexylaminopropyl, N,N'-diethanolaminopropyl, N,N'-diisopropanolaminobutyl, etc.), an alkenyl group which may have a substituent (for instance, 2-methyl-1-propenyl, 2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, 4-methyl-2-hexenyl, vinyl, 2-propenyl, 3-butenyl, etc.), an aralkyl group which may have a subsitituent (for instance, benzyl, phenethyl, 3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, dimethoxybenzyl, cyanobenzyl, nitrobenzyl, etc.), a cycloalkyl group which may have a substituent (for instance, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, 4-methylcyclohexyl, 4-chlorocyclohexyl, 4-methoxycyclohexyl, 4-cyanocyclohexyl, etc.), an aryl group which may have a substituent (for instance, phenyl, tolyl, ethylphenyl, propylphenyl, chlorophenyl, fluorophenyl, bromophenyl, chloro-methyl-phenyl, dichlorophenyl, methoxyphenyl, cyanophenyl, acetamidophenyl, acetylphenyl, butoxyphenyl, etc.), a hydroxide group, and a halogen atom such as a chlorine, bromine or iodine atom.

It is noted that these compounds contain per molecule preferably 1 to 10, more preferably 1 to 6 amino groups, and per molecule preferably 1 to 10, more preferably 1 to 6 amide and/or imide bonds.

Specific, but not exclusive, examples of the compounds used in the present invention are enumerated below. ##STR11##

It is preferred that the heterocyclic compounds containing at least one nitrogen atom and having an inorganic/organic value lying in the range of 0.1 to 4.0 inclusive are aromatic and/or aliphatic, nitrogen-containing heterorings which may have a 3 to 10-membered ring substituent.

More preferable example of these compounds are aziridine, acetidine, pyrrolidine, piperidine, morpholine, piperazine, pyrrole, pyridine, pyridazine, pyrimidine, pyrazine, imidazole, oxazole, pyrazole, thiazole, isoxazole, isothiazole, indole, triazole, tetrazole, quinoline and other like rings.

The above-mentioned substituent, for instance, may be a hydrogen atom, a C.sub.1-22 organic residue which may have a substituent, a hydroxide group, a carboxyl group, a carbonyl group, an amino group and a halogen atom.

It is preferred that the organic residue is:

a C.sub.1-18 alkyl group which may have a substituent (for instance, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, heptyl, hexyl, 2-ethylhexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-hydroxybutyl, 2-methoxyethyl, 2-butoxyethyl, 2-ethoxyethyl, 4-methoxybutyl, methylthioethyl, methylthiobutyl, 2-aminoethyl, N,N'-dimethylaminoethyl, piperidinoethyl, pyrrolidinoethyl, 2-chloroethyl, 2-chlorobutyl, 2-bromoethyl, 2-cyanoethyl, 4-cyanobutyl, etc.), an alkenyl group which may have a substituent (for instance, 2-methyl-1-propenyl, 2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, 4-methyl-2-hexenyl, vinyl, 2-propenyl, 3-butenyl, etc.), an aralkyl group which may have a subsitituent (for instance, benzyl, phenethyl, 3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, dimethoxybenzyl, cyanobenzyl, nitrobenzyl, etc.), a cycloalkyl group which may have a substituent (for instance, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, 4-methylcyclohexyl, 4-chlorocyclohexyl, 4-methoxycyclohexyl, 4-cyanocyclohexyl, etc.), and an aryl group which may have a substituent (for instance, phenyl, tolyl, ethylphenyl, propylphenyl, chlorophenyl, fluorophenyl, bromophenyl, chloro-methyl-phenyl, dichlorophenyl, methoxyphenyl, cyanophenyl, acetamidophenyl, acetylphenyl, butoxyphenyl, etc.).

It is noted that these heterocyclic compounds have per molecule preferably 1 to 10, more preferably 1 to 6 heterocyclic rings.

Specific, but not exclusive, examples of the heterocyclic compounds containing at least one nitrogen atom are enumerated below. ##STR12##

The amine compounds according to this invention may be synthesized by suitable reactions set forth in "Shin Jikken Kagaku Koza 14", published by Maruzen Co., Ltd. (1978) and "J. Am. Chem. Soc.", 72, 3073 (1950) such as SN2 type reactions between amines and halogenized alkyl compounds, SN2 type reactions between heterocyclic rings and halogenized alkyl compounds, reductive amination reactions between amines and carbonyl compounds, amine Michael addition reactions with double bonds, esterification reactions between acid chlorides and alcohols, esterification reactions between carboxylates and halogen compounds, hydrolysis reactions of esters, reactions between amine compounds and isocyanates, reactions between alkanolamines and isocyanate compounds and Gabriel reactions between phthalimide and halogenized alkyl compounds.

Referring now to the amounts of the constituents used per 1000 parts by weight of the treating solution of this invention, the phytic acid and phytate capable of forming a chelate compound with zinc ions lies in the range of 10 to 300 parts by weight, preferably 30 to 100 parts by weight; and the amine compound in the range of 0.1 to 100 parts by weight, preferably 0.1 to 50 parts by weight. It is noted that the amine compounds of this invention may be used alone or in combination with two or more.

To form the treating solution of this invention, these compounds may be dissolved in ion-exchange or tap water. While no critical limitation is placed on in what order they are dissolved in the water, it is preferred that the anionic compound capable of forming a chelate compound with zinc ions is dissloved in the water, followed by the addition of the amine compound. The treating solution may additionally contain pH regulators such as organic and inorganic salts or basic hydroxides, e.g., potassium and sodium hydroxides; wetting agents such as surface active agents, e.g., ethylene glycol, sorbitol, glycerin, gum arabic, dipropylene glycol, dimethylacetamide, hexylene glycol butadiol and butyl cellosolve; antiseptics such as salicylic acid, phenol butyl p-benzoate, sodium dehydroacetate and 4-isothiazolin-3-one compounds; rust preventives such as EDTA, pyrophosphoric acid, metaphosphoric acid, hexametaphosphoric acid and 2-mercaptobenzimidazole; and other additives, all in suitable amounts.

For using the treating solution practically, its pH may preferably be regulated to a value in the range of 3 to 6. This solution may be used as a dampening solution as well, if it is diluted with water.

As the amine compound of this invention is added to phytic acid and phytate, an amine salt of phytic acid is formed. It is presumed that since the amine compound has a higher aliphatic group--this is unlike lower amines and alkanolamine salts, that amine salt is so enhanced in the affinity for the non-image area of photosensitive material when immersed in the desensitizing solution that the ionization and chelation reactions of zinc oxide ions are promoted, resulting in an improvement in the etching rate.

Since the higher the etching rate, the shorter the etching time, the time for which the form plate is immersed in the etching solution can be made shorter than would be possible with the prior art, even at the same running number, thereby preventing incorporation of Zn.sup.2+ ions ascribable to precipitates in the etching solution. In addition, since the amine compound of this invention is higher in the distillation point than lower amines and alkanolamines, there is less changes in the solution composition due to distillation, decomposition and other factors, even when the solution is used for an extended period of time or subject to an increase in the solution temperature. Thus, it is expected that the treating solution of this invention is improved in terms of the stability with time and the running properties.

As described above, the treating solution of this invention does not contain ferrocyanides and ferricyanides that pose a pollution problem and degrade by light and heat, and so is stable, or does not discolor or precipitate, even upon storage over an extended period. In addition, the cyanogen-free, excellent etching solution can provide offset printing plate precursors which is less affected by printing environment than conventional cyanogen-free treating solutions, achieves much more improved film-forming rates and is not subject to scumming and degradation of dot gradation.

The present invention will now be explained more specifically but not exclusively with reference to the examples and comparative examples.

EXAMPLE A1

______________________________________Water 1000 parts by weightPotassium phytate 80 parts by weightDiisopropyl-2-ethylhexylamine 4 parts by weight______________________________________

Comparative Example A1

Here the amine compound was removed from the solution of Ex. A1.

Comparative Example A2

Here diethylamine was used for the amine compound of Ex. A1.

Comparative Example A2

Here monoethanolamine was used in place of the amine compound of Ex. A1.

In each of Ex. A1 and Comp. Ex. A1 and A2, the components were well dissolved in water to prepare a treating solution, which was then regulated to pH 4.3 with the addition of KOH.

These solutions were used for actual printing. The results are set out in Table 1.

TABLE 1______________________________________ Example Comp. Ex. Comp. Ex. Comp. Ex.What Was Estimated A1 A1 A2 A3______________________________________Water Retention ofPlate PrecursorNote: 1) Good Scumming Little LittleI (25.degree. C., 60% RH) .smallcircle. found scumming scumming X found found .smallcircle. .DELTA. .smallcircle. .DELTA.II (35.degree. C., 80% RH) Good Scumming Scumming Scumming .smallcircle. found found found X X XRunning PropertiesNote: 2) Good Scumming Scumming ScummingI .smallcircle. found found found X X X Pricipita- Precipita- tion found tion foundII Good Scumming Scumming Scumming .smallcircle. found found found X X X Pricipita- Precipita- tion found tion foundNote: 3 Good Scumming Little ScummingStability with .smallcircle. found discolora- likely toTime X tion and occur scumming .DELTA. likely to occur .DELTA.______________________________________

The water retention of a plate precursor, running properties and stability with time were estimated as follows.

Note 1) Water Retention of Plate Precursor

A photosensitive material (that was not formed into a printing plate or, in other words, a plate precursor) was passed once through an etching machine, using each of the desensitizing solutions prepared in Example A1 and Comparative Examples A1-A3.

Then, this precursor was used to make 50 prints with Hamada Star 800SX Model made by Hamada Star K. K., using as the dampening solution the treating solution of Ex. A1 which was diluted with water 50 times. Whether or not there was scumming on the 50th print was visually estimated.

Note 2) Running Properties

A photosensitive material ELP-Ix and a fully-automatic Processor ELP404V (Fuji Photo Film Co., Ltd.) were allowed to stand at normal temperature and humidity (25.degree. C. and 65%) for one day. Thereafter, plate-making was carried out to form a duplicate image. The thus obtained 6000 duplicate masters were each passed once through an etching machine containing each of the treating solutions prepared in Example A1 and Comparative Examples A1-A3.

Thereafter, the 6000th master was estimated in terms of printing and scumming, as was case with the water retention of the plate precursor.

Note 3) Stability with Time

The desensitizing solutions of Example A1 and Comparative Examples A1-A3 were placed under thermo-conditions (50.degree. C. and 80% RH) for two weeks. Thereafter, duplicate masters were formed, as was the case with the estimation of running properties, and then passed once through an etching machine containing each of the desensitizing solutions mentioned above. Thereafter, estimation was made in terms of printing and scumming, as was the case with the water retention of the plate precursor.

The water retention of the plate precursor treated with the densensitizing solution of this invention is improved over that treated with Comparative Examples A1-A3. Especially when the environmental conditions are changed to (35.degree. C. and 80% RH), the water retentions of the plate precursors treated with Comp. Ex. A2 and A3 decrease considerably, but that treated with Example A1 does not. In other words, the treating solution of this invention is characterized by being unlikely to be affected by environmental conditions.

The running properties according to Comparative Examples A2 and A3 degrade due to precipitation in the treating solutions, but the treating solution of this invention gives rise to no precipitation and maintains its initial capacity, even after being run 6000 times. In addition, the treating solution of this invention is better than those of Comparative Examples A1-A3 in terms of stability with time, so that it can well stand up to long-term storage.

As mentioned above, only the desensitizing solution of this invention can stand up to environment conditions, continued use and long-term storage and, besides, gives rise to no scumming.

EXAMPLES A2-A25

For the amine compound used in Example A1, amine compounds shown in Table 2 were used in amounts shown in Table 2. Estimation was made following Example A1.

TABLE 2______________________________________Example No. Amine Compound No. Amount (parts by weight)______________________________________A2 1 2A3 1 6A4 1 10A5 2 2A6 2 4A7 2 6A8 2 10A9 3 4A10 8 4A11 10 4A12 14 4A13 23 4A14 29 4A15 31 4A16 34 4A17 42 4A18 45 4A19 54 4A20 56 4A21 60 4A22 62 4A23 67 4A24 71 4A25 93 4______________________________________

Like Example A1, Examples. A2-A25 were all excellent in terms of the water retentions of plate precursors, environmental changes, running properties and stability with time.

EXAMPLES A26-A41

Using some combinations of the amine compounds shown in Table 3 in a constant amount of 4 parts by weight, the water retention of plate precursors, running properties and stability with time were estimated by following the procedures of Example A1.

TABLE 3______________________________________ Combinations of Amine CompoundsExample No. Compound Nos. weight %______________________________________A26 (1)/(2) 50/50A27 (1)/(2) 25/75A28 (1)/(2) 75/25A29 (1)/(24) 50/50A30 (1)/(2)/(3) 25/25/50A31 (1)/(29) 50/50A32 (1)/(34) 50/50A33 (29)/(34) 50/50A34 (1)/(34)/(64) 50/25/25A35 (2)/(34)/(52) 50/25/25A36 (2)/(71)/(83) 50/25/25A37 (54)/(89)/(93) 50/25/25A38 (34)/(52)/(79) 50/25/25A39 (34)/(47)/95) 50/25/25A40 (1)/(34)/(80)/(93) 25/25/25/25A41 (1)/(2)/(34)/(62) 25/25/25/25______________________________________

Like Example A1, Examples A26-A41 are all excellent in terms of the water retentions of plate precursors, environmental changes, running properties and stability with time, indicating that the amine compounds of this invention may be used in combination with no problem. Examples A42-A48

Following the procedures of Example A1, various properties were estimated of a treating solution obtained by adding various wetting agents, antiseptics and rust preventives to the desensitizing solution having the same composition as that of Example A1.

TABLE 4______________________________________Ex. No. Wetting Agent Anticeptic Rust Preventive______________________________________A42 Ethylene glycol Salicylic acid EDTAA43 Ethylene glycol Salicylic acid Metaphosphoric acidA44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazoleA45 Ethylene glycol Sodium Dehydro- EDTA acetateA45 Gum arabic Salicylic acid EDTAA47 Dimethylacet- Salicylic acid EDTA amideA48 Butyl Cello- Salicylic acid EDTA solve______________________________________

Like Example A1, Examples A42-A48 are all excellent in the water retention of plate precursors, environmental changes, running properties and stability with time, indicating that the performance of the desensitizing solution of this invention is not affected by the addition of various additives. Example A49

The dampening solution used was obtained by diluting the treating solution of Ex. A1 five times with distilled water.

Comparative Example A4

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. A1 five times with distilled water.

Comparative Example A5

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. A2 five times with distilled water.

Set out in Table 5 are the results of estimation of Example A49 and Comparative Examples A4 and A5.

TABLE 5______________________________________What Was Estimated Example A49 Comp. Ex. A4 Comp. Ex. A5______________________________________Note: 4) No scumming Scumming was Scumming wasScumming on prints was found found on the found on the until 5000 l000th prints 2000th prints prints______________________________________

Whether or not there was scumming on the prints was estimated as follows.

Note 4) Scumming on Prints

After plate-making had been carried out following the procedures of Note 2), each plate was passed once through an etching machine, using the desensitizing solution of Example A1. Using the plate together with Hamada Star 800SX Model (Hamada Star K. K.) and the dampening solutions of Example A49 and Comp. Ex. A4 and A5, printing was done to count the number of prints until scumming could be visually observed.

As compared with Comp. Ex. A4 and A5, the desensitizing solution of this invention gives rise to no scumming, indicating that it can be Used as a dampening solution with high performance.

EXAMPLE B1

______________________________________Water 1000 parts by weightPotassium phytate 80 parts by weight2-N,N'-dimethylaminopropionic 4 parts by weightacid-2-ethylhexylester______________________________________

Comparative Example B1

Here the amine compound was removed from the solution of Ex. B1.

Comparative Example B2

Here diethylamine was used in place of the amine compound of Ex. B1.

Comparative Example B3

Here monoethanolamine was used in place of the amine compound of Ex. B1.

In each of Ex. B1 and Comp. Ex. B1-B3, the components were well dissolved in water to prepare a treating solution, which was then regulated to pH 4.3 with the addition of KOH.

These solutions were used for actual printing. The results are set out in Table 6.

TABLE 6______________________________________ Example Comp. Ex. Comp. Ex. Comp. Ex.What Was Estimated B1 B1 B2 B3______________________________________Water Retention ofPlate PrecursorNote: 1) Good Scumming Little LittleI (25.degree. C., 60% RH) .smallcircle. found scumming scumming X found found .smallcircle. .DELTA. .smallcircle. .DELTA.II (35.degree. C., 80% RH) Good Scumming Scumming Scumming .smallcircle. found found found X X XRunning PropertiesNote: 2) Good Scumming Scumming ScummingI .smallcircle. found found found X X X Pricipita- Precipita- tion found tion foundII Good Scumming Scumming Scumming .smallcircle. found found found X X X Pricipita- Precipita- tion found tion foundNote: 3 Good Scumming Little ScummingStability with .smallcircle. found discolora- likely toTime X tion and occur scumming .DELTA. likely to occur .DELTA.______________________________________

The water retention of a plate precursor, running properties and stability with time referred to in Table 6 were estimated according to the procedures mentioned in connection with Table 1.

The water retention of the plate precursor treated with the desensitizing solution of this invention is improved over that treated with Comparative Examples B1-B3, Especially when the environmental conditions are changed to (35.degree. C. and 80% RH), the water retentions of the plate precursors treated with Comp. Ex. B2 and B3 decrease considerably, but that treated with Example B1 does not. In other words, the treating solution of this invention is characterized by being unlikely to be affected by environmental conditions.

The running properties according to Comparative Examples B2 and B3 degrade due to precipitation in the treating solutions, but the treating solution of this invention gives rise to no precipitation and maintains its initial capacity, even after being run 6000 times. In addition, the treating solution of this invention is better than those of Comparative Examples B1-B3 in terms of stability with time, so that it can well stand up to long-term storage.

As mentioned above, only the desensitizing solution of this invention can stand up to environment conditions, continued use and long-term storage and, besides, gives rise to no scumming.

EXAMPLES B2-B25

In lieu of the amine compound used in Example B1, amine compounds shown in Table 7 were used in amounts shown in Table 7. Estimation was made following Example B1.

TABLE 7______________________________________Example No. Amine Compound No. Amount (parts by weight)______________________________________B2 101 2B3 101 6B4 101 10B5 102 2B6 102 4B7 102 6B8 102 10B9 106 4B10 108 4B11 109 4B12 122 4B13 130 4B14 141 4B15 153 4B16 169 4B17 179 4B18 193 4B19 196 4B20 197 4B21 206 4B22 221 4B23 230 4B24 237 4B25 247 4______________________________________

Like Example B1, Examples B2-B25 were all excellent in terms of the water retention of plate precursors, environmental changes, running properties and. stability with time.

EXAMPLES B26-B41

Using some combinations of the amine compounds shown in Table 8 in a fixed amount of 4 parts by weight, the water retention of plate precursors, running properties and stability with time were estimated by following the procedures of Example B1.

TABLE 8______________________________________ Combinations of Amine CompoundsExample No. Compound Nos. weight %______________________________________B26 101/102 50/50B27 101/102 25/75B28 101/102 75/25B29 101/196 50/50B30 101/102/103 25/25/50B31 101/169 50/50B32 101/142 50/50B33 142/196 50/50B34 101/142/96 50/25/25B35 102/159/196 50/25/25B36 102/190/196 50/25/25B37 154/197/121 50/25/25B38 196/197/198 50/25/25B39 196/121/136 50/25/25B40 101/196/125/136 25/25/25/25B41 101/102/196/197 25/25/25/25______________________________________

Like Example B1, Examples B26-B41 are all excellent in terms of the water retention of plate precursors, environmental changes, running properties and stability with time, indicating that the amine compounds of this invention may be used in combination with no problem.

EXAMPLES B42-B48

Following the procedures of Example B1, various properties were estimated of a treating solution obtained by adding various wetting agents, antiseptics and rust preventives to the desensitizing solution having the same composition as that of Example B1.

TABLE 9______________________________________Ex. No. Wetting Agent Anticeptic Rust Preventive______________________________________B42 Ethylene glycol Salicylic acid EDTAB43 Ethylene glycol Salicylic acid Metaphosphoric acidB44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazoleB45 Ethylene glycol Sodium Dehydro- EDTA acetateB45 Gum arabic Salicylic acid EDTAB47 Dimethylacet- Salicylic acid EDTA amideB48 Butyl Cello- Salicylic acid EDTA solve______________________________________

Like Example B1, Examples B42-B48 are all excellent in the water retentions of plate precursors, environmental changes, running properties and stability with time, indicating that the performance of the desensitizing solution of this invention is not affected by the addition of various additives.

Example B49

The dampening solution used was obtained by diluting the treating solution of Ex. B1 five times with distilled water.

Comparative Example B4

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. B1 five times with distilled water.

Comparative Example B5

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. B2 five times with distilled water.

Set out in Table 10 are the results of estimation of Example B49 and Comparative Examples B4 and B5.

TABLE 10______________________________________What Was Estimated Example B49 Comp. Ex. B4 Comp. Ex. B5______________________________________Note: 4) No scumming Scumming was Scumming wasScumming on prints was found found on the found on the until 5000 1000th prints 2000th prints prints______________________________________

Whether or not there was scumming on the prints was estimated as follows.

As compared with Comp. Ex. B4 and B5, the desensitizing solution of this invention gives rise to no scumming, indicating that it can be used as a dampening solution with high performance.

EXAMPLE C1

______________________________________Water 1000 parts by weightPotassium phytate 80 parts by weightN'-dimethylaminopropyl- 4 parts by weightN-hexylurea______________________________________

Comparative Example C1

Here the amine compound was removed from the solution of Ex. C1.

Comparative Example C2

Here diethylamine was used in place of the amine compound of Ex. C1.

Comparative Example C3

Here monoethanolamine was used in place of the amine compound of Ex. C1.

In each of Ex. C1 and Comp. Ex. C1-C3, the components were well dissolved in water to prepare a treating solution, which was then regulated to pH 4.3 with the addition of KOH.

These solutions were used for actual printing. The results are set out in Table 11.

TABLE 11______________________________________ Example Comp. Ex. Comp. Ex. Comp. Ex.What Was Estimated C1 C1 C2 C3______________________________________Water Retention ofPlate PrecursorNote: 1) Good Scumming Little LittleA (25.degree. C., 60% RH) .smallcircle. found scumming scumming X found found .smallcircle. .DELTA. .smallcircle. .DELTA.B (35.degree. C., 80% RH) Good Scumming Scumming Scumming .smallcircle. found found found X X XRunning PropertiesNote: 2) Good Scumming Scumming ScummingA .smallcircle. found found found X X X Pricipita- Precipita- tion found tion foundB Good Scumming Scumming Scumming .smallcircle. found found found X X X Pricipita- Precipita- tion found tion foundNote: 3 Good Scumming Little ScummingStability with .smallcircle. found discolora- likely toTime X tion and occur scumming .DELTA. likely to occur .DELTA.______________________________________

The water retention of a plate precursor, running properties and stability with time referred to in Table 6 were estimated according to the procedures mentioned in connection with Table 11.

The water retention of the plate precursor treated with the desensitizing solution of this invention is improved over that treated with Comparative Examples C2-C3. Especially when the environmental conditions are changed to (35.degree. C. and 80% RH), the water retentions of the plate precursors treated with Comp. Ex. C2 and C3 decrease considerably, but that treated with Example C1 does not. In other words, the treating solution of this invention is characterized by being unlikely to be affected by environmental conditions.

The running properties according to Comparative Examples C2 and C3 degrade due to precipitation in the treating solutions, but the treating solution of this invention gives rise to no precipitation and maintains its initial capacity, even after being run 6000 times. In addition, the treating solution of this invention is better than those of Comparative Examples C1-C3 in terms of stability with time, so that it can well stand up to long-term storage.

As mentioned above, only the desensitizing solution of this invention can stand up to environment conditions, continued use and long-term storage and, besides, gives rise to no scumming.

EXAMPLES C2-C25

In lieu of the amine compound Used in Example C1, amine compounds shown in Table 12 were used in amounts shown in Table 12. Estimation was made following Example C1.

TABLE 12______________________________________Example No. Amine Compound No. Amount (parts by weight)______________________________________C2 301 2C3 301 6C4 301 10C5 374 2C6 374 4C7 374 6C8 374 10C9 304 4C10 347 4C11 352 4C12 367 4C13 430 4C14 442 4C15 371 4C16 410 4C17 415 4C18 425 4C19 456 4C20 463 4C21 349 4C22 413 4C23 317 4C24 334 4C25 383 4______________________________________

Like Example C1, Examples C2-C25 were all excellent in terms of the water retention of plate precursors, environmental changes, running properties and stability with time.

EXAMPLES C26-C41

Using some combinations of the amine compounds shown in Table 13 in a fixed amount of 4 parts by weight, the water retention of plate precursors, running properties and stability with time were estimated by following the procedures of Example C1.

TABLE 13______________________________________ Combinations of Amine CompoundsExample No. Compound Nos. weight %______________________________________C26 301/374 50/50C27 301/374 25/75C28 301/374 75/25C29 301/304 50/50C30 301/374/304 25/25/50C31 301/352 50/50C32 301/363 50/50C33 374/415 50/50C34 301/374/430 50/25/25C35 304/374/142 50/25/25C36 304/371/383 50/25/25C37 354/389/393 50/25/25C38 334/352/379 50/25/25C39 334/347/395 50/25/25C40 301/334/380/393 25/25/25/25C41 301/302/334/362 25/25/25/25______________________________________

Like Example C1, Examples C26-C41 are all excellent in terms of the water retention of plate precursors, environmental changes, running properties and stability with time, indicating that the amine compounds of this invention may be used in combination with no problem.

EXAMPLES C42-C48

Following the procedures of Example C1, various properties were estimated of a treating solution obtained by adding various wetting agents, antiseptics and rust preventives to the desensitizing solution having the same composition as that of Example C1.

TABLE 14______________________________________Ex. No. Wetting Agent Anticeptic Rust Preventive______________________________________C42 Ethylene glycol Salicylic acid EDTAC43 Ethylene glycol Salicylic acid Metaphosphoric acidC44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazoleC45 Ethylene glycol Sodium Dehydro- EDTA acetateC45 Gum arabic Salicylic acid EDTAC47 Dimethylacet- Salicylic acid EDTA amideC48 Butyl Cello- Salicylic acid EDTA solve______________________________________

Like Example C1, Examples C42-C48 are all excellent in the water retentions of plate precursors, environmental changes, running properties and stability with time, indicating that the performance of the desensitizing solution of this invention is not affected by the addition of various additives.

Example C49

The dampening solution used was obtained by diluting the treating solution of Ex. C1 five times with distilled water.

Comparative Example C4

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. C1 five times with distilled water.

Comparative Example C5

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. C2 five times with distilled water.

Set out in Table 15 are the results of estimation of Example 049 and Comparative Examples C4 and C5.

TABLE 15______________________________________What Was Estimated Example C49 Comp. Ex. C4 Comp. Ex. C5______________________________________Note: 4) No scumming Scumming was Scumming wasScumming on prints was found found on the found on the until 5000 1000th prints 2000th prints prints______________________________________

Whether or not there was scumming on the prints was estimated as follows.

As compared with Comp. Ex. C4 and C5, the desensitizing solution of this invention gives rise to no scumming, indicating that it can be used as a dampening solution with high performance.

EXAMPLE D1

______________________________________Water 1000 parts by weightPotassium phytate 80 parts by weightN-�N,N'-diethylaminopropyl 4 parts by weightn-dodecylamide______________________________________

Comparative Example D1

Here the amine compound was removed from the solution of Ex. D1.

Comparative Example D2

Here diethylamine was used in place of the amine compound of Ex. D1.

Comparative Example D3

Here monoethanolamine was used in place of the amine compound of Ex. D1.

In each of Ex. D1 and Comp. Ex. D1-D3, the components were well dissolved in water to prepare a treating solution, which was then regulated to pH 4.3 with the addition of KOH.

These solutions were used for actual printing. The results are set out in Table 16.

TABLE 16______________________________________ Example Comp. Ex. Comp. Ex. Comp. Ex.What Was Estimated D1 D1 D2 D3______________________________________Water Retention ofPlate PrecursorNote: 1) Good Scumming Little Little(25.degree. C., 60% RH) .smallcircle. found scumming scumming X found found .smallcircle. .DELTA. .smallcircle. .DELTA.(35.degree. C., 80% RH) Good Scumming Scumming Scumming .smallcircle. found found found X X XRunning PropertiesNote: 2) Good Scumming Scumming Scumming(25.degree. C., 60% RH) .smallcircle. found found found X X X Pricipita- Precipita- tion found tion found(35.degree. C., 80% RH) Good Scumming Scumming Scumming .smallcircle. found found found X X X Pricipita- Precipita- tion found tion foundNote: 3 Good Scumming Little ScummingStability with .smallcircle. found discolora- likely toTime X tion and occur scumming .DELTA. likely to occur .DELTA.______________________________________

The water retention of a plate precursor, running properties and stability with time referred to in Table 16 were estimated according to the procedures mentioned in connection with Table 1.

The water retention of the plate precursor treated with the desensitizing solution of this invention is improved over that treated with Comparative Examples D1-D3. Especially when the environmental conditions are changed to (35.degree. C. and 80% RH), the water retentions of the plate precursors treated with Comp. Ex. D2 and D3 decrease considerably, but that treated with Example D1 does not. In other words, the treating solution of this invention is characterized by being unlikely to be affected by environmental conditions.

The running properties according to Comparative Examples D2 and D3 degrade due to precipitation in the treating solutions, but the treating solution of this invention gives rise to no precipitation and maintains its initial capacity, even after being run 6000 times. In addition, the treating solution of this invention is better than those of Comparative Examples D1-D3 in terms of stability with time, so that it can well stand up to long-term storage.

As mentioned above, only the desensitizing solution of this invention can stand up to environment conditions, continued use and long-term storage and, besides, gives rise to no scumming.

EXAMPLES D2-D25

In lieu of the amine compound used in Example D1, amine compounds shown in Table 17 were used in amounts shown in Table 17. Estimation was made following Example D1.

TABLE 17______________________________________Example No. Amine Compound No. Amount (parts by weight)______________________________________D2 501 2D3 501 6D4 501 10D5 502 2D6 502 4D7 502 6D8 502 10D9 503 4D10 520 4D11 536 4D12 551 4D13 564 4D14 575 4D15 575 4D16 575 4D17 576 4D18 576 4D19 576 4D20 586 4D21 592 4D22 600 4D23 622 4D24 629 4D25 631 4______________________________________

Like Example D1, Examples D2-D25 were all excellent in terms of the water retention of plate precursors, environmental changes, running properties and stability with time.

EXAMPLES D26-D41

Using some combinations of the amine compounds shown in Table 8 in a fixed amount of 4 parts by weight, the water retention of plate precursors, running properties and stability with time were estimated by following the procedures of Example D1.

TABLE 18______________________________________ Combinations of Amine CompoundsExample No. Compound Nos. weight %______________________________________D26 501/502 50/50D27 501/502 25/75D28 501/502 75/25D29 501/575 50/50D30 501/575/504 25/25/50D31 501/520 50/50D32 101/142 50/50D33 575/576 50/50D34 501/575/631 50/25/25D35 504/576/629 50/25/25D36 504/551/575 50/25/25D37 575/586/592 50/25/25D38 576/591/131 50/25/25D39 576/600/623 50/25/25D40 501/551/576/622 25/25/25/25D41 501/502/534/562 25/25/25/25______________________________________

Like Example D1, Examples D26-D41 are all excellent in terms of the water retention of plate precursors, environmental changes, running properties and stability with time, indicating that the amine compounds of this invention may be used in combination with no problem.

EXAMPLES D42-D48

Following the procedures of Example D1, various properties were estimated of a treating solution obtained by adding various wetting agents, antiseptics and rust preventives to the desensitizing solution having the same composition as that of Example D1.

TABLE 19______________________________________Ex. No. Wetting Agent Anticeptic Rust Preventive______________________________________D42 Ethylene glycol Salicylic acid EDTAD43 Ethylene glycol Salicylic acid Metaphosphoric acidD44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazoleD45 Ethylene glycol Sodium Dehydro- EDTA acetateD45 Gum arabic Salicylic acid EDTAD47 Dimethylacet- Salicylic acid EDTA amideD48 Butyl Cello- Salicylic acid EDTA solve______________________________________

Like Example D1, Examples D42-D48 are all excellent in the water retentions of plate precursors, environmental changes, running properties and stability with time, indicating that the performance of the desensitizing solution of this invention is not affected by the addition of various additives.

EXAMPLE D49

The dampening solution used was obtained by diluting the treating solution of Ex. D1 five times with distilled water.

Comparative Example D4

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. D1 five times with distilled water.

Comparative Example D5

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. D2 five times with distilled water.

Set out in Table 20 are the results of estimation of Example D49 and Comparative Examples D4 and D5.

TABLE 20______________________________________What Was Estimated Example D49 Comp. Ex. D4 Comp. Ex. D5______________________________________Note: 4) No scumming Scumming was Scumming wasScumming on prints was found found on the found on the until 5000 l000th prints 2000th prints prints______________________________________

Whether or not there was scumming on the prints was estimated as follows.

As compared with Comp. Ex. D4 and D5, the desensitizing solution of this invention gives rise to no scumming, indicating that it can be used as a dampening solution with high performance.

EXAMPLE E1

______________________________________Water 1000 parts by weightPotassium phytate 80 parts by weightN-2-ethylhexylimidazole 4 parts by weight______________________________________

Comparative Example E1

Here the amine compound was removed from the solution of Ex. E1.

Comparative Example E2

Here diethylamine was used in place of the amine compound of Ex. E1.

Comparative Example E3

Here monoethanolamine was used in place of the amine compound of Ex. E1.

In each of Ex. E1 and Comp. Ex. E1-E3, the components were well dissolved in water to prepare a treating solution, which was then regulated to pH 4.3 with the addition of KOH.

These solutions were used for actual printing. The results are set out in Table 21.

TABLE 21______________________________________ Example Comp. Ex. Comp. Ex. Comp. Ex.What Was Estimated E1 E1 E2 E3______________________________________Water Retention ofPlate PrecursorNote: 1) Good Scumming Little Little(25.degree. C., 60% RH) .smallcircle. found scumming scumming X found found .smallcircle. .DELTA. .smallcircle. .DELTA.(35.degree. C., 80% RH) Good Scumming Scumming Scumming .smallcircle. found found found X X XRunning PropertiesNote: 2) Good Scumming Scumming Scumming(25.degree. C., 60% RH) .smallcircle. found found found X X X Pricipita- Precipita- tion found tion found(35.degree. C., 80% RH) Good Scumming Scumming Scumming .smallcircle. found found found X X X Pricipita- Precipita- tion found tion foundNote: 3 Good Scumming Little ScummingStability with .smallcircle. found discolora- likely toTime X tion and occur scumming .DELTA. likely to occur .DELTA.______________________________________

The water retention of a plate precursor, running properties and stability with time referred to in Table 21 were estimated according to the procedures mentioned in connection with Table 1.

The water retention of the plate precursor treated with the desensitizing solution of this invention is improved over that treated with Comparative Examples E1-E3. Especially when the environmental conditions are changed to (35.degree. C. and 80% RH), the water retentions of the plate precursors treated with Comp. Ex. E2 and E3 decrease considerably, but that treated with Example E1 does not. In other words, the treating solution of this invention is characterized by being unlikely to be affected by environmental conditions.

The running properties according to Comparative Examples E2 and E3 degrade due to precipitation in the treating solutions, but the treating solution of this invention gives rise to no precipitation and maintains its initial capacity, even after being run 6000 times. In addition, the treating solution of this invention is better than those of Comparative Examples E1-E3 in terms of stability with time, so that it can well stand up to long-term storage.

As mentioned above, only the desensitizing solution of this invention can stand up to environment conditions, continued use and long-term storage and, besides, gives rise to no scumming.

EXAMPLES E2-E25

In lieu of the amine compound used in Example E1, amine compounds shown in Table 22 were used in amounts shown in Table 22. Estimation was made following Example E1.

TABLE 22______________________________________Example No. Amine Compound No. Amount (parts by weight)______________________________________E2 701 2E3 701 6E4 701 10E5 723 2E6 723 4E7 723 6E8 723 10E9 705 4E10 715 4E11 725 4E12 732 4E13 736 4E14 44 4E15 750 4E16 755 4E17 760 4E18 764 4E19 767 4E20 768 4E21 783 4E22 773 4E23 777 4E24 798 4E25 800 4______________________________________

Like Example E1, Examples E2-E25 were all excellent in terms of the water retention of plate precursors, environmental changes, running properties and stability with time.

EXAMPLES E26-E41

Using some combinations of the amine compounds shown in Table 23 in a fixed amount of 4 parts by weight, the water retention of plate precursors, running properties and stability with time were estimated by following the procedures of Example E1.

TABLE 23______________________________________ Combinations of Amine CompoundsExample No. Compound Nos. weight %______________________________________E26 701/723 50/50E27 701/723 25/75E28 701/723 75/25E29 701/705 50/50E30 701/702/705 25/25/50E31 701/732 50/50E32 701/736 50/50E33 701/744 50/50E34 701/723/744 50/25/25E35 702/734/752 50/25/25E36 702/771/738 50/25/25E37 754/789/793 50/25/25E38 734/752/779 50/25/25E39 734/747/795 50/25/25E40 701/702/780/793 25/25/25/25E41 701/702/734/762 25/25/25/25______________________________________

Like Example E1, Examples E26-E41 are all excellent in terms of the water retention of plate precursors, environmental changes, running properties and stability with time, indicating that the amine compounds of this invention may be used in combination with no problem.

EXAMPLES E42-E48

Following the procedures of Example E1, various properties were estimated of a treating solution obtained by adding various wetting agents, antiseptics and rust preventives shown Table 24 to the desensitizing solution having the same composition as that of Example E1.

TABLE 24______________________________________Ex. No. Wetting Agent Anticeptic Rust Preventive______________________________________E42 Ethylene glycol Salicylic acid EDTAE43 Ethylene glycol Salicylic acid Metaphosphoric acidE44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazoleE45 Ethylene glycol Sodium Dehydro- EDTA acetateE45 Gum arabic Salicylic acid EDTAE47 Dimethylacet- Salicylic acid EDTA amideE48 Butyl Cello- Salicylic acid EDTA solve______________________________________

Like Example E1, Examples E42-E48 are all excellent in the water retentions of plate precursors, environmental changes, running properties and stability with time, indicating that the performance of the desensitizing solution of this invention is not affected by the addition of various additives.

EXAMPLE E49

The dampening solution used was obtained by diluting the treating solution of Ex. E1 five times with distilled water. Comparative Example E4

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. E1 five times with distilled water.

Comparative Example E5

The dampening solution used was obtained by diluting the treating solution of Comp. Ex. E2 five times with distilled water.

Set out in Table 25 are the results of estimation of Example E49 and Comparative Examples E4 and E5.

TABLE 25______________________________________What Was Estimated Example E49 Comp. Ex. E4 Comp. Ex. E5______________________________________Note: 4) No scumming Scumming was Scumming wasScumming on prints was found found on the found on the until 5000 l000th prints 2000th prints prints______________________________________

Whether or not there was scumming on the prints was estimated as follows.

As compared with Comp. Ex. E4 and E5, the desensitizing solution of this invention gives rise to no scumming, indicating that it can be used as a dampening solution with high performance.

According to this invention, there can be provided a desensitizing or dampening solution for offset printing plate precursors, which pose no pollution problem, can be stable to long-term storage, continued use and environmental changes and can reduce the etching time or is excellent in the desensitizing capability.

Claims

1. A method for electrophotographic offset printing wherein an electrophotographic offset printing plate having a photoconductive layer thereon is exposed to form an image and the exposed photoconductive layer is treated with a desensitizing solution to render non-image areas thereon hydrophilic to prevent adhesion of printing ink to said non-image areas, the improvement which comprises the desensitizing solution comprising an amine compound-containing, cyanogen-free, desensitizing solution for electrophotographic offset printing comprising:

at least one compound selected from the group consisting of phytic acid, metal salts of phytic acid and ammonium salts of phytic acids; and

at least one compound selected from the group consisting of secondary and tertiary amines having the formula (1): ##STR13## wherein R.sub.1 is an aliphatic group having 8 to 18 carbon atoms and R.sub.2 and R.sub.3 each is hydrogen or an aliphatic group having 1 to 18 carbon atoms.

2. A method for electrophotographic offset priming wherein an electrophotographic offset printing plate having a photoconductive layer thereon is exposed to form an image and the exposed photoconductive layer is treated with a desensitizing solution to render non-image areas thereon hydrophilic so as to prevent adhesion of printing ink to said non-image areas, the improvement which comprises the desensitizing solution comprising an amine compound-containing, cyanogen-free solution containing

at least one compound selected from the group consisting of phytic acid, metal salts of phytic acid and ammonium salts of phytic acids; and

at least one compound selected from the group consisting of secondary and tertiary amines having the formula (1): ##STR14## wherein R.sub.1, R.sub.2, and R.sub.3 have at least 9 carbon atoms in all, and R.sub.1 is an aliphatic group having at least 6 carbon atoms and R.sub.2 and R.sub.3 each is hydrogen, an aliphatic group, or, taken together, form a cyclic structure.

3. A method for electrophotographic offset priming wherein an electrophotographic offset printing plate having a photoconductive layer thereon is exposed to form an image and the exposed photoconductive layer is treated with a desensitizing solution to render non-image areas thereon hydrophilic so as to prevent adhesion of printing ink to said non-image areas, the improvement which comprises the desensitizing solution comprising an amine compound-containing, cyanogen-free, desensitizing solution for electrophotographic offset printing comprising:

at least one compound selected from the group consisting of phytic acid, metal salts of phytic acid, and ammonium salts of phytic acid, and

at least one compound selected from the group consisting of urea compounds of formula (5) and urethane compounds of formula (6), each of which contains an amino group of formula (4) and each having an inorganic/organic value in the range of 0.1 to 4.0 ##STR15## wherein a.sub.1, a.sub.2 and a.sub.3 each may be hydrogen or an organic residue, R.sub.7 and R.sub.8 each may be hydrogen, an organic residue, or, taken together, form a cyclic structure, and X is oxygen or sulfur.

4. A method for electrophotographic offset printing wherein an electrophotographic offset printing plate having a photoconductive layer thereon is exposed to form an image and the exposed photoconductive layer is treated with a desensitizing solution to render non-image areas thereon hydrophilic so as to prevent adhesion of printing ink to said non-image areas, the improvement which comprises the desensitizing solution comprising an amine compound-containing, cyanogen-free, desensitizing solution for electrophotographic offset printing comprising:

at least one compound selected from the group consisting of phytic acid, metal salts of phytic acid, and ammonium salts of phytic acid, and

at least one compound selected from the group consisting of an amide of formula (8) which contains an amino group of formula (7): ##STR16## wherein R.sub.9 is a non-substituted alkyl or a substituted alkyl, R.sub.10 is a hydrogen atom or an organic residue, or, taken together, form a cyclic structure and a.sub.4 denotes hydrogen atom, an organic residue, or a substituent selected from the group consisting of halogen atom, a cyano and nitro group.

5. A method for electrophotographic offset printing wherein an electrophotographic offset printing plate having a photoconductive layer thereon is exposed to form an image and the exposed photoconductive layer is treated with a desensitizing solution to render non-image areas thereon hydrophilic so as to prevent adhesion of printing ink to said non-image areas, the improvement which comprises the desensitizing solution comprising an amine compound-containing, cyanogen-free, desensitizing solution for electrophotographic offset printing comprising:

at least one compound selected from the group consisting of phytic acid, metal salts of phytic acid, and ammonium salts of phytic acid, and

at least one compound selected from the group consisting of hetero-cyclic compounds containing at least one nitrogen atom and having an inorganic/organic value in the range from 1.0 to 4.0.