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 a least one nitrogen atom and having an inorganic/organic value of 0.1 to 4.0 inclusive.

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. JP-A-57-107889 discloses a desensitizing solution comprising phytic acid and an amino carboxylic acid. JP-A-62-127288 discloses a fountain solution comprising phytic acid, a chelating agent such as EDTA and a polymer. 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 film forming rate, but have various problems in that ferrocyanide and ferricyanide ions are so unstable to heat and light that upon exposure 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 be 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) (d), (e), and (f) and, optionally at least one selected from (c) (b) secondary and tertiary amine compounds represented by the following general formula (1): wherein R 1 , and R 2 and R 3 have at least 9 carbon atoms in all, and R 1 denotes an aliphatic group having at least 6 carbon atoms and R 2 and R 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 4 -NH 2 wherein R 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): wherein R 5 and R 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: wherein a 1 , a 2 and a 3 each stand for a hydrogen atom and/or an organic residue, R 7 and R 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): wherein R 9 and R 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 4 and a 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 1 stands for a C 8-18 alkyl, cycloalkyl, alkenyl or aralkyl group which may have a subsitituent, for instance, an alkoxy (-OR 1 ), sulfide (-SR 1 ), amino halogen, cyano, nitro or other group. R 2 and R 3 each denote a hydrogen atom and a C 1-18 aliphatic group mentioned for R 1 , or they may be aliphatic rings which can be combined with each other. R 4 denotes an aliphatic group having at least 8 carbon atoms, mentioned for R 1 . R 12 and R 13 each denote a hydrogen atom and a C 1-18 aliphatic group mentioned for R 1 , or they may be aliphatic rings which can be combined with each other. More preferably, R 1 represents: a C 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-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 2 and R 3 each represent: a hydrogen atom, a C 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 2 and R 3 may be combined with each other to form an ethyleneimine, pyrrolidine or piperidine ring. R 4 represents: a C 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, "2EH" refers to (2-ethylhexyl group), "nBu" to -nC 4 H 9 (butyl group), "nHx" to -nC 6 H 13 (hexyl group), "nOct" to -nC 8 H 17 (octyl group), "nDode" to -nC 12 H 25 (dodecyl group) and "nOctdec" to -nC 18 H 37 (octadecyl group). 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 5 and R 6 each denote a hydrogen atom and/or a C 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 5 and R 6 each denote: a C 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 5 and R 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. 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 7 and R 8 each denote a hydrogen atom and/or a C 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 1 , a 2 and a 3 each stand for a hydrogen atom and/or a C 1-18 organic residue, mentioned for R 7 and R 8 , and X denotes an oxygen or sulfur atom. More preferably, R 7 and R 8 each denote: a C 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 7 and R 8 may be combined with each other to form a ring such as an aziridine, pyrrolidine, piperidine, morpholine or other ring. a 1 , a 2 and a 3 each denote: a hydrogen atom and/or a C 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-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.). 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. 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 9 and R 10 each denote a hydrogen atom and/or a C 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 4 and a 5 each stand for a hydrogen atom and/or a C 1-18 organic residue, mentioned for R g and R 10 . More preferably, R 9 and R 10 each denote: a C 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 9 and R 10 may be combined with each other to form a ring such as an aziridine, pyrrolidine, piperidine, morpholine or other ring. a 4 and a 5 each denote: a hydrogen atom and/or a C 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. 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 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 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 substituent (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. 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 01 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 dissolved 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 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 weight Potassium phytate 80 parts by weight Diisopropyl-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. 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°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°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°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 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. Example No. Amine Compound No. Amount (parts by weight) A2 1 2 A3 1 6 A4 1 10 A5 2 2 A6 2 4 A7 2 6 A8 2 10 A9 3 4 A10 8 4 A11 10 4 A12 14 4 A13 23 4 A14 29 4 A15 31 4 A16 34 4 A17 42 4 A18 45 4 A19 54 4 A20 56 4 A21 60 4 A22 62 4 A23 67 4 A24 71 4 A25 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. Example No. Combinations of Amine Compounds Compound Nos. weight % A26 (1)/(2) 50/50 A27 (1)/(2) 25/75 A28 (1)/(2) 75/25 A29 (1)/(24) 50/50 A30 (1)/(2)/(3) 25/25/50 A31 (1)/(29) 50/50 A32 (1)/(34) 50/50 A33 (29)/(34) 50/50 A34 (1)/(34)/(64) 50/25/25 A35 (2)/(34)/(52) 50/25/25 A36 (2)/(71)/(83) 50/25/25 A37 (54)/(89)/(93) 50/25/25 A38 (34)/(52)/(79) 50/25/25 A39 (34)/(47)/95) 50/25/25 A40 (1)/(34)/(80)/(93) 25/25/25/25 A41 (1)/(2)/(34)/(62) 25/25/25/25 Like Example A1, Examples A26-A41 are all excellent in terms 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. Ex. No. Wetting Agent Antiseptic Rust Preventive A42 Ethylene glycol Salicylic acid EDTA A43 Ethylene glycol Salicylic acid Metaphosphoric acid A44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazole A45 Ethylene glycol Sodium Dehydroacetate EDTA A45 Gum arabic Salicylic acid EDTA A47 Dimethylacetamide Salicylic acid EDTA A48 Butyl Cellosolve Salicylic acid EDTA 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. What Was Estimated Example A49 Comp. Ex. A4 Comp. Ex. A5 Note: 4) Scumming on prints No scumming was found until 5000 prints Scumming was found on the 1000th prints Scumming was found on the 2000th 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 C1 Water 1000 parts by weight Potassium phytate 80 parts by weight N'-dimethylaminopropyl -N-hexylurea 4 parts by weight 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. 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 improve over that treated with Comparative Examples C2-C3. Especially when the environmental conditions are changed to (35°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 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. Example No. Amine Compound No. Amount (parts by weight) C2 301 2 C3 301 6 C4 301 10 C5 374 2 C6 374 4 C7 374 6 C8 374 10 C9 304 4 C10 347 4 C11 352 4 C12 367 4 C13 430 4 C14 442 4 C15 371 4 C16 410 4 C17 415 4 C18 425 4 C19 456 4 C20 463 4 C21 349 4 C22 413 4 C23 317 4 C24 334 4 C25 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. Example No. Combinations of Amine Compounds Compound Nos. weight % C26 301/374 50/50 C27 301/374 25/75 C28 301/374 75/25 C29 301/304 50/50 C30 301/374/304 25/25/50 C31 301/352 50/50 C32 301/363 50/50 C33 374/415 50/50 C34 301/374/430 50/25/25 C35 304/374/142 50/25/25 C36 304/371/383 50/25/25 C37 354/389/393 50/25/25 C38 334/352/379 50/25/25 C39 334/347/395 50/25/25 C40 301/334/380/393 25/25/25/25 C41 301/302/334/362 25/25/25/25 Like Example C1, Examples C26-C41 are all excellent in terms 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 sane composition as that of Example C1. Ex. No. Wetting Agent Antiseptic Rust Preventive C42 Ethylene glycol Salicylic acid EDTA C43 Ethylene glycol Salicylic acid Metaphosphoric acid C44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazole C45 Ethylene glycol Sodium Dehydroacetate EDTA C45 Gum arabic Salicylic acid EDTA C47 Dimethylacetamide Salicylic acid EDTA C48 Butyl Cellosolve Salicylic acid EDTA 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 C49 and Comparative Examples C4 and C5. What Was Estimated Example C49 Comp. Ex. C4 Comp. Ex. C5 Note: 4) Scumming on prints No scumming was found until 5000 prints Scumming was found on the 1000th prints Scumming was found on the 2000th 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 weight Potassium phytate 80 parts by weight N-[N,N'-diethylaminopropyl n-dodecylamide 4 parts by weight 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. 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°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 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. Example No. Amine Compound No. Amount (parts by weight) D2 501 2 D3 501 6 D4 501 10 D5 502 2 D6 502 4 D7 502 6 D8 502 10 D9 503 4 D10 520 4 D11 536 4 D12 551 4 D13 564 4 D14 575 4 D15 575 4 D16 575 4 D17 576 4 D18 576 4 D19 576 4 D20 586 4 D21 592 4 D22 600 4 D23 622 4 D24 629 4 D25 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. Example No. Combinations of Amine Compounds Compound Nos. weight % D26 501/502 50/50 D27 501/502 25/75 D28 501/502 75/25 D29 501/575 50/50 D30 501/575/504 25/25/50 D31 501/520 50/50 D32 101/142 50/50 D33 575/576 50/50 D34 501/575/631 50/25/25 D35 504/576/629 50/25/25 D36 504/551/575 50/25/25 D37 575/586/592 50/25/25 D38 576/591/131 50/25/25 D39 576/600/623 50/25/25 D40 501/551/576/622 25/25/25/25 D41 501/502/534/562 25/25/25/25 Like Example D1, Examples D26-D41 are all excellent in terms 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. Ex. No. Wetting Agent Antiseptic Rust Preventive D42 Ethylene glycol Salicylic acid EDTA D43 Ethylene glycol Salicylic acid Metaphosphoric acid D44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazole D45 Ethylene glycol Sodium Dehydroacetate EDTA D45 Gum arabic Salicylic acid EDTA D47 Dimethylacetamide Salicylic acid EDTA D48 Butyl Cellosolve Salicylic acid EDTA 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. What Was Estimated Example D49 Comp. Ex. D4 Comp. Ex. D5 Note: 4) Scumming on prints No scumming was found until 5000 prints Scumming was found on the 1000th prints Scumming was found on the 2000th 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 weight Potassium phytate 80 parts by weight N-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. 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°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 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. Example No. Amine Compound No. Amount (parts by weight) E2 701 2 E3 701 6 E4 701 10 E5 723 2 E6 723 4 E7 723 6 E8 723 10 E9 705 4 E10 715 4 E11 725 4 E12 732 4 E13 736 4 E14 44 4 E15 750 4 E16 755 4 E17 760 4 E18 764 4 E19 767 4 E20 768 4 E21 783 4 E22 773 4 E23 777 4 E24 798 4 E25 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. Example No. Combinations of Amine Compounds Compound Nos. weight % E26 701/723 50/50 E27 701/723 25/75 E28 701/723 75/25 E29 701/705 50/50 E30 701/702/705 25/25/50 E31 701/732 50/50 E32 701/736 50/50 E33 701/744 50/50 E34 701/723/744 50/25/25 E35 702/734/752 50/25/25 E36 702/771/738 50/25/25 E37 754/789/793 50/25/25 E38 734/752/779 50/25/25 E39 734/747/795 50/25/25 E40 701/702/780/793 25/25/25/25 E41 701/702/734/762 25/25/25/25 Like Example E1, Examples E26-E41 are all excellent in terms 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. Ex. No. Wetting Agent Antiseptic Rust Preventive E42 Ethylene glycol Salicylic acid EDTA E43 Ethylene glycol Salicylic acid Metaphosphoric acid E44 Ethylene glycol Salicylic acid 2-Mercaptobenz imidazole E45 Ethylene glycol Sodium Dehydroacetate EDTA E45 Gum arabic Salicylic acid EDTA E47 Dimethylacetamide Salicylic acid EDTA E48 Butyl Cellosolve Salicylic acid EDTA 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. What Was Estimated Example E49 Comp. Ex. E4 Comp. Ex. E5 Note: 4) Scumming on prints No scumming was found until 5000 prints Scumming was found on the 1000th prints Scumming was found on the 2000th 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: An amine compound-containing, but cyanogen-free, desensitizing solution for offset printing, 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) (d), (e) and (f) and, optionally at least one selected from (c) (b) secondary and tertiary amine compounds represented by the following general formula (1): wherein R 1 , and R 2 and R 3 have at least 9 carbon atoms in all, and R 1 denotes an aliphatic group having at least 6 carbon atoms and R 2 and R 3 each stand for a hydrogen atom and an aliphatic group or may optionally be combined with each other to form a cyclic structure, and/or a primary amine compound represented by the following general formula (2): R 4 -NH 2 wherein R 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): wherein R 5 and R 6 each denote a hydrogen atom and/or an organic residue or may be 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, (d) an urea compound represented by the following general formula (5) and/or an 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: wherein a 1 , a 2 and a 3 each stand for a hydrogen atom and/or an organic residue, R 7 and R 8 each denote a hydrogen atom and/or an organic residue or may optionally combined with each 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): wherein R 9 and R 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 4 and a 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 at least one nitrogen atom and having an inorganic/organic value lying in the range of 0.1 to 4.0 inclusive.

Inventors: ITAKURA RYOSUKE, KASAI SEISHI, KATO EIICHI, SERA HIDEFUMI, ITAKURA, RYOSUKE, KASAI, SEISHI, KATO, EIICHI, SERA, HIDEFUMI, ITAKURA, RYOSUKE, C/O FUJI PHOTO FILM CO., LTD., KASAI, SEISHI, C/O FUJI PHOTO FILM CO., LTD., KATO, EIICHI, C/O FUJI PHOTO FILM CO., LTD., SERA, HIDEFUMI, C/O FUJI PHOTO FILM CO., LTD.
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1992
Main classification: B41N3
IPC codes: B41N3