Color-developing agents and color-developing sheets

Provided are a color-developing agent comprising a multivalent metal salt of a salicylic acid derivative and a sulfonated phenol and/or a metal salt thereof and having excellent initial and ultimate color-developing capacities and improved waterproofness; and a color-developing sheet making use of the color-developing agent.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to color-developing agents for recording materials 
(for example, pressure-sensitive copying paper). In particular, the 
present invention provides color-developing agents excellent in initial 
and ultimate color-developing capacities and also in waterproofness. 
Further, this invention also pertains to color-developing sheets making 
use of these color-developing agents. 
2. Description of the Related Art 
Salicylic acid derivatives, for example, metal salts of 3,5-di-substituted 
salicylic acid derivatives are conventionally known to be useful as 
color-developing agents for pressure-sensitive copying paper. Each 
3,5-di-substituted salicylic acid derivative is produced from its 
corresponding 2,4-di-substituted phenol derivative and carbon dioxide, 
namely, by using the Kolbe-Schmitt reaction (see, for example, U.S. Pat. 
No. 3,983,292). However, use of a metal salt of a 3,5-di-substituted 
salicylic acid derivative obtained in this manner, for example, zinc 
3,5-di(.alpha.-methylbenzyl)salicylate, as a color-developing agent for 
pressure-sensitive copying paper creates a problem such that developed 
color images fade away when exposed to water. 
As measures for overcoming this problem in physical property, the following 
production processes have already been proposed. Namely, a salicylate 
ester and styrene are reacted. Subsequent to hydrolysis of the resulting 
salicylate ester resin, a multivalent metal compound is caused to act to 
produce the multivalent metal salt of the salicylic acid resin. For 
example, styrene is reacted with methyl salicylate in the presence of 
concentrated sulfuric acid to obtain a methyl salicylate resin, followed 
by hydrolysis in an aqueous alkaline solution. A multivalent metal 
compound (e.g., zinc sulfate) is then caused to act, whereby the 
multivalent metal salt of the salicylic acid resin is produced (U.S. Pat. 
No. 4,952,648). As an alternative, a salicylic acid and a styrene are 
reacted at 50.degree. to 150.degree. C. in the presence of an acid 
catalyst, followed by the reaction with a metal salt of a fatty acid so 
that the metal salt of a high molecular salicylic acid resin is produced 
(U.S. Pat. No. 4,929,710). Color-developing agents obtained by these 
processes, however, are still unable to bring about an improvement in both 
initial and ultimate color-developing capacities. 
A color-developing agent has been proposed recently, which features 
inclusion of (A) a multivalent metal salt of a salicylic acid derivative 
and (B) a phenol substituted by styrene or the like or a metal salt 
thereof as essential components (Japanese Patent Laid-Open No. 
286304/1994). However this color-developing agent is also still 
insufficient in color-developing capacity. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a color-developing agent 
and a color-developing sheet, which have excellent initial and ultimate 
color-developing capacities and also have improved waterproofness. 
With a view to overcoming the above-mentioned problem, the present 
inventors have proceeded with an extensive investigation. As a result, it 
has been found that a color-developing agent, which is composed of a 
multivalent metal salt of a salicylic acid derivative and a sulfonated 
phenol or a metal salt thereof as essential components, is good in 
waterproofness and is excellent in both initial and ultimate 
color-developing capacities, leading to the present invention. The present 
invention therefore provides: 
(1) A color-developing agent comprising a multivalent metal salt of a 
salicylic acid derivative and a sulfonated phenol or the like (which will 
hereinafter be collectively referred to as a "sulfonated phenol") and/or a 
metal salt thereof. 
(2) A color-developing agent as described above under (1), wherein the 
content of the sulfonated phenol and/or the metal salt thereof is 0.5 to 
40 mole % based on the multivalent metal salt of the salicylic acid 
derivative. 
(3) A color-developing agent as described above under (1), wherein the 
salicylic acid derivative is a salicylic acid substituted by styrene or 
the like (which will hereinafter be collectively referred to as a 
"styrene-substituted salicylic acid") or a derivative thereof. 
(4) A color-developing agent as described above under (1), wherein the 
sulfonated phenol is a styrene-substituted sulfonated phenol. 
(5) A color-developing agent comprising a multivalent metal salt of a 
styrene-substituted salicylic acid derivative and a styrene-substituted 
sulfonated phenol and/or a metal salt thereof, said multivalent metal salt 
having been obtained by reacting styrene or the like (which will 
hereinafter be collectively referred to as a "styrene") with a salicylic 
acid or the like and a phenol or the like (which will hereinafter be 
collectively referred to as a "salicylic acid" and a "phenol", 
respectively) in the presence of sulfuric acid as a catalyst and 
sulfonating agent to obtain a resin and then reacting a multivalent metal 
compound with the resin. 
(6) A process for the production of a color-developing agent comprising a 
multivalent metal salt of a styrene-substituted salicylic acid derivative 
and a styrene-substituted sulfonated phenol and/or a metal salt thereof, 
which comprises reacting a styrene with a salicylic acid and a phenol in 
the presence of sulfuric acid as a catalyst and sulfonating agent to 
obtain a resin and then reacting a multivalent metal compound with the 
resin. 
(7) A process as described above under (6), wherein the phenol is used in 
an amount of 0.5 to 40 mole % based on the salicylic acid. 
(8) A process as described above under (6), wherein the styrene is used in 
an amount 1 to 10 molar times as much as the phenol and salicylic acid. 
(9) A color-developing agent comprising a multivalent metal salt of a 
styrene-substituted salicylic acid derivative and a styrene-substituted 
sulfonated phenol and/or a metal salt thereof, said multivalent metal salt 
having been obtained by conducting a first-stage reaction of reacting a 
phenol and a styrene in the presence of sulfuric acid as a catalyst and 
sulfonating agent and then a second-stage reaction of adding, to the 
resulting reaction mixture, a salicylic acid and then the styrene to 
obtain a resin, followed by the reaction of the resin with a multivalent 
metal salt. 
(10) A process for the production of a color-developing agent comprising a 
multivalent metal salt of a styrene-substituted salicylic acid derivative 
and a styrene-substituted sulfonated phenol and/or a metal salt thereof, 
which comprises conducting a first-stage reaction of reacting a phenol and 
a styrene in the presence of sulfuric acid as a catalyst and sulfonating 
agent and then a second-stage reaction of adding, to the resulting 
reaction mixture, a salicylic acid and then the styrene to obtain a resin, 
followed by the reaction of the resin with a multivalent metal salt. 
(11) A process as described above under (10), wherein the phenol is used in 
an amount of 0.5 to 40 mole % based on the salicylic acid. 
(12) A process as described above under (10), wherein the styrene used in 
the first-stage reaction is in an amount 1 to 10 molar times as much as 
the phenol. 
(13) A process as described above under (10), wherein the total amount of 
the styrene used in the first-stage and second-stage reactions is 1 to 15 
times as much as that of the phenol and salicylic acid. 
(14) A color-developing sheet with a layer formed thereon and comprising a 
color-developing agent as described above under any one of (1) to (5) and 
(9).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The term "salicylic acid derivative" as used herein embraces 
nuclear-substitution salicylic acids in each of which one to four hydrogen 
atoms at 3 to 6 positions of salicylic acid have each been substituted by 
a C.sub.4 or higher alkyl, cycloalkyl, alkoxy, aryl, aryloxy, alkylaryl or 
aralkyl group or a halogen atom; salicylic acid resins each containing two 
or more salicylic acid units as partial skeletons in its principal chain 
or side chain; and mixtures of two or more of these nuclear-substitution 
salicylic acids and salicylic acid resins. Specific examples include, but 
should not be limited to in the present invention, such as: 
3-.alpha.-methylbenzylsalicylic acid, 5-.alpha.-methylbenzylsalicylic acid, 
5-benzylsalicylic acid, 5-cyclohexylsalicylic acid, 5-tert-octylsalicylic 
acid, 5-phenylsalicylic acid, 3-methyl-5-isononylsalicylic acid, 
3-methyl-5-isododecylsalicylic acid, 3-methyl-5-isopentaldecylsalicylic 
acid, 3,5-di(.alpha.-methylbenzyl)salicylic acid, 
3,5-di(tert-butyl)salicylic acid, 
3,5-di(.alpha.,.alpha.-dimethylbenzyl)salicylic acid, 
3,5-di(cyclohexyl)salicylic acid, 
3-methyl-5-(.alpha.-methylbenzyl)salicylic acid, 
3-methyl-5-(.alpha.,.alpha.-dimethylbenzyl)salicylic acid, 
3,5-di-tert-butyl-6-methylsalicylic acid, 3-tert-butyl-5-phenylsalicylic 
acid, 3,5-di-tert-amylsalicylic acid, 3-tert-octyl-6-methylsalicylic acid, 
3-cyclohexyl-5-isononylsalicylic acid, 3-phenyl-5-isononylsalicylic acid, 
3-(.alpha.-methylbenzyl)-5-isononylsalicylic acid, 
3-isopropyl-5-isononylsalicylic acid, 3-isononylsalicylic acid, 
3-isononyl-5-methylsalicylic acid, 3-isononyl-5-cyclohexylsalicylic acid, 
3-isononyl-5-tert-butylsalicylic acid, 3-isononyl-5-phenylsalicylic acid, 
3-isononyl-5-(.alpha.-methylbenzyl)salicylic acid, 
3-isononyl-5-(4,.alpha.-dimethylbenzyl)salicylic acid, 
3-isononyl-5-(.alpha.,.alpha.-dimethylbenzyl)salicylic acid, 
3-(.alpha.,.alpha.-dimethylbenzyl)-5-isononylsalicylic acid, 
3-isononyl-6-methylsalicylic acid, 5-isononylsalicylic acid, 
3-tert-butyl-5-isononylsalicylic acid, 3,5-diisononylsalicylic acid, 
3-indodecylsalicylic acid, 3-indodecyl-5-methylsalicylic acid, 
3-isododecyl-6-methylsalicylic acid, 3-isopropyl-5-indodecylsalicylic 
acid, 3-indodecyl-5-ethylsalicylic acid, 5-indodecylsalicylic acid, 
3-isopentadecylsalicylic acid, 3-isopentadecyl-5-methylsalicylic acid, 
3-isopentadecyl-6-methylsalicylic acid, 5-isopentadecylsalicylic acid, 
3-cyclohexyl-5-(.alpha.-methylbenzyl)salicylic acid, 
3-phenyl-5-(.alpha.-methylbenzyl)salicylic acid, 
3-phenyl-5-(.alpha.,.alpha.-dimethylbenzyl)salicylic acid, 
3-(.alpha.-methylbenzyl)-5-methylsalicylic acid, 
3-(.alpha.-methylbenzyl)-6-methylsalicylic acid, 
3-(.alpha.-methylbenzyl)-5-phenylsalicylic acid, 
3-(.alpha.-methylbenzyl)-5-(.alpha.,.alpha.-dimethylbenzyl)salicylic acid, 
3-(.alpha.-methylbenzyl)-5-bromosalicylic acid, 
3-(.alpha.,4-dimethylbenzyl)-5-methylsalicylic acid, 
3,5-di(.alpha.,4-dimethylbenzyl)salicylic acid, 
3-.alpha.-methylbenzyl-5-(.alpha.,.alpha.-dimethylbenzyl)salicylic acid, 
3-.alpha.-methylbenzyl-5-bromosalicylic acid, 
3-(.alpha.,.alpha.-dimethylbenzyl)-5-methylsalicylic acid, 
3-(.alpha.,.alpha.-dimethylbenzyl)-6-methylsalicylic acid, 
5-(4-mesitylmethylbenzyl)salicylic acid, 
3-.alpha.-methylbenzyl-5-(1,3-diphenylbutyl)salicylic acid, 
3-(1,3-diphenylbutyl)-5-.alpha.-methylbenzylsalicylic acid, 
3-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)-benzyl]salicylic acid, 
3-.alpha.-methylbenzyl-5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]s 
alicylic acid, 
3-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl-5-.alpha.-methylbenzylsa 
licylic acid, benzylated styrenated salicylic acids and pinenated salicylic 
acids. 
As the salicylic acid derivative, preferred is a styrene-substituted 
salicylic acid derivative obtained by reacting 1 to 10 moles of the 
corresponding styrene with 1 mole of the corresponding salicylic acid 
derivative. 
Illustrative of the styrene include, but are not limited to, styrene, 
2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 
4-ethylstyrene, 3-isopropylstyrene, 4-isopropylstyrene, 4-n-butylstyrene, 
4-tert-butylstyrene, 4-cyclohexylstyrene, 4-n-octylstyrene, 
4-n-decylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 
3-methoxystyrene, 4-methoxystyrene, 4-ethoxystyrene, 
.alpha.-methylstyrene, .alpha.-ethylstyrene, .alpha.-n-butylstyrene, 
.alpha.-isobutylstyrene, .alpha.,.beta.-dimethylstyrene, 
.alpha..beta.-diethylstyrene, .alpha.-methyl-.beta.-isopropylstyrene, 
.alpha.-n-propyl-.beta.-methylstyrene, 
4-(.alpha.,.alpha.-dimethylbenzyl)styrene, 4-phenylstyrene, 
4-fluorostyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene and 
4-bromostyrene. These styrenes can be used either singly or in 
combination. Preferred are styrene and alkyl-substituted styrenes such as 
4-methylstyrene. 
Examples of the multivalent metal, which constitutes the multivalent metal 
salt of the salicylic acid derivative useful in the present invention, 
include divalent, trivalent and tetravalent metals such as zinc, calcium, 
magnesium, barium, lead, aluminum, zirconium, vanadium and tin. Among 
these, preferred are zinc, aluminum and tin, with zinc being particularly 
preferred. 
The multivalent metal salt of the salicyclic acid derivative can be 
produced in a manner known per se in the art. Examples include a process 
in which an alkali metal salt of a salicylic acid derivative and a 
multivalent metal salt are reacted in water or in a solvent in which the 
alkali metal salt and the multivalent metal salt are both soluble; and a 
process in which a salicylic acid derivative is mixed with a multivalent 
metal compound, followed by thermal modification. 
Examples of the sulfonated phenol usable in the present invention include 
sulfonated phenols such as 4-hydroxy-benzenesulfonic acid, 
2-hydroxy-benzenesulfonic acid and 4-hydroxy-benzene1,3-disulfonic acid; 
and styrene-substituted sulfonated phenols such as 
3-(.alpha.-methylbenzyl)-4-hydroxy-benzenesulfonic acid, 
3-(.alpha.-methylbenzyl)-4-hydroxy-benzene-1,5-disulfonic acid, 
5-(.alpha.-methylbenzyl)-2-hydroxy-benzenesulfonic acid, 
3-(.alpha.-methylbenzyl)-2-hydroxy-benzenesulfonic acid, 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2-hydroxy-benzenesulfon 
ic acid, 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2-hydroxy-benzene1,3-su 
lfonic acid, 3,5-di(.alpha.-methylbenzyl)-4-hydroxy-benzenesulfonic acid, 
3,5-di(.alpha.-methylbenzyl)-2-hydroxy-benzenesulfonic acid, 
3,5-di(.alpha.,.alpha.-dimethylbenzyl)-4-hydroxy-benzenesulfonic acid, 
3,5-di(.alpha.,.alpha.-dimethylbenzyl)-2-hydroxy-benzenesulfonic acid, 
3-.alpha.-methylbenzyl-5-(1,3-diphenylbutyl)-2-hydroxy-benzenesulfonic 
acid, 
3-(1,3-diphenylbutyl)-5-(.alpha.-methylbenzyl)-2-hydroxy-benzenesulfonic 
acid, 
3-(.alpha.-methylbenzyl)-5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl 
]-2-hydroxy-benzenesulfonic acid, 
3-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-5-(.alpha.-methylbenzyl 
)-2-hydroxy-benzenesulfonic acid and 
3,5-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2-hydroxy-benzenesu 
lfonic acid. Likewise included are sulfonated 2-phenylphenols such as 
2-phenylphenol-4-sulfonic acid, 2-phenylphenol-6-sulfonic acid and 
2-phenylphenol-4,6-disulfonic acid; styrene-substituted sulfonated 
2-phenylphenols such as 6-(.alpha.-methylbenzyl)-2-phenylphenol-4-sulfonic 
acid, 6-(.alpha.,.alpha.-dimethylbenzyl)-2-phenylphenol-4-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2-phenylphenol-4-sulfon 
ic acid, 6-(1,3-diphenylbutyl)-2-phenylphenol-4-sulfonic acid, 
4-(.alpha.-methylbenzyl)-2-phenylphenol-6-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-2-phenylphenol-6-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2-phenylphenol-6-sulfon 
ic acid and 4-(1,3-diphenylbutyl)-2-phenylphenol-6-sulfonic acid; 
sulfonated 3-phenylphenols such as 3-phenylphenol-2-sulfonic acid, 
3-phenylphenol-4-sulfonic acid, 3-phenylphenol-6-sulfonic acid, 
3-phenylphenol-2,4-disulfonic acid, 3-phenylphenol-2,6-disulfonic acid and 
3-phenylphenol-4,6-disulfonic acid; styrene-substituted sulfonated 
3-phenylphenols such as 6-(.alpha.-methylbenzyl)-3-phenylphenol-4-sulfonic 
acid, 6-(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-4-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-4-sulfon 
ic acid, 6-(1,3-diphenylbutyl)-3-phenylphenol-4-sulfonic acid, 
2-.alpha.-methylbenzyl-3-phenylphenol-4-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-4-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-4-sulfon 
ic acid, 2-(1,3-diphenylbutyl)-3-phenylphenol-4-sulfonic acid, 
2,6-di(.alpha.-methylbenzyl)-3-phenylphenol-4-sulfonic acid, 
2,6-di(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-4-sulfonic acid, 
2,6-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-4-su 
lfonic acid, 2,6-di(1,3-diphenylbutyl)-3-phenylphenol-4-sulfonic acid, 
4-.alpha.-methylbenzyl-3-phenylphenol-6-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-6-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-6-sulfon 
ic acid, 4-(1,3-diphenylbutyl)-3-phenylphenol-6-sulfonic acid, 
2-.alpha.-methylbenzyl-3-phenylphenol-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-6-sulfon 
ic acid, 2-(1,3-diphenylbutyl)-3-phenylphenol-6-sulfonic acid, 
2,4-di(.alpha.-methylbenzyl)-3-phenylphenol-6-sulfonic acid, 
2,4-di(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-6-sulfonic acid, 
2,4-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-6-su 
lfonic acid, 2,4-(1,3-diphenylbutyl)-3-phenylphenol-6-sulfonic acid, 
6-(.alpha.-methylbenzyl)-3-phenylphenol-2-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-2-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-2-sulfon 
ic acid, 6-(1,3-diphenylbutyl)-3-phenylphenol-2-sulfonic acid, 
4-(.alpha.-methylbenzyl)-3-phenylphenol-2-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-2-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-2-sulfon 
ic acid, 4-(1,3-diphenylbutyl)-3-phenylphenol-2-sulfonic acid, 
4,6-di(.alpha.-methylbenzyl)-3-phenylphenol-2-sulfonic acid, 
4,6-di(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-2-sulfonic acid, 
4,6-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-phenylphenol-2-su 
lfonic acid, 4,6-di(1,3-diphenylbutyl)-3-phenylphenol-2-sulfonic acid, 
6-(.alpha.-methylbenzyl)-3-phenylphenol-2,4-disulfonic acid, and 
4-(.alpha.,.alpha.-dimethylbenzyl)-3-phenylphenol-2,6-disulfonic acid; 
sulfonated 4-phenylphenols such as 4-phenylphenol-2-sulfonic acid, and 
4-phenylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
4-phenylphenols such as 2-(.alpha.-methylbenzyl)-4-phenylphenol-6-sulfonic 
acid, 2-(.alpha.,.alpha.-dimethylbenzyl)-4-phenylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4-phenylphenol-6-sulfon 
ic acid, and 2-(1,3-diphenylbutyl)-4-phenylphenol-6-sulfonic acid; 
sulfonated 3-methylphenols such as 3-methylphenol-2-sulfonic acid, 
3-methylphenol-4-sulfonic acid, 3-methylphenol-6-sulfonic acid, 
3-methylphenol-2,4-disulfonic acid, 3-methylphenol-2,6-disulfonic acid, 
3-methylphenol-4,6-disulfonic acid, and 3-methylphenol-2,4,6-trisulfonic 
acid; styrene-substituted sulfonated 3-methylphenols such as 
6-(.alpha.-methylbenzyl)-3-methylphenol-4-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-4-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-4-sulfon 
ic acid, 6-(1,3-diphenolbutyl)-3-methylphenol-4-sulfonic acid, 
2-(.alpha.-methylbenzyl)-3-methylphenol-4-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-4-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-4-sulfon 
ic acid, 2-(1,3-diphenylbutyl)-3-methylphenol-4-sulfonic acid, 
2,6-di(.alpha.-methylbenzyl)-3-methylphenol-4-sulfonic acid; 
2,6-di(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-4-sulfonic acid, 
2,6-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-4-su 
lfonic acid, 2,6-di(1,3-diphenylbutyl)-3-methylphenol-4-sulfonic acid, 
4-(.alpha.-methylbenzyl)-3-methylphenol-6-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-6-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-6-sulfon 
ic acid, 4-(1,3-diphenylbutyl)-3-methylphenol-6-sulfonic acid, 
2-(.alpha.-methylbenzyl)-3-methylphenol-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-6-sulfon 
ic acid, 2-(1,3-diphenylbutyl)-3-methylphenol-6-sulfonic acid, 
2,4-di(.alpha.-methylbenzyl)-3-methylphenol-6-sulfonic acid, 
2,4-di(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-6-sulfonic acid, 
2,4-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-6-su 
lfonic acid, 2,4-di(1,3-diphenylbutyl)-3-methylphenol-6-sulfonic acid, 
6-(.alpha.-methylbenzyl)-3-methylphenol-2-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-2-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-2-sulfon 
ic acid, 6-(1,3-diphenylbutyl)-3-methylphenol-2-sulfonic acid, 
4-(.alpha.-methylbenzyl)-3-methylphenol-2-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-2-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-2-sulfon 
ic acid, 4-(1,3-diphenylbutyl)-3-methylphenol-2-sulfonic acid, 
4,6-(.alpha.-methylbenzyl)-3-methylphenol-2-sulfonic acid, 
4,6-di(.alpha.,.alpha.-dimethylbenzyl)-3-methylphenol-2-sulfonic acid, 
4,6-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-2-su 
lfonic acid, 4,6-di(1,3-diphenylbutyl)-3-methylphenol-2-sulfonic acid, 
6-(1,3-diphenylbutyl)-3-methylphenol-2,4-disulfonic acid and 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-3-methylphenol-2,6-disu 
lfonic acid; sulfonated 2-ethylphenols such as 2-ethylphenol-4-sulfonic 
acid, 2-ethylphenol-6-sulfonic acid and 2-ethylphenyl-4,6-disulfonic acid; 
styrene-substituted sulfonated 2-ethylphenols such as 
6-(.alpha.-methylbenzyl)-2-ethylphenol-4-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-2-ethylphenol-4-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2-ethylphenol-4-sulfoni 
c acid, 6-(1,3-diphenylbutyl)-2-ethylphenol-4-sulfonic acid, 
4-(.alpha.-methylbenzyl)-2-ethylphenol-6-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-2-ethylphenol-6-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2-ethylphenol-6-sulfoni 
c acid and 4-(1,3-diphenylbutyl)-2-ethylphenol-6-sulfonic acid; sulfonated 
4-isopropylphenols such as 4-isopropylphenol-2-sulfonic acid and 
4-isopropylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
4-isopropylphenols such as 
2-(.alpha.-methylbenzyl)-4-isopropylphenol-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-4-isopropylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4-isopropylphenol-6-sul 
fonic acid and 2-(1,3-diphenylbutyl)-4-isopropylphenol-6-sulfonic acid; 
sulfonated 4-tert-butylphenols such as 4-tert-butylphenol-2-sulfonic acid 
and 4-tert-butylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
4-tert-butylphenols such as 
2-(.alpha.-methylbenzyl)-4-tert-butylphenol-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-4-tert-butylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4-tert-butylphenol-6-su 
lfonic and 2-(1.,3-diphenylbutyl)-4-tert-butylphenol-6-sulfonic acid; 
sulfonated 4-cyclohexylphenols such as 4-cyclohexylphenol-2-sulfonic acid, 
4-cyclohexylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
4-cyclohexylphenols such as 
2-(.alpha.-methylbenzyl)-4-cyclohexylphenol-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-4-cyclohexylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4-cyclohexylphenol-6-su 
lfonic acid and 2-(1,3-diphenylbutyl)-4-cyclohexylphenol-6-sulfonic acid; 
sulfonated 4-tert-octylphenols such as 4-tert-octylphenol-2-sulfonic acid 
and 4-tert-octylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
4-tert-octylphenols such as 
2-(.alpha.-methylbenzyl)-4-tert-octylphenol-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-4-tert-octylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4-tert-octylphenol-6-su 
lfonic acid and 2-(1,3-diphenylbutyl)-4-tert-octylphenol-6-sulfonic acid; 
sulfonated 4-nonylphenols such as 4-nonylphenol-2-sulfonic acid and 
4-nonylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
4-nonylphenols such as 2-(.alpha.-methylbenzyl)-4-nonylphenol-6-sulfonic 
acid, 2-(.alpha.,.alpha.-dimethylbenzyl)-4-nonylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4-nonylphenol-6-sulfoni 
c acid and 2-(1,3-diphenylbutyl)-4-nonylphenol-6-sulfonic acid; sulfonated 
4-decylphenols such as 4-decylphenol-2-sulfonic acid and 
4-decylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
4-decylphenols such as 2-(.alpha.-methylbenzyl)-4-decylphenol-6-sulfonic 
acid, 2-(.alpha.,.alpha.-dimethylbenzyl)-4-decylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4-decylphenol-6-sulfoni 
c acid and 2-(1,3-diphenylbutyl)-4-decylphenol-6-sulfonic acid; sulfonated 
cumylphenols such as 2,4-xylenol-6-sulfonic acid, 
2,4-di-tert-butylphenol-6-sulfonic acid, 2-methyl-4-nonylphenol-6-sulfonic 
acid, cumylphenol-2-sulfonic acid and cumylphenol-2,6-disulfonic acid; 
styrene-substituted sulfonated cumylphenols such as 
2-(.alpha.-methylbenzyl)-cumylphenol-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-cumylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-cumylphenol-6-sulfonic 
acid and 2-(1,3-diphenylbutyl)cumylphenol-6-sulfonic acid; sulfonated 
4-benzylphenols such as 4-benzylphenol-2-sulfonic acid and 
4-benzylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
4-benzylphenols such as 2-(.alpha.-methylbenzyl)-4-benzylphenol-6-sulfonic 
acid, 2-(.alpha.,.alpha.-dimethylbenzyl)-4-benzylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4-benzylphenol-6-sulfon 
ic acid and 2-(1,3-diphenylbutyl)-4-benzylphenol-6-sulfonic acid; 
sulfonated phenylethylphenols such as phenylethylphenol-2-sulfonic acid 
and phenylethylphenol-2,6-disulfonic acid; styrene-substituted sulfonated 
phenylethylphenols such as 
2-(.alpha.-methylbenzyl)-phenylethylphenol-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)phenylethylphenol-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-phenylethylphenol-6-sul 
fonic acid and 2-(1,3-diphenylbutyl)-phenylethylphenol-6-sulfonic acid; 
sulfonated bisphenol As such as 2,4-dimethylbenzylphenol-6-sulfonic acid, 
bisphenol A-2-sulfonic acid, bisphenol A-6-sulfonic acid, bisphenol 
A-2,6-disulfonic acid, bisphenol A-2,2'-disulfonic acid, bisphenol 
A-2,6'-disulfonic acid, bisphenol A-2,2',6-trisulfonic acid and bisphenol 
A-2,2',6,6'-tetrasulfonic acid; styrene-substituted sulfonated bisphenol 
A's such as 6-(.alpha.-methylbenzyl)-bisphenol A-2-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol A-2-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-bisphenol A-2-sulfonic 
acid, 6-(1,3-diphenylbutyl)-bisphenol A-2-sulfonic acid, 
2'-(.alpha.-methylbenzyl)-bisphenol A-2-sulfonic acid, 
2'-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol A-2-sulfonic acid, 
2'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzylbisphenol A-2-sulfonic 
acid, 2'-(1,3-diphenylbutyl)bisphenol A-2-sulfonic acid, 
6'-.alpha.-methylbenzylbisphenol A-2-sulfonic acid, 
6'-(.alpha.,.alpha.-dimethylbenzyl)bisphenol A-2-sulfonic acid, 
6'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl-bisphenol A-2-sulfonic 
acid, 6'-(1,3-diphenylbutyl)-bisphenol A-2-sulfonic acid, 
6,6'-di(.alpha.-methylbenzyl)bisphenol A-2-sulfonic acid, 
2',6-di(.alpha.,.alpha.-dimethylbenzyl)-bisphenol A-2-sulfonic acid, 
6-(.alpha.-methylbenzyl)-6'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzy 
l]-bisphenol A-2-sulfonic acid, 
6-(1,3-diphenylbutyl)-2'-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol 
A-2-sulfonic acid and 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]bisphenol 
A-2,6'-disulfonic acid; sulfonated bisphenol B's such as bisphenol 
B-2-sulfonic acid, bisphenol B-6-sulfonic acid, bisphenol B-2,6-disulfonic 
acid, bisphenol B-2,2'-disulfonic acid, bisphenol B-2,6'-disulfonic acid, 
bisphenol B-2,2',6-trisulfonic acid and bisphenol 
B-2,2',6,6'-tetrasulfonic acid; styrene-substituted sulfonated bisphenol 
B's such as 6-(.alpha.-methylbenzyl)bisphenol B-2-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)bisphenol B-2-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-bisphenol B-2-sulfonic 
acid, 6-(1,3-diphenylbutyl)-bisphenol B-2-sulfonic acid, 
2'-.alpha.-methylbenzyl-bisphenol B-2-sulfonic acid, 
2'-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol B-2-sulfonic acid, 
2'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-bisphenol B-2-sulfonic 
acid, 2'-(1,3-diphenylbutyl)-bisphenol B-2-sulfonic acid, 
6'-.alpha.-methylbenzyl-bisphenol B-2-sulfonic acid, 
6'-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol B-2-sulfonic acid, 
6'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl-bisphenol B-2-sulfonic 
acid, 6'-(1,3-diphenylbutyl)-bisphenol B-2-sulfonic acid, 
6,6'-.alpha.-methylbenzyl-bisphenol B-2-sulfonic acid, 
2',6-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol B-2-sulfonic acid, 
6-(.alpha.-methylbenzyl)-6'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzy 
l]-bisphenol B-2-sulfonic acid, 
6-(1,3-diphenylbutyl)-2'-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol 
B-2-sulfonic acid and 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]bisphenol 
B-2,6'-disulfonic acid; sulfonated bisphenol F's such as bisphenol 
F-2-sulfonic acid, bisphenol F-6-sulfonic acid, bisphenol F-2,6-disulfonic 
acid, bisphenol F-2,2'-disulfonic acid, bisphenol F-2,6'-disulfonic acid, 
bisphenol F-2,2',6-trisulfonic acid and bisphenol 
F-2,2',6,6'-tetrasulfonic acid; styrene-substituted sulfonated bisphenol 
F's such as 6-(.alpha.-methylbenzyl)-bisphenol F-2-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol F-2-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-bisphenol F-2-sulfonic 
acid, 6-(1,3-diphenylbutyl)-bisphenol F-2-sulfonic acid, 
2'-(.alpha.-methylbenzyl)-bisphenol F-2-sulfonic acid, 
2'-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol F-2-sulfonic acid, 
2'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-bisphenol F-2-sulfonic 
acid, 2'-(1,3-diphenylbutyl)bisphenol F-2-sulfonic acid, 
6'-.alpha.-methylbenzylbisphenol F-2-sulfonic acid, 
6'-(.alpha.,.alpha.-dimethylbenzyl)bisphenol F-2-sulfonic acid, 
6'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-bisphenol F-2-sulfonic 
acid, 6'-(1,3-diphenylbutyl)-bisphenol F-2-sulfonic acid, 
6,6'-.alpha.-methylbenzyl-bisphenol F-2-sulfonic acid, 
2',6-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol F-2-sulfonic acid, 
6-(.alpha.-methylbenzyl)-6'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzy 
l]-bisphenol F-2-sulfonic acid, 
6-(1,3-diphenylbutyl)-2'-(.alpha.,.alpha.-dimethylbenzyl)-bisphenol 
F-2-sulfonic acid and 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]bisphenol 
F-2,6'-disulfonic acid; sulfonated 4,4'-dihydroxy-diphenyls such as 
4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
4,4'-dihydroxy-diphenyl-5-sulfonic acid, 
4,4'-dihydroxy-diphenyl-3,5-disulfonic acid, 
4,4'-dihydroxy-diphenyl-3,3'-disulfonic acid, 
4,4,-dihydroxy-diphenyl-3,5'-disulfonic acid, 
4,4'-dihydroxy-diphenyl,3,3',5-trisulfonic acid and 
4,4'-dihydroxy-diphenyl-3,3',5,5'-tetrasulfonic acid; styrene-substituted 
sulfonated 4,4'-dihydroxy-diphenyls such as 
5-(.alpha.-methylbenzyl)-4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5-(.alpha.,.alpha.-dimethylbenzyl)-4,4'-dihydroxy-diphenyl-3-sulfonic 
acid, 5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4,4'-dihydroxy-di 
phenyl-3-sulfonic acid, 
5-(1,3-diphenylbutyl)-4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
3'-(.alpha.-methylbenzyl)-4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
3'-(.alpha.,.alpha.-dimethylbenzyl)-4,4'-dihydroxy-diphenyl-3-sulfonic 
acid, 
3'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4,4'-dihydroxy-dipheny 
l-3-sulfonic acid, 
3'-(1,3-diphenylbutyl)-4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5'-(.alpha.-methylbenzyl)-4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5'-(.alpha.,.alpha.-dimethylbenzyl)-4,4'-dihydroxy-diphenyl-3-sulfonic 
acid, 
5'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)-benzyl]-4,4'-dihydroxy-diphen 
yl-3-sulfonic acid, 
5'-(1,3-diphenylbutyl)-4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5,5'-(.alpha.-methylbenzyl)-4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
3',5-(.alpha.,.alpha.-dimethylbenzyl)-4,4'-dihydroxy-diphenyl-3-sulfonic 
acid, 
5-(.alpha.-methylbenzyl)-5'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzy 
l]-4,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5-(1,3-diphenylbutyl)-3'-(.alpha.,.alpha.-dimethylbenzyl)-4,4'-dihydroxy-d 
iphenyl-2-sulfonic acid and 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4,4'-dihydroxy-diphenyl 
-3,5'-sulfonic acid; sulfonated 2,4'-dihydroxy-diphenyls such as 
2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
2,4'-dihydroxy-diphenyl-5-sulfonic acid, 
2,4'-dihydroxy-diphenyl-3'-sulfonic acid, 
2,4'-dihydroxy-diphenyl-5'-sulfonic acid, 
2,4'-dihydroxy-diphenyl-3,5-disulfonic acid, 
2,4'-dihydroxy-diphenyl-3,3'-disulfonic acid, 
2,4'-dihydroxy-diphenyl-3,5'-disulfonic acid, 
2,4'-dihydroxy-diphenyl-3,5,5'-trisulfonic acid and 
2,4'-dihydroxy-diphenyl-3,3',5,5'-tetrasulfonic acid; styrene-substituted 
sulfonated 2,4'-dihydroxy-diphenyls such as 
5-(.alpha.-methylbenzyl)-2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5-(.alpha.,.alpha.-dimethylbenzyl)-2,4'-dihydroxy-diphenyl-3-sulfonic 
acid, 5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,4'-dihydroxy-di 
phenyl-3-sulfonic acid, 
5-(1,3-diphenylbutyl)-2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
3'-(.alpha.-methylbenzyl)-2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
3'-(.alpha.,.alpha.-dimethylbenzyl)-2,4'-dihydroxy-diphenyl-3-sulfonic 
acid, 
3'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,4'-dihydroxy-dipheny 
l-3-sulfonic acid, 
3'-(1,3-diphenylbutyl)-2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5'-(.alpha.-methylbenzyl)-2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5'-(.alpha.,.alpha.-dimethylbenzyl)-2,4'-dihydroxy-diphenyl-3-sulfonic 
acid, 
5'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)-benzyl]-2,4'-dihydroxy-diphen 
yl-3-sulfonic acid, 
5'-(1,3-diphenylbutyl)-2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5,5'-(.alpha.-methylbenzyl)-2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
3',5-(.alpha.,.alpha.-dimethylbenzyl)-2,4'-dihydroxy-diphenyl-3-sulfonic 
acid, 
5-(.alpha.-methylbenzyl)-5'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzy 
l]-2,4'-dihydroxy-diphenyl-3-sulfonic acid, 
5-(1,3-diphenylbutyl)-3'-(.alpha.,.alpha.-dimethylbenzyl)-2,4'-dihydroxy-d 
iphenyl-2-sulfonic acid, 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,4'-dihydroxy-diphenyl 
-3,5'-sulfonic acid and 
3,5-(.alpha.,.alpha.-dimethylbenzyl)-2,4'-dihydroxy-diphenyl-3,5'-sulfonic 
acid; sulfonated 2,2'-dihydroxy-diphenyls such as 
2,2'-dihydroxy-diphenyl-3-sulfonic acid, 
2,2'-dihydroxy-diphenyl-5-sulfonic acid, 
2,2'-dihydroxy-diphenyl-3'-sulfonic acid, 
2,2'-dihydroxy-diphenyl-5'-sulfonic acid, 
2,2'-dihydroxy-diphenyl-3,5-disulfonic acid, 
2,2'-dihydroxy-diphenyl-3,3'-disulfonic acid, 
2,2'-dihydroxy-diphenyl-5,5'-disulfonic acid, 
2,2'-dihydroxy-diphenyl-3,5'-disulfonic acid, 
2,2'-dihydroxy-diphenyl-3,5,5'-trisulfonic acid and 
2,2'-dihydroxy-diphenyl-3,3',5,5'-tetrasulfonic acid; styrene-substituted 
sulfonated 2,2'-dihydroxy-diphenyls such as 
5-(.alpha.-methylbenzyl)-2,2'-dihydroxy-diphenyl-3-sulfonic acid, 
5-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-diphenyl-3'-sulfonic 
acid, 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,2'-dihydroxy-diphenyl 
-5'-sulfonic acid, 
5-(1,3-diphenylbutyl)-2,2'-dihydroxy-diphenyl-5',3-sulfonic acid, 
3'-(.alpha.-methylbenzyl)-2,2'-dihydroxy-diphenyl-5-sulfonic acid, 
3'-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-diphenyl-5-sulfonic 
acid, 
3'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,2'-dihydroxy-dipheny 
l-5'-sulfonic acid, 
3'-(1,3-diphenylbutyl)-2,2'-dihydroxy-diphenyl-5-sulfonic acid, 
5'-(.alpha.-methylbenzyl)-2,2'-dihydroxy-diphenyl-5-sulfonic acid, 
5'-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-diphenyl-5-sulfonic 
acid, 
5'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,2'-dihydroxy-dipheny 
l-5-sulfonic acid, 
5'-(1,3-diphenylbutyl)-2,2'-dihydroxy-diphenyl-5-sulfonic acid, 
5,5'-(.alpha.-methylbenzyl)-2,2'-dihydroxy-diphenyl-3-sulfonic acid, 
3',5-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-diphenyl-5'-sulfonic 
acid, 
5-(.alpha.-methylbenzyl)-5'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzy 
l]-2,2'-dihydroxy-diphenyl-3-sulfonic acid, 
5-(1,3-diphenylbutyl)-3'-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-d 
iphenyl-5'-sulfonic acid, 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,2'-dihydroxy-diphenyl 
-3,5'-disulfonic acid and 
3,5-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-diphenyl-3,5'-disulfon 
ic acid; sulfonated 4,4'-dihydroxy-3,3'-dipropyl-diphenyls such as 
4,4'-dihydroxy-3,3'-dipropyl-diphenyl-5-sulfonic acid, 
4,4'-dihydroxy-3,3'-dipropyl-diphenyl-5'-sulfonic acid and 
4,4'-dihydroxy-3,3'-dipropyl-diphenyl-5,5'-disulfonic acid; 
styrene-substituted sulfonated 4,4'-dihydroxy-3,3'-dipropyl-diphenyls such 
as 
5-(.alpha.-methylbenzyl)-4,4'-dihydroxy-3,3'-dipropyl-diphenyl-5'-sulfonic 
acid, 
5-(.alpha.,.alpha.-dimethylbenzyl)-.alpha.,.alpha.-dimethylbenzyl-diphenyl 
-5'-sulfonic acid, 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-4,4'-dihydroxy-3,3'-dip 
ropyl-diphenyl-5'-sulfonic acid, 
5-(1,3-diphenylbutyl)-4,4'-dihydroxy-3,3'-dipropyl-diphenyl-5'-sulfonic 
acid, 
5'-(.alpha.-methylbenzyl)-4,4'-dihydroxy-3,3'-dipropyl-diphenyl-5-sulfonic 
acid, 
5'-(.alpha.,.alpha.-dimethylbenzyl)-4,4'-dihydroxy-3,3'-dipropyl-diphenyl- 
5-sulfonic acid, 
5'-[.alpha.-methyl-4'-(.alpha.-methyl-benzyl)benzyl]-4,4'-dihydroxy-3,3'-d 
ipropyl-diphenyl-5-sulfonic acid and 
5'-(1,3-diphenylbutyl)-4,4'-dihydroxy-3,3'-dipropyl-diphenyl-5-sulfonic 
acid; sulfonated 2,2'-dihydroxy-6,6'-dimethyl-diphenyls such as 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3-sulfonic acid, 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-5-sulfonic acid, 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3'-sulfonic acid, 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-5'-sulfonic acid, 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3,5-disulfonic acid, 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3,3'-disulfonic acid, 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-5,5'-disulfonic acid, 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3,5'-disulfonic acid, 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3,5,5'-trisulfonic acid and 
2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3,3',5,5,-tetrasulfonic acid; 
styrene-substituted sulfonated 2,2'-dihydroxy-6,6'-dimethyl-diphenyls such 
as 
5-(.alpha.-methylbenzyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3-sulfonic 
acid, 
5-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3 
'-sulfonic acid, 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,2'-dihydroxy-6,6,-dim 
ethyl-diphenyl-5'-sulfonic acid, 
5-(1,3-diphenylbutyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl-5',3-sulfonic 
acid, 
3'-(.alpha.-methylbenzyl)-2,2'-dihydroxy-6,6,-dimethyl-diphenyl-5-sulfonic 
acid, 
3'-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl- 
5-sulfonic acid, 
3'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,2'-dihydroxy-6,6'-di 
methyl-diphenyl-5'-sulfonic acid, 
3'-(1,3-diphenylbutyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl-5-sulfonic 
acid, 
5'-(.alpha.-methylbenzyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl-5-sulfonic 
acid, 
5'-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl- 
5-sulfonic acid, 
5'-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,2'-dihydroxy-6,6'-di 
methyl-diphenyl-3-sulfonic acid, 
5'-(1,3-diphenylbutyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl-5-sulfonic 
acid, 
5,5'-(.alpha.-methylbenzyl)-2,2'-dihydroxy-6,6'-dimethyl-diphenyl-3-sulfon 
ic acid, 
3',5-(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-6,6'-dimethyl-dipheny 
l-5'-sulfonic acid, 
5-(.alpha.-methylbenzyl)-5'-[.alpha.-methyl-4'-(methylbenzyl)benzyl]-2,2'- 
dihydroxy-6,6'-dimethyl-diphenyl-3-sulfonic acid, 
5-(1,3-diphenylbutyl)-3'-(.alpha.,.alpha.-dimethylbenzyl)-2,2,-dihydroxy-6 
,6'-dimethyl-diphenyl-5'-sulfonic acid, 
5-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-2,2'-dihydroxy-6,6'-dim 
ethyl-diphenyl-3,5'-disulfonic acid and 
3,5-di(.alpha.,.alpha.-dimethylbenzyl)-2,2'-dihydroxy-6,6'-dimethyl-diphen 
yl-3',5'-disulfonic acid; sulfonated catechols such as catechol-4-sulfonic 
acid, catechol-6-sulfonic acid and catechol-4,6-disulfonic acid; 
styrene-substituted sulfonated catechols such as 
6-(.alpha.-methylbenzyl)-catechol-4-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-catechol-4-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-catechol-4-sulfonic 
acid, 6-(1,3-diphenylbutyl)-catechol-4-sulfonic acid, 
4-(.alpha.-methylbenzyl)-catechol-6-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-catechol-6-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-catechol-6-sulfuric 
acid, and 4-(1,3-diphenylbutyl)-catechol-6-sulfonic acid; sulfonated 
resorcins such as resorcin-2-sulfonic acid, resorcin-4-sulfonic acid, 
resorcin-6-sulfonic acid, resorcin-2,4-disulfonic acid, 
resorcin-2,6-disulfonic acid and resorcin-4,6-disulfonic acid; 
styrene-substituted sulfonated resorcins such as 
6-(.alpha.-methylbenzyl)-resorcin-4-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-resorcin-4-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-resorcin-4-sulfonic 
acid, 6-(1,3-diphenylbutyl)-resorcin-4-sulfonic acid, 
2-(.alpha.-methylbenzyl)-resorcin-4-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-resorcin-4-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]resorcin-4-sulfonic 
acid, 2-(1,3-diphenylbutyl)-resorcin-4-sulfonic acid, 
2,6-di(.alpha.-methylbenzyl)-resorcin-4-sulfonic acid, 
2,6-di(.alpha.,.alpha.-dimethylbenzyl)-resorcin-4-sulfonic acid, 
2,6-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-resorcin-4-sulfonic 
acid, 2,6-di(1,3-diphenylbutyl)-resorcin-4-sulfonic acid, 
4-(.alpha.-methylbenzyl)-resorcin-6-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-resorcin-6-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-resorcin-6-sulfonic 
acid, 4-(1,3-diphenylbutyl)-resorcin-6-sulfonic acid, 
2-(.alpha.-methylbenzyl)-resorcin-6-sulfonic acid, 
2-(.alpha.,.alpha.-dimethylbenzyl)-resorcin-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-resorcin-6-sulfonic 
acid, 2-(1,3-diphenylbutyl)-resorcin-6-sulfonic acid, 
2,4-di(.alpha.-methylbenzyl)-resorcin-6-sulfonic acid, 
2,4-di(.alpha.,.alpha.-dimethylbenzyl)-resorcin-6-sulfonic acid, 
2,4-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-resorcin-6-sulfonic 
acid, 2,4-di(1,3-diphenylbutyl)-resorcin-6-sulfonic acid, 
6-(.alpha.-methylbenzyl)-resorcin-2-sulfonic acid, 
6-(.alpha.,.alpha.-dimethylbenzyl)-resorcin-2-sulfonic acid, 
6-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-resorcin-2-sulfonic, 
6-(1,3-diphenylbutyl)-resorcin-2-sulfonic acid, 
4-(.alpha.-methylbenzyl)-resorcin-2-sulfonic acid, 
4-(.alpha.,.alpha.-dimethylbenzyl)-resorcin-2-sulfonic acid, 
4-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-resorcin-2-sulfonic 
acid, 4-(1,3-diphenylbutyl)-resorcin-2-sulfonic acid, 
4,6-di(.alpha.-methylbenzyl)-resorcin-2-sulfonic acid, 
4,6-di(.alpha.,.alpha.-dimethylbenzyl)-resorcin-2-sulfonic acid, 
4,6-di[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-resorcin-2-sulfonic 
acid and 4,6-di(1,3-diphenylbutyl)-resorcin-2-sulfonic acid; sulfonated 
hydroquinones such as hydroquinone-2-sulfonic acid and 
hydroquinone-2,6-disulfonic acid; styrene-substituted sulfonated 
hydroquinones such as 2-(.alpha.-methylbenzyl)-hydroquinone-6-sulfonic 
acid, 2-(.alpha.,.alpha.-dimethylbenzyl)-hydroquinone-6-sulfonic acid, 
2-[.alpha.-methyl-4'-(.alpha.-methylbenzyl)benzyl]-hydroquinone-6-sulfonic 
acid and 2-(1,3-diphenylbutyl)-hydroquinone-6-sulfonic acid; 
2,6-dihydroxytoluene-4-sulfonic acid; 2-methylhydroquinone-6-sulfonic 
acid; 6-tert-butyl-catechol-4-sulfonic acid; 
2-tert-butylhydroquinone-6-sulfonic acid; 2-octylhydroquinone-6-sulfonic 
acid; 2-tridecylhydroquinone-6-sulfonic acid; and 
2-pentadecylhydroquinone-6-sulfonic acid. The sulfonated phenol, however, 
should not be limited thereto. These sulfonated phenols can be used either 
singly or in combination. 
Preferred examples include styrene-substituted sulfonated phenols which 
have each been obtained by reacting 1 to 10 moles of the corresponding 
styrene with 1 mole of the corresponding sulfonated phenol. 
Examples of the metal, which forms the metal salt of the sulfonated phenol 
and is useful in the present invention, include monovalent to tetravalent 
metals such as sodium, potassium, zinc, calcium, magnesium, barium, lead, 
aluminum, zirconium, vanadium, and tin. 
Illustrative of the phenol usable in the present invention include, in 
addition to phenol, such phenol derivatives will be described next. 
Specific examples include, but are not limited to, phenylphenols such as 
o-phenylphenol, m-phenylphenol and p-phenylphenol; alkyl- and 
aralkyl-phenols such as m-cresol, o-ethylphenol, p-isopropylphenol, 
p-tert-butylphenol, p-cyclohexylphenol, p-tert-octylphenol, nonylphenol, 
p-decylphenol, 2,4-xylenol, 2,4-di-tert-butylphenol, 
2-methyl-4-nonylphenol, cumylphenol, p-benzylphenol, phenylethylphenol and 
2,4-dimethylbenzylphenol; and diphenols and polyphenols such as bisphenol 
A, bisphenol B, bisphenol F, 4,4'-dihydroxy-diphenyl, 
2,4'-dihydroxydiphenyl, 2,2'-dihydroxy-diphenyl, 
4,4'-dihydroxy-3,3'-dipropyl-diphenyl, 
2,2'-dihydroxy-6,6'-dimethyldiphenyl, catechol, resorcin, hydroquinone, 
2,6-dihydroxytoluene, 2-methylhydroquinone, tert-butylcatechol, 
2-tert-butylhydroquinone, 2-octylhydroquinone, 2-tridecylhydroquinone, 
2-pentadecylhydroquinone, 2,5-dibutylhydroquinone, 
2,6-ditridecylhydroquinone, 2,3,6-trimethylhydroquinone, 
1,2,3-trihydroxybenzene, and 1,3,5-trihydroxybenzene. These phenols can be 
used either singly or in combination. 
Examples of the salicylic acid usable in the present invention include, but 
are not limited to, salicylic acid, 3-methylsalicylic acid, 
4-methylsalicylic acid, 5-methylsalicylic acid, 3-n-butylsalicylic acid, 
6-methylsalicylic acid, 5-isopropylsalicylic acid, 4-n-pentylsalicylic 
acid, 5-cyclohexylsalicylic acid, 5-n-octylsalicylic acid, 
5-tert-octylsalicylic acid, 5-nonylsalicylic acid, 4-n-dodecylsalicylic 
acid, 4-methoxysalicylic acid, 6-methoxysalicylic acid, 5-ethoxysalicylic 
acid, 6-isopropoxysalicylic acid, 4-n-hexyloxysalicylic acid, 
4-n-decyloxysalicylic acid, 5-fluorosalicylic acid, 3-chlorosalicylic 
acid, 4-chlorosalicylic acid, 5-chlorosalicylic acid and 5-bromosalicylic 
acid. In the process of the present invention, these salicylic acids can 
also be used in the form of their esters, although a hydrolysis process 
becomes necessary. These salicylic acids can be used either singly or in 
combination. Preferred are salicylic acid and alkyl-substituted salicylic 
acids such as 3-methylsalicylic acid. 
As a production process of the color-developing agent according to the 
present invention, it may be mentioned, for example, to mix the 
multivalent metal salt of the salicylic acid derivative and the sulfonated 
phenol and/or the metal salt thereof as solutions or melts after 
separately synthesizing them by methods known per se in the art. 
Where the salicylic acid derivative is a styrene-substituted salicylic acid 
derivative, the color-developing agent can be produced, for example, by 
reacting the corresponding styrene with the corresponding salicylic acid 
and phenol in the presence of sulfuric acid as a catalyst and sulfonating 
agent to obtain a resin and then reacting the corresponding multivalent 
metal salt with the resin. This process permits easy production under mild 
conditions and is hence preferred especially from the industrial 
viewpoint. Therefore the present invention also include, for example, the 
following processes: 
(1) A process for the production of a color-developing agent comprising a 
multivalent metal salt of a styrene-substituted salicylic acid derivative 
and a styrene-substituted sulfonated phenol and/or a metal salt thereof, 
which comprises reacting a styrene with a salicylic acid and a phenol in 
the presence of sulfuric acid to obtain a resin and then reacting a 
multivalent metal compound with the resin (hereinafter called the 
"one-step process"). 
(2) A process as described above under (1), wherein the phenol is used in 
an amount of 0.5 to 40 mole % based on the salicylic acid. 
(3) A process as described above under (1), wherein the styrene is used in 
an amount 1 to 10 molar times as much as the phenol and salicylic acid. 
In the above one-step process, the phenol is used preferably in an amount 
of 0.5 to 40 mole %, with 1 to 30 mole % being particularly preferred, on 
the basis of the salicylic acid. The range of from 0.5 to 40 mole % is 
excellent in both initial and ultimate color-producing capacities. 
Although no particular limitation is imposed on the amount of the styrene 
to be used, the styrene can be used in an amount, preferably about 1 to 10 
molar times, more preferably about 1.5 to 8 molar times, most preferably 
about 2 to 6 molar times as much as the phenol and salicylic acid. 
The sulfuric acid employed in the one-step process of the present invention 
serves as a reaction catalyst for the salicylic acid and the styrene and 
also for the phenol and the styrene and also as a sulfonating agent for 
the phenol. The sulfuric acid can be used in an amount at least equimolar 
to, more preferably of from 100 to 200 mole % based on the phenol and also 
of from 10 to 200 wt. %, more preferably from 20 to 100 wt. % based on the 
salicylic acid. Further, the concentration of the sulfuric acid may 
preferably be at least about 90 wt. %, with 97 wt. % or higher being 
particularly preferred. Fuming sulfuric acid can be used in combination. 
The one-step process can be carried out in the presence of an organic 
solvent although use of such an organic solvent is not essential. Any 
organic solvent can be used as desired insofar as it is inert to the 
reactions. Illustrative of the organic solvent include, but are not 
limited to, hydrocarbon solvents such as hexane, octane, decane, 
cyclohexane, benzene, toluene and xylene; and halogenated hydrocarbon 
solvents such as dichloromethane, 1,2-dichloroethane, tetrachloromethane, 
1,1-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 
chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, 
1,2,4-trichlorobenzene, o-chlorotoluene, m-chlorotoluene and 
p-chlorotoluene. These solvents can be used either singly or in 
combination. 
Although no particular limitation is imposed on the amount of the organic 
solvent to be used, its use in a large amount itself merely leads to 
reduced work efficiency and production efficiency. In general, the organic 
solvent can be used preferably in an amount 100 or smaller (volume/weight) 
times as much as the weight of the salicylic acid and the phenol. 
The styrene can be fed either continuously or intermittently at plural 
stages by conventional means or device (for example, one of various 
continuous dropping devices and various fixed displacement pumps). 
Needless to say, any other modified method can of course be used insofar 
as it can be practiced from the standpoint of process engineering can be 
used. 
Upon feeding the styrene, the styrene can be fed as is or as a solution in 
the organic solvent mentioned above. 
When the styrene is added to the salicylic acid and the phenol in the 
presence of sulfuric acid, the styrene can be fed at such a feeding rate 
that its feeding can be completed in about 0.5 to about 15 hours, 
preferably about 1 to about 10 hours, although no particular limitation is 
imposed thereon. 
Upon practice of the one-step process according to the present invention, 
the reaction temperature is preferably lower than 60.degree. C. but not 
lower than -20.degree. C., with 10.degree. to 50.degree. C. being more 
preferred. 
When the reaction temperature is lower than 60.degree. C. but not lower 
than -20.degree. C., the resulting color-developing agent can be easily 
converted into fine particles upon dispersion and after the dispersion, 
the water dispersion has excellent stability. Although the above reaction 
can be practiced under atmospheric pressure, it can also be practiced 
under either a reduced pressure or an elevated pressure. 
The resin, which has been obtained by reacting the styrene to the salicylic 
acid and the phenol in the presence of sulfuric acid as described above, 
can be used in the subsequent reaction with the multivalent metal compound 
either after taking it out of the reaction system by a method known per se 
in the art or continuously without taking it out of the reaction system. 
The reaction with the multivalent metal compound is similar to the 
reaction in the above-mentioned production process of the multivalent 
metal salt of the salicylic acid derivative. 
Upon practice of the present invention, it is also possible to charge 
sulfuric acid, the phenol and, if desired, an organic solvent in 
predetermined amounts in a reaction vessel, to add a predetermined amount 
of the styrene to the resultant mixture, to add a predetermined amount of 
the salicylic acid to the reaction mixture from the first step, and then 
to add a predetermined amount of styrene. Namely, the present invention 
also provides the following processes: 
(1) A process for the production of a color-developing agent comprising a 
multivalent metal salt of a styrene-substituted salicylic acid derivative 
and a styrene-substituted sulfonated phenol or a metal salt thereof, which 
comprises conducting a first-stage reaction of reacting a phenol and a 
styrene in the presence of sulfuric acid and then a second-stage reaction 
of adding, to the resulting reaction mixture, a salicylic acid and then 
the styrene to obtain a resin, followed by the reaction of the resin with 
a multivalent metal salt (hereinafter called the "two-step process"). 
(2) A process as described above under (1), wherein the phenol is used in 
an amount of 0.5 to 40 mole % based on the salicylic acid used in the 
second stage reaction. 
(3) A process as described above under (1), wherein the styrene used in the 
first-stage reaction is in an amount 1 to 10 molar times as much as the 
phenol. 
(4) A process as described above under (1), wherein the total amount of the 
styrene used in the first-stage and second-stage reactions is 1 to 15 
times as much as that of the phenol and salicylic acid. 
Although no particular limitation is imposed on the amount of the styrene 
to be employed in the two-step process, it can be used in the first-stage 
reaction in an amount preferably about 1 to 10 molar times, more 
preferably about 1.5 to 8 molar times, most preferably about 2 to 6 molar 
times as much as the phenol in view of balancing of various physical 
properties such as color-producing ability, waterproofness and light 
fastness. Based on the total amount of the phenol and the salicylic acid, 
its amount is preferably from about 1 to 15 molar times, more preferably 
from about 1.5 to 8 times. 
In this two-step process, sulfuric acid serves as a sulfonating agent for 
the phenol and also as a reaction catalyst for the phenol and the styrene 
in the first-stage reaction, and acts as a reaction catalyst for the 
salicylic acid and the styrene and also for the reaction product of the 
first-stage reaction and the styrene. The amount and concentration of 
sulfuric acid are similar to the corresponding conditions for the 
single-step process. The two-step process can be practiced in the presence 
of an organic solvent although use of such an organic solvent is not 
essential. The kind and amount of the organic solvent are similar to the 
corresponding conditions for the single-step process. 
The reaction temperature is similar to the corresponding condition for the 
single-step process in both the first-stage and second-stage reactions. As 
has been described above, the resin obtained in accordance with the 
two-step process can be taken out of the reaction system by a method known 
per se in the art. Alternatively, the resin can be provided, as is, for 
the subsequent reaction with the multivalent metal compound without taking 
it out of the reaction system. The reaction with the multivalent metal 
compound is similar to the above-described process for the preparation of 
the multivalent metal salt of the salicylic acid derivative. 
Upon feeding the styrene to the phenol in the presence of sulfuric acid in 
the first-stage reaction, no particular limitation is imposed on the 
feeding rate. It is however preferred to feed the styrene at such a rate 
that its feeding can be completed in about 0.2 to about 15 hours, more 
preferably in about 0.5 to about 5 hours. Upon feeding the styrene 
subsequent to the charging of the salicylic acid in the second-stage 
reaction, no particular limitation is imposed either on its feeding rate, 
although the styrene can preferably be fed at such a rate that its feeding 
can be completed in about 0.5 to about 15 hours, more preferably in about 
1 to about 10 hours. Further, the styrene can be fed in a manner and form 
similar to those in the single-step process in both the first-stage and 
second-stage reactions. 
In the production of the color-developing sheet according to the present 
invention, the color-developing agent according to the present invention 
can be used, to an extent not preventing desired effects of the present 
invention, in combination with a salicylic acid derivative and/or a 
sulfonated phenol synthesized separately and also with one or more known 
color-developing agents, for example, acid clay minerals such as acid 
clay, activated clay, attapulgite and bentonite, phenol resins such as 
phenol-formaldehyde resins and phenol-salicylic acid-formaldehyde resins, 
and metal salts, such as the zinc salts, of aromatic carboxylic acids such 
as phthalic acid and salicylic acid. Upon preparation of a dispersion of 
the color-developing agent, a known dispersing method can be applied. For 
example, the color-developing agent can be ground and dispersed to 
particle sizes of usually 3 .mu.m or smaller, preferably 2 .mu.m or 
smaller in the presence of a binder, a pigment and the like in water by 
means such as a ball mill, attritor or sand grinder. 
Although no particular limitation is imposed on the binder, usable 
exemplary binders include, as water-soluble binders, polyvinyl alcohol, 
casein, starch and its derivatives, methylcellulose, ethylcellulose, 
carboxymethylcellulose, carboxyethylcellulose, hydroxyethylcellulose and 
polyacrylamide. Further, for example, water-insoluble binders such as 
synthetic rubber latexes or synthetic rubber emulsions of 
styrene-butadiene-acrylic compound copolymers, vinyl chloride-vinyl 
acetate copolymers, ethylene-vinyl acetate copolymers polyurethanes, 
poly(acrylate esters) and poly(butyl methacrylate). 
Usable examples of the pigment include zinc oxide, zinc carbonate, calcium 
carbonate, magnesium carbonate, barium carbonate, magnesium sulfate, 
barium sulfate, titanium oxide, talc, kaolin, diatomaceous earth, aluminum 
hydroxide, magnesium hydroxide, alumina and silica. 
To improve dispersion properties of the dispersion, it is also possible to 
add one or more of various known dispersants, for example, alkali metal 
salts, alkaline earth metal salts and ammonium salts of sulfonated 
products of polymers such as polystyrene, styrene-maleic anhydride 
copolymers, styrene-acrylic acid copolymers and styrene-methacrylic acid 
copolymers. 
The dispersion may also be added, as needed, with one or more of various 
additives (for example, ultraviolet absorbents, defoaming agents, 
surfactants, pH regulators, viscosity modifiers, plasticizers, and organic 
high-molecular compounds). Other known dispersing methods can also be 
adopted. Namely, the color-developing agent is dissolved in an organic 
solvent such as toluene, methyl ethyl ketone, ethyl acetate or ethylene 
dichloride and, if necessary, a water-soluble solvent such as methyl 
alcohol, ethyl alcohol, acetone or dioxane can be added to the 
above-prepared solution. In the presence of a dispersant such as a 
water-soluble high-molecular substance or a surfactant, the resulting 
mixture is strongly agitated in a homomixer, a high-pressure homogenizer 
or the like to convert the color-developing agent into fine particles of 
about 0.1 to 2 .mu.m, followed by the elimination of the organic solvent 
through evaporation. The dispersion so prepared is then coated on a base 
material (for example, paper, a plastic sheet, synthetic paper, or a 
composite sheet thereof) by a coating apparatus such as an air knife 
coater, a blade coater, a sizing press coater or a flood coater to form a 
color-developing agent layer so that a color-developing sheet can be 
produced. 
Although no particular limitation is imposed on the weight (coat weight) of 
the color-developing agent layer on the base material, the 
color-developing agent can be applied preferably in an amount of 0.5 
g/m.sup.2 or more, preferably 0.5 to 10 g/m.sup.2 in terms of dry weight. 
Further, the proportion of the color-developing agent of the present 
invention in the color-developing agent layer is preferably 5 wt. % or 
higher, more preferably from 5 to 70 wt. %. 
Where the base material is paper, it is also possible to incorporate the 
color-developing agent upon making the paper. As a further alternative, 
the color-developing agent can be either dissolved or suspended in an 
organic solvent to prepare a coating formulation, followed by the coating 
of a base material with the coating formulation. 
Although no particular limitation is imposed on the form of the 
color-developing sheet according to the present invention, illustrative 
forms include: 
(1) a CF-sheet for use in combination with a CB-sheet coated on the back 
side thereof with microcapsules containing an electron-donating 
chromogenic compound and a capsule oil, 
(2) a CF/CB-sheet provided with a color-developing agent layer on a front 
side of the sheet and a microcapsule layer on a rear side of the sheet so 
that it can inserted between a CB-sheet and a CF sheet to obtain plural 
copies, and 
(3) a self-contained copying sheet with both microcapsules and a 
color-developing agent coated on the same side of the sheet. 
In the self-contained copying sheet as one of the above-described forms of 
the color-developing sheet according to the present invention, the 
microcapsules can be produced by dissolving an electron-donating 
chromogenic compound in a capsule oil and then subjecting the resultant 
solution, for example, to coacervation. 
Illustrative of the electron-donating chromogenic compound includes various 
known compounds such as triarylmethane compounds, diarylmethane compounds, 
Rhodamine-lactam compounds, fluoran compounds, indolylphthalide compounds, 
pyridine compounds, spiro compounds, fluorene compounds and phenothiazine 
compounds. 
Usable examples of the capsule oil include various oils such as cotton seed 
oil, castor oil, kerosene, paraffin, chlorinated paraffin, naphthene oil, 
alkylated biphenyls, alkylated terphenyls, alkylated naphthalenes, 
diarylalkanes, hydrogenated terphenyl and dialkyl phthalates. These 
capsule oils can be used either singly or in combination. 
The present invention will hereinafter be described in further detail by 
the following examples. It should however be borne in mind that the 
present invention is not limited to or by these examples. 
EXAMPLE 1 
Production of color-developing agent 
A glass-made reaction vessel was charged with 27.6 g (0.20 mole) of 
salicylic acid, 12.1 g (43 wt. % based on the salicylic acid, calculated 
as 100% sulfuric acid) of 98% sulfuric acid and 50 g of 
1,2-dichloroethane. While maintaining the resultant solution at 45.degree. 
C. under stirring, 62.5 g (0.6 mole) of styrene were fed over 8 hours 
through a dropping funnel. After the feeding, stirring was conducted at 
the same temperature for additional 2 hours, followed by the addition of 
water. The mixture so obtained was neutralized with an aqueous solution of 
sodium hydroxide. Further, 6.0 g (0.02 mole) of 
2-hydroxy-5-nonyl-benzenesulfonic acid were added and after mixing, 
1,2-dichloroethane was distilled off. The aqueous solution was added 
dropwise over 3 hours into 217.4 g of a 12.6 wt. % aqueous solution of 
zinc sulfate heptahydrate, the latter aqueous solution having been 
maintained at 20.degree. C. or lower, and the resulting mixture was 
stirred for 2 hours. Thereafter, the reaction product was caused to 
coagulate at 30.degree. C., collected by filtration, washed with water and 
then dried, whereby 99.1 g of a color-developing agent were obtained as 
white crystals. 
Production and evaluation of color-developing sheet 
1. Preparation of dispersion 
Using the above-described color-developing agent, a mixture of the 
below-described composition was processed at 25.degree. C. for 4 hours in 
a sand grinder so that a dispersion of the color-developing agent was 
obtained. 
______________________________________ 
Color-developing agent 50 g 
Sodium salt of sulfonated polystyrene 
2 g 
Water 120 g 
______________________________________ 
2. Preparation of coating formulation 
Using the above-described dispersion, a coating formulation of the 
following composition was prepared. 
______________________________________ 
Dispersion 8.0 g 
Light calcium carbonate 
30 g 
Starch 0.8 g 
Synthetic rubber latex 0.8 g 
Water 77.4 g 
______________________________________ 
3. Production of color-developing sheets (CF-sheets) 
The above coating formulation was coated on a wood-free paper web (50 
g/m.sup.2) to give a dry coat weight of 5.0 g/m.sup.2. The thus-coated 
paper web was dried to produce color-developing sheets (CF-sheets). 
4. Evaluation of color-developing sheets for pressure-sensitive paper 
(1) Measurement of produced color densities 
Measurement of each produced color density was conducted in a room 
air-conditioned at 20.degree. C. and 65%RH. 
A commercial CB-sheet for producing a blue color ["N-40", trade name; 
product of Mitsubishi Paper Mills, Ltd.], which was coated with 
microcapsules containing Crystal Violet lactone (CVL) as a principal 
electron-donating chromogenic compound, and each pressure-sensitive 
copying color-developing sheet (CF-sheet) obtained by the above-described 
method were brought into a contiguous relation at their coated sides, and 
are then passed between rollers so that the color was developed under a 
nip pressure. 
Upon elapsed times of 10 seconds and 24 hours after the application of the 
nip pressure, the density of the thus-developed color was measured. 
The density of each color so produced was measured using a .SIGMA.-80 
differential colorimeter and was indicated by a Y value. A smaller Y value 
indicates development of the color at a higher density. 
(2) Waterproofness test of produced color images 
After each color-developing sheet with the color developed in the manner 
described above under (1) was immersed for 24 hours in water of 20.degree. 
C., the density of the color image was measured using the .SIGMA.-80 
differential colorimeter and was indicated by a Y value. The smaller the Y 
value and the smaller the difference from the Y value before the test, the 
better the waterproofness of the produced color image. 
The results of the evaluation are collectively presented in Table 9, along 
with the results of evaluations in the below-described examples and 
comparative examples. 
In each of the following examples and comparative examples, only the 
production of the color-developing agent will be described. The production 
and evaluation of the color-developing sheet were conducted as in Example 
1. 
EXAMPLE 2 
A glass-made reaction vessel was charged with 26.2 g (0.19 mole) of 
salicylic acid, 0.9 g (0.01 mole) of phenol, 12.1 g of 98% sulfuric acid 
and 50 g of 1,2-dichloroethane. While maintaining the resultant solution 
at 45.degree. C. under stirring, 62.5 g (0.6 mole) of styrene were fed 
over 8 hours through a dropping funnel. After the feeding, stirring was 
conducted at the same temperature for additional 2 hours, followed by the 
addition of water. The mixture so obtained was neutralized with an aqueous 
solution of sodium hydroxide, and 1,2-dichloroethane was distilled off. 
The aqueous solution was added dropwise over 3 hours into 217.4 g of a 
12.6 wt. % aqueous solution of zinc sulfate heptahydrate, the latter 
aqueous solution having been maintained at 20.degree. C. or lower, and the 
resulting mixture was stirred for 2 hours. Thereafter, the reaction 
product was caused to coagulate at 30.degree. C., collected by filtration, 
washed with water and then dried, whereby 94.0 g of a color-developing 
agent were obtained as white crystals. 
The thus-obtained color-developing agent was analyzed by high-performance 
liquid chromatography. As a result, the color-developing agent was 
confirmed to contain, in addition to a salicylic acid derivative and a 
styrene polymer, 1.0 wt. % (0.54 mole % based on the salicylic acid 
derivative) of hydroxybenzenesulfonic acid, 2.3 wt. % (4.09 mole % based 
on the salicylic acid derivative) of 
.alpha.-methylbenzyl-hydroxybenzenesulfonic acid and 0.4 wt. % (0.52 mole 
% based on the salicylic acid derivative) of 
di(.alpha.-methylbenzyl)-hydroxybenzenesulfonic acid. 
EXAMPLES 3-7 
In a similar manner to Example 2 except that the amounts of the salicylic 
acid and phenol were changed as shown in Table 1, color-developing agents 
of the present invention were obtained. 
TABLE 1 
__________________________________________________________________________ 
Color- 
Salicylic acid Sulfuric 
developing 
(SA) Phenol Phenol/SA Styrene acid agent 
g (mole) 
g (mole) 
(molar ratio .times. 100) 
g (mole) 
g g 
__________________________________________________________________________ 
Example 3 
27.49 
(0.1990) 
0.09 
(0.0010) 
0.5 62.5 
(0.60) 
12.1 94.5 
Example 4 
26.82 
(0.1942) 
0.55 
(0.0058) 
3 62.5 
(0.60) 
12.1 94.3 
Example 5 
25.11 
(0.1818) 
1.71 
(0.0182) 
10 62.5 
(0.60) 
12.1 96.0 
Example 6 
21.24 
(0.1538) 
4.35 
(0.0462) 
30 62.5 
(0.60) 
12.1 98.4 
Example 7 
19.74 
(0.1429) 
5.37 
(0.0571) 
40 62.5 
(0.60) 
12.1 98.1 
__________________________________________________________________________ 
EXAMPLES 8-13 
In a similar manner to Example 2 except that phenol was replaced by 
p-phenylphenol and the raw materials were used in a ratio as shown in 
Table 2, color-developing agents of the present invention were obtained. 
TABLE 2 
__________________________________________________________________________ 
Color- 
Salicylic acid p-Phenyl- Sulfuric 
developing 
(SA) phenol PPP/SA Styrene acid agent 
g (mole) 
g (mole) 
(molar ratio .times. 100) 
g (mole) 
g g 
__________________________________________________________________________ 
Example 8 
27.49 
(0.1990) 
0.17 
(0.0010) 
0.5 62.5 
(0.60) 
12.1 94.6 
Example 9 
26.82 
(0.1942) 
0.99 
(0.0058) 
3 62.5 
(0.60) 
12.1 94.8 
Example 10 
26.24 
(0.1900) 
1.70 
(0.0100) 
5.26 62.5 
(0.60) 
12.1 94.8 
Example 11 
25.11 
(0.1818) 
3.10 
(0.0182) 
10 62.5 
(0.60) 
12.1 97.4 
Example 12 
21.24 
(0.1538) 
7.86 
(0.0462) 
30 62.5 
(0.60) 
12.1 101.9 
Example 13 
19.74 
(0.1429) 
9.72 
(0.0571) 
40 62.5 
(0.60) 
12.1 102.5 
__________________________________________________________________________ 
EXAMPLES 14-19 
In a similar manner to Example 2 except that o-phenylphenol was used 
instead of phenol and the raw materials were used in a ratio as shown in 
Table 2, color-developing agents of the present invention were obtained. 
TABLE 3 
__________________________________________________________________________ 
Color- 
Salicylic acid o-Phenyl- Sulfuric 
developing 
(SA) phenol OPP/SA Styrene acid agent 
g (mole) 
g (mole) 
(molar ratio .times. 100) 
g (mole) 
g g 
__________________________________________________________________________ 
Example 14 
27.49 
(0.1990) 
0.17 
(0.0010) 
0.5 62.5 
(0.60) 
12.1 95.0 
Example 15 
26.82 
(0.1942) 
0.99 
(0.0058) 
3 62.5 
(0.60) 
12.1 94.8 
Example 16 
26.24 
(0.1900) 
1.70 
(0.0100) 
5.26 62.5 
(0.60) 
12.1 95.2 
Example 17 
25.11 
(0.1818) 
3.10 
(0.0182) 
10 62.5 
(0.60) 
12.1 98.0 
Example 18 
21.24 
(0.1538) 
7.86 
(0.0462) 
30 62.5 
(0.60) 
12.1 103.2 
Example 19 
19.74 
(0.1429) 
9.72 
(0.0571) 
40 62.5 
(0.60) 
12.1 104.1 
__________________________________________________________________________ 
EXAMPLE 20 
In a similar manner to Example 5 except that m-phenylphenol was used (in an 
amount of 10 mole % based on the salicylic acid) instead of phenol, 
color-developing agent of the present invention was obtained in an amount 
of 98.5 g. 
EXAMPLES 21-26 
In a similar manner to Example 2 except that cumylphenol was used in lieu 
of phenol and the raw materials were used in a ratio as shown in Table 4, 
color-developing agents of the present invention were obtained. 
TABLE 4 
__________________________________________________________________________ 
Color- 
Salicylic acid Sulfuric 
developing 
(SA) Cumylphenol 
Cumylphenol/SA 
Styrene acid agent 
g (mole) 
g (mole) 
(molar ratio .times. 100) 
g (mole) 
g g 
__________________________________________________________________________ 
Example 21 
27.49 
(0.1990) 
0.21 
(0.0010) 
0.5 62.5 
(0.60) 
12.1 94.6 
Example 22 
26.82 
(0.1942) 
1.23 
(0.0058) 
3 62.5 
(0.60) 
12.1 95.0 
Example 23 
26.24 
(0.1900) 
2.12 
(0.0100) 
5.26 62.5 
(0.60) 
12.1 95.3 
Example 24 
25.11 
(0.1818) 
3.86 
(0.0182) 
10 62.5 
(0.60) 
12.1 98.2 
Example 25 
21.24 
(0.1538) 
9.81 
(0.0462) 
30 62.5 
(0.60) 
12.1 106.0 
Example 26 
19.74 
(0.1429) 
12.12 
(0.0571) 
40 62.5 
(0.60) 
12.1 104.9 
__________________________________________________________________________ 
EXAMPLES 27-32 
In a similar manner to Example 2 except that nonylphenol was used instead 
of phenol and the raw materials were used in a ratio as shown in Table 5, 
color-developing agents of the present invention were obtained. 
TABLE 5 
__________________________________________________________________________ 
Color- 
Salicylic acid Sulfuric 
developing 
(SA) Nonylphenol 
Nonylphenol/SA 
Styrene acid agent 
g (mole) 
g (mole) 
(molar ratio .times. 100) 
g (mole) 
g g 
__________________________________________________________________________ 
Example 27 
27.49 
(0.1990) 
0.22 
(0.0010) 
0.5 62.5 
(0.60) 
12.1 94.8 
Example 28 
26.82 
(0.1942) 
1.29 
(0.0058) 
3 62.5 
(0.60) 
12.1 95.0 
Example 29 
26.24 
(0.1900) 
2.20 
(0.0100) 
5.26 62.5 
(0.60) 
12.1 95.3 
Example 30 
25.11 
(0.1818) 
4.01 
(0.0182) 
10 62.5 
(0.60) 
12.1 98.3 
Example 31 
21.24 
(0.1538) 
10.18 
(0.0462) 
30 62.5 
(0.60) 
12.1 104.2 
Example 32 
19.74 
(0.1429) 
12.58 
(0.0571) 
40 62.5 
(0.60) 
12.1 105.3 
__________________________________________________________________________ 
EXAMPLES 33-38 
In a similar manner to Example 2 except that bisphenol A was used in place 
of phenol and the raw materials were used in a ratio as shown in Table 6, 
color-developing agents of the present invention were obtained. 
TABLE 6 
__________________________________________________________________________ 
Color- 
Salicylic acid Sulfuric 
developing 
(SA) Bisphenol A 
Bisphenol A/SA 
Styrene acid agent 
g (mole) 
g (mole) 
(molar ratio .times. 100) 
g (mole) 
g g 
__________________________________________________________________________ 
Example 33 
27.49 
(0.1990) 
0.23 
(0.0010) 
0.5 62.5 
(0.60) 
12.1 94.6 
Example 34 
26.82 
(0.1942) 
1.32 
(0.0058) 
3 62.5 
(0.60) 
12.1 95.1 
Example 35 
26.24 
(0.1900) 
2.28 
(0.0100) 
5.26 62.5 
(0.60) 
12.1 95.4 
Example 36 
25.11 
(0.1818) 
4.16 
(0.0182) 
10 62.5 
(0.60) 
12.1 98.5 
Example 37 
21.24 
(0.1538) 
10.55 
(0.0462) 
30 62.5 
(0.60) 
12.1 104.6 
Example 38 
19.74 
(0.1429) 
13.06 
(0.0571) 
40 62.5 
(0.60) 
12.1 105.8 
__________________________________________________________________________ 
EXAMPLES 39-44 
In a similar manner to Example 2 except that phenol was replaced by 
4,4'-dihydroxy-diphenyl and the raw materials were used in a ratio as 
shown in Table 7, color-developing agents of the present invention were 
obtained. 
TABLE 7 
__________________________________________________________________________ 
Color- 
Salicylic acid 4,4'-dihydroxy- 
4,4'-dihydroxy- Sulfuric 
developing 
(SA) diphenyl diphenyl/SA 
Styrene acid agent 
g (mole) 
g (mole) 
(molar ratio .times. 100) 
g (mole) 
g g 
__________________________________________________________________________ 
Example 39 
27.49 
(0.1990) 
0.19 
(0.0010) 
0.5 62.5 
(0.60) 
12.1 95.0 
Example 40 
26.82 
(0.1942) 
1.08 
(0.0058) 
3 62.5 
(0.60) 
12.1 94.8 
Example 41 
26.24 
(0.1900) 
1.86 
(0.0100) 
5.26 62.5 
(0.60) 
12.1 95.1 
Example 42 
25.11 
(0.1818) 
3.39 
(0.0182) 
10 62.5 
(0.60) 
12.1 97.7 
Example 43 
21.24 
(0.1538) 
8.60 
(0.0462) 
30 62.5 
(0.60) 
12.1 102.7 
Example 44 
19.74 
(0.1429) 
10.69 
(0.0571) 
40 62.5 
(0.60) 
12.1 103.4 
__________________________________________________________________________ 
EXAMPLES 45-50 & COMATIVE EXAMPLE 1 
In a similar manner to Example 2 except that hydroquinone was used in lieu 
of phenol and the raw materials were used in a ratio as shown in Table 8, 
color-developing agents of the present invention were obtained. 
TABLE 8 
__________________________________________________________________________ 
Color- 
Salicylic acid Sulfuric 
developing 
(SA) Hydroquinone 
Hydroquinone/SA 
Styrene acid agent 
g (mole) 
g (mole) 
(molar ratio .times. 100) 
g (mole) 
g g 
__________________________________________________________________________ 
Example 45 
27.49 
(0.1990) 
0.11 
(0.0010) 
0.5 62.5 
(0.60) 
12.1 94.5 
Example 46 
26.82 
(0.1942) 
0.88 
(0.0058) 
3 62.5 
(0.60) 
12.1 94.6 
Example 47 
26.24 
(0.1900) 
1.10 
(0.0100) 
5.26 62.5 
(0.60) 
12.1 94.2 
Example 48 
25.11 
(0.1818) 
2.00 
(0.0182) 
10 62.5 
(0.60) 
12.1 96.3 
Example 49 
21.24 
(0.1538) 
5.09 
(0.0462) 
30 62.5 
(0.60) 
12.1 99.0 
Example 50 
19.74 
(0.1429) 
6.29 
(0.0571) 
40 62.5 
(0.60) 
12.1 98.9 
Comp. Ex. 1 
27.6 
(0.2) -- -- 62.5 
(0.60) 
12.1 95.2 
__________________________________________________________________________ 
EXAMPLE 51 
A glass-made reaction vessel was charged with 2.1 g (0.01 mole) of 
cumylphenol, 12.1 g (45 wt. % based on the salicylic acid, calculated as 
100% sulfuric acid) of 98% sulfuric acid and 50 g of 1,2-dichloroethane. 
While maintaining the resultant solution at 30.degree. C. under stirring, 
2.6 g (0.025 mole) of styrene were fed over 0.5 hour through a dropping 
funnel, followed by stirring for additional 1 hour at the same 
temperature. Further, 26.2 g (0.19 mole) of salicylic acid were charged 
into the reaction vessel and then 59.9 g (0.575 mole) of styrene were 
likewise fed over 8 hours. After the feeding, stirring was conducted at 
the same temperature for additional 2 hours, followed by the addition of 
water. The mixture so obtained was neutralized with an aqueous solution of 
sodium hydroxide, and 1,2-dichloroethane was distilled off. The aqueous 
solution was added dropwise over 3 hours into 217.4 g of a 12.6 wt. % 
aqueous solution of zinc sulfate heptahydrate, the latter aqueous solution 
having been maintained at 20.degree. C. or lower, and the resulting 
mixture was stirred for 2 hours. Thereafter, the reaction product was 
caused to coagulate at 30.degree. C., collected by filtration, washed with 
water and then dried, whereby 95.2 g of a color-developing agent were 
obtained as white crystals. 
COMATIVE EXAMPLE 2 
This comparative example was conducted following the process disclosed in 
Japanese Patent Laid-Open No. 286304/1994 referred to above. 
A glass-made reaction vessel was charged with 1.9 g (0.02 mole) of phenol 
and 0.2 g of methanesulfonic acid. While maintaining the resultant 
solution at 120.degree. C. under stirring, 4.2 g (0.04 mole) of styrene 
were fed over 2 hours through a dropping funnel, whereby a pale-yellow, 
transparent reaction product composed of 1 mole of phenol and 2 moles of 
styrene was obtained. Another reaction vessel was charged with 27.6 g 
(0.20 mole) of salicylic acid, 12.1 g (43 wt. % based on the salicylic 
acid, calculated as 100% sulfuric acid) of 98% sulfuric acid and 50 g of 
1,2-dichloroethane. While maintaining the resultant solution at 45.degree. 
C. under stirring, 62.5 g (0.6 mole) of styrene were fed over 8 hours 
through the dropping funnel. Stirring was conducted at the same 
temperature for additional 2 hours, followed by the addition of water. 
After the mixture so obtained was neutralized with an aqueous solution of 
sodium hydroxide, the reaction product synthesized before and composed of 
1 mole of phenol and 2 moles of styrene was added, followed by stirring. 
1,2-Dichloroethane was distilled off. The resultant aqueous solution was 
added dropwise over 3 hours into 217.4 g of a 12.6 wt. % aqueous solution 
of zinc sulfate heptahydrate, the latter aqueous solution having been 
maintained at 20.degree. C. or lower, and the resulting mixture was 
stirred for 2 hours. Thereafter, the reaction product was caused to 
coagulate at 30.degree. C., collected by filtration, washed with water and 
then dried, whereby 100.1 g of a color-developing agent were obtained as 
white crystals. 
TABLE 9 
______________________________________ 
Example or 
Produced color density 
Color density 
Comparative 
10 seconds 24 hours after 
Example later later waterproofness test 
______________________________________ 
1 43.2 34.1 36.2 
2 42.8 33.7 35.8 
3 43.4 33.9 36.0 
4 43.0 33.8 35.5 
5 42.0 33.6 35.6 
6 43.6 34.0 36.6 
7 43.8 34.3 36.7 
8 43.0 34.0 36.7 
9 42.4 33.8 36.6 
10 42.8 33.8 35.5 
11 41.5 33.7 35.9 
12 43.2 34.1 36.4 
13 43.5 34.5 36.7 
14 42.3 33.5 36.3 
15 42.0 33.7 35.0 
16 41.7 33.7 35.7 
17 41.0 33.6 35.1 
18 42.5 34.0 36.1 
19 43.2 34.1 36.8 
20 41.2 33.5 35.3 
21 43.6 33.7 36.1 
22 43.1 33.9 35.8 
23 43.0 33.1 35.9 
24 42.5 33.0 35.0 
25 43.5 34.1 36.2 
26 43.7 34.4 36.8 
27 43.1 34.2 35.9 
28 42.7 34.1 35.4 
29 42.5 34.0 35.7 
30 41.6 33.9 35.6 
31 43.3 34.3 36.5 
32 43.5 34.6 36.6 
33 43.7 34.8 36.7 
34 43.5 34.7 36.6 
35 43.1 34.7 36.8 
36 42.0 34.6 36.4 
37 43.9 34.9 36.9 
38 44.2 35.1 37.1 
39 42.9 34.0 36.1 
40 42.2 33.7 35.5 
41 41.8 33.5 35.9 
42 41.2 33.3 35.8 
43 42.7 34.1 36.2 
44 43.5 34.4 36.6 
45 43.8 33.3 35.6 
46 43.2 33.4 35.6 
47 42.9 33.7 35.7 
48 42.2 33.5 35.5 
49 43.7 34.0 35.9 
50 44.1 34.6 36.6 
1 48.5 36.9 39.3 
2 49.0 37.6 41.1 
______________________________________ 
From the results of Table 9, it is evident that a color-developing sheet 
available from the use of a color-developing agent obtained in accordance 
with this invention is excellent in the storage stability (waterproofness) 
of produced color marks and is also excellent in both initial and ultimate 
color-developing capacities. 
The present invention has made it possible to industrially obtain a 
color-developing agent, which is excellent in both initial and ultimate 
color-developing capacities, with ease under extremely mild reaction 
conditions.