Method for preventing scale formation and corrosion in circulating water

An agent for water treatment comprises a water-soluble polymer obtained by polymerizing a monomer component containing a water-soluble monomer capable of dissolving in water of 50.degree. C. in the amount of 1 weight % or more, having an ethylenically unsaturated group, and exhibiting fluorescence. The water-soluble polymer has a ratio of fluorescence intensity FL.sub.1 /FL.sub.2 larger than 1, wherein FL.sub.1 is an intensity of fluorescence obtained in dissolving a water-soluble polymer in a concentration of 10 ppm in pure water, and FL.sub.2 is an intensity of fluorescence obtained in dissolving phenol in a concentration of 0.1 ppm in pure water.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an agent for water treatment which is effective 
in preventing scale formation, and more particularly to an agent for water 
treatment which contains a water-soluble polymer derived from a 
water-soluble monomer component exhibiting fluorescence and which is 
excellent in resistance of the polymer to gelation (hereinafter referred 
to as "gelation resistance"). 
2. Description of the Related Art 
An organic compound such as water-soluble polymer has been widely used as 
an agent for preventing scale formation and an inhibitor against metal 
corrosion to prevent scale formation and corrosion in an aqueous system 
such as boiler water and cooling water. In the case of being used for 
preventing scale formation or inhibiting metal corrosion, the 
water-soluble polymer cannot exhibit a sufficient prevention or inhibiting 
effect unless the concentration of polymer in water is kept within a 
predetermined range. Accordingly, in practice, it is verified whether the 
polymer maintains its concentration at an optimum operation value by 
measuring the concentration of polymer for use in water treatment in an 
aqueous system while circulating boiler water or cooling water. 
As a method for measuring the concentration of polymer for use in water 
treatment, there have been known colorimetric method, nephelometric 
method, lithium tracer method, and fluorescent tracer method. These 
methods have suffered the following problems. In colorimetric method and 
nephelometric method, normally, a great deal of time is required for 
manual measurement. Even if the measurement is conducted automatically, 
time required for such automatic measurement cannot be shortened either. 
On the other hand, lithium tracer method and fluorescent tracer method are 
not a direct measurement method of directly measuring the concentration of 
polymer, but an indirect measurement method. Accordingly, in the case 
where a consumption amount of polymer is greatly changed due to an 
exceeded concentration of water which is to be treated and formation of 
scale, these indirect measurement methods fail to grasp the consumption 
amount of polymer accurately. 
Recently, there have been proposed methods of measuring the concentration 
of polymer in a simplified, speedy and accurate manner by directly 
introducing a compound capable of absorbing ultra-violet radiation 
(European Laid-open Patent Publication No. EP647596) or a fluorescent 
substance (Japanese Laid-open Patent Publication No. 5-163591) into a 
polymer for water treatment. Introducing a compound capable of absorbing 
ultra-violet radiation and a fluorescent substance (hereinafter referred 
to as a "labeled compound") into a polymer is performed utilizing a 
polymer reaction of reacting a functional group in the polymer with a 
functional group in the labeled compound. However, in the case of polymer 
reaction, the reaction rate of the functional group in the polymer is low, 
and it is difficult to introduce the labeled compound into the polymer at 
a specified amount. Hence, the concentration of polymer in water to be 
treated cannot be accurately measured. Further, kinds of labeled compounds 
which have a functional group reactable with a functional group in polymer 
are few, and the combination of these polymers and labeled compounds are 
also limited. 
There has also been proposed a method of introducing a labeled compound 
into a polymer by adding for copolymerization a labeled compound having an 
unsaturated double bond into a reaction system in obtaining a polymer for 
use in water treatment. However, all labeled compound monomers obtainable 
at the present have lipophilicity. Accordingly, an additional process of 
removing a solvent by distillation is required after copolymerization in 
an organic solution, which not only makes the process of obtaining 
water-soluble polymer for use in water treatment cumbersome but also is 
not advantageous in the aspect of environment, preventing a fire, cost 
performance and saving natural resources. Moreover, the introducing rate 
of labeled compound monomers is low, for which an improvement has been 
demanded. 
SUMMARY OF THE INVENTION 
In view thereof, it is an object of the present invention to provide an 
agent for water treatment comprising a water-soluble polymer capable of 
being produced by polymerization in an aqueous system and of measuring the 
concentration of water-soluble polymer existing in water to be treated in 
a simplified, speedy and accurate manner. 
An agent for water treatment according to the present invention comprises a 
water-soluble polymer obtained by polymerizing a monomer component 
containing a water-soluble monomer capable of dissolving in water of 
50.degree. C. in the amount of 1 weight % or more, having an ethylenically 
unsaturated group, and exhibiting fluorescence, the water-soluble polymer 
having a ratio of fluorescence intensity FL.sub.1 /FL.sub.2 larger than 1, 
wherein FL.sub.1 is an intensity of fluorescence obtained in dissolving a 
water-soluble polymer in the concentration of 10 ppm in pure water, and 
FL.sub.2 is an intensity of fluorescence obtained in dissolving phenol in 
the concentration of 0.1 ppm in pure water. 
The water-soluble monomer may preferably have an oxyalkylene chain 
represented by --CHR.sup.1 (CH.sub.2).sub.m O!.sub.n -- to show a 
favorable water solubility, wherein R.sup.1 is a hydrogen or a methyl 
group, m is an integer from 1 to 3, and n is an integer from 1 to 100. 
In particular, the water-soluble monomer may preferably be represented by 
the following formula I: 
##STR1## 
wherein A.sup.1 and A.sup.2 are independently a hydrogen, a methyl group 
or --COOX, respectively; A.sup.3 is a hydrogen, a methyl group, --COOX or 
--CH.sub.2 COOX; and A.sup.1 and A.sup.2 are not --COOX at the same time; 
A.sup.1 and A.sup.2 are independently a hydrogen or a methyl group 
respectively when A.sup.3 is --COOX or --CH.sub.2 COOX; X is a hydrogen, 
an alkaline metal, an alkaline earth metal, an ammonium group or an 
organic amine group; R.sup.2 is one of --COO--, --CH.sub.2 COO--, 
--CONH--, --CH.sub.2 CONH--, --NH--, --(CH.sub.2).sub.k NH--, wherein k is 
an integer from 1 to 4, and --(CH.sub.2).sub.1 O--, wherein l is an 
integer from 1 to 4; R.sup.1 is a hydrogen or a methyl group, m is an 
integer from 1 to 3, n is an integer from 1 to 100; and R.sup.3 is an 
organic group derived from a cyclic aryl or a heterocyclic compound having 
a conjugated double bond. 
When deriving the water-soluble polymer using the water-soluble monomer 
showing fluorescence, the water-soluble polymer may preferably be obtained 
by polymerizing a monomer component comprising 0.1 to 15 mol % of 
water-soluble monomer having an ethylenically unsaturated group and 
showing fluorescence; 70 to 95 mol % of monomer having carboxyl group(s) 
consisting of one or more kinds of monocarboxylic acid monomer or 
polycarboxylic acid monomer; and 5 to 30 mol % of 3-allyloxy-2-hydroxy 
propane sodium sulfonate in which the total amount of the monomers becomes 
100 mol %. 
Preferably, the water-soluble polymer may be obtained by polymerization in 
an aqueous system and a degree of gelation of said water-soluble polymer 
may be not larger than 0.02. With the above arrangement, attainable is the 
water-soluble polymer for use in water treatment which is excellent in 
grasping the concentration of water-soluble polymer in water, gelation 
resistance, and inhibiting formation of scale and corrosion, without the 
necessity of polymerization in an organic solution in which a cumbersome 
process of removing a solvent by distillation is required.

DETAILED DESCRIPTION OF THE INVENTION 
Through continued researches, the present inventors have found a 
water-soluble monomer into which a fluorescent substance is introduced and 
come up with the present invention. It should be noted that an agent for 
water treatment according to the present invention includes an agent of 
preventing scale formation and corrosion, and a flocculant, however, the 
inventive water treatment agent is not limited to the above. 
The gist of the present invention resides in that a water-soluble monomer 
having an ethylenically unsaturated group, exhibiting fluorescence, and 
capable of dissolving in water of 50.degree. C. in the amount of 1 weight 
% or more (hereinafter merely referred to as a "water-soluble monomer") is 
used to obtain a water-soluble polymer for use in water treatment. In the 
present invention, it is required that an intensity of fluorescence of 
water-soluble polymer is large enough so that the concentration of 
water-soluble polymer existing in water can be measured in a simplified, 
speedy and accurate manner. Accordingly, an essential requirement in the 
present invention is set in such a manner that a ratio of fluorescence 
intensity FL.sub.1 /FL.sub.2 is larger than 1, wherein denoted at FL.sub.1 
is an intensity of fluorescence obtained in dissolving water-soluble 
polymer in the concentration of 10 ppm in pure water, and denoted at 
FL.sub.2 is an intensity of fluorescence obtained in dissolving phenol in 
the concentration of 0.1 ppm in pure water. It should be noted that in the 
present invention the intensity of fluorescence is obtained with the use 
of a fluorescence spectrophotometer (a product of Nippon Bunko K.K., 
FP-777 type, photomal voltage of Low). The fluorescence intensity ratio 
FL.sub.1 /FL.sub.2 is preferably 5 or more, and more preferably 10 or 
more. It may also be preferable that an intensity of fluorescence FL.sub.3 
which is obtained in solving water-soluble monomer which is a constituent 
of water-soluble polymer in the concentration of 0.1 ppm in pure water is 
larger than FL.sub.2 in order to increase the fluorescence intensity of 
water-soluble polymer. This is because the larger the fluorescence 
intensity of water-soluble monomer, the larger the fluorescence intensity 
of water-soluble polymer, with the result that the concentration of 
water-soluble polymer can be measured easily. The fluorescence intensity 
ratio of FL.sub.3 /FL.sub.2 is preferably 5 or more, and more preferably 
10 or more. 
Any water-soluble monomer can be used as far as the monomer exhibits 
fluorescence and can be solved in water of 50.degree. C. in the amount of 
1 weight % or more (preferably 2 weight % or more). In particular, there 
may preferably be used monomer in which an oxyalkylene chain represented 
by --CHR.sup.1 (CH.sub.2).sub.m O!.sub.n --, wherein R.sup.1 is a 
hydrogen or methyl group, m is an integer from 1 to 3, and n is an integer 
from 1 to 100, is bonded. Water solubility is obtained by setting the 
integers m and n in the above oxyalkylene chain at a desired value within 
the above range. Preferably, if the integer n is 5 or more, the 
water-soluble monomer assuredly exhibits a favorable water solubility (the 
ability of dissolving in water of 50.degree. C. in the amount of 5 weight 
% or more). 
Further, since the moiety represented by --CHR.sup.1 (CH.sub.2).sub.m 
O!.sub.n -- is nonion, this moiety is effective in suppressing a gelation 
of water-soluble polymer at a low level and enhancing gelation resistance. 
Considering the solubility into water and the water-treatment ability of 
water-soluble polymer for use in water treatment, the integer n is 
preferably from 6 to 40, and more preferably lies in the range of 8 to 30. 
It may be appreciated that the oxyalkylene chain may comprise in such a 
manner that R.sup.1 in one oxyalkylene is a hydrogen and that in another 
oxyalkylene is a methyl group if the integer n is 2 or more. In other 
words, the oxyalkylene chain may include an ethylene oxide (ethylene 
glycol)-propylene oxide (propylene glycol) block chain (wherein m is 1). 
The most preferable compound among the water-soluble monomers having an 
ethylenically unsaturated group and exhibiting fluorescence according to 
the present invention can be represented by the following formula I: 
##STR2## 
wherein A.sup.1 and A.sup.2 are independently a hydrogen, a methyl group 
or --COOX, respectively; A.sup.3 is a hydrogen, a methyl group, --COOX or 
CH.sub.2 COOX; and A.sup.1 and A.sup.2 are not --COOX at the same time; 
A.sup.1 and A.sup.2 are independently a hydrogen or a methyl group 
respectively when A.sup.3 is --COOX or --CH.sub.2 COOX; X is a hydrogen, 
an alkaline metal, an alkaline earth metal, an ammonium group or an 
organic amine group; R.sup.2 is one of --COO--, --CH.sub.2 COO--, 
--CONH--, --CH.sub.2 CONH--, --NH--, --(CH.sub.2).sub.k NH-- (wherein k is 
an integer from 1 to 4), and --(CH.sub.2).sub.1 O-- (wherein l is an 
integer from 1 to 4); R.sup.1 is a hydrogen or a methyl group, m is an 
integer from 1 to 3, n is an integer from 1 to 100; and R.sup.3 is an 
organic group derived from an aryl or a heterocyclic compound having a 
conjugated double bond. 
The above water-soluble monomer (I) has the moiety --CHR.sup.1 
(CH.sub.2).sub.m O!.sub.n -- for applying water solubility to the monomer 
and the moiety R.sup.3 having fluorescence. R.sup.3 is an organic group 
derived from an aryl or a heterocyclic compound having a conjugated double 
bond, and an organic residue of aryl or heterocyclic compound having the 
conjugated double bond and one of the functional groups capable of being 
added to the oxyalkylene chain in the water-soluble monomer (I) such as 
amino group, hydroxyl group, mercapto group, carboxyl group, and halogen. 
More specifically, in order to obtain water-soluble monomer (I) exhibiting 
fluorescence, the following two methods can be taken. One of the methods 
is: an aryl or heterocyclic compound having a conjugated double bond and 
one of the functional groups such as amino group, hydroxyl group, mercapto 
group, carboxyl group, and halogen is reacted with alkyleneoxide, and then 
added with an unsaturated monomer through R.sup.2 represented in the above 
formula I. The other method is: an unsaturated monomer is added with 
alkyleneoxide through R.sup.2 ; and a hydroxyl group at one end of the 
oxyalkylene chain of the monomer obtained by the additional reaction is 
reacted with an aryl or heterocyclic compound having a conjugated double 
bond and one of the functional groups such as amino group, hydroxyl group, 
mercapto group, carboxyl group, and halogen. 
Examples of cyclic aryl (aromatic) compound or heterocyclic compound which 
has a functional group and a conjugated double bond usable both in the 
above two methods are: compounds having an amino group such as aniline, 
naphthyl amine, 2-aminofluorene, aminoanthracene, aminoanthraquinone, 
imidazole, phenylimidazole, 2-phenylbenzoimidazole, carbazole, 
aminobiphenyl; compounds having a hydroxyl group such as phenol, naphthol, 
fluorenol, 9-hydroxyanthracene, 2-hydroxynaphtoquinone, 
hydroxyanthraquinone, pyrenemethanol, hydroxycoumarin, hydroxyflavone, 
hydroxybiphenyl, xanthydrol, dibenzosuberenol, 9-anthracenemethanol, 
acenaphthylene; compounds having a mercapto group such as thiophenol, 
thionaphthol; compounds having a carboxyl group such as benzoic acid, 
naphthalenecarboxylic acid, 9-fluorenecarboxylic acid, 
9-anthracenecarboxylic acid, anthraquinone-2-carboxylic acid, phenyl 
benzoate; and compounds having a halogen group such as benzyl chloride, 
chloromethylanthracene, chloromethylanthraquinone. 
Examples of water-soluble monomer (I) are: polyethyleneglycol 
phenylether(meth)acrylate, polyethyleneglycol phenylether(meth)allylether, 
polypropyleneglycol phenylether(meth)acrylate, polypropyleneglycol 
phenylether(meth)allylether; polyethyleneglycol 
phenylthioether(meth)acrylate, polyethyleneglycol 
phenylthioether(meth)allylether, polypropyleneglycol 
phenylthioether(meth)acrylate, polypropyleneglycol 
phenylthioether(meth)allylether; 
polyethyleneglycol-2-phenylylaminoethylether (meth)acrylate, 
polyethyleneglycol-2-phenylaminoethylether (meth)allylether, 
polypropyleneglycol-2-phenylaminoethylether (meth)acrylate, 
polypropyleneglycol-2-phenylaminoethylether (meth)allylether; 
polyethyleneglycol benzoate(meth)acrylate, polyethyleneglycol 
benzoate(meth)allylether, polypropyleneglycol benzoate(meth)acrylate, 
polypropyleneglycol benzoate(meth)allylether; polyethyleneglycol 
benzylether(meth)acrylate, polyethyleneglycol benzylether(meth)allylether, 
polypropyleneglycol benzylether(meth)acrylate, polypropyleneglycol 
benzylether(meth)allylether; polyethyleneglycol 
naphthylether(meth)acrylate, polyethyleneglycol 
naphthylether(meth)allylether, polyethyleneglycol 
naphthylether(meth)acrylate, polyethyleneglycol 
naphthylether(meth)allylether; 
polyethyleneglycol-2-naphthylaminoethylether (meth)acrylate, 
polyethyleneglycol-2-naphthylaminoethylether (meth)allylether; 
polyethyleneglycol naphthoate(meth)acrylate, polyethyleneglycol 
naphthoate(meth)allylether; polyethyleneglycol 
naphthylmethylether(meth)acrylate, polyethyleneglycol 
naphthylmethylether(meth)allylether; 
polyethyleneglycol-9-anthrylmethylether(meth)acrylate, 
polyethyleneglycol-9-anthrylmethylether(meth)allylether; 
polyethyleneglycol-2-anthrylaminoethylether(meth)acrylate, 
polyethyleneglycol-2-anthrylaminoethylether(meth)allylether; 
polyethyleneglycol anthoate(meth)acrylate, polyethyleneglycol 
anthoate(meth)allylether; polyethyleneglycol fluorenylether(meth)acrylate, 
polyethyleneglycol fluorenylether(meth)allylether; 
polyethyleneglycol-2-fluorenylaminoethylether(meth)acrylate, 
polyethyleneglycol-2-fluorenylaminoethylether(meth)allylether; 
polyethyleneglycol fluorene-9-carboxylate(meth)acrylate, 
polyethyleneglycol fluorene-9-carboxylate(meth)allylether; 
polyethyleneglycol naphthoquinonylether(meth)acrylate, polyethyleneglycol 
naphthoquinonylether(meth)allylether; polyethyleneglycol 
anthraquinonylether(meth)acrylate, polyethyleneglycol 
anthraquinonylether(meth)allylether; 
polyethyleneglycol-2-anthraquinonylaminoethylether(meth)acrylate; 
polyethyleneglycol anthraquinone-2-carboxylate(meth)acrylate, 
polyethyleneglycol anthraquinone-2-carboxylate(meth)allylether; 
polyethyleneglycol pyrenylether(meth)acrylate, polyethyleneglycol 
pyrenylether(meth)allylether; polyethyleneglycol 
coumarylether(meth)acrylate, polyethyleneglycol 
coumarylether(meth)allylether; N-polyoxyethylene imidazole(meth)acrylate, 
N-polyoxyethylene phenylimidazole(meth)acrylate, 
N-polyoxyethylene-2-phenylbenzoimidazole (meth)acrylate, N-polyoxyethylene 
carbazole(meth)acrylate; polyethyleneglycol biphenylether(meth)acrylate, 
polyethyleneglycol biphenylether(meth)allylether; 
polyethyleneglycol-2-biphenylaminoethylether(meth)acrylate, 
polyethyleneglycol-2-biphenylaminoethylether(meth)allylether; 
polyethyleneglycol phenylbenzoate(meth)acrylate, polyethyleneglycol 
phenylbenzoate(meth)allylether; polyethyleneglycol phenylether 
monomaleate, polypropyleneglycol phenylether monomaleate; 
polyethyleneglycol phenylthioether monomaleate, polypropyleneglycol 
phenylthioether monomaleate; polyethyleneglycol-2-phenylaminoethylether 
monomaleate, polypropyleneglycol-2-phenylaminoethylether monomaleate; 
polyethyleneglycol benzoate monomaleate, polypropyleneglycol benzoate 
monomaleate; polyethyleneglycol benzylether monomaleate, 
polypropyleneglycol benzylether monomaleate; polyethyleneglycol 
naphthylether monomaleate, polyethyleneglycol-2-naphthylaminoethylether 
monomaleate; polyethyleneglycol naphthoate monomaleate, polyethyleneglycol 
naphthylmethylether monomaleate; polyethyleneglycol-9-anthrylmethylether 
monomaleate, polyethyleneglycol-2-anthrylaminoethylether monomaleate, 
polyethyleneglycol anthoate monomaleate; polyethyleneglycol fluorenylether 
monomaleate, polyethyleneglycol-2-fluorenylaminoethylether monomaleate; 
polyethyleneglycol fluorene-9-carboxylate monomaleate; polyethyleneglycol 
naphthoquinonylether monomaleate, polyethyleneglycol anthraquinonylether 
monomaleate, polyethyleneglycol-2-anthraquinonylaminoethylether 
monomaleate; polyethyleneglycol anthraquinone-2-carboxylate monomaleate; 
polyethyleneglycol pyrenylether monomaleate, polyethyleneglycol 
coumarylether monomaleate; N-polyoxyethylene imidazole monomaleate, 
N-polyoxyethylene phenylimidazole monomaleate, 
N-polyoxyethylene-2-phenylbenzoimidazole monomaleate, N-polyoxyethylene 
carbazole monomaleate; polyethyleneglycol biphenylether monomaleate, 
polyethyleneglycol-2-biphenylaminoethylether monomaleate, 
polyethyleneglycol phenylbenzoate monomaleate. 
One or more kinds of the above monomers can be used as the water-soluble 
polymer (I). It should be noted that the moiety corresponding to 
polyethylene glycol or polypropylene glycol in the above illustrated 
compounds contains a block of 
polyethyleneglycol-polypropyleneglycol(ethyleneoxide-propyleneoxide). 
Water-soluble polymer according to the present invention exhibits 
fluorescence by making water-soluble monomer having fluorescence one of a 
unit constituting the water-soluble polymer to accurately measure the 
concentration of water-soluble polymer in water. 
Further, since the inventive water-soluble polymer uses monomer having a 
large intensity of fluorescence, the intensity of fluorescence of polymer 
obtained from this monomer becomes also large. Accordingly, when such 
water-soluble polymer is used as an agent for water treatment, the 
concentration of water-soluble polymer can be measured accurately and 
easily. Moreover, since the above compounds having fluorescence are 
water-soluble monomers, they can be polymerized with other monomers which 
will be described later in an aqueous system. Accordingly, a specified 
amount of these fluorescent compounds can be assuredly introduced into the 
polymer in an aqueous system. In addition, it is remarkably advantageous 
in that an effective polymerization in an aqueous solution can be adopted 
in the aspect of environment, preventing a fire, cost performance, and 
saving natural resources. 
To synthesize water-soluble polymer showing excellent performance as an 
agent for water treatment, monomer having carboxyl group(s) consisting of 
one or more kinds of monocarboxylic acid monomer or polycarboxylic acid 
monomer and monomers other than the above (hereinafter merely referred to 
as "other monomers") if necessary may preferably be used in combination 
with the fluorescent water-soluble monomer for copolymerization. With the 
addition of these monomers, water-soluble polymer can be polymerized in an 
aqueous system in a simplified manner, and the thus obtained water-soluble 
polymer is excellent in preventing scale formation, inhibiting corrosion, 
and resistible against gelation. 
Each monomer may preferably be used in the amount shown below. 
Specifically, fluorescent water-soluble monomer is used in the amount of 
0.1 to 15 mol %; monomer having carboxyl group(s) consisting of one or 
more kinds of monocarboxylic acid monomer or polycarboxylic acid monomer 
is used in the amount of 70 to 99.9 mol %; and the other monomers are used 
in the amount of 0 to 30 mol % in which the total amount of the monomers 
becomes 100 mol %. Polymer obtained from these monomers can exhibit 
properties such as water solubility and scale formation preventing 
ability, and fluorescence in a well-balanced manner within the above 
range. 
If the amount of monomer showing fluorescence is reduced, the fluorescent 
moiety to be introduced into the polymer is reduced, which makes it 
difficult to trace the concentration of the polymer in water. On the 
contrary, if water-soluble monomer exhibiting fluorescence is introduced 
into the polymer in the amount of 15 mol % or more, the ability of 
preventing scale formation and inhibiting corrosion is gradually 
deteriorated. This is also not favorable. If the other monomers are used 
in the amount exceeding 30 mol %, there is the likelihood that polymer 
obtained using these monomers may show deteriorated water solubility. 
Examples of monomer having carboxyl group(s) consisting of one or more 
kinds of monocarboxylic acid monomer or polycarboxylic acid monomer are: 
monomers of unsaturated monocarboxylic acid such as acrylic acid, 
methacrylic acid, .alpha.-hydroxyacrylic acid, and crotonic acid, and 
salts thereof; and monomers of unsaturated polycarboxylic acid such as 
maleic acid, fumaric acid, itaconic acid, citraconic acid, and aconic 
acid, and salts thereof. One or more kinds of these monomers can be used 
as monomer having carboxyl group(s). 
Examples of basic compounds which can form salts together with the monomers 
having carboxyl group(s) are: hydroxides of alkaline metal such as sodium, 
potassium, and lithium or carbonates thereof; alkylamines such as ammonia, 
monomethyl amine, dimethyl amine, triethyl amine; and alkanolamins such as 
monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, 
sec-butanolamin. It may be appreciated that salts of polycarboxylic acid 
monomer occupy all or part of the carboxylic group(s). 
Examples of the other monomers are: monomers having a sulfonic acid group 
such as vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, 
and monomer derived from diene compounds such as isoprene and butadiene 
one of a conjugated double bond of which has undergone sulfonation; 
sulfoethylmethacrylate and sulfopropylmethacrylate, and salts thereof; 
monomers having a hydroxyl group such as 2-hydroxyethylmethacrylate (HEMA) 
and glycerylmonoallylether (GMAE); monomers having an amino group such as 
acrylamide, methacrylamide, allylamine; alkyl(meth)acrylate such as 
methylacrylate, monomers having an amide group and sulfonic acid group 
such as 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and salts 
thereof; monomers having a hydroxyl group and sulfonic acid group such as 
3-allyloxy-2-hydroxypropane sulfonic acid (HAPS) and salts thereof. The 
salts illustrated in the above monomers are salts obtained with the 
above-mentioned basic compounds. 
Among the monomers having carboxyl group(s) and the other monomers which 
can be used together with the fluorescent water-soluble monomer, the 
following is favorably used: maleic acid or acrylic acid; combination of 
maleic acid and acrylic acid; combination of acrylic acid and 
allylsulfonic acid; combination of maleic acid and styrenesulfonic acid; 
combination of acrylic acid and 2-hydroxyethyl(meth)acrylate, combination 
of acrylic acid, 2-hydroxyethyl(meth)acrylate, and methylacrylate; and 
combination of monomers having carboxyl group and HAPS. In particular, if 
HAPS is used in the amount of 5 to 30 mol % in the other monomer, gelation 
resistance is remarkably improved. Accordingly, water-soluble polymer can 
be obtained eliminating the likelihood of gelation during operation of 
aqueous system such as boiler water or cooling water, and ability of 
inhibiting corrosion can be remarkably improved. 
In case of using HAPS as the other monomers, HAPS can be introduced in an 
effective manner by adding fluorescent water-soluble monomer in the amount 
of 0.1 to 15 mol %, monomer having carboxyl group(s) consisting of one or 
more kinds of monocarboxylic acid monomer or polycarboxylic acid monomer 
in the amount of 70 to 95 mol %, and HAPS in the amount of 5 to 30 mol % 
to make the total amount of monomer 100 mol %. 
According to the present invention, polymerization in an aqueous system is 
recommendable as a method of synthesizing water-soluble polymer. 
Specifically, the polymerization in an aqueous solution in which 
exclusively water is used as a medium for polymerization is preferable due 
to its simple use. The aqueous solution polymerization can be performed 
using a known method, i.e., with the use of a water soluble polymerization 
initiator, e.g., persulfates such as ammonium persulfate, sodium 
persulfate, potassium persulfate, peroxides such as hydrogen peroxide, 
persuccinic acid, peracetic acid, cumene hydroperoxide, and azo compounds 
such as 2,2'-azobis(2-amidinopropane)hydrochloride. A polymerization 
accelerator such as sodium hydrogen sulfite and ascorbic acid may be used 
together in the aqueous solution polymerization. Polymer obtained by the 
aqueous solution polymerization can be directly used as an agent for water 
treatment without any chemical treatment. If necessary, the polymer may be 
used as a water treatment agent after attaining a desired neutralization 
level with the addition of the aforementioned basic compounds. Preferably, 
the weight-average molecular weight of water-soluble polymer lies in the 
range from 500 to 50000, and in view of water treating ability as a water 
treatment agent, may preferably lies in the range from 500 to 20000. 
Gelation of the inventive water-soluble polymer is defined based on a 
measurement value of absorbance under the following conditions. 
Measurement Condition on Gelation 
Vessel: 500 cc tall beaker 
Polymer: concentration of 40 ppm in a sample solution (solid concentration) 
Sample Solution: 400 g of aqueous solution of CaCl.sub.2 in the 
concentration of 400 ppm 
Temperature: 50.degree. C. 
pH 8 
Period for placing the vessel in a stationary state: 1 hour 
Measurement method: The solution was stirred for 5 minutes by the use of a 
stirrer, sampling was performed for the solution after stirring, and the 
absorbance of solution (ABS) was measured at UV 380 nm in a cell of 50 mm. 
The degree of gelation is expressed using a numerical value for evaluating 
how easily water-soluble polymer is precipitated under the existence of 
calcium ion in water, and examined by measuring the degree of turbidity of 
the sample solution when the sample solution is heated under the existence 
of calcium ion based on absorbance of ultraviolet ray. The higher the 
numerical value of absorbance, the greater the turbidity of solution 
containing the polymer, which shows that a greater amount of polymer is 
precipitated in the sample solution under the existence of calcium ion. 
Polymer having a higher degree of gelation is liable to be insoluble in 
water such as boiler water and cooling water, and hence, the ability of 
preventing metal corrosion and scale formation is remarkably lowered. 
Accordingly, polymer which does not cause gelation is desirably used to 
stably maintain the scale formation or corrosion preventing ability at a 
desired level. It is preferable to maintain the degree of gelation G not 
larger than 0.02 as shown in the following parameter, and more preferable 
to maintain the degree of gelation not larger than 0.01. 
The following the parameter showing the degree of gelation. The less the 
numerical value, the higher the ability of preventing corrosion and scale 
formation as an agent for water treatment. 
G.ltoreq.0.01: hardly cause gelation 
0.01&lt;G.ltoreq.0.1: not liable to cause gelation 
0.1&lt;G.ltoreq.0.2: liable to cause gelation 
0.2.ltoreq.G: liable to cause gelation greatly 
The inventive water treatment agent containing water-soluble polymer can be 
used in a similar manner as used in a conventional water treatment agent 
by e.g., injecting the agent in a predetermined amount in advance or 
intermittently into circulating water so as to keep the concentration of 
water treatment agent in the water at a predetermined level. Generally, 
the additive amount of 1 to 50 ppm is sufficiently effective as the water 
treatment agent. 
The inventive water treatment agent may be added with phosphorus compounds 
such as phosphoric acid, polyphosphoric acid, and phosphonic acid and/or 
zinc phosphides according to needs, as well as the above-mentioned 
water-soluble polymer. These compounds are more effective in preventing 
corrosion. Further, it may be appreciated that a chlorine agent such as 
chlorine gas, calcium hypochlorite, sodium hypochlorite, and sodium 
isocyanuric acid chloride is added for slime control. 
According to the present invention, polymerization in an aqueous system can 
be performed with the use of water-soluble monomer having fluorescence. 
Accordingly, eliminated is a cumbersome process of removing an organic 
solvent by distillation when an organic solution is used for 
polymerization, which is advantageous in providing polymer for use in 
water treatment in the aspect of preventing a fire, cost performance, and 
saving natural resources. Since water-soluble monomer having fluorescence 
can be introduced in a specified amount into the water-soluble polymer, 
and this polymer exhibits a high degree of intensity of fluorescence, the 
concentration of polymer to be added to water can be measured in a 
simplified, speedy, and accurate manner. 
EXAMPLES 
Examples of the present invention are given below. These are, however, 
given for the purpose of illustration only and are by no means intended to 
limit the scope of the invention. Percentage (%) given in the description 
below means weight %. In the examples, measurement of the degree of 
gelation was conducted using the aforementioned measurement method, and 
weight-average molecular weight, polymerization rate, intensity of 
fluorescence, corrosion rate, and scale inhibiting rate were obtained 
using the following methods. 
Weight-average Molecular Weight! 
Weight-average molecular weight of sample polymer obtained by 
polymerization was measured using gel permeation chromatography (GPC). In 
the GPC, a column of ASAHI pack GFA-7MF (a product of Asahi Kasei Kogyo 
K.K.) was used with an eluate of 0.5% aqueous solution of phosphoric acid, 
and a standard sample of poly sodium acrylate (a product of Sowa Kagaku 
K.K.) was used as a molecular weight standard sample 
Rate of Polymerization! 
The polymerization rate was calculated on the basis of solid concentration 
in a polymerization system after completion of polymerization and the 
amount of monomer used. 
Intensity of Fluorescence! 
A sample polymer was dissolved in ultra pure water to prepare an aqueous 
solution containing the sample polymer in the amount of 10 mg/liter. 
Thereafter, the aqueous solution was put in a cell of non-fluorescence of 
10 mm square and had its intensity of fluorescence measured by using a 
fluorescence spectrophotometer (a product of Nippon Bunko K.K.; FP-777 
type) at the photomal voltage Low, the excited wave length of 230 nm, and 
the fluorescence wave length of 350 nm. It should be noted that the 
excited wave length was 294 nm and the fluorescence wave length was 358 nm 
in EXAMPLE 8 and in COMATIVE EXAMPLE 1; 226 nm and 293 nm in EXAMPLEs 
10 and 11; 325 nm and 453 nm in COMATIVE EXAMPLE 2, respectively. 
Corrosion Rate! 
Test water for testing corrosion rate was prepared with 134 ppm for calcium 
hardness (as CaCO.sub.3), 170 ppm for total hardness (as CaCO.sub.3), 600 
ppm for M alkalinity, 95 ppm for concentration of chloride ions, 32 ppm 
for concentration of sulfate ions, and at pH 8 to 8.5. The thus prepared 
test water was poured in a 500 ml beaker. 50 ppm sample polymer as purity 
was added into the test water in the beaker at a temperature of 40.degree. 
C. and pH 8.0. A low carbon steel SS-1 of 40 mm in width, 20 mm in length, 
and 1 mm in thickness (=0.213 dm.sup.2) was degreased with acetone and 
polished with a sandpaper of #400. Thereafter, the low carbon steel was 
rinsed with acetone, dried in the air, and had the weight thereof measured 
to obtain a test piece. 
The test water in which the above test piece was soaked in a hung state 
with a string was stirred at a speed of 100 rpm for 5 consecutive days. 
Thereafter, the test piece was taken out from the test water and then 
immersed in an aqueous solution containing 15% HCl and 1% IBIT (acid 
corrosion inhibitor) for about 15 seconds to rinse off a product generated 
by corrosion. Then, the test piece had its surface rinsed off with 
acetone, dried in the air, and had the weight thereof measured up to 0.1 
mg. A difference in weight between before and after the test was 
calculated as the degree of corrosion, i.e., by the unit of mdd 
(mg/dm.sup.2 /day). At this time, a reference test piece which had not 
been soaked in the test water was also immersed in the aqueous solution 
containing 15% HCl and 1% IBIT for about 15 seconds to measure the 
difference in weight between before and after the test. The weight 
difference for the reference test piece was used as a correction value. 
Scale Inhibiting Rate! 
170 g of water was put in 225 ml glass bottle, 10 g of 1.56% aqueous 
solution of CaCl.sub.2.2H.sub.2 O was mixed with 5 g of 0.02% aqueous 
solution containing the sample polymer (3 ppm for a supersaturated aqueous 
solution obtained accordingly). The mixture was added with 10 g of aqueous 
solution of NaHCO.sub.3 and 7 g of NaCl to make the total amount 200 g. 
Then, 530 ppm supersaturated aqueous solution of CaCO.sub.3 was sealed and 
heated at a temperature of 70.degree. C. for 8 hours. After the 
supersaturated aqueous solution was cooled, a product of precipitation was 
filtered through a membrane filter of 0.1 .mu.m. The filtrate was analyzed 
according to JIS K0101, and a scale inhibiting rate (%) of inhibiting 
formation of calcium carbonate as scale was calculated using the following 
equation: 
EQU Scale inhibiting rate (%)=(C-B)(A-B).times.100 
wherein A is the concentration of calcium (%) dissolved in the test 
solution before the test; B is the concentration of calcium (%) in the 
filtrate without the addition of scale formation inhibitor; and C is the 
concentration of calcium (%) in the filtrate after the test. 
Example 1 
145 g of deionized water was put in a 1-liter four-necked flask provided 
with a thermometer, a stirrer and a reflux condenser, and stirring was 
continued at a temperature of 90.degree. C. Titration was carried out for 
270 g of 40% aqueous solution of acrylic acid, 100 g of 3% aqueous 
solution of ammonium persulfate, and 115 g of 15% aqueous solution of 
polyethyleneglycol naphthyletheracrylate (addition product of 
ethyleneglycol of 20 mol). Titration of these solutions was performed at 
the same time, and the polymerization of these monomers was carried out 
for 3.5 hours. After the completion of polymerization, 75 g of 50% aqueous 
solution of sodium hydroxide was added for neutralization to obtain 
water-soluble polymer (1). The results of evaluation of the water-soluble 
polymer (1) are shown in TABLE 1. The water-soluble polymer (1) was 
precipitated with methanol, purified, dried, and dissolved in heavy water 
(D.sub.2 O ) for NMR-analysis. As a result of analysis, the peak of 
polymerizable double bond disappeared, and it was verified that the 
absorption of --CH--CH and --CH.sub.2 -- appeared. NMR spectrum of 
water-soluble polymer obtained in EXAMPLE 1 is shown in FIGS. 1 and 2. 
FIG. 2 is a graph enlargedly showing NMR spectrum corresponding to 7 to 8 
ppm of water-soluble polymer obtained in EXAMPLE 1. 
TABLE 1 
______________________________________ 
EX- EX- 
AMPLE 1 
AMPLE 2 
______________________________________ 
water-soluble monomer (I) 
115 g -- 
15% aqueous solution of 
PEG-naphthyletheracrylate (EO: 20 mol) 
20.5% aqueous solution of 
-- 100 g 
PEG-allylether naphthylether (EO: 25 mol) 
40% aqueous solution of acrylic acid 
270 g -- 
40% aqueous solution of sodium acrylate 
-- -- 
50% aqueous solution of sodium methacrylate 
-- 333 g 
deionized water 145 g 207 g 
3% aqueous solution of (NH.sub.4).sub.2 S.sub.2 O.sub.8 
100 g -- 
3% aqueous solution of (NH.sub.4).sub.2 S.sub.2 O.sub.8 
-- 60 g 
50% aqueous solution of NaOH 
75 g -- 
weight-average molecular weight 
20,000 15,000 
polymerization rate (weight %) 
98 97 
ratio of fluorescence intensity (FL.sub.1 /FL.sub.2) 
25 18 
degree of gelation 0.06 0.08 
corrosion rate, mdd (mg/dm.sup.2 /day) 
28 39 
scale inhibiting rate (%) 
95 98 
______________________________________ 
N.B. PEG is the abbreviation of polyethyleneglycol, and EO is the 
abbreviation of ethyleneoxide. 
Example 2 
207 g of deionized water was put in a four-necked flask for polymerization 
similar to that used in EXAMPLE 1. 25 mol of ethyleneoxide was 
additionally reacted to naphthol with sodium hydroxide as a catalyst, and 
then reacted with the same equivalent of allylalcohol to obtain 
polyethyleneglycol allylethernaphthylether. Then, titration was carried 
out for 100 g of 20.5% aqueous solution of polyethyleneglycol 
allylethernaphthylether, 333 g of 50% aqueous solution of sodium 
methacrylate, and 60 g of 5% aqueous solution of ammonium persulfate. 
Titration of these solutions was performed at the same time for 3.5 hours 
for polymerization to obtain water-soluble polymer (2). The results of 
evaluation of the water-soluble polymer (2) are shown in TABLE 1. 
Example 3 
135 g of deionized water was put in a 1-liter four-necked flask provided 
with a thermometer, a stirrer and a reflux condenser, and stirring was 
continued at a temperature of 100.degree. C. Titration was carried out for 
350 g of 40% aqueous solution of acrylic acid, 70 g of 40% aqueous 
solution of allyloxy-2-hydroxy propane sodium sulfonate, 100 g of 7% 
aqueous solution of ammonium persulfate, and 150 g of 18.5% aqueous 
solution of polyethyleneglycol naphthyletheracrylate (addition product of 
ethyleneglycol of 30 mol). Titration of these solutions was performed at 
the same time for 3.5 hours for polymerization. After the completion of 
polymerization, 140 g of 48% aqueous solution of sodium hydroxide was 
added for neutralization to obtain water-soluble polymer (3). The results 
of evaluation of the water-soluble polymer (3) are shown in TABLE 2. 
Examples 4 to 12 
In a manner similar to EXAMPLE 3, water-soluble polymers (4) to (12) shown 
in TABLEs 2 and 3 were obtained according to EXAMPLEs 4 to 12, and the 
property of these polymers (4) to (12) was evaluated. The results of 
evaluation are shown in TABLEs 2 and 3. 
TABLE 2 
__________________________________________________________________________ 
Ex. 3 
Ex. 4 
Ex. 5 
Ex. 6 
Ex. 7 
Ex. 8 
__________________________________________________________________________ 
water-soluble monomer (I) 
150 g 
150 g 
150 g 
300 g 
-- -- 
18.5% aqueous solution of PEG- 
(0.9) 
(1.0) 
(1.2) 
(2.8) 
naphthyletheracrylate (EO: 30 mol) 
35% aqueous solution of PEG- 
-- -- -- -- 400 g 
-- 
naphthyletheracrylate (EO: 20 mol) 
(11.3) 
25% aqueous solution of N- 
-- -- -- -- -- 150 g 
polyoxyethylene carbazole acrylate (1.2) 
(EO: 20 mol) 
40% aqueous solution of acrylic acid 
350 g 
270 g 
205 g 
200 g 
-- 270 g 
(93) 
(84) 
(73.9) 
(87.2) 
80% aqueous solution of acrylic acid 
-- -- -- -- 80 g 
150 g 
(77.5) 
(91.8) 
40% aqueous solution of HAPS 
70 g 
145 g 
210 g 
70 g 
70 g 
70 g 
(6.1) 
(15) 
(24.9) 
(10) 
(11.2) 
(7.0) 
deionized water 135 g 
135 g 
135 g 
135 g 
135 g 
300 g 
48% aqueous solution of NaOH 
140 g 
105 g 
80 g 
80 g 
65 g 
120 g 
weight-average molecular weight 
12,000 
7,000 
9,000 
4,000 
3,000 
5,000 
polymerization rate (weight %) 
99 98 97 96 95 98 
ratio of fluorescence intensity 
20 21 21 55 125 13 
(FL.sub.1 /FL.sub.2) 
degree of gelation 
0.006 
0.001 
0.001 
0.017 
0.003 
0.008 
corrosion rate, mdd (mg/dm.sup.2 /day) 
19 9 12 14 11 20 
scale inhibiting rate (%) 
95 96 93 95 92 94 
__________________________________________________________________________ 
N.B. PEG is the abbreviation of polyethyleneglycol, EO is the abbreviation 
of ethyleneoxide, and HAPS is the abbreviation of 3-allyloxy-2-hydroxy 
propane sodium sulfonate. In the TABLE, the unit of numerical value for 
each monomer is mol %. 
TABLE 3 
______________________________________ 
Ex. 9 Ex. 10 Ex. 11 Ex. 12 
______________________________________ 
water-soluble monomer (I) 
100 g 100 g -- -- 
18.5% aqueous solution of PEG- 
(1.9) (2.3) 
phenyletheracrylate (EO: 7 mol) 
18.5% aqueous solution of 
-- -- 150 g -- 
PEG-naphthylether methacrylate (0.9) 
(EO: 30 mol) 
18.5% aqueous solution of 
-- -- -- 150 g 
PEG-naphthylether acrylate (1.2) 
(EO: 30 mol) 
40% aqueous solution of acrylic 
350 g -- 250 g 170 g 
acid (92) (93) (58.8) 
40% aqueous solution of 
-- 350 -- -- 
methacrylic acid (90.6) 
40% aqueous solution of HAPS 
70 g 70 g 70 g 350 g 
(6.1) (7.1) (6.1) (40) 
deionized water 180 g 180 g 180 g 50 g 
48% aqueous solution of NaOH 
140 g 120 g 140 g 70 g 
weight-average molecular weight 
8,000 6,000 5,000 11,000 
polymerization rate (weight %) 
99 98 98 97 
ratio of fluorescence intensity 
5 8 18 20 
(FL.sub.1 /FL.sub.2) 
degree of gelation 
0.007 0.013 0.009 0.019 
corrosion rate, mdd (mg/dm.sup.2 /day) 
22 24 21 125 
scale inhibiting rate (%) 
95 90 94 82 
______________________________________ 
N.B. PEG is the abbreviation of polyethyleneglycol, EO is the abbreviation 
of ethyleneoxide, and HAPS is the abbreviation of 3-allyloxy-2-hydroxy 
propane sodium sulfonate. In the TABLE, the unit of numerical value for 
each monomer is mol %. 
Comparative Example 1 
Into a 500 ml four-necked flask provided with a thermometer, a stirrer and 
a reflux condenser, 18 g of acrylic acid, 2 g of N-vinylcarbazole, and 80 
ml of isopropanol solvent were added. Then, a solution in which 0.25 g of 
thioglycolic acid-2-ethylhexyl was dissolved in 10 ml of isopropanol and a 
solution in which 1 g of t-butylperoxypivalate was dissolved in 10 ml of 
isopropanol were added to perform polymerization in a solution. After the 
completion of solution polymerization, the isopropanol was removed by 
distillation, 48% aqueous solution of sodium hydroxide was added for 
neutralization to obtain water-soluble polymer (13). The results of 
evaluation of the property of this water-soluble polymer (13) are shown in 
TABLE 4. 
TABLE 4 
______________________________________ 
COM- 
COMATIVE 
ATIVE 
EXAMPLE 1 EXAMPLE 2 
______________________________________ 
product obtained by polymerization 
18g of acrylic 
in solution using acrylic acid and N- 
acid, 2g of N- 
vinylcarbazole vinylcarbazole 
product obtained by polymer 1g of poly- 
reaction of 6-amino-7- maleic acid, 
hydroxy-4-methylcoumarin in 19.1mg of 6- 
aqueous solution of polymaleic acid 
amino-7-hy- 
droxy-4- 
methyl- 
coumarin 
weight-average molecular weight 
5,000 5,000 
polymerization rate (weight %) 
89 -- 
ratio of fluorescence intensity 
14 2 
(FL.sub.1 /FL.sub.2) 
degree of gelation 
0.20 0.55 
scale inhibiting rate (%) 
45 60 
______________________________________ 
Comparative Example 2 
1 g for solid concentration of aqueous solution of polymaleic acid having 
the number-average molecular weight of 5000 was added, and pH was adjusted 
at 4.7 with the addition of aqueous solution of sodium hydroxide. 19.1 mg 
of 6-amino-7-hydroxy-4-methylcoumarin was reacted to polymaleic acid with 
0.02 g of dehydration to synthesize water-soluble polymer (14) exhibiting 
fluorescence. The results of evaluation of the property of this polymer 
(14) are shown in TABLE 4. 
As shown in TABLEs 1 to 3, the inventive water-soluble polymer has a large 
ratio of intensity of fluorescence, and is excellent in gelation 
resistance, scale inhibiting rate, and in corrosion inhibiting ability. On 
the contrary, as shown in TABLE 4, COMATIVE EXAMPLE 1 in which the 
water-soluble polymer is synthesized by polymerization in a solution shows 
poor performance in gelation resistance, scale inhibiting rate, and 
corrosion inhibiting ability. Also, COMATIVE EXAMPLE 2 in which the 
water-soluble polymer obtained through polymer reaction shows poor 
performance in gelation resistance and scale inhibiting rate compared to a 
preferred example according to the present invention. 
Effect of the Invention 
The inventive agent for water treatment is obtainable by synthesizing 
water-soluble polymer in an aqueous system with the use of water-soluble 
monomer exhibiting fluorescence. Accordingly, eliminated is a cumbersome 
process of removing an organic solvent by distillation when polymerization 
is performed with an organic solution. In addition, it is also 
advantageous in the aspect of environment, preventing a fire, cost 
performance and saving natural resources. Fluorescent substances can be 
introduced to water-soluble polymer in a specified amount by adopting the 
aqueous system polymerization. This is advantageous in measuring the 
concentration of water-soluble polymer easily, speedy and accurately and 
in remarkably improving the accuracy of measuring the concentration of 
polymer in water. 
It should be appreciated that the use of fluorescent water-soluble monomer 
having a nonionic oxyalkylene chain is effective in suppressing the degree 
of gelation and in greatly enhancing the ability of inhibiting scale 
formation and corrosion. In particular, the use of HAPS and monomer having 
carboxyl group together with water-soluble monomer exhibiting fluorescence 
as a monomer component for water-soluble polymer is more effective in 
lowering the degree of gelation and in obtaining an agent for water 
treatment excellent in inhibiting scale formation and corrosion. 
Accordingly, the inventive agent for water treatment is advantageously 
usable as an agent for inhibiting scale formation and corrosion, and an 
agent for dispersing sludge, flocculant, and the like.