U.S. patent application number 10/234883 was filed with the patent office on 2003-04-03 for inhibiting metallic corrosion in aqueous systems.
Invention is credited to Ghosh, Tirthankar, Hann, William M., Weinstein, Barry.
Application Number | 20030063999 10/234883 |
Document ID | / |
Family ID | 23228642 |
Filed Date | 2003-04-03 |
United States Patent
Application |
20030063999 |
Kind Code |
A1 |
Ghosh, Tirthankar ; et
al. |
April 3, 2003 |
Inhibiting metallic corrosion in aqueous systems
Abstract
The use of polymeric corrosion inhibiting compositions
incorporating heterocyclic groups is disclosed. The polymers form a
protective barrier on metallic components to aqueous systems and
remain substantive on metallic surfaces over a wide pH range.
Moreover, the polymers are resistant to oxidizing biocides, and are
substantially impervious to repeated or prolonged exposure to
corrosive agents.
Inventors: |
Ghosh, Tirthankar; (Oreland,
PA) ; Hann, William M.; (Gwynedd, PA) ;
Weinstein, Barry; (Dresher, PA) |
Correspondence
Address: |
ROHM AND HAAS COMPANY
PATENT DEPARTMENT
100 INDEPENDENCE MALL WEST
PHILADELPHIA
PA
19106-2399
US
|
Family ID: |
23228642 |
Appl. No.: |
10/234883 |
Filed: |
September 4, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60316340 |
Sep 4, 2001 |
|
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Current U.S.
Class: |
422/16 ; 252/390;
422/28 |
Current CPC
Class: |
C23F 11/173 20130101;
C08F 22/40 20130101 |
Class at
Publication: |
422/16 ; 422/28;
252/390 |
International
Class: |
C23F 011/14 |
Claims
What is claimed is:
1. A process for inhibiting corrosion of metallic components in
contact with an aqueous system comprising the step of adding to the
system an effective amount of one or more polymers comprising: i)
at least one repeating unit selected from a functionalized imide
component of Formula Ia, a functionalized amide component of
Formula Ib and combinations of Ia and Ib: 3wherein n is 0 or 1; R
and R.sub.1 are independently selected from the group consisting of
hydrogen, methyl, and C.sub.2-C.sub.4 alkyl; a heterocycle
comprising unsaturated or aromatic heterocycles having one or more
hetero atoms selected from the group N, O, S and combinations
thereof, the heterocycle chemically bonded to a nitrogen atom via a
hetero atom which is part of the heterocycle or a carbon atom of
the heterocycle; R.sub.3 is selected from the group consisting of
hydrogen, methyl, ethyl, C.sub.3-C.sub.18 branched and straight
chain, alkyl and alkenyl groups; and R.sub.4 is selected from the
group consisting of H, CH.sub.3, C.sub.2H.sub.5, C.sub.6H.sub.5 and
C.sub.3-C.sub.18 branched and straight chain alkyl groups and
C.sub.3-C.sub.18 alkenyl groups; ii) at least one ethylenically
unsaturated monomer component selected from maleic anhydride,
itaconic anhydride, cyclohex-4-enyl tetrahydrophthalic anhydride,
and monomers of Formula II: Formula II CH(R5)=C(R6)(R7) wherein
R.sub.5 is selected from hydrogen, phenyl, methyl, ethyl,
C.sub.3-C.sub.18 branched and straight chain alkyl and alkenyl
groups; R.sub.6 is independently selected from hydrogen, methyl,
ethyl, phenyl, C.sub.3-C.sub.18 branched and straight chain alkyl
and alkenyl groups, OR.sub.8 and CH.sub.2OR.sub.8 groups wherein
R.sub.8 is acetate, glycidyl, methyl, ethyl, C.sub.3-C.sub.18
branched and straight chain alkyl and alkenyl groups, and groups
having the formula [CH.sub.2CH(R.sub.a)O].sub.mR.sub.b wherein
R.sub.a is hydrogen, methyl, ethyl, and phenyl, m is an integer
from 1-20 and R.sub.b is independently hydrogen, methyl, ethyl,
phenyl and benzyl; and R.sub.7 is independently selected from H,
CH.sub.3, C.sub.2H.sub.5, CN, a COR.sub.9 group wherein R.sub.9 is
OH, NH.sub.2, OR.sub.8 group wherein R.sub.8 is a group described
previously and a NR.sub.cR.sub.d group wherein R.sub.c and R.sub.d
are the same group or different groups, are parts of a 5-membered
or 6-membered ring system, hydrogen, hydroxymethyl, methoxy methyl,
ethyl and C.sub.3-C.sub.18 branched and straight chain alkyl and
alkenyl groups branched and straight chain alkyl and alkenyl
groups; and iii) optionally one or more end groups selected from
initiator fragments, chain transfer fragments, solvent fragments
and combinations thereof.
2. The process according to claim 1, wherein the weight average
molecular weight of the polymer is from 400 to 20,000 and the pH of
the aqueous system is from 6 to 10.
3. The process according to claim 1, wherein the amount of polymer
added to the aqueous system is from 1 to 500 ppm, based on the
weight of the aqueous system.
4. The process according to claim 1, wherein the polymer is added
to the aqueous system on a periodic or a continuous basis.
5. The process according to claim 1, wherein the polymer is added
to the aqueous system as formulation with one or more additives
selected from the group consisting biocidal compositions, corrosion
inhibitor compositions known in the art, scale inhibiting
compositions, dispersants, defoamers, inert fluorescent tracers and
combinations thereof.
6. The process according to claim 1, wherein the polymer comprises
a functionalized imide component of Formula 1a selected from
succinimide, glutarimide and combinations thereof; wherein the
heterocycle is selected from the group consisting of imidazole,
thiophene, pyrrole, oxazole, thiazoles and their respective
isomers, substituted thiazoles and their respective isomers,
pyrazole, tetrazole, pyridine, pyridazine, pyrimidine, pyrazine,
triazoles and their respective isomers and combinations thereof;
and wherein the ethylenically unsaturated monomer component is
selected from the group consisting of maleic anhydride, itaconic
anhydride, cyclohex-4-enyl tetrahydrophthalic anhydride, ethylene,
propylene, butylene, isobutylene, di-isobutylene, propylene
tetramer (C.sub.12-C.sub.14), propylene dimer trimer
(C.sub.18-C.sub.22), 1-butene, 1-octene, 1-decene; styrene,
.alpha.-methyl styrene, hydroxy styrene, styrene sulfonic acid,
butadiene; vinyl acetate, vinyl butyrate, vinyl esters, vinyl
chloride, vinylidene chloride, stilbene, divinyl benzene,
(meth)acrylic acid, C.sub.3-C.sub.18 (meth)acrylate esters,
C.sub.3-C.sub.18 (meth)acrylamides and (meth)acrylonitrile.
7. The process according to claim 1 wherein one or more of the
polymers is of formula III: (A)x(B)y(C)z wherein A is an optional
end group component selected from initiator fragments, chain
transfer fragments, solvent fragments and combinations thereof;
wherein B is a functionalized imide component of Formula Ia, a
functionalized amide component of Formula Ib and combinations of Ia
and Ib; wherein C is an ethylenically unsaturated monomer component
selected from maleic anhydride, itaconic anhydride, cyclohex-4-enyl
tetrahydrophthalic anhydride, and monomers of Formula II; and
wherein x, y, z are integers values chosen such that (y+z)/x is
greater than 2.
8. The polymer according to claim 7 wherein A is selected from the
group consisting of dialkyl peroxides, alkyl hydroperoxides,
n-dodecyl isopropyl alcohol, alkyl phosphonates, alkyl phosphites,
aryl phosphinic acids, alkyl phosphinic acids, hypophosphites,
aldehydes, formates, toluene, xylenes, C.sub.9-C.sub.10
alkylaromatics, and Aromatic 100; wherein the heterocycle attached
to B is selected from the group consisting of imidazole, triazole
and their respective isomers, thiophene, pyrrole, oxazole,
thiazoles and their respective isomers, pyrazole, substituted
thiazoles and their respective isomers, tetrazole, pyridine,
pyridazine, pyrimidine, pyrazine, and combinations thereof; and
wherein C is selected from the group consisting of maleic
anhydride, itaconic anhydride, cyclohex-4-enyl tetrahydrophthalic
anhydride, ethylene, propylene, butylene, isobutylene,
di-isobutylene, propylene tetramer (C.sub.12-C.sub.14), propylene
dimer trimer (C.sub.18-C.sub.22), 1-butene, 1-octene, 1-decene;
styrene, cc-methyl styrene, hydroxy styrene, styrene sulfonic acid,
butadiene; vinyl acetate, vinyl butyrate, vinyl esters, vinyl
chloride, vinylidene chloride, stilbene, divinyl benzene,
(meth)acrylic acid, C.sub.3-C.sub.18 (meth)acrylate esters,
C.sub.3-C.sub.18 (meth)acrylamides and (meth)acrylonitrile.
9. The process according to claim 1 wherein one or more of the
polymers is of formula IV: Formula IV (A)x(B)y(B')z wherein A is an
end group selected from initiators fragments, chain transfer
fragments, solvent fragments and combinations thereof; wherein B is
a functionalized imide component of Formula Ia selected from
succinimide, glutarimide and combinations thereof; wherein B'
includes at least one unit selected from a functionalized imide
component or a functionalized amide component selected from
succinimide, glutarimide and combinations thereof, wherein the
nitrogen atom of each component of B' is chemically bonded to a
group selected from C.sub.1-C.sub.18 branched or straight chain
alkyl, C.sub.1-C.sub.18 alkyl or alkenyl substituted aryl, which is
in turn chemically bonded to a pendant functional group selected
from an amine group, amide group, carboxylic acid group, alcohol
group or a group having the formula
[CH.sub.2CH(R.sub.a)O].sub.mR.sub.b wherein R.sub.a is hydrogen,
methyl, ethyl, and phenyl, m is an integer from 2-20 and R.sub.b is
independently hydrogen, methyl, ethyl, phenyl and benzyl; and
wherein x, y, z are integers values chosen such that (y+z)/x is
greater than 2.
10. The process according to claim 9 wherein the group attached to
B' is an C.sub.1-C.sub.18 branched or straight chain alkyl amine
and the pendant heterocycle attached to B is selected from the
group consisting of imidazole, triazole and their respective
isomers, thiophene, pyrrole, oxazole, thiazoles and their
respective isomers, pyrazole, substituted thiazoles and their
respective isomers, tetrazole, pyridine, pyridazine, pyrimidine,
pyrazine, and combinations thereof.
Description
[0001] The present invention relates to a process for inhibiting
corrosion of metallic components in contact with aqueous and
non-aqueous systems. More particularly, the invention is directed
to introducing oligomeric and polymeric compositions as fluid
additives in aqueous systems that are effective corrosion
inhibitors over a wide range of pH and render metals passive to
repeated attack by oxidants and oxidizing biocides. In addition,
the invention relates to a process for applying anti-corrosive
coatings to metallic components.
[0002] Metallic components used in industrial processes and heating
ventilation and air conditioning (HVAC) operations that are in
contact with fluid media such as, for example, cooling water
experience three major problems: metal corrosion, deposition of
solids and the growth of microorganisms. The three problems are
interrelated in that the ability to control one problem often
influences the ability to effectively control the remaining
problems. The most common method to address the problems is to add
a combination of chemical agents and corrosion inhibitors to the
fluid media in contact with the metallic components. Polymeric
dispersants and phosphonates are commonly used to inhibit the
deposit of solids referred to as scale. Biocidal compositions, in
particular oxidizing biocides such as chlorine or bromine, are
often used to control the deposition and growth of microorganisms.
The most challenging problem in the development of new
anti-corrosive compositions is providing effective chemical agents
which inhibit corrosion and which do not produce an adverse
environmental impact themselves or upon treatment with oxidizing
biocides.
[0003] Corrosion may be defined as the gradual weight loss of a
metallic component through some chemical process or series of
chemical reactions. Metals in contact with aqueous systems such as
sea water, fresh water and brackish water and exposed to oxidants
contained therein such as chlorine, acid, bleach, caustic and
dissolved oxygen are prone to corrosion. Metal alloys using more
corrosion resistant metals (e.g. Ti, Cr, Ni) are one means of
improving corrosion resistance. However, such alloys are costly,
difficult to process and manufacture, and experience problems with
corrosion at joints, welds, and under repeated exposure to
corrosive agents. Inorganic compositions such as chromates,
phosphates or zinc compositions and organic compositions such as
tolyltriazole (TTA) and benzotriazole (BZT) are corrosion
inhibitors applied to metals or added to fluids in contact with
metallic components which inhibit or slow down the rate of metal
corrosion. Azoles, for example, are film forming compositions that
adsorb to metallic surfaces and provide a barrier to contact with
an aqueous system. The effectiveness of a particular composition is
usually a trade off of its anti-corrosion properties as compared to
its inherent limitations such as cost, long term performance and
environmental impact. Since metal corrosion occurs under a variety
of environmental conditions, specific inhibitor compositions have
been developed to provide corrosion resistance for specific
situations.
[0004] A common corrosion inhibitor for metals such as copper and
its alloys are film forming azoles such as tolyltriazole (TTA) and
benzotriazole (BZT). TTA has been usefully employed as a corrosion
inhibitor for metallic components manufactured from copper and
copper alloys. When such metals, protected with TTA films, are
exposed to oxidizing biocides such as chlorine, however, the
corrosion protection breaks down. After film breakdown, it is
difficult to form new protective films in TTA treated aqueous
systems that are periodically or continuously chlorinated. Very
high dosages of TTA are frequently applied in an attempt to improve
performance, often with limited success. Other problems associated
with combining triazoles and oxidizing biocides in aqueous systems
include by-products that are less effective corrosion inhibitors,
by products which are volatile and that have objectionable odors
and halogen containing by products that are toxic to the
environment if released from the aqueous system. Moreover, it is
believed that the decomposition product of TTA may be more toxic
than TTA, which itself is toxic to fish populations. Under the
conditions found in cooling water treatment equipment, the
decomposition product of TTA is believed to be an N-chlorinated
compound, which is relatively volatile and susceptible to removal
by stripping in the cooling tower, further reducing the levels of
corrosion inhibitor and oxidizing biocide in the system.
[0005] When copper containing metals corrode, excessive
concentrations of copper are released and subsequently discharged
in to rivers that often serve as reservoirs of cooling water. The
toxic effects of copper on fish populations and other organisms in
aqueous ecosystems is well established. In addition, excessive
concentrations of copper ions can redeposit on mild steel
components, setting up a galvanic oxidation-reduction couple
leading to severe metal pitting.
[0006] U.S. Pat. No. 4,282,007 discloses a corrosion inhibiting
additive for a fuel composition, which is the reaction product of a
C.sub.15-C.sub.30 hydrocarbyl succinic acid anhydride and
aminotriazole. However, such fuels contain acidic contaminants from
alcohols and the additives are only effective at inhibiting
corrosion of metal surfaces exposed to acidic conditions.
Accordingly, it would be desirable to provide alternative methods
of inhibiting metallic corrosion in aqueous systems that
incorporate corrosion inhibitors that are effective over a wide
range of pH, that are resistant to oxidizing biocides and that have
minimal environmental impact.
[0007] The inventors recognized a need to provide corrosion
inhibiting compositions having substantive film forming ability
that are effective over a wide pH range in aqueous or non-aqueous
systems, that are resistant to oxidizing biocides and that can
withstand repeated and prolonged chemical attack by corrosive
agents such as chlorine. The inventors discovered polymeric
corrosion inhibiting compositions that are products of reactions
between anhydrides and heterocycles which are surprisingly
effective copper corrosion inhibitors and remain substantive on
metallic surfaces over a wide pH range in aqueous and non-aqueous
systems, are resistant to oxidizing biocides, and are substantially
impervious to repeated or prolonged exposure to corrosive
agents.
[0008] The present invention provides a process for inhibiting
corrosion of metallic components in contact with an aqueous system
comprising the step of adding to the system an effective amount of
one or more polymers comprising at least one repeating unit
selected from a functionalized imide component of Formula Ia, a
functionalized amide component of Formula Ib and combinations of
Formulas Ia and Ib: 1
[0009] wherein n is 0 or 1; R and R.sub.1 are independently
selected from hydrogen, methyl, and C.sub.2-C.sub.4 alkyl; a
heterocycle which comprises unsaturated or aromatic heterocycles
having one or more hetero atoms selected from N, O, S and
combinations thereof, the heterocycle chemically bonded to a
nitrogen atom of Formula 1a or 1b via a hetero atom which is part
of the heterocycle or a carbon atom of the heterocycle; R.sub.3 is
selected from hydrogen, methyl, ethyl, C.sub.3-C.sub.18 branched
and straight chain, alkyl and alkenyl groups; and R.sub.4 is
selected from H, CH.sub.3, C.sub.2H.sub.5, C.sub.6H.sub.5 and
C.sub.3-C.sub.18 branched or straight chain alkyl and alkenyl
groups.
[0010] Accordingly, the present invention provides a process for
inhibiting corrosion of metallic components in contact with an
aqueous system comprising the step of adding to the system an
effective amount of corrosion inhibiting polymer comprising:
[0011] i) at least one repeating unit selected from a
functionalized imide component of Formula Ia, a functionalized
amide component of Formula Ib and combinations of Ia and Ib;
[0012] ii) at least one ethylenically unsaturated monomer component
selected from maleic anhydride, itaconic anhydride, cyclohex-4-enyl
tetrahydrophthalic anhydride, and monomers of Formula II:
[0013] Formula II
CH(R5)=C(R6)(R7)
[0014] wherein R.sub.5 is selected from hydrogen, phenyl, methyl,
ethyl, C.sub.3-C.sub.18 branched and straight chain alkyl and
alkenyl groups; R.sub.6 is independently selected from hydrogen,
methyl, ethyl, phenyl, C.sub.3-C.sub.18 branched and straight chain
alkyl and alkenyl groups, OR.sub.8 and CH.sub.2OR.sub.8 groups
wherein R.sub.8 is acetate, glycidyl, methyl, ethyl,
C.sub.3-C.sub.18 branched and straight chain alkyl and alkenyl
groups, and groups having the formula
[CH.sub.2CH(R.sub.a)O].sub.mR.sub.b wherein R.sub.a is hydrogen,
methyl, ethyl, and phenyl, m is an integer from 1-20 and R.sub.b is
independently hydrogen, methyl, ethyl, phenyl and benzyl; and
R.sub.7 is independently selected from H, CH.sub.3, C.sub.2H.sub.5,
CN, a COR.sub.9 group wherein R.sub.9 is OH, NH.sub.2, OR.sub.8
group wherein R.sub.8 is a group described previously and a
NR.sub.cR.sub.d group wherein R.sub.c and R.sub.d are the same
group or different groups, are parts of a 5-membered or 6-membered
ring system, hydrogen, hydroxymethyl, methoxy methyl, ethyl and
C.sub.3-C.sub.18 branched and straight chain alkyl and alkenyl
groups branched and straight chain alkyl and alkenyl groups;
and
[0015] optionally one or more end groups selected from initiator
fragments, chain transfer fragments, solvent fragments and
combinations thereof.
[0016] Alternatively, the present invention provides a process for
inhibiting corrosion of metallic components in contact with an
aqueous system comprising the step of adding to the system an
effective amount of corrosion inhibiting polymer of formula
III:
[0017] Formula III
(A)x(B)y(C)z
[0018] wherein A is an optional end group component selected from
initiator fragments, chain transfer fragments, solvent fragments
and combinations thereof; wherein B is a functionalized imide
component of Formula Ia, a functionalized amide component of
Formula Ib and combinations of Ia and Ib; wherein C is an
ethylenically unsaturated monomer component selected from maleic
anhydride, itaconic anhydride, cyclohex-4-enyl tetrahydrophthalic
anhydride, and monomers of Formula II; and wherein x, y, z are
integers values chosen such that (y+z)/x is greater than 2.
[0019] The present invention also provides a process for inhibiting
corrosion of metallic components in contact with an aqueous system
comprising the step of adding to the system an effective amount of
one or more polymers of Formula III:
[0020] Formula III
(A)x(B)y(C)z
[0021] wherein A is an end group component selected from initiator
fragments, chain transfer fragments, solvent fragments and
combinations thereof; wherein B is a functionalized imide component
of Formula Ia, a functionalized amide component of Formula Ib and
combinations of Ia and Ib; wherein C is an ethylenically
unsaturated monomer component selected from maleic anhydride,
itaconic anhydride, cyclohex-4-enyl tetrahydrophthalic anhydride,
and monomers of Formula II; and wherein x, y, z are integers values
chosen such that (y+z)/x is greater than 2.
[0022] The present invention also provides a process for inhibiting
corrosion of metallic components in contact with an aqueous system
comprising the step of adding to the system an effective amount of
one or more polymers comprising:
[0023] i) one or more end groups selected from initiator fragments,
chain transfer fragments, solvent fragments and combinations
thereof;
[0024] ii) at least one repeating unit selected from a
functionalized imide component of Formula Ia, a functionalized
amide component of Formula Ib and combinations of Ia and Ib;
and
[0025] iii) at least one unit selected from a functionalized imide
component or a functionalized amide component selected from
succinimide, glutarimide and combinations thereof, wherein the
nitrogen atom of each component of B' is chemically bonded to a
group selected from C.sub.1-C.sub.18 branched or straight chain
alkyl, C.sub.1-C.sub.18 alkyl or alkenyl substituted aryl, which is
in turn chemically bonded to a pendant functional group selected
from an amine group, amide group, carboxylic acid group, alcohol
group or a group having the formula
[CH.sub.2CH(R.sub.a)O].sub.mR.sub.b wherein R.sub.a is hydrogen,
methyl, ethyl, and phenyl, m is an integer from 2-20 and R.sub.b is
independently hydrogen, methyl, ethyl, phenyl and benzyl.
[0026] Alternatively, the present invention also provides a process
for inhibiting corrosion of metallic components in contact with an
aqueous system comprising the step of adding to the system an
effective amount of one or more polymers of Formula IV:
[0027] Formula IV
(A)x(B)y(B')z
[0028] wherein A is an end group selected from initiators
fragments, chain transfer fragments, solvent fragments and
combinations thereof; wherein B is a functionalized imide component
of Formula Ia selected from succinimide, glutarimide and
combinations thereof; wherein B' includes at least one unit
selected from a functionalized imide component or a functionalized
amide component selected from succinimide, glutarimide and
combinations thereof, wherein the nitrogen atom of each component
of B' is chemically bonded to a group selected from
C.sub.1-C.sub.18 branched or straight chain alkyl, C.sub.1-C.sub.18
alkyl or alkenyl substituted aryl, which is in turn chemically
bonded to a pendant functional group selected from an amine group,
amide group, carboxylic acid group, alcohol group or a group having
the formula [CH.sub.2CH(R.sub.a)O].sub.mR.sub.b wherein R.sub.a is
hydrogen, methyl, ethyl, and phenyl, m is an integer from 2-20 and
R.sub.b is independently hydrogen, methyl, ethyl, phenyl and
benzyl; and wherein x, y, z are integers values chosen such that
(y+z)/x is greater than 2.
[0029] The present invention also provides a process for inhibiting
corrosion of metallic components in contact with an aqueous system
comprising the step of adding to the system an effective amount of
a corrosion inhibiting formulation including one or more corrosion
inhibiting polymer compositions and one or more additives selected
from the group consisting of biocidal compositions, corrosion
inhibiting compositions different from those of the present
invention, scale inhibiting compositions, dispersants, defoamers,
inert tracers and combinations thereof.
[0030] Accordingly, the present invention provides a process for
inhibiting corrosion of metallic components used in the manufacture
of equipment associated with aqueous and non-aqueous systems that
require corrosion protection. "Aqueous system" refers to any system
containing metallic components which contain or are in contact with
aqueous fluids on a periodic or continuous basis. The term "aqueous
fluids" refers to fluids containing 5 weight percent or more water
and includes water-based fluids. Water based fluids refer to fluids
containing a minimum of 40 percent by weight water, the remainder
being suspended and/or dissolved solids and compounds that are
soluble in water. "Non-aqueous system" refers to any system
containing metallic components which contain or are in contact with
non-aqueous fluids on a periodic or continuous basis. Non-aqueous
fluids may be miscible or immiscible in water.
[0031] Typical aqueous systems include, for example, recirculating
cooling units, open recirculating cooling units that utilize
evaporation as a source of cooling, closed loop cooling units, heat
exchanger units, reactors, equipment used for storing and handling
liquids, boilers and related steam generating units, radiators,
flash evaporating units, refrigeration units, reverse osmosis
equipment, gas scrubbing units, blast furnaces, paper and pulp
processing equipment, sugar evaporating units, steam power plants,
geothermal units, nuclear cooling units, water treatment units,
food and beverage processing equipment, pool recirculating units,
mining circuits, closed loop heating units, machining fluids used
in operations such as for example drilling, boring, milling,
reaming, drawing, broaching, turning, cutting, sewing, grinding,
thread cutting, shaping, spinning and rolling, hydraulic fluids,
cooling fluids, oil production units and drilling fluids. Typical
examples of aqueous fluids include fresh water, brackish water, sea
water, waste water, mixtures of water and salts (known as brines),
mixtures of water and alcohol such as methanol, ethanol and
ethylene glycol, mixtures of water and acids such as mineral acids,
mixtures of water and bases such as caustic and combinations
thereof. Aqueous systems treated using the compositions of this
invention may contain dissolved oxygen or may contain no oxygen.
The aqueous systems may contain other dissolved gases such as, for
example, carbon dioxide, ammonia and hydrogen sulfide.
[0032] In the descriptions that follow, the terms oligomer, polymer
and co-polymer are used. Oligomer refers to compositions produced
by the polymerization of one or more monomer units wherein the
number of monomer units incorporated in the oligomer are between 2
and about 10. Polymer refers to compositions produced by the
polymerization of one or more monomer units with no restriction on
the number of types of monomer units incorporated in the polymer.
Co-polymer refers to compositions produced by the polymerization of
two different monomer units with no restriction on the number of
either monomer units incorporated in the co-polymer.
[0033] The metallic components in contact with the aqueous system
are processed from any metal for which corrosion and/or scaling can
be prevented. Typical examples of metals requiring corrosion
protection are copper, copper alloys, aluminum, aluminum alloys,
ferrous metals such as iron, steels such as low carbon steel,
chromium steel and stainless steel, iron alloys and combinations
thereof.
[0034] Different types of metal corrosion are encountered in
aqueous systems such as, for example, uniform corrosion over the
entire metal surface and localized corrosion such as pitting and
crevice forming. Often, control of localized corrosion may be the
critical factor in prolonging the useful life of the metal
components in contact with the aqueous system. Aqueous systems
containing significant concentrations (also referred to as
"levels") of anions such as chloride and sulfate are prone to both
uniform and localized corrosion. These anions are often present in
the aqueous fluids used in the system. Uniform and localized
corrosion often result in the failure of the metallic components
requiring replacement or extensive repairs and maintenance, both
shutting down operation of the aqueous system. Therefore, the
present invention provides polymeric compositions for inhibiting
corrosion in aqueous systems.
[0035] The corrosion resistant polymer compositions usefully
employed in the present invention are substantially resistant or
impervious to oxidizing biocides including for example oxidants
such as oxygen, ozone and hydrogen peroxide, halogens such as
chlorine, bromine, and iodine, combinations of oxidants such as
NaOCl and alkali salts of Group VII (Group 17 according to the
nomenclature of the International Union of Pure and Applied
Chemists) elements, organic compounds such as hydantinoids,
cyanuric acid derivatives, substituted cyanuric acid derivatives
such as chloro cyanuric acid, alkali and alkaline earth salts of
cyanuric acid and cyanuric acid derivatives, and combinations
thereof. In addition, the anti-corrosive compositions are
substantially resistant or impervious to repeated and prolonged
exposure to corrosive agents including for example chlorine,
bromine, and iodine; hypochlorite and its alkali metal salts such
as sodium hypochlorite; hypochloric acid; chlorous acid; mineral
acids such as hydrochloric acid, sulfuric acid and phosphoric acid;
perchloric acid, basic compounds such as lye, caustics, bleaches,
and ammonia; reducing agents such as sulfides, sulfites and alkali
metal sulfides; and combinations thereof.
[0036] The corrosion inhibiting compositions of the present
invention are effective in highly acidic or basic aqueous systems,
namely, at pH between 0.5 and 14. It is preferred that the
corrosion inhibiting compositions are added to the aqueous systems
at pH between 6 and 10.
[0037] All polymers and corrosion inhibiting polymer compositions
usefully employed in the present invention include at least one
repeating unit selected from a functionalized imide component
having Formula Ia, a functionalized amide component having Formulas
Ib and combinations of Ia and Ib: 2
[0038] Preferably n is 0. Preferably R and R.sub.1 are hydrogen.
Preferably, R.sub.3 is selected from C.sub.3-C.sub.18 branched and
straight chain alkyl groups. Preferably, Preferably, R.sub.4 is
selected from C.sub.3-C.sub.18 branched and straight chain alkyl
groups.
[0039] Suitable heterocycles usefully employed in accordance with
the invention include for example 5 to 7-membered heterocycles
having some degree of unsaturation, aromatic heterocycles having at
least one hetero atom selected from N, O or S atoms and
combinations thereof. The heterocycle is chemically bonded to a
nitrogen atom of the imide or amide component via a hetero atom
which is part of the heterocycle or a carbon atom of the
heterocycle. In addition, suitable heterocycles include for example
5 to 7-membered heterocycles that are fused together to form larger
9 to 14-membered heterocycles having more than one type or
combination of N, O or S atoms, isomers of such heterocycles and
combinations thereof.
[0040] Preferred heterocyclic groups include for example imidazole,
triazole, thiophene, pyrrole, oxazole, azoles, indazoles thiazoles
and their respective isomers such as thiazol-4-yl, thiazol-3-yl,
and thiazol-2-yl, substituted thiazoles and their respective
isomers such as 2-amino thiazol-4-yl, pyrazole, tetrazole,
pyridine, pyridazine, pyrimidine, pyrazine, indazoles, triazoles
and their respective isomers such as 1, 2, 3-triazole,
1,2,4-triazole, and combinations thereof.
[0041] The nitrogen atom constituting the functionalized imide
components and functionalized amide components of B further is
chemically bonded to an atom that constitutes the heterocycle. In
an embodiment wherein the corrosion inhibiting composition is
oligomeric or polymeric, the functionalized imide components and
functionalized amide components are incorporated in to the backbone
of the oligomer or polymer and further include the heterocyclic
group.
[0042] In a separate embodiment, the nitrogen atom constituting the
functionalized imide components and functionalized amide components
of B' is chemically bonded to a group selected from
C.sub.1-C.sub.18 branched or straight chain alkyl, C.sub.1-C.sub.18
alkyl or alkenyl substituted aryl, which is in turn chemically
bonded to a pendant functional group selected from an amine group,
amide group, carboxylic acid group, alcohol group or a group having
the formula [CH.sub.2CH(R.sub.a)O].sub.mR.sub.b wherein R.sub.a is
hydrogen, methyl, ethyl, and phenyl, m is an integer from 2-20 and
R.sub.b is independently hydrogen, methyl, ethyl, phenyl and
benzyl. Preferred examples include C.sub.1-C.sub.25 alkyl amines
such as butyl amine, hexyl amine, octyl amine, decyl amine, dodecyl
amine and stearyl amine; octyl amine; and C.sub.1-C.sub.25 alkyl
amides such as hexyl amide, n-octyl amide, decyl amide and stearyl
amide.
[0043] Accordingly, this invention provides a process for
inhibiting corrosion of metallic components in contact with an
aqueous system comprising the step of adding to the system an
effective amount of a corrosion inhibiting polymer comprising
chemical components A, B and C; wherein A optionally includes one
or more end groups selected from initiator fragments, chain
transfer fragments, solvent fragments and combinations thereof;
wherein B includes at least one repeating unit selected from a
functionalized imide component of Formula Ia, a functionalized
amide component of Formula Ib and combinations of Ia and Ib; and
wherein C represents at least one ethylenically unsaturated monomer
component of Formula II. The components A, B and C are arranged
randomly within the polymer and can be arranged sequentially in
accordance with the invention.
[0044] Component A includes for example any initiator fragment
derived from any initiator useful in initiating free radical
addition polymerization. Such initiator fragments include, but are
not limited to, peroxyesters, such as t-butylperbenzoate,
t-amylperoxybenzoate, t-butylperoxy-2-ethylhexonate,
butylperacatate and t-butylperoxylmaleic acid; dialkylperoxides
such as di-t-butylperoxide, dicumylperoxide and
t-butylcumylperoxide; diacylperoxides such as benzoylperoxide,
lauroylperoxide and acetylperoxide; hydroperoxides such as cumene
hydroperoxides and t-butylhydroperoxide; azo compounds such as
azonitriles, azaamidines, cyclic azoamidines, alkylazo compounds
such as azodi-tert-octane.
[0045] Component A further includes for example end groups
resulting from any chain transfer agent used in controlling the
molecular weight of a free radical polymerization. Suitable chain
transfer agents include but are not limited to alcohols, alkyl and
aromatic thiols, alkyl phosphites, aryl phosphinic acids, alkyl
phosphinic acids, hypophosphites, aldehydes, formates, alkylhalides
and alkyl aromatic such as toluene, xylenes, and C9-10
alkylaromatics such as Aromatic 100.
[0046] Component B refers to more than one of either a
functionalized imide component or a functionalized amide component
having respective Formulas Ia and lb. Preferred B components are
selected from succinimide, glutarimide and combinations thereof.
The nitrogen atom that constitute the imide or amide portion of
component B must be chemically bonded to at least one atom of a
R.sub.2 group which in turn is chemically bonded to a pendant
heterocycle. R.sub.2 groups consisting of 2 to 8 consecutive atoms
between the nitrogen atom of the imide or amide portion of B and
the heterocycle are more preferred. R.sub.2 groups consisting of 3
to 6 consecutive atoms between the imide or amide portion of B and
the heterocycle are most preferred.
[0047] Component C includes ethylenically unsaturated monomers of
Formula III. Examples of suitable monomers include (meth)acrylic
acid, methyl (meth)acrylate, hydroxy (meth)acrylate, 2-hydroxyethyl
acrylate, 2-hydroxy propyl acrylate, butyl (meth)acrylate,
2-ethylhexyl acrylate, decyl acrylate, lauryl (meth)acrylate,
isodecyl (meth)acrylate, hydroxyethyl (meth)acrylate, and
hydroxypropyl (meth)acrylate; cyclic anhydrides such as maleic
anhydride; anhydrides such as itaconic anhydride, and
cyclohex-4-enyl tetrahydrophthalic anhydride; olefins such as
ethylene, propylene, butylene, isobutylene, di-isobutylene,
d-limonene; olefin oligomers such as propylene tetramer
(C.sub.12-C.sub.14) and propylene dimer trimer (C.sub.18-C.sub.22);
.alpha.-olefins such as 1-butene, 1-octene and 1-decene,
1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene,
Gulftene.RTM. 20-24, Gulftene.RTM. 24-28; styrene, and substituted
styrenes such as .alpha.-methyl styrene, .alpha.-methylstyrene,
4-hydroxystyrene, styrene sulfonic acid; butadiene; vinyl acetate,
vinyl butyrate and other vinyl esters; and vinyl monomers such as
vinyl chloride, vinylidene chloride; vinyl ethers such as methyl
vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl
ether, isobutyl vinyl ether; allyl ethers such as allyl ether,
allyl ethyl ether, allyl butyl ether, allyl gylcidyl ether, allyl
carboxy ethyl ether; ethoxy vinyl ethers such as
vinyl-2-(2-ethoxy-ethoxy)ethyl ether, methoxyethoxy vinyl ether,
vinyl acetate, vinyl formamide and vinyl acetamide, stilbene;
divinyl benzene; (meth)acrylic monomers such as (meth)acrylate
esters, (meth)acrylamides, and (meth)acrylonitrile. The use of the
term "(meth)" followed by another term such as acrylate or
acrylamide, as used throughout the disclosure, refers to both
acrylates or acrylamides and methacrylates and methacrylamides,
respectively. Preferred monomers of component C include ethylene,
propylene, isobutylene, di-isobutylene, propylene tetramer
(C.sub.12-C.sub.14), and propylene dimer trimer
(C.sub.18-C.sub.22).
[0048] The corrosion inhibiting compositions usefully employed in
the present invention have weight average molecular weights that
range from 400 to 20,000. More preferred are compositions having
weight average molecular weights that range from 400 to 10,000.
Most preferred are compositions having weight average molecular
weights that range from 400 to 5,000. Weight average molecular
weights of the polymeric compositions were measured by GPC
techniques using styrene as a standard.
[0049] Polymers usefully employed according to the invention can be
prepared by conventional emulsion, solution or suspension
polymerization, including those processes disclosed in U.S. Pat.
No. 4,973,409. Solution polymerization is preferred.
[0050] The polymerization of monomers is performed in a suitable
solvent and in the presence of an initiator. Suitable solvents
include for example water, dioxane, ketones such as
4-methylbutan-2-one, aromatic hydrocarbons such as toluene, xylene
and xylene isomers, alcohols such as methanol and ethanol and
ethers such as dioxane. Suitable reaction initiators include for
example azo(bis)isobutyronitrile (AIBN), organic peroxides such as
benzoyl peroxide, di-t-butyl peroxide, hydroperoxides such as
t-butyl hydroperoxide and t-amyl hydroperoxide, hydrogen peroxide,
sodium perborate, alkali metal persulfates and ammonium
persulfate.
[0051] The corrosion inhibiting polymer compositions are easily
prepared in two steps. The first step includes for example
polymerization of one or more monomers such as maleic anhydride
with one or more ethylenically unsaturated monomer units of C such
as di-isobutylene. The anhydride portion of the resulting
co-polymer is then converted via one or more post polymerization
functionalization reactions such as condensation, amidation,
imidation, or esterification to afford polymer compositions of
Formula 1a or 1b. For example, the anhydride portion of the
resulting co-polymer reacts with one or more heterocycles, such as
an amino triazole or an amino pyridine via a condensation, to
afford polymer compositions of Formula 1a or 1b. Alternatively, the
compositions are easily prepared by polymerizing one or more
functionalized monomer units of B with one or more ethylenically
unsaturated monomer units of C to afford polymer compositions of
Formula 1a or 1b.
[0052] The polymer products of either process for the purpose of
isolation may be subjected to partial or complete evaporation under
reduced pressure. The unpurified reaction products may be used as
the polymer composition of the present invention. The reaction
products may also be purified. The pruification procedure consists
of: a) evaporation of reaction solvent and washing with a water
immiscible organic solvent such as ether, followed by evaporation
of this solvent or b) evaporation of the reaction solvent,
dissolving the polymer product in a suitable solvent and
precipitating the polymer with a suitable non-solvent such as
toluene or xylenes.
[0053] Polar groups incorporated in the polymers from the
heterocyclic groups, the end groups and the amide/imide components
strongly adsorb to metallic surfaces. The polymeric nature of the
compositions coupled with high numbers of polar anchoring groups
provide effective corrosion inhibition for metals and metal alloys
by forming films exhibiting superior barrier properties over a
broader range of pH, while remaining substantially impervious to
corrosive agents present in aqueous systems and maintaining their
anti-corrosive effectiveness over repeated additions of oxidizing
biocides and corrosive agents such as chlorine for extended time
periods.
[0054] The corrosion inhibiting polymer compositions of the
invention have the following advantages: improved chlorine
resistance, low toxicity and environmental impact as compared to
azoles such as TTA and BZT, a wide range of pH stability,
formulated in safe and cost effective manner and are detected and
monitored at ppm concentrations (also referred to as traceability).
Improved chlorine resistance results in lower concentrations of
metal ions such Cu.sup.2+ discharged in to the aqueous system in
compliance with EPA regulatory discharge restrictions, reduced
galvanic corrosion, increased useful life of metallic components,
reduced levels of polymer required for corrosion protection and
elimination of odors associated with azoles. The low toxicity of
the polymer compositions results in a lowered environmental impact
as evidenced by relatively lower aquatic toxicological profiles.
The polymer composition stability in a wide pH range allows for
reductions or elimination of caustic providing reduced handling and
shipping hazards. The polymers are made from inexpensive,
commercially available monomer feedstocks and are easily formulated
with other biocides, scale inhibitors and any other required
additives known to be useful in treatment of aqueous systems. The
heterocyclic group incorporated in the polymer provides a means to
monitor low concentrations (ppm levels) of the polymer in the
aqueous system via UV-vis absorption or fluorescence techniques,
also referred to as traceability. An inert fluorescent tracer can
also be incorporated in to the polymer as well to determine and
monitor static and dynamic levels of the polymer in the aqueous
system. The traceability of the polymers at ppm levels provides a
means to detect the polymer concentration in the aqueous system and
control the feed or dose rate required, resulting in significant
cost performance. In practice, the amount of polymer compositions
of Formula 1a or 1b used to treat the aqueous system varies
according to the protective function required.
[0055] The polymer compositions of the present invention can
preferably be added to the aqueous system at active amounts ranging
between 0.1 to 50,000 ppm (0.00001 to 5 weight %), preferably from
1 to 500 ppm, most preferably from 1 to 100 ppm, based on the
weight of the aqueous system.
[0056] The polymer compositions of this invention are used to
prepare corrosion inhibiting formulations by combining the polymer
with one or more additives known to be useful in treating aqueous
systems such as for example biocidal compositions, any other
corrosion inhibiting composition known in the art, scale inhibiting
compositions, dispersants, defoamers, inert fluorescent tracers and
combinations thereof.
[0057] To enhance their solubility and compatibility in
formulations and fluid media, the corrosion inhibitors of the
present invention can be formulated with surfactants, defoamers,
co-solvents and hydrotropes or their pH can be altered with
suitable acids or bases. Examples of suitable surfactants include
but are not limited to Rhodafac.RTM. RS 610 or Rhodafac.RTM. RE 610
manufactured by Rhodia, Inc. Examples of suitable defoamers include
but are not limited to GE silicone antifoam AF60. Suitable
co-solvents include for example ethanol, isopropanol, ethylene
glycol and propylene glycol. Suitable hydrotropes include
Monatrope.RTM. 1250A manufactured by Uniqema, and sodium xylene
sulfonate.
[0058] Suitable scale inhibitors include for example polyphosphates
and polycarboxylic acids and copolymers such as described in U.S.
Pat. No. 4,936,987.
[0059] The corrosion inhibitors of the present invention can also
be used with other agents to enhance corrosion inhibition of
copper, aluminum, mild steel, alloys of these and other metals.
Examples of these agents include phosphates or phosphoric acid,
polyphosphates such as tetrapotassium pyrophosphate and sodium
hexametaphosphate, zinc, tolyltriazole, benzotriazole and other
azoles, molybdate, chromate, phosphonates such as
1-hydroxyethylidene-1,1-diphosphonic acid, aminotris(methylene
phosphonic acid), hydroxyphosphonoacetic acid and
2-phosphonobutane-1,2,4-tricarboxylic acid, polymeric corrosion
inhibitors such as poly(meth)acrylic acid or polymaleic acid and
copolymers of acrylic, methacrylic and maleic acid, as well as
their alkali metal and alkaline earth metal salts.
[0060] In addition, the corrosion inhibitors may also be used with
other agents such as scale inhibitors and dispersants. Examples of
these agents include poly(meth)acrylic acid, polymaleic acid,
copolymers of acrylic, methacrylic or maleic acid, phosphonates as
previously described, and chelants such as nitrilotriacetic acid or
ethylenediamine tetraacetic acid, as well as their metal salts. The
agents described may be applied in a single formulation or applied
separately.
[0061] The polymer compositions of the invention are usefully
employed as fluid additives such as coolants, antifreezes, metal
working fluids, lubricants, brake fluids, transmission fluids,
aircraft de-icing fluids, fluids for polishing electronic devices
(e.g. in chemical mechanical planarization (CMP) processes),
soldering additives, anti-abrasive compounds, direct metal
treatment fluids, cleaning agents and detergents for photographic
processes, anti-corrosive coatings, caulks, sealants and pressure
sensitive adhesives in contact with metallic components.
[0062] In a preferred embodiment, corrosion inhibiting compositions
are usefully employeded in accordance with the present invention as
fluid additives in contact with metallic components.
[0063] In an alternative embodiment, the corrosion inhibiting
composition are usefully employed as anti-corrosive coatings by
techniques which are well known in the coatings art. First, if the
composition is an elastomeric coating, caulk, sealant or pressure
sensitive adhesive composition is to be pigmented, at least one
pigment is well dispersed in an aqueous medium under high shear
such as is afforded by a COWLES.RTM. mixer or, for more viscous
compositions such as caulks and sealants, a high intensity mixer or
mill. Then the waterborne polymer is added under lower shear
stirring along with other elastomeric coating, caulk, sealant or
pressure sensitive adhesive adjuvants as desired. Alternatively,
the aqueous emulsion polymer may be included in the pigment
dispersion step. The aqueous composition may contain conventional
elastomeric coating, caulk, sealant or pressure sensitive adhesive
adjuvants such as, for example, tackifiers, pigments, emulsifiers,
coalescing agents, buffers, neutralizers, thickeners or rheology
modifiers, humectants, wetting agents, biocides, plasticizers,
antifoaming agents, colorants, waxes, and anti-oxidants.
[0064] The solids content of the aqueous coating composition may be
from about 10% to about 85% by volume. The viscosity of the aqueous
composition may be from 0.05 to 2000 Pa.s (50 cps to 2,000,000
cps), as measured using a Brookfield viscometer; the viscosities
appropriate for different end uses and application methods vary
considerably.
[0065] The oligomeric and polymeric corrosion inhibiting
compositions may be applied by conventional application methods
such as, for example, brushing and spraying methods such as, for
example, roll coating, dipping doctor-blade application, printing
methods, an aerosol, air-atomized spray, air-assisted spray,
airless spray, high volume low pressure spray, air-assisted airless
spray, caulk guns, and trowels.
[0066] In addition to metals, the polymeric corrosion inhibiting
compositions may be applied to substrates including but not limited
to for example, plastic including sheets and films, wood,
previously painted surfaces, cementitious substrates, asphaltic
substrates or the like, with or without a prior substrate treatment
such as an acid etch or corona discharge or a primer.
[0067] The following examples are presented to illustrate the
invention and the results obtained by the test procedures.
[0068] Abbreviations
[0069] AA=acrylic acid
[0070] BA=butyl acrylate
[0071] MMA=methyl methacrylate
[0072] AN=acrylonitrile
[0073] EHA=2-ethylhexyl acrylate
[0074] DI water=deionized water
EXAMPLES AND COMPARATIVE EXAMPLES
[0075] Preparation of Corrosion Inhibiting Compositions.
Example 1
[0076] Preparation of Polymer Containing Succinic Anhydride and
Diisobutyl Groups (P1).
[0077]
[0078] A 1.8 L reactor was charged with 150.8 g of maleic anhydride
flakes, 485 g of dry reagent grade xylenes, 179.4 g diisobutylene
and 0.3 g of p-toluene sulfonic acid. The reactor was sealed. It
was flushed with nitrogen and a vacuum of-15 psig. was established.
Heating to 160.degree. C. was started and the initiator feed was
prepared by dissolving 27.5 g of di-t-butylperoxide in 90 g of
xylenes. When the reactor temperature had reached 160.degree. C.
the initiator solution was fed for 15 minutes at 2 g/min. Heating
is stopped and the reaction is exothermic to 175.degree. C. and 32
psig. The remaining initiator solution is added at 1 g/min for 85
min. During this time the reactor is maintained at 175-180.degree.
C. with stirring at 160 rpm. After the initiator feed is the
heating is continued for 30 min. The reaction mixture is cooled and
the reactor is drained at room temperature and pressure. This
procedure gives 928 g of solution containing 35.2% solids. This
solution (P1) is used for the functionalization process.
Example 2
[0079] Preparation of Polymer Containing Succinic Anhydride Groups
(P2).
[0080] To a 1-liter, 4-neck flask equipped with mechanical stirrer,
a reflux condenser topped with nitrogen inlet, and a thermocouple,
was added 200 g of maleic anhydride and 200 g of technical grade
xylenes. After flushing the reactor with an inert gas, the contents
are heated to 60.degree. C. to dissolve the maleic anhydride and
then 1.00 g of n-octylamine (NOA) is added. The stirred reactor
contents are heated to reflux (140-145.degree. C.) and 20.0 g of
di-t-butylperoxide (DBP) in 167 g of xylenes is gradually added
over two hours. The solution was maintained under reflux for two
hours. The reactor is modified for vacuum distillation and xylenes
are distilled off to obtain a solution of P2 at the desired
concentration.
Example 3
[0081] Functionalization of P2-synthesis of A.
[0082] To a solution of 50 g of P2 in 45 g dioxane heated to
60.degree. C. is slowly added a solution of 26.2 g of
3-amino-1,2,4-triazole in 30 g of a 1:1 dioxane/methanol mixture.
The reaction is heated at 60.degree. C. for 90 minutes. After
cooling, the reaction mixture is concentrated to 45% solids and the
pH is adjusted to 6 to give A.
Example 4
[0083] Functionalization of P2-synthesis of B.
[0084] To a solution of 40 g of P2 in 30 g dioxane heated to
60.degree. C. is slowly added a slurry of 13.6 g of 3-aminoindazole
in 106 g of dioxane. The reaction is heated at 60.degree. C. for
120 minutes. After cooling, the reaction mixture is concentrated to
50% solids and the pH is adjusted to 7 to give B.
Example 5
[0085] Functionalization of P1-synthesis of C.
[0086] To a solution of 10 g P1 (45% solid) in 30 mL of xylenes, is
slowly added 1.68 g of 3-amino-1,2,4-triazole and the mixture is
heated under reflux for 4 h. The xylene is removed under reduced
pressure, and the crude product is washed with water (3.times.100
mL) to give 5.8 g of C.
Example 6
[0087] Functionalization of P1-synthesis of D and E.
[0088] To a solution of 20 g of P-1 (45% solids) in 20 mL of
xylenes is slowly added 3.36 g of 3-amino-1,2,4-triazole. The
reaction mixture is heated under reflux for 4 h and then allowed to
cool to room temperature. The xylene layer is decanted and the
xylene removed under reduced pressure to obtain 1.1 g of D. The
residue is washed with water on a suction filter to obtain 9.8 g of
E.
Example 7
[0089] Functionalization of P1-synthesis of F and G.
[0090] To 5.0 g of 4(1-H-imidazole-1-yl)-aniline is added slowly a
mixture of 16 g (45% solids) P1 and 16 mL xylene. The reaction
mixture is heated under reflux for 4 hours, then allowed to cool to
room temperature. The xylene layer is decanted and the xylene is
removed under reduced pressure to obtain 2.0 g of F. The
precipitate is dissolved into 300 mL acetone and then the solvents
are removed under reduced pressure to obtain 9.2 g of G.
[0091] Corrosion Resistance Testing
[0092] The following procedure was utilized to determine the
corrosion resistance of the polymer compositions of the invention
under conditions of chlorination. This test places emphasis on the
ability of the corrosion inhibiting polymer compositions to resist
penetration of chlorine through the adsorbed film on a copper
surface.
[0093] Formulation Stock Solution:
[0094] A stock solution was prepared containing 1000 ppm of
phosphoric acid (as PO.sub.4.sup.3-, 1.21 g of 85%
H.sub.3PO.sub.4), 625 ppm of 1-hydroxyethylidene-1,1-disphosphonic
acid (as PO.sub.4.sup.3-, 1.13 g of 60% HEDP, Dequest.RTM. 2010,
Solutia) and 625 ppm of Acumer.RTM. 2000 copolymer supplied at
39.5% actives by Rohm and Haas Company (1.58 g). To complete the
stock solution, water was added to the mixture to afford a total
weight of 998 g. The pH was adjusted to 10.5 and then 1000 ppm
tetrapotassium pyrophosphate (as P.sub.4.sup.3-, 1.74 g of TKPP)
was added. The pH of the final mixture was adjusted to 11.0.
[0095] Polymer Stock Solution:
[0096] Each polymer was prepared as 1000 ppm (as actives) in an
appropriate solvent (water, methanol or isopropanol).
[0097] Preparation of a Test Solution:
[0098] To a container was added the following:
[0099] (a) 125 mL of an aqueous solution containing 500 ppm NaCl,
200 ppm CaCl.sub.2 (as CaCO.sub.3), 100 ppm MgCl.sub.2 (as
CaCO.sub.3), 400 ppm total alkalinity (as CaCO.sub.3), adjusting
the solution to pH 7.0;
[0100] (b) 1 mL of formulation stock solution; and
[0101] (c) 0.38 g of polymer stock solution (resulting in 3 ppm
actives)
[0102] wherein the solution is maintained at pH 7.0.
[0103] Preparation of Test Apparatus:
[0104] Stainless steel reference electrode-sand with 600 grit SiC
paper, rinse with water, rinse with isopropanol, rinse with water,
towel dry.
[0105] 18 gauge copper working electrode-sand with 600 grit SiC
paper, since with the water, rinse with isopropanol, rinse with
water, rinse with acetone then air dry.
[0106] Two stainless steel wires and one copper wire were inserted
into the container containing 125 mL of test solution, anchoring
the wires through a lid on top of the container. The copper wire is
bent into a loop so that the volume/surface area of water to copper
is 264 mL/in.sup.2. The test solution was stirred at 300 rpm at
room temperature for 18 h. After 18 h, 5 ppm NaOCl was added (as
Cl.sub.2). After 30 minutes, corrosion rate was measured as mil per
year (mpy) using an EG&G Princeton Applied Research
Potentiostat/Galvanostat Model 273.
[0107] For test without chlorine, the above procedure was used with
the following conditions substituted where appropriate: NaCl (1000
ppm), Ca/Mg (100 ppm/50 ppm as CaCO.sub.3), volume/surface area 492
mL/in.sup.2, 4 h polymer film formation time (unstirred).
1TABLE I CORROSION INHIBITING COMPOSITIONS AND COMPARATIVE EXAMPLES
mpy mpy (3 ppm) Example Sample (3 ppm) with NaOCl Comparative None
3.42 3.09 Comparative Cobratec 0.05 1.24 TT-100 PMC Comparative
Cobratec 0.02 2.16 99 PMC 3 A -- 5.10 4 B -- 4.01 5 C -- 2.13 6 D
-- 0.88 E -- 2.70 7 F -- 0.50 G -- 2.05
[0108] As Table I shows, the best performance in terms of corrosion
resistance and chlorine resistance was obtained for Examples 6 and
7. The Examples performed better than TTA, BZT with regard to
chlorine resistance (Comparative examples 1 and 2). Overall, most
of the examples were comparable to TTA and BZT in terms of chlorine
resistance, confirming that they are attractive alternatives to TTA
and BZT.
* * * * *