U.S. patent application number 16/397455 was filed with the patent office on 2019-10-24 for green high-efficiency corrosion inhibitor.
This patent application is currently assigned to Baker Hughes, a GE company, LLC. The applicant listed for this patent is Baker Hughes, a GE company, LLC. Invention is credited to Gaurav Agrawal, Abdulaziz Abdulrhman Almathami, Taher Bakr Hafiz, Manuel Hoegerl.
Application Number | 20190323130 16/397455 |
Document ID | / |
Family ID | 61241773 |
Filed Date | 2019-10-24 |
United States Patent
Application |
20190323130 |
Kind Code |
A1 |
Hafiz; Taher Bakr ; et
al. |
October 24, 2019 |
GREEN HIGH-EFFICIENCY CORROSION INHIBITOR
Abstract
A corrosion inhibitor for use in aqueous fluids, e.g. brine,
which contact a metal surface, contains a blend or cross-linked
reaction product of a main chain type polybenzoxazine (MCTPB) and a
chitosan component selected from the group consisting of chitosan,
chitosan glycol, and combinations thereof. The MCTPB can be made by
reacting formaldehyde, bisphenol A, and tetraethylenepentamine
(TEPA). The corrosion inhibitor may contain a small amount of an
inorganic acid and/or an organic acid. Suitable organic acids
include, but are not necessarily limited to organic acid selected
from the group of carboxylic acid consisting of formic acid, acetic
acid, propionic acid, butyric acid, valeric acid, caproic acid,
citric acid, oxalic acid, malic acid, lactic acid, benzoic acid, or
selected from the group of sulfonic acids consisting of
p-toluenesulfonic acid, trifluoromethanesulfonic acid,
2-aminoethanesulfonic acid, alkyl-aryl-sulfonic acids such as
dodecylbenzenesulfonate, polymeric sulfonic acids, fluorinated
derivatives of these organic acids, and combinations thereof.
Inventors: |
Hafiz; Taher Bakr; (Dhahran
City, SA) ; Almathami; Abdulaziz Abdulrhman; (Al
Dammam, SA) ; Agrawal; Gaurav; (Aurora, CO) ;
Hoegerl; Manuel; (Al Khobar, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes, a GE company, LLC |
Houston |
TX |
US |
|
|
Assignee: |
Baker Hughes, a GE company,
LLC
Houston
TX
|
Family ID: |
61241773 |
Appl. No.: |
16/397455 |
Filed: |
April 29, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15246107 |
Aug 24, 2016 |
10316415 |
|
|
16397455 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23F 11/173 20130101;
C23F 11/04 20130101; C09K 2208/32 20130101; C09K 8/54 20130101 |
International
Class: |
C23F 11/04 20060101
C23F011/04; C09K 8/54 20060101 C09K008/54; C23F 11/173 20060101
C23F011/173 |
Claims
1. A corrosion inhibitor for inhibiting or preventing the corrosion
of a metal surface in contact with an aqueous fluid, the corrosion
inhibitor comprising: a blend of main chain type polybenzoxazine
(MCTPB) and a chitosan component selected from the group consisting
of chitosan, chitosan glycol, and combinations thereof; a
cross-linked reaction product of chitosan and MCTPB; and
combinations thereof.
2. The corrosion inhibitor of claim 1 where the weight ratio of
chitosan to MCTPB ranges from about 5 to 1 to about 0.5 to 3.5.
3. The corrosion inhibitor of claim 1 where the weight ratio of
chitosan to MCTPB ranges from about 1.5 to 2.5 to about 0.5 to
1.5.
4. The corrosion inhibitor of claim 1 where the corrosion inhibitor
contains from about 0.01 wt % to about 1 wt %, based on the total
corrosion inhibitor, of an acid selected from the group consisting
of: an organic acid selected from the group of carboxylic acid
consisting of formic acid, acetic acid, propionic acid, butyric
acid, valeric acid, caproic acid, citric acid, oxalic acid, malic
acid, lactic acid, benzoic acid, or selected from the group of
sulfonic acids consisting of p-toluenesulfonic acid,
trifluoromethanesulfonic acid, 2-aminoethanesulfonic acid,
alkyl-aryl-sulfonic acids such as dodecylbenzenesulfonate,
polymeric sulfonic acids, fluorinated derivatives of these organic
acids, and combinations thereof; an inorganic acid selected from
the group consisting of hydrochloric acid, sulfuric acid,
phosphoric acid, and combinations thereof; and combinations
thereof.
5. The corrosion inhibitor of claim 1 where the MCTPB is made by
reacting formaldehyde, bisphenol A, and tetraethylenepentamine
(TEPA).
6. The corrosion inhibitor of claim 5 where the mole ratio of
formaldehyde to bisphenol A to TEPA is about 4:1:1.
7. A corrosion inhibitor for inhibiting or preventing the corrosion
of a metal surface in contact with an aqueous fluid, the corrosion
inhibitor comprising: a blend of main chain type polybenzoxazine
(MCTPB) and a chitosan component selected from the group consisting
of chitosan, chitosan glycol, and combinations thereof; a
cross-linked reaction product of chitosan and MCTPB; from about
0.01 wt % to about 1 wt %, based on the total corrosion inhibitor,
of an acid; and combinations thereof, where the weight ratio of
chitosan to MCTPB ranges from about 5 to 1 to about 0.5 to 3.5.
8. The corrosion inhibitor of claim 7 where the weight ratio of
chitosan to MCTPB ranges from about 1.5 to 2.5 to about 0.5 to
1.5.
9. The corrosion inhibitor of claim 7 where the acid is selected
from the group consisting of: an organic acid selected from the
group of carboxylic acid consisting of formic acid, acetic acid,
propionic acid, butyric acid, valeric acid, caproic acid, citric
acid, oxalic acid, malic acid, lactic acid, benzoic acid, or
selected from the group of sulfonic acids consisting of
p-toluenesulfonic acid, trifluoromethanesulfonic acid,
2-aminoethanesulfonic acid, alkyl-aryl-sulfonic acids such as
dodecylbenzenesulfonate, polymeric sulfonic acids, fluorinated
derivatives of these organic acids, and combinations thereof; an
inorganic acid selected from the group consisting of hydrochloric
acid, sulfuric acid, phosphoric acid, and combinations thereof; and
combinations thereof.
10. The corrosion inhibitor of claim 7 where the MCTPB is made by
reacting formaldehyde, bisphenol A, and tetraethylenepentamine
(TEPA).
11. The corrosion inhibitor of claim 10 where the mole ratio of
formaldehyde to bisphenol A to TEPA is about 4:1:1.
12. A composition comprising: brine; and corrosion inhibitor for
inhibiting or preventing the corrosion of a metal surface in
contact with an aqueous fluid, the corrosion inhibitor comprising:
a blend of main chain type polybenzoxazine (MCTPB) and a chitosan
component selected from the group consisting of chitosan, chitosan
glycol, and combinations thereof; a cross-linked reaction product
of chitosan and MCTPB; and combinations thereof.
13. The composition of claim 12 where the weight ratio of chitosan
to MCTPB in the corrosion inhibitor ranges from about 5 to 1 to
about 0.5 to 3.5.
14. The composition of claim 12 where the weight ratio of chitosan
to MCTPB in the corrosion inhibitor ranges from about 1.5 to 2.5 to
about 0.5 to 1.5.
15. The composition of claim 12 where the corrosion inhibitor
contains from about 0.01 wt % to about 1 wt %, based on the total
corrosion inhibitor, of an acid selected from the group consisting
of: an organic acid selected from the group of carboxylic acid
consisting of formic acid, acetic acid, propionic acid, butyric
acid, valeric acid, caproic acid, citric acid, oxalic acid, malic
acid, lactic acid, benzoic acid, or selected from the group of
sulfonic acids consisting of p-toluenesulfonic acid,
trifluoromethanesulfonic acid, 2-aminoethanesulfonic acid,
alkyl-aryl-sulfonic acids such as dodecylbenzenesulfonate,
polymeric sulfonic acids, fluorinated derivatives of these organic
acids, and combinations thereof; an inorganic acid selected from
the group consisting of hydrochloric acid, sulfuric acid,
phosphoric acid, and combinations thereof; and combinations
thereof.
16. The composition of claim 12 where in the corrosion inhibitor
the MCTPB is made by reacting formaldehyde, bisphenol A, and
tetraethylenepentamine (TEPA).
17. The composition of claim 16 where the mole ratio of
formaldehyde to bisphenol A to TEPA is about 4:1:1.
18. The composition of claim 12 where the amount of corrosion
inhibitor in the brine ranges from about 1 to about 500 ppm.
19. The composition of claim 12 where the brine is selected from
the group consisting of brine used to recover oil and/or gas from a
subterranean formation, brine produced from an oil or gas well,
brine used in the processing of oil and/or gas, and combinations
thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 15/246,107 filed Aug. 24, 2016 and issued as U.S. Pat. No.
______ on ______, 2019, incorporated herein by reference in its
entirety.
TECHNICAL FIELD
[0002] The present invention relates to methods and compositions
for inhibiting and preventing the corrosion of metals in contact
with aqueous fluids; and more particularly relates to methods and
compositions for inhibiting and preventing the corrosion of metals
in contact with brines, which methods include blends with or
reaction products of chitosan.
TECHNICAL BACKGROUND
[0003] During the production life of an oil or gas well, the
production zone within the well is typically subjected to numerous
treatments. Corrosion of metallic surfaces, such as downhole
tubulars, during such treatments is not uncommon and is evidenced
by surface pitting, localized corrosion and loss of metal. Metallic
surfaces subject to such corrosion are carbon steels, ferritic
alloy steels, and high alloy steels including chrome steels, duplex
steels, stainless steels, martensitic alloy steels, austenitic
stainless steels, precipitation-hardened stainless steels and high
nickel content steels.
[0004] Additionally, aqueous fluids, such as those used in drilling
and completion, have a high salt content which causes corrosion.
Such aqueous fluids containing salts are typically called "brines"
and may be intentionally formed or may be naturally formed, such as
the brines which are in the form of produced water that is yielded
along with the oil and gas. Gases, such as carbon dioxide and
hydrogen sulfide, also generate highly acidic environments to which
metallic surfaces become exposed. For instance, corrosion effects
from brine and hydrogen sulfide are seen in flow lines during the
processing of gas streams. The presence of methanol, often added to
such streams to prevent the formation of undesirable hydrates,
further often increases the corrosion tendencies of metallic
surfaces.
[0005] Further, naturally occurring and synthetic gases are often
conditioned with absorbing acidic gases, carbon dioxide, hydrogen
sulfide, and hydrogen cyanide. Degradation of the absorbent and
acidic components as well as the generation of by-products (from
reaction of the acidic components with the absorbent) results in
corrosion of metallic surfaces.
[0006] On occasion, a component within a H.sub.2S scavenger may be
corrosive. An example of this is glyoxal.
[0007] The use of corrosion inhibitors during well treatments to
prevent or inhibit the rate of corrosion on metal components and to
protect wellbore tubular goods is well known. Commercial corrosion
inhibitors are usually mixtures or blends that contain at least one
component selected from nitrogenous compounds, such as amines,
acetylenic alcohols, organic phosphates, carboxylic acids or
reaction products thereof, mutual solvents and/or alcohols,
surfactants, oil derivatives, and inorganic and/or organic metal
salts.
[0008] Many conventional corrosion inhibitors used to reduce the
rate of acid attack on metallic surfaces and to protect the tubular
goods of the wellbore are becoming unacceptable in oilfield
treatment processes. For instance, many conventional corrosion
inhibitors have become unacceptable due to environmental protection
measures that have been undertaken. Further, in some instances,
such as in stimulation processes requiring strong acids, high
temperatures, long duration jobs and/or special alloys, the cost of
corrosion inhibitors may be so high that it becomes a significant
portion of total costs. Thus, there is a need for corrosion
inhibitors to be as efficient as possible.
[0009] It would be desirable to find alternative corrosion
inhibitors which are cost effective and which are capable of
controlling, reducing or inhibiting corrosion. It would also be
desirable if such corrosion inhibitors were "green" that is, were
environmentally friendly, and had little or no environmental
concerns, or which had reduced environmental concerns as compared
with current commercially available corrosion inhibitors.
SUMMARY
[0010] There is provided in one non-restrictive version, a method
for inhibiting or preventing the corrosion of a metal surface in
contact with an aqueous fluid, where the method includes
introducing an effective amount of a corrosion inhibitor into the
aqueous fluid in contact with the metal surface to inhibit or
prevent corrosion of the metal surface. The corrosion inhibitor
includes, but is not necessarily limited to, a blend of main chain
type polybenzoxazine (MCTPB) and a chitosan component selected from
the group consisting of chitosan, chitosan glycol, and combinations
thereof and/or a cross-linked reaction product of chitosan and
MCTPB.
[0011] There is additionally provided in another non-limiting
embodiment a corrosion inhibitor composition for inhibiting or
preventing the corrosion of a metal surface in contact with an
aqueous fluid, where the corrosion inhibitor composition includes,
but is not necessarily limited to, a blend of main chain type
polybenzoxazine (MCTPB) and a chitosan component selected from the
group consisting of chitosan, chitosan glycol, and combinations
thereof and/or a cross-linked reaction product of chitosan and
MCTPB.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a graph of the corrosion inhibition effect of
chitosan/MCTPB blend plotted as corrosion rate in mpy as a function
of the amount of chitosan/MCTPB blend introduced into the brine;
and
[0013] FIG. 2 is a graph of the corrosion efficiency of the
chitosan/MCTPB blend plotted as corrosion efficiency in % as a
function of the amount of chitosan/MCTPB blend introduced into the
brine.
DETAILED DESCRIPTION
[0014] It has been discovered that a bio-based polymer blend or
reaction product of chitosan (CHI) and Main Chain Type
polybenzoxazine (MCTPB) is a green corrosion inhibitor in the
application of preventing or inhibiting the corrosion of
steel/metallic based substrates in the presence of aqueous fluids,
including, but not necessarily limited to, brine, and more
particularly oilfield and refinery aqueous fluids. The blend is
safe and easy to prepare with no strong acid being required and
without the addition of other additives or catalysts. Neither toxic
materials nor undesirable byproducts are generated during the
polymerization and blending of the corrosion inhibitor described
herein. A new, bio-based, green corrosion inhibitor will be
described that in preliminary laboratory testing has shown the
potential to reduce carbon steel corrosion by over 99% when used at
the concentration level of 500 ppm. This new chemistry is based on
bio-based polymer blends or reaction products of chitosan and Main
Chain Type polybenzoxazine (MCTPB). The raw materials to make MCTPB
are commercially available. In one non-limiting embodiment the
described chemistry could also be used as a coating. Corrosion
mitigation is a multi-billion industry, within which green
chemistries are gaining a foothold commercially.
[0015] The application of the polymer blend as corrosion inhibitor
was studied and evaluated according to NACE standard MT0284
(solution A) that represents a wide range of oilfield brine
corrosive environments. The CHI/MCTPB blend showed an excellent
performance and was found to be an excellent corrosion inhibitor as
compared with chitosan used alone.
[0016] As previously discussed, in the petroleum, petrochemical,
and oil gas industries a major cause of carbon steel well/piping
system failure is corrosion, especially, when metal pipes and other
equipment is used in low pH (acidic) brine environments. The use
and development of a green natural polymer blend or reaction
product for coating or other applications has been discovered as
described herein. The polymer blend or reaction products described
herein can be easily injected in the process to inhibit or reduce
the corrosion rate.
[0017] As discussed, the biological-based (bio-based) polymer blend
or reaction product (CHI/MCTPB) has been discovered to be a useful
corrosion inhibitor. Also the blends and/or reaction products
discussed herein can be further developed for coating applications.
By "main chain" type polybenzoxazine is meant that the benzoxazine
functionality is part of the polymer backbone, in contrast to the
benzoxazine functionality being in a pendent side chain. The main
chain type or side-chain type polybenzoxazines are known to have
good ductility.
[0018] Without being limited to any particular theory, it is
believed that the presence of an amine group (--NH.sub.2) in the
structure of chitosan and both benzoxazine and amine groups in
MCTPB would contribute to corrosion protection in case of steel
based substrates. In the process of synthesizing and purifying
benzoxazine there are no, or only limited environmental concerns.
Benzoxazine polymers are already used in the electronic industry
and aerospace industry in many countries.
Polymer Blend and Treatment Preparation
[0019] The structures of chitosan and Main Chain-Type Poly
Benzoxazine (CHI & MCTPB) are shown below:
##STR00001##
[0020] The benzoxazine polymer is synthesized by the reaction of
bisphenol A with formaldehyde and a primary amine such as
tetraethylenepentamine (TEPFA), whose structures are shown below,
followed by an ice bath. The mole ratio of formaldehyde to
bisphenol A to TEPA is about 4:1:1. The benzoxazine monomer is
polymerized to give MCTPB.
##STR00002##
[0021] A CHI/MCTPB was prepared and synthesized according to the
procedure reported by Almandi A. Alhwaige; Tarek Agag; Ishida, H.;
Syed Qutubuddin, dx.doi.org/10.102/bm4002014|Biomacromolecules
2013, 14, 1806-1815, incorporated herein by reference in its
entirety, by mixing (CHI/MCTPB) in aqueous acetic acid solution
(1%).
[0022] It is expected that while formaldehyde may be the necessary
aldehyde in the synthesis, that other bis-phenol compounds and
derivatives could be used in place of the Bisphenol A. Other
primary amines besides TEPA may also be used as long as there are
present two primary amine functionalities. However, it is possible
that aldehydes other than formaldehyde may work.
[0023] It is expected that chitosan glycol may work together with
or in place of chitosan. Chitosan glycol is generally more water
soluble than chitosan which may enhance the inhibitor properties
and efficiency of the resulting blend.
[0024] First, in one non-limiting embodiment, MCTPB was prepared as
follows: [0025] Place 12.06 g, 52.82 mmol of Bisphenol A in an ice
bath temperature range from 0-5.degree. C., mix the solution with
50 mL 1,4-dioxane. [0026] Add 10 g, 52.82 mmol of TEPA into the
mixture. [0027] Gradually add 17.15 g, 211.3 mmol of formaldehyde
under stirring until a homogeneous phase of the liquid mixture is
reached.
[0028] Second, the following procedure was used for prepare the
chitosan and MCTPB blends: [0029] Blends of CHI and MCTPB
(Bisphenol A-TEPA) in ratios of 2:1 with suitable amounts of CHI
and MCTPB were mixed in 30 mL of 1 wt % acetic acid solution.
[0030] CHI was dissolved in 1 wt % acetic acid solution under
continuous magnetic stirring at temperature from 15 to 30.degree.
C. [0031] Separately MCTPB (Bisphenol A-TEPA) was dissolved in 1 wt
% aqueous acetic acid. [0032] Gradually or drop wise, the solution
of CHI was added to MCTPD solution under vigorous stirring until
the mixture became homogeneous.
[0033] In one non-limiting embodiment the weight ratio of chitosan
to MCTPB from about 1.5 to 2.5 independently to about 0.5 to 1.5;
alternatively about 2 to 1 independently to about 5 to 1; in
another non-restrictive embodiment the weight ratio is about 0.5 to
3.5. The term "independently" as used herein with respect to a
range means that any lower threshold may be combined with any upper
threshold to give a suitable alternative range.
[0034] In another non-limiting embodiment, at least one inorganic
or organic acid is present to help dissolve the chitosan. The
corrosion inhibitor may comprise or contain from about 0.01 wt %
independently to about 1 wt %, alternatively from about 0.05 wt %
independently to about 0.5 wt %, based on the total corrosion
inhibitor, of an organic acid and/or an inorganic acid. Suitable
inorganic acids to lower the pH to help solubilize the chitosan
include, but are not necessarily limited to, hydrochloric acid,
sulfuric acid, phosphoric acid, and combinations thereof. Suitable
organic acids are selected from the group of carboxylic acid
consisting of formic acid, acetic acid, propionic acid, butyric
acid, valeric acid, caproic acid, citric acid, oxalic acid, malic
acid, lactic acid, benzoic acid, or selected from the group of
sulfonic acids consisting of p-toluenesulfonic acid,
trifluoromethanesulfonic acid, 2-aminoethanesulfonic acid,
alkyl-aryl-sulfonic acids such as dodecylbenzenesulfonate,
polymeric sulfonic acids, and combinations thereof. Fluorinated
derivatives of these organic acids would also be acceptable. It
would be additionally suitable to use a buffered system to create a
lower pH value to solubilize the chitosan, which buffered system
would use the above-noted acids and suitable bases, and the
corresponding base salts.
Corrosion Study
[0035] FIG. 1 presents the corrosion rate in mpy (mils per year) of
the bio-based polymer blend chitosan/main chain type
polybenzoxazine inhibitor at different concentrations for the
protection of carbon steel test specimens. The brine used was 5%
NaCl+0.5% acetic acid (CH.sub.3COOH). The test period was 336
hours. It may be seen that the corrosion rate decreased
significantly with increasing the corrosion inhibitor concentration
as compared to the test specimen without corrosion inhibitor
(control).
[0036] The corrosion inhibitor polymer blend showed excellent
corrosion efficiency as presented in FIG. 2. The bio-based polymer
blend corrosion efficiency is 71.8%, 89.4%, 92.6% and 99.7% at
concentrations of 20 ppm, 100 ppm, 200 ppm and 500 ppm,
respectively.
[0037] It is not entirely clear if the corrosion inhibitor is a
blend or a reaction product of chitosan and MCTPB. Without being
restricted to a particular theory, it is believed that the initial
mixture of CHI and MCTPB at room temperature is a polymer blend.
The two polymers are believed to coordinate or orient to each other
via reversible hydrogen bonding. Depending on further temperature
treatment, the two polymers may undergo covalent crosslinking at
temperatures of 60-80.degree. C. or above. There may or may not be
some degree of crosslinking already happening at lower
temperatures.
[0038] In another non-limiting embodiment about how the corrosion
inhibition functions, the polymer blend or reaction product does
not form a coating. It is believed that both polymers bear
functional groups suitable to adsorb onto the metal surface and
coordinate to each other. In other words, the polymers form an
adsorption film on top of the metal. However, there is the
possibility that the polymer mixture forms covalent bonds between
the two polymer types and thus forms a polymer coating. The
interaction of the polymer with the metal surface and competing
influences from salts and organic phase needs more investigation to
study physical and/or chemical adsorption.
[0039] In the foregoing specification, the invention has been
described with reference to specific embodiments thereof, and has
been described as effective for inhibiting corrosion of a metal
surface in contact with an aqueous fluid, in particular brine.
However, it will be evident that various modifications and changes
can be made thereto without departing from the broader scope of the
invention as set forth in the appended claims. Accordingly, the
specification is to be regarded in an illustrative rather than a
restrictive sense. For example, specific combinations of aqueous
fluids, chitosan components, polybenzoxazines, primary amines,
aldehydes, organic acids, proportions, and other components falling
within the claimed elements and parameters, but not specifically
identified or tried in a particular method or composition, are
anticipated to be within the scope of this invention. For instance,
the methods and compositions described herein are also applicable
to aqueous fluids other than brines including, but are not
necessarily limited to, aqueous fluids used to recover oil and/or
gas from a subterranean formation, aqueous fluids produced from an
oil or gas well, aqueous fluids used in the processing of oil or
gas, and the like. In particular, the corrosion inhibitors
described herein may be used in drilling fluids and completion
fluids. Similarly, it is expected that the methods described herein
may be successfully practiced using different loadings,
compositions, manufacturing processes, equipment, temperature
ranges, and proportions than those described or exemplified
herein.
[0040] The words "comprising" and "comprises" as used throughout
the claims is interpreted to mean "including but not limited
to".
[0041] The present invention may also suitably consist of or
consist essentially of the elements disclosed. Alternatively, the
compositions and methods may be practiced in the absence of an
element not disclosed. For instance, there may be provided a method
for inhibiting or preventing the corrosion of a metal surface in
contact with an aqueous fluid, where the method consists
essentially of or consists of introducing an effective amount of a
corrosion inhibitor into the aqueous fluid in contact with the
metal surface to inhibit or prevent corrosion of the metal surface,
where the corrosion inhibitor is selected from the group consisting
of: a blend of main chain type polybenzoxazine (MCTPB) and a
chitosan component selected from the group consisting of chitosan,
chitosan glycol, and combinations thereof; a cross-linked reaction
product of chitosan and MCTPB; and combinations thereof.
[0042] In another non-limiting embodiment, there may be provided
corrosion inhibitor for inhibiting or preventing the corrosion of a
metal surface in contact with an aqueous fluid, the corrosion
inhibitor consisting essentially of or consisting of a blend of
main chain type polybenzoxazine (MCTPB) and a chitosan component
selected from the group consisting of chitosan, chitosan glycol,
and combinations thereof; a cross-linked reaction product of
chitosan and MCTPB; and combinations thereof.
[0043] As used herein, the terms "comprising," "including,"
"containing," "characterized by," and grammatical equivalents
thereof are inclusive or open-ended terms that do not exclude
additional, unrecited elements or method acts, but also include the
more restrictive terms "consisting of" and "consisting essentially
of" and grammatical equivalents thereof. As used herein, the term
"may" with respect to a material, structure, feature or method act
indicates that such is contemplated for use in implementation of an
embodiment of the disclosure and such term is used in preference to
the more restrictive term "is" so as to avoid any implication that
other, compatible materials, structures, features and methods
usable in combination therewith should or must be, excluded.
[0044] As used herein, the singular forms "a," "an," and "the" are
intended to include the plural forms as well, unless the context
clearly indicates otherwise.
[0045] As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
[0046] As used herein, relational terms, such as "first," "second,"
"top," "bot-tom," "upper," "lower," "over," "under," etc., are used
for clarity and convenience in understanding the disclosure and
accompanying drawings and do not connote or depend on any specific
preference, orientation, or order, except where the context clearly
indicates otherwise.
[0047] As used herein, the term "substantially" in reference to a
given parameter, property, or condition means and includes to a
degree that one of ordinary skill in the art would understand that
the given parameter, property, or condition is met with a degree of
variance, such as within acceptable manufacturing tolerances. By
way of example, depending on the particular parameter, property, or
condition that is substantially met, the parameter, property, or
condition may be at least 90.0% met, at least 95.0% met, at least
99.0% met, or even at least 99.9% met.
[0048] As used herein, the term "about" in reference to a given
parameter is inclusive of the stated value and has the meaning
dictated by the context (e.g., it includes the degree of error
associated with measurement of the given parameter).
* * * * *