Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Maintaining environment nondestructive to metal
Reexamination Certificate
1997-07-11
2001-01-23
Hruskoci, Peter A. (Department: 1724)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Maintaining environment nondestructive to metal
C210S700000, C252S181000, C252S389210, C252S389520, C422S019000
Reexamination Certificate
active
06177047
ABSTRACT:
This application claims the benefit of priority under 35 U.S.C. §119 of EPO No. 96870096.3 filed Jul. 30, 1996.
This invention relates to water-treatment technology, particularly industrial water-treatment, to compositions suitable for use in water-treatment operations and method for the treatment of aqueous systems. The compositions of the invention comprise phosphonates, such as aminopolymethylene phosphonates, zinc salts and source of metal ions. In the method aspects, comparable ingredients are used in narrowly defined levels.
The art relating to water-treatment technology, including water-treatment compositions and methods for the treatment of aqueous systems, is crowded and diverse. Industrial water-treatment technology aims at providing cumulative benefits including corrosion inhibition properties and effective control of scale formation in, for example, cooling circuits. A variety of inorganic corrosion-inhibitor compounds has in the past been suggested and/or used in aqueous systems. The use of the like compounds, for example chromates, nitrites, sulfates, phosphates and polyphosphates, was limited for technical, toxicological and/or environmental reasons. Combinations of polyphosphonates and zinc salts have more recently found widespread application and were known to exhibit effective corrosion inhibition and scale inhibition properties. However, the use of polyphosphonate/zinc salt combinations is known to be subject to stability deficiencies, e.g. precipitation which can adversely affect the suitability for beneficially using such combinations in industrial water treatment. U.S. Pat. No. 5,230,819 describes the use of diphosphonic acids as corrosion inhibitors in liquid systems. CN-A-2.061.249 describes the use of cationic alkyl phosphonium as corrosion inhibitors in aqueous systems. U.S. Pat. No. 4,692,317 describes method for inhibiting corrosion in aqueous systems by adding to the system a phosphonohydroxyacetic acid or a salt thereof and a selected cationic polymer. The known technology, while marginally effective under narrowly-defined in-use parameters, was known to exhibit substandard storage stability properties, particularly precipitation of active ingredient combinations and correspondingly diminished water-treatment properties inclusive of reduced corrosion inhibition and marginal hardness scale control.
It is therefore an object of this invention to generate water-treatment technology capable of simultaneously providing excellent scale-inhibition properties and effective corrosion inhibition benefits.
It is a further object of this invention to provide water-treatment technology, particularly compositions, which are not subject to stability problems which might reduce inhibitor properties.
Yet another object of this invention is to generate superior water-treatment technology commensurate with ever-increasing requirements.
The foregoing and other objects can now be beneficially met with the aid of the water-treatment technology of this invention, particularly the compositions and the use thereof in industrial water-treatment.
The technology of this invention relates to water-treatment compositions capable of inhibiting metal corrosion comprising from
a: 5% to 60% by weight of phosphonic acid or a salt thereof having a formula selected from the following formulae:
(H) N-oxides of the aminophosphonates of formulae: (A), (B), (C), (D) and (F) wherein
Z is —CHR
1
PO
3
R
2
;
R is H, CH
3
, C
2
H
5
or M;
M is a metal ion or ammonium;
R
1
is H, CH
3
, CR
3
, C
6
H
5
, SO
3
H, CH
2
COOH;
R
2
is an alkyl group having from 1 through 5 carbon atoms;
R
3
is PO
3
R
2
, H;
R
4
is OH, NH
2
, N(R
1
)
2
, N(Z)
2
, COOH;
R
5
is CH
2
CH
2
COOH, N(CH
2
OH)
2
;
n is 1-6, preferably 2-4;
m is 2-6, preferably 2-41;
x is 0-6, preferably 0-3;
y is 0-6, preferably 0-1;
b: a water-soluble or water dispersible zinc salt in a level such that the molar ratio of said zinc salt to said phosphonic acid is in the range of from 1:2 to 6:1; and
c: a source of water-soluble or water-dispersible metal salt of aluminum, boron, silicon, gallium, germanium, indium and titanium in a level of from 0.01% to 1.0% by weight on the basis of the metal constituent of the salt.
The metal salt is preferably represented by water-soluble aluminum salts. A preferred phosphonic acid can be represented by amino-tri-methylenephosphonic acid.
In the method aspect of the invention aqueous systems are treated by adding thereto a phosphonic acid or salt thereof having a formula selected from the group of (A) through (H) in a level of from 1 ppm to 1000 ppm, more preferably 10 ppm to 500 ppm in combination with a water-soluble or water-dispersible zinc salt and a source of water-soluble or water-dispersible metal salt of aluminum, boron, silicone, gallium, geranium, indium and titanium in a level from 0.1 ppm to 100 ppm on the basis of the metal constituent of the salt. The zinc salt is used in the claimed method in a level such that the molar ratio of said zinc salt to said phosphonic acid is in the level of from 1:2 to 6:1.
The %-indication stand, unless specified differently, for “% by weight”. The terms “water-treatment” and “industrial water-treatment” are used interchangeably.
The water-treatment compositions herein comprise from a phosphonic acid, or a salt thereof, having a formula selected from the group of formulae annotated (A- through (H). The phosphonic component generally represents from 5% to 60%, preferably from 8% to 50% of the treatment composition. Optimized levels can vary depending upon the contemplated utilization and the quantitative and qualitative selections of complementary essential ingredients. Level fine-tuning can be effected routinely based on day-to-day measures and experiences.
The phosphonic acid component can be represented by known species including those having established water treatment functionality. The individually recited compounds (A) through (H) can be used as such or in admixture.
Specific examples of formula (A) are those wherein R is H or M, R
1
is H, x is 0 or 1, y is 0 or 1, n is 3 and m is 2. Individual species of (A) include diethylenetriamine penta(methylenephosphonic acid) and ethylenedipropylene tetraamino hexa(methylenephosphonic acid).
Specific examples of formula (B) carry the following moieties: x is 0 or 1 and n is 2 to 6. Individual species of (B
1
) are amino tris(methylenephosphonic acid), hexamethylenediamine tetra(methylenephosphonic acid) and ethylenediamine tetra(methylenephosphonic acid) whereas n in B
2
can from 1 to &egr;5, preferably 2 to 3.
Formula (C) can be represented by individual species wherein R
2
is C
1-3
alkyl, R
3
is PO
3
H
2
, and R
4
is OH or N(Z)
2
. Operable species of formula (C) are 1-hydroxy ethylidene(1,1-diphosphonic acid) and aminoethane-1, 1-diphosphonic acid,N,N-bis(methylenephosphonic acid).
In Examples of (D) n can have a value of 1 or 2. A specific example of a (D) compound is ethanolaminedimethylene phosphonic acid.
Formula (E) can be represented by butan-2-phosphono-1,2,4-tricarboxylic acid whereas in formula (F) R is H to thus produce an operable compound namely N,N-dihydroxymethylethane-1,1-diphosphonic acid.
The phosphonic acid component can, depending upon pH conditions, be represented by the acid as such, by the corresponding salts, inclusive of alkali metal salts, such as sodium, potassium and lithium, earth-alkali metal salts e.g. calcium or magnesium, or ammonium and/or ethanol amines inclusive of mono- and di-species.
The phosphonic acid components are known ingredients which can be produced by means of conventional methods.
The compositions and methods of this invention employ a water-soluble and/or water-dispersible zinc salt. The terms “soluble” and dispersible” refer to the medium of application. Thus in the context of the contemplated water-treatment application, the aqueous medium represent generally more than 95%, usually more than 98% water. The term “dispersible” is meant to express “stably dispersible” i.e. non-precipitating. The water-soluble zinc salts are preferred.
The zinc salt c
Kuczynski Krzysztof
Ledent Michel Alex Omer
Hruskoci Peter A.
Lesko Paul A.
Sieckmann Gordon F.
Thompson Colburn LLP
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