Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Maintaining environment nondestructive to metal
Reexamination Certificate
1999-05-25
2001-05-29
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Maintaining environment nondestructive to metal
C422S007000, C252S390000, C252S394000
Reexamination Certificate
active
06238621
ABSTRACT:
This invention relates to corrosion inhibiting compositions. This invention further relates to aqueous metal working compositions containing the corrosion inhibiting compositions of the invention and a method of inhibiting corrosion of ferrous metals.
BACKGROUND OF THE INVENTION
It is known that corrosion is a problem in aqueous fluids utilized for the working of metals. Corrosion inhibitors are commonly added to aqueous fluids to mitigate corrosion of ferrous metals. Typical examples of corrosion inhibitors known in the art are zinc chromate, dithiophosphates, metal sulfonates, alkanolamines, alkyl amines, borate compounds, carboxylic acids including polyaspartic acid at high pH (10 and above), alkyl amidocarboxylic acids, sodium molybdate, boric acid with various ethanol amines, benzoic acid and nitro derivatives thereof, ammonium benzoate, triethanolamine salts of carboxylic acids with a carboxymethyl thio group, tungstates, phosphates, polyphosphates, phosphonates, nitrates and silicates.
U.S. Pat. No. 5,723,061 discloses an antifreeze composition containing a corrosion inhibitor system comprising a mixture of at least two aromatic or aliphatic dicarboxylic acids or alkali metal, ammonium or amine salts thereof, at least one 1,3-diazole chosen from imidazole, benzimidazole, imidazoline and the hydrocarbon derivatives thereof, and at least one triazole compound such as benzotriazole, tolyltriazole, or N-substituted derivatives thereof. The '061 patent also states that GB-1,004,259 discloses a corrosion inhibitor composition comprising a mixture of benzotriazole and/or methylbenzotriazole and an alkali metal, ammonium, amine or alkanolamine salt of a C
6
to C
30
saturated dicarboxylic acid.
WO 96/39549 discloses corrosion inhibiting formulations for use in closed water systems comprising at least one water soluble fatty acid salt of the formula R
1
(COOX)
n
wherein R
1
is alkyl or hydroxyalkyl having at least 2 carbon atoms, preferably 2-18 carbon atoms, and n is 2 or 3, and optionally at least one additive which may be a corrosion inhibitor, selected from the group of alkali metal borates, alkali metal molybdates, hydrocarbyl triazoles, silicates, morpholine, ethylenediamine, pyridine and pyrrolidine.
U.S. Pat. No. 3,945,931 discloses an aqueous metal working fluid containing amido acids of the formula
wherein R is an open chain aliphatic hydrocarbon group having between 9 and 25 carbon atoms, and n and n′ are whole numbers or zero, the same or not, the sum of n and n′ being equal to 1 or 2. The fluids of the '931 patent optionally contain salts of phosphoric esters, as well as other additives such as anti-foam agents, bactericides and anti-corrosive agents. The anti-corrosive agents can be alkaline nitrates, phosphates, borates, etc.
U.S. Pat. No. 5,599,779 discloses synergistic rust inhibitor compositions consisting of N-acyl sarcosines of the formula
wherein R represents alkyl or alkenyl group of 8-18 carbon atoms, a dicarboxylic acid of the formula HOOC(CH
2
)
x
COOH wherein x is an integer from 4 to 46, and an amine selected from a primary, secondary or tertiary alkyl amine or an imidazoline, and the molar ratio of sarcosine to dicarboxylic acid to amine is about 2:1:2 to 7:1:2.
While amido acids have been disclosed for use in aqueous metal working fluids and triazoles have been disclosed as corrosion inhibitors in aqueous compositions, it has now been surprisingly discovered that the amido acids or salts thereof of the invention produce a synergistic corrosion inhibiting effect in aqueous compositions, particularly aqueous metal working compositions, when combined in specific proportions with the aryltriazoles or 3-amino-1,2,4-triazole of the invention.
BRIEF SUMMARY OF THE INVENTION
It is an object of the invention to provide corrosion inhibiting compositions having a synergistic corrosion inhibiting effect. It is a further object of the invention to provide aqueous metal working fluid compositions containing the corrosion inhibiting compositions of the invention.
According to the invention, a corrosion inhibiting composition is provided which comprises (a) at least one amido acid or salt thereof having the formula
and (b) at least one of an aryltriazole having the formula
or 3-amino-1,2,4-triazole wherein the molar ratio of (a) to (b) is about 0.34:1 to about 5:1.
Further according to the invention, a metal working composition is provided which comprises water and a corrosion inhibiting composition in an amount effective to inhibit corrosion at a pH in the range of 6-12, wherein the corrosion inhibiting composition is as defined above. The metal working compositions of the invention optionally contain a polyaspartic polymer in the acid, salt or amide form thereof. Such polyaspartic polymer containing metal working fluids are described in U.S. Pat. Nos. 5,401,428 and 5,616,544, which are incorporated by reference herein. In addition, a method of making the above metal working composition is provided.
Still further according to the invention, a method of inhibiting corrosion in an aqueous metal working composition is provided which comprises adding the above corrosion inhibiting composition to an aqueous metal working fluid composition in an amount effective to inhibit corrosion at a pH in the range of 6-12.
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the invention relates to a corrosion inhibiting composition comprising (a) at least one amido acid or salt thereof having the formula
wherein R is an alkyl or alkenyl group having about 4 to about 21 carbon atoms, M and M′ are cations independently selected from hydrogen, alkali metal or amine salts, and m and n independently represent an integer from 0 to 2; and (b) at least one of an aryltriazole having the formula
or 3-amino-1,2,4-triazole, wherein Y is an alkyl group having 1 to about 6 carbon atoms or —COO
−
M
+
, M″ is hydrogen or an alkali metal, and p is an integer from 0 to 4; wherein the molar ratio of (a) to (b) is about 0.34:1 to about 5:1.
The amido acids or salts thereof of the invention are represented by the formula:
wherein R is an alkyl or alkenyl group having about 4 to about 21 carbon atoms, M and M′ are cations independently selected from hydrogen, alkali metal or amine salts, and m and n independently represent an integer from 0 to 2. Suitable amine salts include the cations derived from ammonia and any water-soluble amine-containing organic compound. Examples of suitable amine salts include, but are not limited to, cations represented by the formula (R′)
4
N
+
wherein each R′ is independently hydrogen, alkyl having 1-10 carbon atoms, aminoalkyl having 2-10 carbon atoms, or hydroxyalkyl having 2-10 carbon atoms. When each of R′ is hydrogen, the cation is ammonium, i.e. NH
4
N
+
. When at least one R′ is other than hydrogen, (R′)
4
N
+
can be a primary, secondary or tertiary ammonium, or a quaternary ammonium. Preferably, the amine salt is triethanolammonium or ammonium. Preferably, m is 0 and n is 1 or 2. More preferably, m is 0 and n is 2. It is also preferred that at least one of M and M′ is other than hydrogen. When at least one of M and M′ is other than hydrogen, it is preferably an alkali metal or trihydroxyalkylammonium, and more preferably sodium, potassium or triethanolammonium. The number of carbon atoms in R is preferably about 6 to about 17 carbon atoms, and more preferably about 7 to about 15 carbon atoms.
Examples of the amido acids or salts thereof include, but are not limited to, N-cocoyl-L-glutamic acid, sodium N-cocoyl-L-glutamate, triethanolamine N-cocoyl-L-glutamate, triethanolamnine N-lauroyl-L-glutamate, sodium N-lauroyl-L-glutamate, N-stearoyl-L-glutamic acid, sodium N-stearoyl-L-glutamate, N-cocoyl-L-aspartic acid, sodium N-cocoyl-L-aspartate, triethanolamine N-cocoyl-L-aspartate, triethanolamine N-lauroyl-L-aspartate, sodium N-lauroyl-L-aspartate, N-stearoyl-L-aspartic acid and sodium N-stearoyl-L-aspartate. The currently preferred amido ac
Chou Yueting
Kalota Dennis J.
Silverman David C.
Cross LaToya I.
Lesko Paul A.
Solutia Inc.
Thompson & Coburn LLP
Upchurch Greg
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