Use Of N-Methyl-N-Acylglucamine As Corrosion Inhibitor

Abstract

The invention relates to the use of one or more M-methyl-N-acylglucamines of the formula (I) wherein R.sup.1 represents a linear or branched, saturated or unsaturated hydrocarbon group having 7 to 21 carbon atoms, as a corrosion inhibitor.

##STR00001##

Claims

1. A method of preventing or attenuating the formation of corrosion on a metal surface, comprising the step of contacting the metal surface with a composition comprising at least one N-methyl-N-acylglucamine of the formula (I) ##STR00006## in which R.sup.1 is a linear or branched, saturated or unsaturated hydrocarbyl group having 7 to 21 carbon atoms.

2. The method as claimed in claim 1, in which R.sup.1 is an aliphatic group.

3. The method as claimed in claim 1, in which R.sup.1 is a hydrocarbyl group having 11 to 17 carbon atoms.

4. The method as claimed in claim 1, in which R.sup.1 is an alkyl or alkenyl group.

5. The method as claimed in claim 1, in which R.sup.1 is a linear C.sub.13- or C.sub.17-alkyl group.

6. The method as claimed in claim 1, in which 2 to 6 different compounds of the formula (I) are employed.

7. The method as claimed in claim 1, in which the compound of the formula (I) contains at least 80% by weight of N-methyl-NC.sub.12-acylglucamine and N-methyl-NC.sub.14-acylglucamine.

8. The method as claimed in claim 1, in which the compound of the formula (I) contains at least 80% by weight of N-methyl-NC.sub.16-acylglucamine and N-methyl-NC.sub.18-acylglucamine.

9. The method as claimed in claim 1, wherein the composition further comprises at least one organic acid of the formula (II), or salts thereof,
R.sup.2COOM(II) in which R.sup.2 is a linear or branched alkyl group or a linear or branched, mono- or polyunsaturated alkenyl group having 5 to 29 carbon atoms, and M is hydrogen or one or more cations, where the cations are present in charge-balancing amounts, and c) at least one alkanolamine of the formula (III)
NR.sup.1R.sup.2R.sup.3(III) in which R.sup.1, R.sup.2 and R.sup.3 are hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a linear or branched hydroxyalkyl group having 2 to 5 carbon atoms and 1 or 2 hydroxyl groups or a hydroxy ether group having 2 to 6 carbon atoms, with the proviso that at least one of the radicals is a hydroxyalkyl group or a hydroxy ether group.

10. The method as claimed in claim 9, in which R.sup.2 of the formula (II) is an alkyl or alkenyl radical having 9 to 21 carbon atoms.

11. The method as claimed in claim 9, wherein the composition comprises a) 1% to 50% by weight of one or more N-methyl-N-acylglucamines of the formula (I), b) 0.1% to 23% by weight of at least one organic acid, or salt thereof, of formula (II) and c) 0.05% to 42% by weight of at least one alkanolamine of formula (III) and d) ad 100% by weight further components.

12. The method as claimed in claim 11, in which the further components are selected from the group consisting of one or more emulsifiers, one or more biocides, one or more further corrosion inhibitors, one or more AW additives, one or more EP additives, one or more defoamers, one or more antioxidants, one or more coupling agents, one or more alkali metals or alkaline earth metals, one or more solubilizers, pH regulators and water.

13. The method as claimed in claim 11, wherein 5% to 40% by weight of the composition composed of components a) to c) or a) to d) is mixed with one or more oils in an amount of 60% to 95% by weight, based on the total amount comprising components a) to c) or a) to d) and the one or more oils.

14. The method as claimed in claim 13, wherein the one or more oils are selected from the group consisting of mineral oils, paraffins, isoparaffins, cycloparaffins, naphthenes, saturated cyclic hydrocarbons, aromatic hydrocarbons, synthetic oils, poly-alpha-olefins, polyalkylene glycols (PAGs) and ester oils.

15. The method as claimed in claim 14, wherein the oil is a mineral oil.

16. A composition comprising at least one N-methyl-N-acylglucamine of the formula (I) ##STR00007## in which R.sup.1 is a linear or branched, saturated or unsaturated hydrocarbyl group having 7 to 21 carbon atoms.

17. A detergent for metal comprising at least one composition as claimed in claim 16.

18. A cooling lubricant emulsion comprising at least one composition as claimed in claim 16.

19. A corrosion inhibitor comprising at least one composition as claimed in claim 16.

Description

EXAMPLES

[0114] All percentages, unless stated otherwise, should be understood to mean percent by weight (% by weight).

[0115] Determination of the corrosion-inhibiting effect of a mixture of N-methyl-NC.sub.12-acylglucamine and N-methyl-NC.sub.14-acylglucamine (Glu1) and a mixture of N-methyl-NC.sub.16-acylglucamine and N-methyl-NC.sub.18-acylglucamine (Glu2) compared to demineralized water (H2O, dem.) on iron

[0116] A corrosion protection test is conducted in accordance with DIN 51360-2, in which freshly prepared solutions of (Glu1) and (Glu2) in different dilutions in demineralized water are passed through gray iron turnings (GG25 type) on a round filter. This was done by wetting the gray iron turnings on the filter paper with the solutions and, for comparison, with demineralized water for 2 hours each, and the corrosion residues formed on the filter paper were assessed.

[0117] Assessment of corrosion pursuant to DIN 51 360-2:

0 no corrosion/unchanged
1 traces of corrosion/not more than 3 corrosion marks
2 slight corrosion/not more than 1% of the surface discolored
3 moderate corrosion/not more than 5% of the surface discolored
4 severe corrosion/more than 5% of the surface discolored

[0118] The results are compiled in table 1.

TABLE-US-00001 TABLE 1 Corrosion of iron in the presence of N-methyl-N-acylglucamines (Glu1) and (Glu2), and, for comparison, corrosion of iron in demineralized water Concentration H.sub.2O, [% by wt.] Glu2 Glu1 dem. 5 3 3 10 2 3 15 0 2 100 4

[0119] Determination of the corrosion-inhibiting action of a mixture of N-methyl-NC.sub.12-acylglucamine and N-methyl-NC.sub.14-acylglucamine (Glu1) and a mixture of N-methyl-NC.sub.16-acylglucamine and N-methyl-NC.sub.18-acylglucamine (Glu2) in the presence of tall oil fatty acid (TOFA), coconut fatty acid (CC) and mono- or di- or triethanolamine in accordance with DIN 51360-2

TABLE-US-00002 TABLE 2 Test formulations: Component [% by wt.] 1 2 3 4 5 6 7 8 9 Glu1 0 0 0 0 0 0 0 64 0 Glu2 100 64 0 64 0 64 0 0 0 CC 0 0 0 0 0 0 0 15 15 TOFA 0 15 15 15 15 15 15 0 0 Monoethanolamine 0 21 21 0 0 0 0 0 0 Diethanolamine 0 0 0 21 21 0 0 0 0 Triethanolamine 0 0 0 0 0 21 21 21 21 Propylene glycol 0 0 12.8 0 12.8 0 12.8 0 0 Glycerol 0 0 3.5 0 3.5 0 3.5 0 0 Water 0 0 47.7 0 47.7 0 47.7 0 64

[0120] The corrosion protection test is conducted in accordance with DIN 51360-2, by preparing 2% solutions with water having 20 German degrees of hardness (20 dH) from each of test formulations 1 to 9 from table 2 and using these solutions to wet gray iron turnings (GG25 type) on a round filter for 2 hours each and assessing the corrosion residues formed on the filter paper. The results are compiled in table 3.

TABLE-US-00003 TABLE 3 Corrosion of gray iron turnings in the presence of a mixture of N-methyl-N-acylglucamines (Glu1, Glu2), fatty acid and alkanolamines compared to N-methyl-N-acylglucamines (Glu2) alone (formulation 1) and in comparison with fatty acid and alkanolamines without N-methyl-N-acylglucamine (3, 5 and 7 and 9) Test formulation 1(C) 2 3(C) 4 5(C) 6 7(C) 8 9(C) Corrosion protection 2-3 0 1-2 0 1-2 0 2 0 2

[0121] Determination of the corrosion-inhibiting action (Glu2) in the presence of tall oil fatty acid and mono- or di- or triethanolamine on aluminum

[0122] A corrosion protection test is conducted in accordance with EEH1020-AA-1049 with the aluminum alloys AlZnMgCu1.5 and AlMgSi1. 2% test formulations from table 2 were each prepared with water having 20 German degrees of hardness (20 dH), and the test specimens of the abovementioned alloys were each half-immersed and the solutions at 40 C. and left therein for 24 hours. Thereafter, the test specimens are pulled out of the solutions, rinsed with demineralized water and then acetone, and dried. Both the part immersed into the solution (solution) and the exposed part (atmosphere) of the test specimens are assessed according to the abovementioned criteria.

[0123] The results are summarized in table 4.

TABLE-US-00004 TABLE 4 Corrosion of aluminum alloys in the presence of a mixture of the N- methyl-N-acylglucamine (Glu2), fatty acid and alkanolamines (test formulation 2, 4 and 6) compared to fatty acid and alkanolamines without N-methyl-N-acylglucamine (test formulation 3, 5 and 7) Test formulation Corrosion protection 2 3(C) 4 5(C) 6 7(C) AlZnMgCu1.5, 1 3 0 1-2 0 1 atmosphere AlZnMgCu1.5 0 0 0 1 0 0 solution AlMgSi1 atmosphere 0-1 3 0-1 0 0-1 2 AlMgSi1 solution 0 0 0 2 0 0