NEW ANTIFREEZE AGENTS AND COOLANTS FOR FUEL CELLS, STORAGE BATTERIES AND BATTERIES

Abstract

Substantially water-free antifreezes for cooling systems can be used as coolants and antifreezes without further dilution with water.

Claims

1: A ready-to-use antifreeze composition for cooling systems, comprising a component (A) and a component (B), wherein component (A) comprises at least one alkylene glycol derivative of formula (I) ##STR00008## wherein R.sup.1 is hydrogen or C.sub.1- to C.sub.4-alkyl, R.sup.2 is C.sub.1- to C.sub.4-alkyl, R.sup.3 is hydrogen or methyl, and n is on arithmetic average a number from 3.0 to 4.0; and wherein component (B) comprises at least one corrosion inhibitor selected from the group consisting of (Ba) an orthosilicate ester and/or an alkoxyalkylsilane, (Bb) an azole derivative, and (Bc) a compound of general formula (II) ##STR00009## wherein R.sup.4 is an organic radical having 6 to 10 carbon atoms, p and q are independently of one another a positive integer from 1 to 30, and each Xi for i=1 to p and 1 to q are independently of one another selected from the group consisting of —CH.sub.2—CH.sub.2—O—, —CH.sub.2—CH(CH.sub.3)—O—, —CH(CH.sub.3)—CH.sub.2—O—, —CH.sub.2—C(CH.sub.3).sub.2—O—, —C(CH.sub.3).sub.2—CH.sub.2—O—, —CH.sub.2—CH(C.sub.2H.sub.5)—O—, —CH(C.sub.2H.sub.5)—CH.sub.2—O—, —CH(CH.sub.3)—CH(CH.sub.3)—O—, —CH.sub.2—CH.sub.2—CH.sub.2—O— and —CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2—O—; and with the proviso that the composition comprises: less than 1 wt % of water, a proportion of alkylene glycol derivatives of formula (I) wherein n≤2 of not more than 10 wt %, a proportion of alkylene glycol derivatives of formula (I) wherein n≥5 of not more than 5 wt %, and a proportion of monoethylene glycol, diethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propylene glycol or glycerol, if present, of not more than 10 wt %.

2: The composition according to claim 1, wherein the composition has an electrical conductivity at 25° C. of at most 50 μS/cm.

3: The composition according to claim 1, wherein the composition has a boiling point at 1013 hPa of at least 200° C.

4: The composition according to claim 1, wherein the composition has a kinematic viscosity at 100° C. according to ASTM D445 of at most 4 mm.sup.2/s.

5: The composition according to claim 1, wherein the composition has a kinematic viscosity at minus 40° C. according to ASTM D445 of not more than 600 mm.sup.2/s.

6: The composition as claimed in claim 1, wherein the composition has a specific heat capacity at 50° C. of at least 2.0 kJ/kg×K.

7: The composition according to claim 1, wherein the composition has a thermal conductivity of at least 0.15 W/m×K.

8: The composition according to claim 1, wherein the at least one corrosion inhibitor comprises a compound of the general formula (II), and wherein the structural element R.sup.4—N< of the general formula (II) is derived from at least one amine selected from the group consisting of n-hexylamine, 2-methylpentylamine, n-heptylamine, 2-heptylamine, iso-heptylamine, 1-methylhexylamine, n-octylamine, 2-ethylhexylamine, 2-aminooctane, 6-methyl-2-heptylamine, n-nonylamine, iso-nonylamine, n-decylamine, 2-propylheptylamine, and mixtures thereof.

9: The composition according to claim 1, wherein the at least one corrosion inhibitor comprises an azole derivative, and wherein the azole derivative is selected from the group consisting of benzimidazole, benzotriazole, tolyltriazole, and hydrogenated tolyltriazole.

10: The composition according to claim 1, comprising: 95 to 99.9 wt % of component (A) and 0.1 to 5 wt % of component (B).

11: The composition according to claim 1, wherein component (A) comprises more than one of the alkylene glycol derivative of formula (I), and wherein a ratio of alkylene glycol derivatives of formula (I) wherein n=3 to those wherein n=4 is from 100:0 to 40:60.

12: The composition according to claim 1, consisting of component (A), component (B), optionally at least one further corrosion inhibitor (C) distinct from component (B) and optionally at least one further compound selected from the group consisting of a bitterant a dye, a defoamer, and an antioxidant.

13: A method of cooling systems in fuel cells, batteries, and/or rechargeable batteries, the method comprising: employing the composition according to claim 1 as a coolant or antifreeze for cooling systems in fuel cells, batteries and/or rechargeable batteries.

14: A coolant for lithium-ion rechargeable batteries, comprising the composition according to claim 1.

15: A coolant or antifreeze for fuel cells, comprising the composition according to claim 1, wherein the composition comprises up to 50 wt % of deionized water based on the total aqueous mixture.

16: The coolant or antifreeze for fuel cells according to claim 15, wherein the aqueous mixture has an electrical conductivity at 25° C. of not more than 50 μS/cm.

17: A method for cooling, comprising: employing the composition according to claim 1 as a coolant, transferring heat from a heat source at a temperature from 60° C. to 300° C. to the coolant via at least one first heat exchanger, passing this coolant in a cooling circuit to at least one second heat exchanger, and removing heat from the coolant at a temperature from minus 50° C. to 100° C. in said second heat exchanger, wherein the temperature of the removal of heat from the coolant is at least 50° C. lower than the temperature of the heat source.

18: The composition according to claim 1, wherein the composition comprises a proportion of alkylene glycol derivatives of formula (I) wherein n≤2 of not more than 3 wt %.

19: The composition according to claim 1, wherein the composition comprises a proportion of alkylene glycol derivatives of formula (I) wherein n≥5 of not more than 2 wt %.

20: The composition according to claim 1, wherein the composition comprises a proportion of monoethylene glycol, diethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propylene glycol, or glycerol, of 0 wt % to not more than 3 wt %.

Description

EXAMPLES

Test Methods:

[0210] Unless otherwise stated the values reported in this specification were determined using the following methods:

TABLE-US-00001 Boiling point ASTM D 1120 Density ASTM D 1122 Electrical conductivity ASTM D 1125 Specific heat capacity DIN EN ISO 11357-4 Thermal conductivity sphere gap method Water content ASTM D 1123 Flash point ISO 2719 Ignition temperature DIN 51794 Refractive index ASTM D 1218 Reserve alkalinity ASTM D 1121 pH ASTM D 1287

Compositions

[0211] The following compositions were prepared (reported in wt %):

Comparison:

[0212]

TABLE-US-00002 No. 1 2 3 4 5 Triethylene glycol 95.50 88.50 81.50 74.50 67.50 monomethyl ether Tetraethylene 4.50 11.50 18.50 25.50 32.50 glycol monomethyl ether Sum 100.00 100.00 100.00 100.00 100.00 Kinematic viscosity, 254.3 298.9 319.8 360 393.6 −40° C., mm.sup.2/s (ASTM D 445) Kinematic viscosity, 47.7 53.5 56.6 61.4 65.8 −20° C., mm.sup.2/s (ASTM D 445) Kinematic viscosity, 1.3919 1.4208 1.4658 1.5099 1.5621 100° C., mm.sup.2/s (ASTM D 445) No. 6 7 8 9 10 Triethylene glycol 93.60 86.60 79.90 72.60 65.60 monomethyl ether Tetraethylene glycol 2.60 9.60 16.60 23.60 30.60 monomethyl ether Additive mixture* 2.00 2.00 2.00 2.00 2.00 Diisopropanolamine 1.00 1.00 1.00 1.00 1.00 Octyldiethanolamine 0.80 0.80 0.80 0.80 0.80 Sum 100.00 100.00 100.00 100.00 100.00 Kinematic viscosity, 284.4 315.3 349.9 389.2 477.6 −40° C., mm.sup.2/s (ASTM D 445) Kinematic viscosity, 52.0 56.3 60.5 65.4 70.4 −20° C., mm.sup.2/s (ASTM D 445) Kinematic viscosity, 1.4934 1.8668 1.8067 1.6869 1.6973 100° C., mm.sup.2/s (ASTM D 445) No. 11 12 13 Triethylene glycol 92.20 89.20 82.20 monomethyl ether Tetraethylene glycol 4.00 7.00 14.00 monomethyl ether Additive mixture* 2.00 2.00 2.00 Diisopropanolamine 0 0 0 Octyldiethanolamine 1.8 1.8 1.8 Sum 100.00 100.00 100.00 Kinematic viscosity, 262.4 273.91 306.27 −40° C., mm.sup.2/s (ASTM D 445) Kinematic viscosity, 49.2 50.861 55.128 −20° C., mm.sup.2/s (ASTM D 445) Kinematic viscosity, 1.4224 1.4458 1.4895 100° C., mm.sup.2/s (ASTM D 445) *The employed 2 parts of additive mixture are composed of the nonferrous metal corrosion inhibitor tolyltriazole, antioxidant and a fatty alcohol ethoxylates corrosion inhibitor dissolved in 1.67 parts of triethylene glycol monomethyl ether.

[0213] The corrosion test afforded the following values for reserve alkalinity before/after corrosion (measured in ml of 0.1 M HCl/10 ml of test volume), pH before/after corrosion and corrosive erosion in mg/cm.sup.2 over 336 h according to ASTM D1384:

TABLE-US-00003 1 2 3 4 5 No. (comp) (comp) (comp) (comp) (comp) Reserve alkalinity 0 0 0 0 0 before corrosion Reserve alkalinity 0 0 0 0 0 after corrosion pH before corrosion 5.84 6.04 6.18 6.1 6.08 pH after corrosion 2.58 2.67 2.68 3.07 3.3 Al 0.05 0.22 0.31 0.12 0.38 Cu −0.16 −0.26 −0.28 −0.3 −0.18 Brass −0.17 −0.3 −0.23 −0.29 −0.19 Steel −3.66 −3.25 −2.27 −1.45 −0.99 Gray iron −2.54 −2.51 −2.17 −1.69 −1.24 Soft solder −1.87 −1.36 −1.38 −0.94 −1.02 No. 6 7 8 9 10 Reserve alkalinity 10.8 10.78 10.82 10.85 10.75 before corrosion Reserve alkalinity 8.63 8.56 8.91 8.79 8.77 after corrosion pH before corrosion 9.5 9.6 9.7 9.8 9.9 pH after corrosion 9.9 9.3 9.9 9.9 10.0 Al 0.04 0.1 0.06 0.06 0.05 Cu −0.43 −0.41 −0.42 −0.43 −0.44 Brass 0.07 0.07 0.07 0.08 0.08 Steel 0.04 0.03 0.03 0.02 0.04 Gray iron 0.09 0.11 0.11 0.07 0.14 Soft solder −0.07 −0.06 −0.06 −0.05 −0.05 No. 11 12 13 Reserve alkalinity 7.76 7.98 8.03 before corrosion Reserve alkalinity 6.76 6.25 6.42 after corrosion pH before corrosion 9.4 9.64 9.68 pH after corrosion 9.4 9.45 9.47 Al 0.05 0.05 0.1 Cu −0.03 −0.02 −0.02 Brass 0.06 0.06 0.07 Steel 0.02 0.03 0.03 Gray iron 0.13 0.1 0.08 Soft solder −0.17 −0.18 −0.14

[0214] In the supernatant liquid from the corrosion test according to ASTM D1384 the following contents of metals were determined by ICP spectrometry (inductively coupled plasma) [ppm]:

TABLE-US-00004 1 2 3 4 5 No. (comp) (comp) (comp) (comp) (comp) Fe 18 16 8 28 31 Cu 9 7 5 6 9 Al <3 <3 <3 <3 <3 Zn 5 3 <3 3 4 Sn 6 6 3 5 6 Pb 13 7 8 5 8 No. 6 7 8 9 10 Fe <3 <3 <3 <3 <3 Cu 18 18 18 18 19 Al <3 <3 <3 <3 <3 Zn <3 <3 <3 <3 <3 Sn <3 <3 <3 <3 <3 Pb <3 <3 <3 <3 <3 No. 11 12 13 Fe <3 <3 <3 Cu 3 <3 3 Al <3 <3 <3 Zn <3 <3 <3 Sn <3 <3 <3 Pb <3 <3 <3

[0215] It is apparent that in the compositions according to the present invention the incorporation particularly of iron ions but also of copper ions into the liquid is markedly reduced. It is thus possible to keep the electrical conductivity of the inventive compositions low. The pH is further kept stable during the corrosion and shows only a slight change.

[0216] This is apparent from the following measured electrical conductivities (at 25° C. in μS/cm) before/after corrosion:

TABLE-US-00005 1 (comp) 6 7 8 9 10 11 12 13 Before 0 1.2 1.1 1 0.9 0.9 1.1 0.8 0.7 corrosion After corr 0.3 1.6 1.4 1.3 1.2 1.3 1.3 1.5 1.3

[0217] It is apparent that the comparative composition shows a more marked relative increase in electrical conductivity than the inventive compositions.

[0218] Corrosion test according to ASTM D1384 and corrosive erosion in mg/cm.sup.2 over 4 weeks:

TABLE-US-00006 No. 20**** 14 15 16 17 18 19 (comp.) Triethylene glycol 90 86.2 86.2 88.2 89.95 86.2 monomethyl ether Tetraethylene glycol 10 10 10 10 10 10 monomethyl ether Octyldiethanolamine 1.8 1.8 1.8 1.8 Additive mixture: Tolyltriazole* 0.05 0.05 0.05 Antioxidant** 0.03 0.03 Emulsifiers*** 0.25 0.25 0.25 Triethylene glycol 1.67 1.7 1.72 monomethyl ether Defoamer 0.001 0.001 0.001 0.001 0.001 0.001 Sum 100 100 100 100 100 100 The components employed in the additive mixture have the following activity: *Tolyltriazole as an inhibitor against nonferrous metal corrosion **Antioxidant for preventing/reducing oxidation of the alkylene glycol ethers ***Mixture of fatty alcohol ethoxylates ****Cooling composition based on monoethylene glycol/water (60/40 w/w) according to EP 1399523 B1, example 5, comparison.

TABLE-US-00007 No. 20 14 15 16 17 18 19 (comp.) Erosion mg/ mg/ mg/ mg/ mg/ mg/ mg/ cm.sup.2 cm.sup.2 cm.sup.2 cm.sup.2 cm.sup.2 cm.sup.2 cm.sup.2 Cu −0.69 −0.17 −0.18 −0.80 −0.59 −0.30 −0.07 Soft solder −2.58 −0.17 −0.21 −0.23 −2.23 −0.26 −1.70 Brass −0.83 −0.03 −0.05 −0.13 −0.77 −0.01 −0.13 Steel −6.11 0.00 −0.01 −0.01 14.39 0.00 −37.65 Gray iron −5.80 0.07 0.08 0.09 −3.70 0.12 −48.79 Al −1.72 0.05 0.03 0.57 −0.46 0.05 −0.03

[0219] It is apparent from the above table that the N-octyldiethanolamine particularly preferred according to the invention shows particular advantages as an inhibitor of the corrosion of ferrous materials, particularly steel and gray iron.

[0220] It further exhibits an activity as a nonferrous metal corrosion inhibitor and can partially replace the conventionally employed tolyltriazole as same.

[0221] Corrosion test of composition number 15 based on ASTM D1384 with the following modifications: Distilled water was employed and made up to a 50 wt % aqueous solution and only three metals (brass, steel and aluminum) considered representative for fuel cells were employed. The results of the corrosion test were determined after 4 and 7 days.

TABLE-US-00008 No. 15 15 days 4 7 Erosion mg/cm.sup.2 mg/cm.sup.2 Brass 0.01 −0.07 Steel 0.00 −0.01 Al 0.10 0.09

[0222] Profile of electrical conductivity at different temperatures and admixture of double-distilled water having a conductivity of 0.8 μS/cm at 25° C./1.5 μS/cm at 60° C.

TABLE-US-00009 Wt % Conductivity Conductivity composition Wt % μS/cm at μS/cm at of Ex 15 of water 25° C. 60 ° C. 100 0 0.8 1.3 99 1 1.0 1.9 98 2 1.2 2.4 97 3 1.5 3.0 96 4 1.7 3.7 95 5 2.0 4.4 90 10 3.4 9.0 80 20 7.5 22.4 70 30 13.7 38.0 60 40 19.2 50.4 50 50 24.7 63.2

[0223] It is apparent that the analyzed inventive composition from example 15 remains below the critical conductivity of 25 μS/cm at 25° C. even upon 1:1 dilution with double-distilled water and remains below a critical conductivity of 10 μS/cm upon admixture of 20 wt % of double-distilled water.