Coolant with low electrical conductivity
Coolants with low electrical conductivity and corresponding coolant concentrates are useful for cooling systems of vehicles with electric engines, fuel cells, or hybrid engines with a combination of combustion engines with electric engines or a combination of combustion engines with fuel cells.
1 . A coolant, comprising:
(A) at least one glycol,
(B) water,
(C) at least one azole derivative,
(D) at least one ester of orthosilicic acid or alkoxy alkylsilane,
(E) at least one tertiary amine bearing at least one 2-hydroxyethyl- or 2-hydroxypropyl-group,
(F) at least one monocarboxylic acid,
(G) optionally, at least one silicophosphonate, and
(H) optionally, at least one further coolant additive,
wherein
a molar ratio between the at least one tertiary amine (E) and the at least one monocarboxylic acid (F) is from 1:0.1 to 1:0.6, and
components (C) to (H) are present in amounts so that the coolant exhibits an electrical conductivity of less than 50 μS/cm.
2 . The coolant according to claim 1 , wherein the at least one glycol (A) is selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propanediol, a higher poly alkylene glycol, an alkylene glycol ether, and glycerol.
3 . The coolant according to claim 1 , wherein the at least one azole derivative (C) is selected from the group consisting of benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole, (2-benzothiazylthio) acetic acid, and (2-benzothiazylthio) propionic acid.
4 . The coolant according to claim 1 , wherein the at least one ester of orthosilicic acid (D) is orthosilicic acid tetra ethyl ester or orthosilicic acid tetra methyl ester.
5 . The coolant according to claim 1 , wherein the at least one tertiary amine (E) is selected from the group consisting of
a compound of the general formula (I)
wherein
R 2 and R 3 independently of another each are a linear or branched alkyl substituent comprising 1 to 18 carbon atoms, or together form a five- or six-membered ring including the nitrogen atom,
X i is —CH 2 —CH 2 —O—, —CH 2 —CH(CH 3 )—O— or —CH(CH 3 )—CH 2 —O—, and
n is a positive integer from 1 to 5,
a compound of the general formula (II)
wherein
R 4 is a linear or branched alkyl substituent comprising 1 to 18 carbon atoms,
each Xi for i=1 to p and 1 to q, is independently selected from the group consisting of —CH 2 —CH 2 —O—, —CH 2 —CH(CH 3 )—O—, and —CH(CH 3 )—CH 2 —O—, and
p and q independently of another are a positive integer from 1 to 5, and
a tertiary amine bearing three 2-hydroxyethyl- or 2-hydroxypropyl-groups.
6 . The coolant according to claim 5 , wherein the at least one tertiary amine (E) is of the general formula (I), and is at least one selected from the group consisting of dimethyl ethanolamine, dimethyl propanolamine, diethyl ethanolamine, diethyl propanolamine, di-n-butyl ethanolamine, di-n-butyl propanolamine, N-hydroxyethyl pyrrolidine, N-hydroxyethyl piperidine, and N-hydroxyethyl morpholine.
7 . The coolant according to claim 5 , wherein the at least one tertiary amine (E) is of the general formula (II), and is a bis(2-hydroxyethyl) amine or bis(2-hydroxypropyl) amine bearing as substituent R 4 n-hexyl, 2-methylpentyl, n-heptyl, 2-heptyl, isoheptyl, 1-methylhexyl, n-octyl, 2-ethylhexyl, 2-octyl, 6-methyl-2-heptyl, n-nonyl, isononyl, n-decyl and 2-propylheptyl or a mixture thereof.
8 . The coolant according to claim 5 , wherein the at least one tertiary amine (E) is the tertiary amine bearing three 2-hydroxyethyl- or 2-hydroxypropyl-groups, and is selected from the group consisting of triethanolamine and tripropanolamine.
9 . The coolant according to claim 5 , wherein in the compound of the general formula (I), R 2 and R 3 are independently of another a linear alkyl substituent comprising 6 to 12 carbon atoms.
10 . The coolant according to claim 5 , wherein in the compound of the general formula (I), n is 1.
11 . The coolant according to claim 5 , wherein in the compound of the general formula (II), R 4 is a linear alkyl substituent comprising 6 to 12 carbon atoms.
12 . The coolant according to claim 5 , wherein in the compound of the general formula (II), p and q are 1.
13 . The coolant according to claim 1 , wherein the at least one monocarboxylic acid (F) is aliphatic, aromatic or cycloaliphatic.
14 . The coolant according to claim 13 , wherein the at least one monocarboxylic acid (F) is aliphatic with 5 to 14 carbon atoms.
15 . The coolant according to claim 1 , wherein the at least one monocarboxylic acid (F) is linear or branched.
16 . The coolant according to claim 1 , wherein the at least one monocarboxylic acid (F) is selected from the group consisting of 2-ethylhexanoic acid and isononanoic acid.
17 . The coolant according to claim 1 , wherein no carboxylic acids with a functionality of more than 1 are present.
18 . The coolant according to claim 1 , wherein a water content is not more than 5 wt %.
19 . The coolant according to claim 1 , wherein components (C) to (H) are present in amounts so that the coolant exhibits an electrical conductivity of less than 45 μS/cm.
20 . A method of cooling a vehicle, the method comprising:
adding a coolant into a cooling system of a vehicle with an electric engine, fuel cell, or hybrid engine with a combination of a combustion engine with an electric engine or a combination of a combustion engine with a fuel cell;
wherein the coolant comprises:
(A) at least one glycol,
(B) water,
(C) at least one azole derivative,
(D) at least one ester of orthosilicic acid or alkoxy alkylsilane,
(E) at least one tertiary amine bearing at least one 2-hydroxyethyl- or 2-hydroxypropyl-group,
(F) at least one monocarboxylic acid,
(G) optionally, at least one silicophosphonate, and
(H) optionally, at least one further coolant additive,
wherein
a molar ratio between the at least one tertiary amine (E) and the at least one monocarboxylic acid (F) is from 1:0.1 to 1:0.6, and
components (C) to (H) are present in amounts so that the coolant exhibits an electrical conductivity of less than 50 μS/cm.