RU2299271C1 - Corrosion inhibitor for low-freezing coolant fluid - Google Patents

Abstract

FIELD: corrosion protection.

SUBSTANCE: corrosion inhibitor applicable in cooling systems of internal combustion engines and as heat carrier in heat-exchange apparatuses is composed of, wt %: sebacic acid 6.0-7.0, succinic acid 5.0-6.0, sodium hydroxide 7.0-8.0, benzoic acid 1.5-2.5, water 30.0-45.0, o-phenylenediamine-sodium nitrite-benzoic acid reaction product 1.5-3.0, and ethylene glycol - the balance.

EFFECT: increased corrosion resistance of all structural materials of cooling system and reduced toxicity inhibited coolants.

2 tbl, 15 ex

Description

The invention relates to the field of chemical technology, in particular to corrosion inhibitors for low-freezing liquids used in cooling systems of internal combustion engines and as heat carriers in heat exchangers.

Corrosion inhibitor compositions are known (CS patent 226394, IPC 7 C 23 F 11/10, publ. 1985; JP patent 59-157161, IPC 7 C 09 K 3/00, publ. 1984), but they do not prevent the corrosion of cast iron and steel and antifreeze, manufactured on the basis of an inhibitor of ferrous metals (CS patent 213153, IPC 7 C 23 F 11/10, publ. 1984), is aggressive to brass.

The closest in composition, properties and the achieved goal is a corrosion inhibitor for antifreeze based on ethylene glycol (RU patent 2241784, IPC 7 C 23 F 11/08, publ. 2004 - prototype) of the following composition, wt.%:

Adipic acid 6.5-7.5 Benzoic acid 2.0-3.0 Sodium hydroxide 4,5-5,0 Sodium tetraborate decahydrate 4.0-4.5 2-mercaptobenzthiazole alkali metal salt 0.10-0.15 Water 10.0-12.0 The product of the interaction of o-phenylenediamine with sodium nitrite and benzoic acid in ethylene glycol 2.5-5.0 Ethylene glycol rest

The disadvantage of the inhibitor, despite the rather high anti-corrosion properties, is the presence of sodium tetraborate in its composition, which has an adverse effect on the human body.

The objective of the invention is to reduce the corrosion activity of a corrosion inhibitor for the manufacture of low-freezing coolants in relation to all structural materials of the engine cooling system while reducing their toxicity.

The technical result of the invention is to increase the corrosion resistance of all structural materials of the engine cooling system and reduce the toxicity of coolants.

This object is achieved in that the corrosion inhibitor for low-freezing ethylene glycol-based cooling liquids containing sodium hydroxide, benzoic acid, water and the product of the interaction of o-phenylenediamine with sodium nitrite and benzoic acid in ethylene glycol additionally contains sebacic and succinic acid in the following ratio of components, wt.%:

Sebacic acid 6.0-7.0 succinic acid 5.0-6.0 Benzoic acid 1.5-2.5 Sodium hydroxide 7.0-8.0 Water 30.0-45.0 The product of the interaction of o-phenylenediamine with sodium nitrite and benzoic acid in ethylene glycol 1.5-3.0 Ethylene glycol rest

Comparative analysis with the prototype shows that this composition of the corrosion inhibitor differs from the known introduction of new components and, thus, this technical solution meets the criterion of novelty.

The use of new components in this composition in combination with those known for their specified ratio provides properties that are manifested only in this technical solution: high corrosion stability of the composition relative to structural materials (copper, brass, solder, steel, cast iron, aluminum) while reducing its toxicity. When studying other technical solutions in this field of technology, signs that distinguish the claimed invention from the prototype were not identified, which ensures that this technical solution meets the criterion of significant differences.

The product of the interaction of o-phenylenediamine with sodium nitrite and benzoic acid in ethylene glycol is used according to TU 2422-009-57253465-2003.

The preparation of a corrosion inhibitor of this composition is carried out by sequential mixing of the components at 80-85 ° C.

Example 1. First, the product of the interaction of o-phenylenediamine with sodium nitrite and benzoic acid in ethylene glycol is prepared by successively dissolving the components in ethylene glycol at a weight ratio of, respectively, (1.2-1.6) :( 0.8-1.2): (1.4-1.8) :( 10-12) at 50-60 ° C for 1 hour. 30.0 g of water, 46.50 g of ethylene glycol, 6.00 g of sebacic acid, 6, 00 g of succinic acid, 2.00 g of benzoic acid, 7.50 g of sodium hydroxide and 2.00 g of the product of the interaction of o-phenylenediamine with sodium nitrite and benzoic acid in ethylene glycol. The mixture is stirred for 1 h until the components are completely dissolved.

Other formulations are prepared similarly.

From the composition of the corrosion inhibitor shown in table 1 (examples 1-15), samples of coolants are prepared for testing for corrosion activity by diluting it with an aqueous solution of ethylene glycol (54-56 vol.%) In a ratio of 1: 5-1: 6, respectively.

Corrosion tests of coolants are carried out according to ASTM D-1384 for 336 hours at 88 ± 1 ° C.

Comparative results of corrosion tests of samples according to the invention, prototype and standards according to GOST 28084 are shown in table 2.

As can be seen from tables 1 and 2, compositions 1-5 have high anticorrosive properties.

A decrease in the content of sebacic acid below 6.0 wt.% Causes an increased corrosive effect of the liquid on copper, brass and solder (example 6), and an increase in its concentration above 7.0 wt.% Negatively affects the corrosion loss of ferrous metals and aluminum (example 7 )

With a decrease in the content of benzoic acid below 1.5 wt.%, Increased corrosion of aluminum is noted (example 8), and an increase in its content above 2.5 wt.% Does not lead to a positive effect (example 9).

A decrease in sodium hydroxide content below the lower limit leads to significant corrosion of ferrous metals (example 10), and its increase above 80 wt.% Causes corrosion of aluminum (example 11).

A decrease in the concentration of succinic acid below 5.0 wt.% Leads to a significant corrosion loss of ferrous metals (example 12), and an increase in its concentration above 6.0 wt.% Does not enhance the positive effect (example 13).

The decrease in the content of the product of the interaction of o-phenylenediamine with sodium nitrite and benzoic acid below 1.5 wt.% Negatively affects the corrosion behavior of copper (example 14), and at its concentrations exceeding the upper limit, the positive effect is not enhanced (example 15).

At water concentrations below and above the declared limits (30.0-45.0 wt.%), Precipitation is observed in the samples.

Thus, the low-freezing coolant obtained on the basis of this corrosion inhibitor has high protective properties with respect to structural materials of internal combustion engines and has a reduced toxicity.

Table 1.
Corrosion inhibitor compositions for preparing test coolants. Name of components one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen fifteen Sebacic acid 6.00 6.80 6.20 6.50 7.00 5.90 7.10 7.00 6.90 6.80 6.70 7.00 6.20 6.80 6.80 succinic acid 6.00 5.80 5.50 5.00 5.30 5.10 5.50 5.30 5.10 5.40 5.20 4.90 6.10 6.00 5.30 Benzoic acid 2.00 2.20 2,50 1.80 1,50 1.80 2.20 1.40 2.60 1,50 2.10 2,50 1,60 1.75 2.15 Sodium hydroxide 7.50 7.05 7.90 7.20 7.35 7.30 7.70 7.70 7.50 6.90 8.10 7.20 7.80 7.45 7.75 The product of the interaction of o-phenylene diamine with sodium nitrite and benzoic acid in ethylene glycol 2.00 1,50 3.00 2,50 2.00 1,50 2,50 3.00 2.00 2.00 2.00 2,50 2,50 1.00 3,50 Water 30,0 35.0 35.0 40,0 45.0 40,0 40,0 40,0 35.0 40,0 40,0 40,0 35.0 35.0 40,0 Ethylene glycol Rest

Table 2.
The results of corrosion tests of the claimed composition to the requirements of GOST 28084 for loss in mass. Material Structure GOST 28084 requirements one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen fifteen prototype Copper 1,1 1,0 1,2 0.9 1,5 2.9 0.8 1,0 1,1 0.8 0.8 0.9 1,0 3.2 1,1 1,2 3.75 Brass 1,2 1,6 1.3 1.3 1,6 3.0 1,0 1,2 2.0 1,6 1.4 1,2 1,6 2.0 1.4 1.8 3.75 Solder 1.8 2.1 2.0 1.8 1,5 3.6 1.3 1.9 1.8 2.0 1.4 1.8 1.9 2.2 1.9 2.0 7.50 Steel 0.8 0.7 0.8 0.5 0.8 0.5 2,5 0.6 0.4 3.6 0.7 3.8 0.5 0.6 0.7 0.7 3.75 Cast iron 0.9 0.8 0.4 0.5 0.6 0.6 3.9 0.5 0.6 4.4 1,0 5,4 0.8 0.9 0.8 0.8 3.75 Aluminum 0.9 0.8 1,0 1,1 1,2 0.6 3,7 4.2 0.9 1.3 6.0 1.8 1.3 1,2 1,2 2.1 3.75

Claims (1)

Corrosion inhibitor for low-freezing ethylene glycol-based cooling fluids containing sodium hydroxide, benzoic acid, water and the reaction product of o-phenylenediamine with sodium nitrite and benzoic acid in ethylene glycol, characterized in that it additionally contains sebacic and succinic acids in the following ratio of components, wt .%: Sebacic acid 6.0-7.0 succinic acid 5.0-6.0 Benzoic acid 1.5-2.5 Sodium hydroxide 7.0-8.0 Water 30.0-45.0 Interaction product o-phenylenediamine with sodium nitrite and benzoic acid in ethylene glycol 1.5-3.0 Ethylene glycol Rest