JPH01311099A - Antifreezing solution - Google Patents

Abstract

PURPOSE:To provide an antifreezing agent having excellent corrosion resistance against Al and iron by adding a phosphate salt, Mg compound, mercaptobenzothiazole sodium salt, nitrate salt, benzoate salt and molybdate salt to a composition comprising a glycol and water and subsequently adjusting the solution to a specific pH. CONSTITUTION:A phosphate salt (e.g., orthophosphoric acid or lithium salt thereof), magnesium compound (e.g., magnesium oxide), mercaptobenzothiazole sodium salt, nitrate salt (e.g., sodium salt), benzoate salt and molybdata salt (e.g., sodium molybdata) are added in amounts of preferably 0.5-3.0wt.%, 0.005-0.050wt.%, 0.1-0.50wt.%, 0.1-0.50wt.%, 2.0-7.0wt.% and 0.3-0.7wt.%, respectively, to a composition comprising a glycol and water. The added composition is adjusted to a pH of 6.5-9.0, preferably 7.0-8.0, to provide the objective antifreezing solution.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an antifreeze solution comprising glycols, water, and a corrosion inhibitor used for preventing freezing of cooling water of a liquid-cooled internal combustion engine. More specifically, the present invention relates to an antifreeze liquid that is used as a coolant for an automobile engine and is effective in maintaining the functions of the cooling system of an automobile engine, in addition to preventing freezing and preventing rust and corrosion.

(Prior Art) Conventionally, the coolant for liquid-cooled internal combustion engines, such as automobile engines, has been made mainly of alcohols or glycols to prevent freezing in the final stage, and various corrosion inhibitors have been added to this to make it antifreeze. A tilted antifreeze solution is used that also has anti-corrosion properties.

(Problems to be solved by the invention) - Alcohols used for boat fishing include methyl alcohol, ethyl alcohol, isopro, and rual, and glycols include ethylene glycol, propylene glycol, and hexylene. Glycol, glycerin, etc. are used alone or in combination. Among these, antifreeze containing monoethylene glycol as a main ingredient is particularly used as a coolant in the cooling system of an automobile engine.

In the case of monoethylene glycol aqueous solution, -
Anti-freeze effect up to -37.0°C can be obtained at 15.5°C and 50% by volume.

Alcohols or glycols are oxidized by contact with air, producing acidic alcohol or glycol oxides. Under high temperature conditions of 50.-100°C, the production of alcohol or glycol oxides is further promoted. These acidic alcohols or glycols significantly accelerate the corrosion of various metals constituting the cooling system of an internal combustion engine, especially an automobile engine.

IK corrosion of various metals constituting the cooling system of an internal combustion engine causes a decrease in thermal conductivity due to deposition of corrosion products or blockage of radiator pipes, causing the engine to overheat.

For antifreeze solutions whose main components are alcohols or glycols, 1 g of a corrosion inhibitor is added because the alcohols or glycols themselves have no anticorrosion effect.

As anticorrosive agents, sand, V1 salt, nitrate, phosphate, silicate, sodium benzoate, sodium salt of mercaptobenzothiazole, benzotriazole, methylbenzotriazole, triethanolamine, jetanolamine, mono At least one selected from ethanolamine, triisopropanolamine, diisopropanazine, monoisopropanazine, cyclohexylamine, ethylenediamine, hydrazine, pyridine, morpholine, etc. is used.

Representative among these are borax, triethanolamine phosphate, triethanolamine benzoate, triethanolamine nitrite, and triethanolamine sodium silicate. Borax has been widely used as an effective anti-corrosion agent for cast iron engines, but in recent years, aluminum parts have been adopted as automobile parts become lighter in order to conserve resources and energy. It has become a problem to have one.

When an aqueous ethylene glycol solution containing borax is used in the cooling system of an automobile engine, it can corrode the aluminum alloy that is the material of the engine's cylinder head and cylinder block, and the corrosion products can clog the radiator. Are known.

On the other hand, triethanolamine phosphate has excellent anticorrosion properties for iron-based and aluminum materials, and has been used as an anticorrosive agent in place of borax. It has been reported that the coexistence of amines and nitrites should be avoided, and benzoic acid sorter alone is not effective enough to replace these anticorrosive agents.

On the other hand, sodium silicate is also effective as a corrosion inhibitor, but there is a problem in that the sodium silicate gels and separates during long-term storage.

That is, an object of the present invention is to provide an antifreeze solution that is a composition that does not contain amines and has particularly excellent aluminum corrosion resistance. As a result of extensive research, the present inventors found that in an antifreeze solution consisting of glycols and water, (A) phosphoric acids, (n) magnesium compounds, (C) mercaptobenzothiazole sorta, (D) nitrates, (E) benzoic acid, The object of the present invention could be achieved by containing an acid salt, (de)molybdate, and having a pH in the range of 6.5 to 9.0.

(Means for Solving the Problems) The present invention provides an antifreeze solution consisting of glycols and water, which contains <A) phosphoric acids, (B) magnesium compounds, (C) mercaptobenzothiazole soda, (D) nitrates, (E The present invention relates to an antifreeze solution containing a benzoate salt, (F) a molybdate salt, and having a pH in the range of 6.5 to 9.0.

Examples of the phosphoric acids of the present invention include phosphoric acids and salts thereof. In addition to orthophosphoric acid, first to tertiary salts of alkali metals such as lithium, sodium, and potassium can be used. The amount added is 0.1 to 5.0 to the undiluted antifreeze solution.
Saturn%, preferably 0.5 to 3.0 Saturn%.

Magnesium compounds of the present invention include magnesium oxide, magnesium hydroxide, red sea bream permanganate,
Magnesium chromate, magnesium fluoride, magnesium iodide, magnesium carbonate, magnesium phosphate, magnesium sulfate, magnesium titanate, magnesium tanksudate, magnesium borate, magnesium phosphate, magnesium dihydrogen phosphate, magnesium ammonium phosphate, magnesium formate, magnesium acetate , Magnesium propionate, Magnesium acetate, Magnesium valerate, Magnesium laurate, Magnesium stearate, Magnesium oleate, Magnesium glutamate, Red sea bream sium lactate, Magnesium oparate, Magnesium malate, Magnesium tartrate, Magnesium hydrogen tartrate, Malein Magnesium acid, magnesium citrate, magnesium oxalate, magnesium malonate, magnesium sebacate, magnesium benzoate, magnesium phthalate, magnesium salicylate, manganese, magnesium derrate, and the like can be used.

The amount of the magnesium compound of the present invention added is o, oot to o, oso, preferably 0.0 to the stock solution of antifreeze.
The range is from 0.05 to 0.50%.

The amount of sodium mercaptobenzothiazole of the present invention added is in the range of 0.05 to 0.70% by weight, preferably 0.1 to 0.50% by weight, based on the stock solution of antifreeze.

As the nitrate of the present invention, alkali metal salts such as sodium salts and potassium salts are used. The amount of nitrate added is in the range of 0.05 to 0.70% by weight, preferably 0.1 to 0.650% by weight, based on the stock solution of the antifreeze solution.

As the benzoate of the present invention, 7' alkali metal salts such as sodium salts and potassium salts are used. The amount of benzoate added is in the range of 1.0 to 7.0% by weight, preferably 2.0 to .7.0% by weight, based on the stock solution of the antifreeze solution.

As the molybdate of the present invention, alkali metal salts of molybdic acid such as sodium molybdate and potassium molybdate can be used.

The amount of molybdates added is 0.
10 to 1.0% by weight, preferably 0.3 to 0.7% by weight
is within the range of

In addition, methylbenzotriazole, benzotriazole, etc. can be used.

For adjusting the P11 of the antifreeze solution, ordinary bases and gate substances can be used, but as the alkaline substance for adjusting the pH, hydroxides of alkali metals such as lithium, sodium, potassium, etc. are preferably used. The adjustment range for P I-1 is 6.5.
-9.0, preferably 7.0-8°O. If the pH is higher than this range, the corrosion resistance against aluminum will be poor,
If it is too low, iron corrosion will occur, so it should be adjusted within the above range.

Antifoaming agents such as silicone oil, mineral oil, alcohol, and higher fatty acid ester can be added to the antifreeze solution of the present invention.

(Example) Next, the antifreeze solution of the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Metal corrosion test method [JIS-2234 (Antifreeze/α) Core aluminum casting, cast iron, steel, brass, solder, copper metal test pieces were used, mixed with mixed water (148 mg of sodium sulfate, 165 mg of sodium chloride, and 165 mg of sodium bicarbonate). Soak in antifreeze diluted to 30% by volume with 138 mg of sodium dissolved in 11 parts of distilled water, and blow dry smoked air to 100 ± 10 ool 7'1 lIn.
Since the flow rate of the antifreeze liquid is 88±2℃, the antifreeze temperature is 6.
It was held for 72 hours. T of each metal pa before and after the test! The amount was measured and the change in mass was determined.

The change in mass of each metal was determined from the following equation.

C:= (m2-m1>/Swhere, C: Change in mass (m g i' dl)
m1: Mass of test C before test (m g) 10
2: Mass of test piece after test (mg)S:
Total surface area of test piece before test (2) Examples 1 to 6 The formulations shown in Table 1 were dissolved in 5 parts of tap water or 95 parts by weight of monoethylene glycol at the blending ratio shown in Table 1. The liquids were mixed.

The following tests and measurements were performed on each sample.

The metal corrosion test results are shown in Table-1.

Comparative Example 1-5 The formulation shown in Table 1 was dissolved in 5 parts by weight of tap water or 95 parts by weight of monoethylene glycol at the blending ratio shown in Table 1, and both solutions were mixed.

The following tests and measurements were performed on the samples.

The metal corrosion test results are shown in Table-1.

(Effect of the invention) In the antifreeze solution comprising glycols and water of the present invention, (A>phosphoric acid, (B) magnesium compound, (0) mercaptobenzothiazole soda, <D) acid salt, (E) ammonium, By containing υ, fragrant salt, (l molybdate), and having p l-( in the range of 6.5 to 9.0), the corrosion prevention effect on aluminum and iron is significantly improved.

Claims (1)

[Claims] (1) In an antifreeze solution consisting of glycols and water, (A) phosphoric acids, (B) magnesium compounds, (C) mercaptobenzothiazole soda, (D) nitrates, (E) benzoates, (F) molybdic acid An antifreeze solution comprising: a salt, and having a pH in the range of 6.5 to 9.0.