JPH07157886A - Non-amine based anti-freeze for aluminum engine - Google Patents

Abstract

PURPOSE:To obtain a pollution-free non-amine based anti-freeze for Al engine excellent in corrosion resistance by blending a specific quantity of benzoic acid, molybdic acid, benzotriazol and nitrate with an anti-freezing component such as ethylene glycol. CONSTITUTION:The pollution free anti-freeze and coolant free from problems such as corrosion generated in the Al alloy engine, problems such as carcinogenicity induced by nitrosoamine and the generation of environmental pollution is obtained by blending 500-50000ppm one or two kinds of benzoic acid, p-tert-butyl benzoic acid and the salt, 50-5000ppm one or more kind of molybdic acid, tungstic acid and the salt, 5-5000ppm benzotriazol, triazol or the salt and 5-5000ppm nitrate with the anti-freezing component of ethylene glycol and/or propylene glycol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-amine antifreeze liquid for aluminum engines, which comprises non-polluting components.

[0002]

2. Description of the Related Art Due to the carcinogenicity of nitrosamine, antifreeze and coolant used in the cooling system of automobiles, motorcycles, diesel vehicles, and internal combustion engines for ships have been developed from 1977 to 1978. The use of amine + nitrite as a constituent was banned in Sweden. In addition, the Norwegian government announced on October 1, 1987 (October 1987
From January 1st), the use of antifreeze and coolant with triethanolamine was also prohibited. These prohibition measures are also related to the effluent standards set by law. Against these strict environmental regulations, Japanese automobile manufacturers
When exporting a car to the European market, an antifreeze liquid that is an antifreeze liquid diluted and mixed with water is injected into the engine coolant of the car before shipment, so it is a non-amine type antifreeze liquid and coolant that does not produce nitrosamine, and is anticorrosive. There is a strong demand for a non-amine-based antifreeze solution for aluminum engines, which has excellent measures, especially for aluminum engines.

Initially, the antifreeze and the coolant were products which were not friendly to the global environment and whose drainage control was not taken into consideration in which the anticorrosion performance was prioritized. Antifreeze and coolant are used as cooling water for internal combustion engines, and antifreeze is used to prevent cooling water from freezing in winter.
Coolants are used throughout the year for antifreeze and summer overheat protection, as well as for metal corrosion protection. In these compositions, those containing ethylene glycol as an antifreezing component and propylene glycol for low pollution as main components, and an anticorrosive component and a defoaming component added thereto are used.

In the cooling system of an internal combustion engine, the metal used is copper,
There is a wide variety of solder, brass, steel, cast iron, aluminum alloys, and especially solder, cast iron, and aluminum alloys are prone to contact corrosion with dissimilar metals.To prevent this, a chromic acid-based rust inhibitor Was used as the most effective one. However, due to the recent pollution of chromic acid, it cannot be used, and development of pollution-free is desired,
Furthermore, due to the carcinogenicity problem of nitrosamines, it has become the most important issue not only in Japan but also in exported vehicles for the suppliers that supply antifreeze and coolant to automobile manufacturers.

Further, since aluminum alloy is used as a material for passenger car engines in order to save resources and to reduce the weight of automobiles, aluminum alloy cylinder blocks have an unprecedented aluminum alloy due to aluminum heat transfer surface corrosion. Cylinder corrosion elution is occurring, which is a problem. This claim frequently occurs in non-amine antifreezes and non-amine coolants, and there is a strong desire for the completion of non-amine antifreezes. Standards such as ASTM D4340 have been established to determine the elution of antifreeze liquid due to heat transfer surface corrosion of aluminum alloy cylinder blocks. According to this test method, an antifreeze solution that corrodes the aluminum alloy test piece violently is easily confirmed. Particularly, conventional antifreeze solutions containing sodium borate and sodium orthophosphate, potassium orthophosphate, and sodium silicate, which show anticorrosive effects against various metals, and coolants cause corrosion elution when used in the conventional composition.

[0006]

From the above, the present invention is an antifreeze solution which does not cause problems such as corrosion to aluminum alloy engines, does not cause problems such as carcinogenicity, is pollution-free and does not cause environmental pollution. And to provide coolant.

[0007]

For these reasons, the non-amine antifreeze for aluminum engines of the present invention has excellent performance as an antifreeze without the use of conventional anticorrosive components, and meets the above-mentioned various demands. It can respond.
The present inventors have carried out research and development of an antifreeze solution containing sodium benzoate and sodium p-tert-butylbenzoate as main ingredients, and sodium molybdate, sodium tungstate, benzotriazole and tolyltriazole have been completed to complete the present invention. .

The non-amine antifreeze for aluminum engines of the present invention comprises (1) benzoic acid and p-tertiary butyl with one or two antifreeze components selected from ethylene glycols and propylene glycols. One or two selected from the group consisting of benzoic acid and salts thereof is added to 500 to 50,000 ppm, (2) one or more selected from the group consisting of molybdic acid, tungstic acid, and salts thereof. 50 to 5000ppm, (3) benzotriazole, tolyltriazole, and 5 to 5000ppm of one or more selected from the group consisting of salts thereof.
And (4) at least 5-5000 ppm of one of the nitrates is blended.

The characteristics of the non-amine type antifreeze for aluminum engines of the present invention include the following (A) to (D). That is, (A) a non-amine-based antifreeze for aluminum engines,
It is an environmentally friendly, non-polluting antifreeze that does not contain amines and nitrite and does not produce carcinogenic nitrosamines. (B) In an internal combustion engine using an aluminum alloy,
The heat transfer surface corrosion can be completely suppressed. (C) Not only corrosion protection for a cooling system of an internal combustion engine using an aluminum alloy, but also sufficient corrosion protection effect even if a wide variety of dissimilar metals other than the aluminum alloy are used. (D) The liquid phase of the used solution is stable, and there is almost no change with time such as formation of precipitates and deterioration of the active ingredient. And so on.

Next, each component used in the present invention will be described. (1) Benzoic acid and p-tert-butylbenzoic acid and salts thereof, especially sodium benzoate and p-
Sodium tert-butyl benzoate is used because it has significant effects on corrosion resistance, high temperature resistance, and durability. In particular, sodium p-tert-butyl benzoate has an excellent reserve alkalinity. In large diesel vehicles, combustion gas may enter the engine cooling liquid (mixed liquid of antifreeze liquid) from the gap between the gaskets of the cylinder head of the engine to generate sulfurous acid, so keep sufficient alkalinity. It is necessary to neutralize these acids to prevent increased corrosion. Benzoic acid and p-tert-butylbenzoic acid and their salts are
It is an anticorrosive agent that can sufficiently cope with these phenomena, especially p-
When tertiary butyl benzoate sodium is used together with sodium benzoate, the effect is further doubled. Due to these effects, this component is a basic anticorrosive agent for all-purpose non-amine antifreeze that can be used for engines of all vehicle types, ships and motorcycles without distinction from passenger cars, aluminum engine cars and large diesel cars. In addition,
As salts of these components, salts used in this type of field such as potassium salts can be used in addition to sodium salts.

(2) Sodium molybdate and sodium tungstate are used because they are effective in preventing corrosion of steel and aluminum alloys. (3) Benzotriazole and tolyltriazole are added because they are extremely effective not only for preventing corrosion of copper and brass but also for corrosion of solder. (4) Sodium nitrate is used because it is extremely effective in preventing corrosion of aluminum alloys and steel. When each of the components (1) to (4) of the present invention is used within the above range, it exhibits the performance as an antifreeze liquid without causing corrosion of various metals and heat transfer surface corrosion of aluminum alloys.

Furthermore, the present inventors have found that sodium p-benzoate and p-tert-butyl benzoate p
The H buffering effect is effectively p due to the synergistic action with other additives.
We have discovered a new fact that H is adjusted to near neutral and the heat transfer surface corrosion of aluminum alloy is suppressed.

[0013]

EXAMPLES Next, the antifreezing liquid for aluminum engines of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Test Example 1 Sodium chloride, sodium sulfate and sodium hydrogen carbonate were added to distilled water so that the concentrations of chlorine ion, sulfate ion and hydrogen carbonate ion were 100 ppm, respectively.
JIS water for metal corrosion test was prepared. Then, the respective components of the non-amine antifreeze for aluminum engine are added so that the components have the concentrations shown in Table 1 to prepare sample Nos. 1 to 4 and comparative sample Nos. 5 to 9. In addition, commercially available products A, B and C were used as comparative examples.
Regarding each of these samples, JISK-2234 (antifreeze)
According to the metal corrosion test method specified in 1987, six metal test pieces made of an aluminum alloy casting, cast iron, steel, brass, solder, and copper produced according to the test method were used.
A continuous test for 336 hours (14 days) was performed while blowing dry air at a rate of 88 ± 2 ° C. at a rate of 100 ± 10 ml / min. Test solution concentration Add 70v / v% of JIS compound water to 30v / v% of sample (antifreeze). The total volume of test solution shall be 750 ml. The degree of corrosion of each metal was evaluated by the amount C of change in mass obtained from the following calculation formula.

[Equation 1] In the formula, C is the amount of change in mass (mg / cm ² ), W is the mass of the metal test piece before the test (mg), W ′ is the mass of the metal test piece after the test (mg), and S is the value before the test. Total surface area of metal test piece (cm ² )
Indicates. The results obtained are shown in Table 2.

Test Example 2 Further, an aluminum alloy heat transfer surface corrosiveness test according to ASTM D4340 standard was conducted on each of the above samples. The test method is as follows. Test conditions (1) Test temperature 135 ° C x 168 hours (2) Test solution concentration Add 75v / v% distilled water to 25v / v% antifreeze. Dissolve 165 mg / l of sodium chloride so that chlorine ion is 100 ppm based on the total amount of the solution. The total volume of test solution shall be 500 ml. (3) Initial pressure 2.0 Kg / cm ² (4) Material of test piece Aluminum alloy AC-2B (5) Size of test piece Disc with diameter 65 mm and thickness 13 mm Calculation and recording method:

[Equation 2] In the formula, C: change in mass (mg / cm ² ) M ₁ : mass of test piece before test (mg) M ₂ : mass of test piece after test (mg) S: sample of test piece before test The contact area (cm ² ) of the obtained results are shown in Table 2.

[0016]

[Table 1]

[0017]

[Table 2]

Since Examples 1 to 4 contain the anticorrosive active ingredient in the specified concentration, they pass the metal corrosion of JIS K-2234 antifreeze. Also, in the aluminum alloy heat transfer surface corrosiveness test of ASTM D4340 method, any sample is satisfied although there is a significant difference depending on the amount of the additive. Comparative Example No. 5 is sodium benzoate and sodium p-tert-butylbenzoate in the anticorrosive ingredients, No. 6 is sodium benzoate, No. 7 is sodium molybdate and sodium tungstate, and No. 8 is The test results when benzotriazole, tolyltriazole and No. 9 of sodium nitrate were excluded from the respective formulations, the metal corrosion test of JISK-2234 antifreeze shows a significant difference in each formulation, but the weight value is within specifications. become. However, in the ASTMD4340 standard aluminum alloy heat transfer surface corrosion test, N
o. 6 gives satisfactory results, but other comparative formulations No.
Nos. 5, No. 7, No. 8 and No. 9 deviate from the reference values and corrode.

Comparative Example Commercially available product A is an exclusive coolant for passenger cars, which shows excellent test results for products containing no amine, sodium borate and sodium orthophosphate, and JIS K-2234 antifreeze metal corrosion test and A
Satisfactory results have also been obtained in the aluminum alloy heat transfer surface corrosion test of STMD4340. Comparative example Commercial product B
Is a dedicated coolant for heavy-duty diesel vehicles, containing no amine but sodium borate, sodium orthophosphate and potassium orthophosphate. This product passes the metal corrosion test of JIS K-2234 antifreeze, but corrodes in the heat transfer surface corrosivity test of ASTM D4340 standard. However, it is the best for cast iron engines and there is no particular problem for large diesel vehicles. However, it cannot be used on aluminum engines or passenger cars. Comparative example Commercial product C
Is a dedicated coolant for heavy duty diesel vehicles and passes the metal corrosion test of JISK-2234 antifreeze because it contains sodium borate and a large amount of sodium orthophosphate and potassium orthophosphate, but the aluminum alloy heat transfer surface of ASTM D4340 standard. It corrodes violently in the corrosiveness test. However, this does not pose any problem for the use of large diesel vehicles. However, it cannot be used for passenger cars and aluminum engine cars.

Referenced ASTM Test Method (1) ASTM D4340 defines the test method, but does not define the corrosion amount specification value. (2) ASTM D3306 has a prescribed corrosion amount of 1 mg / cm ²
It is as follows.

[0021]

As is apparent from the above test results, the non-amine antifreeze solution of the present invention can be used throughout the year as an antifreeze solution and coolant for ordinary passenger cars, large diesel vehicles, etc. as well as vehicles equipped with an aluminum engine. .

Claims (1)

[Claims] 1. One or two antifreeze components selected from ethylene glycol and propylene glycol are selected from the group consisting of (1) benzoic acid, p-tert-butylbenzoic acid, and salts thereof. 1 or 2
From 500 to 50,000 ppm, (2) molybdic acid, tungstic acid, and one or more selected from the group consisting of salts thereof, from 50 to 5,000 ppm, (3) benzotriazole, tolyltriazole and their salts A non-amine antifreeze for an aluminum engine, characterized in that at least one or two or more selected from the group consisting of 5 to 5000 ppm and (4) one of nitrates is blended at least from 5 to 5000 ppm.