JP2884336B2 - Coolant composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling liquid composition which is mixed in cooling water of an internal combustion engine of an automobile or the like to prevent freezing of the cooling water.

[0002]

2. Description of the Related Art Conventionally, a cooling liquid mainly containing a melting point depressant such as alcohols or glycols has been added to cooling water of an automobile engine to prevent freezing in winter.
However, alcohols and glycols not only have no rust-preventive action, but are oxidized by contact with oxygen during circulation at high temperatures, and the resulting oxides promote the corrosion of the metal that forms the cooling water flow path. There is.

[0003] Therefore, the cooling liquid is generally phosphate, borate, carbonate, sulfate, nitrate, molybdate, benzoate, silicate, benzotriazole, sodium salt of mercaptobenzothiazole, tolyltriazole. ,
A rust preventive selected from triethanolamine salts and the like is added to prevent corrosion of metal when used in a predetermined amount mixed with cooling water.

However, as aluminum parts are frequently used for the purpose of saving resources and energy, it has become clear that the conventional coolant does not have sufficient corrosion resistance to aluminum-based metals. For example, borate has excellent anticorrosion properties on cast iron materials, but has no effect on aluminum-based metal materials. Triethanolamine phosphate has anticorrosion properties against both iron-based metals and aluminum-based metals. However, it reacts with nitrite to produce nitrosamines, which is problematic in durability against corrosion. Silicates also have an anticorrosion property against aluminum-based metals, but have a problem in that they are gelated and separated during long-term storage or use, and the anticorrosion properties are reduced.

Therefore, JP-A-1-306492 discloses that a magnesium compound or a sodium salt of mercaptobenzothiazole is used as a rust preventive in place of amines or silicates, and the pH is adjusted to a range of 6.5 to 9.0. An antifreeze is disclosed. This antifreeze has sufficient anticorrosion properties against aluminum-based metals.

[0006]

However, in the antifreeze described in the above publication, the addition amount of the magnesium compound is 0.00
The amount is as large as about 1 to 0.08% by weight, so that there is a problem that the amount of other rust preventives to be added is restricted and the cost is high. Also,
As the output of the engine increases, the surface temperature of the metal of some engines becomes extremely high. In the case of such engine cooling water, an increase in the amount of the magnesium compound or the like leads to an increase in the amount of scale-like deposits on the engine head, which may cause a decrease in engine heat radiation.

The present invention has been made in view of such circumstances, and an object of the present invention is to ensure high rust resistance even when the amount of a rust inhibitor such as a magnesium compound is small.

[0008]

According to a first aspect of the present invention, there is provided a coolant composition comprising a melting point depressant selected from alcohols and glycols, a phosphate, a borate, a nitrate, and a molybdenum. Acid salts, benzoates, silicates,
At least one rust preventive selected from triazoles, thiazoles, sebacic acid and octylic acid; a calcium compound having a metal element concentration of 0.00005 to 0.02% by weight; and at least one of polyphosphoric acid and oligomeric or polymeric carboxylic acids And characterized in that:

[0009] The coolant composition according to the second aspect of the present invention comprises a melting point depressant selected from alcohols and glycols, and phosphates, borates, nitrates, molybdates, benzoates, and silicates. , Triazoles, thiazoles,
At least one rust inhibitor selected from sebacic acid and octylic acid, and a metal element concentration of 0.00005 to 0.02% by weight
Of calcium compound and metal element concentration of 0.00005 to
It is characterized by containing 0.02% by weight of a magnesium compound and at least one of polyphosphoric acid and carboxylic acid in an oligomer or polymer state.

[0010] The cooling liquid composition according to claim 3 further comprises:
Melting point depressants selected from alcohols and glycols, phosphates, borates, nitrates, molybdates, benzoates, silicates, triazoles, thiazoles,
At least one rust inhibitor selected from sebacic acid and octylic acid, and a metal element concentration of 0.00005 to 0.02% by weight
And a polyphosphoric acid .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As alcohols and glycols which are melting point depressants, methanol, ethanol, 2
-Propanol, monoethylene glycol, propylene glycol and the like can be used alone or in combination of two or more. Calcium compounds and magnesium compounds include oxides, hydroxides, permanganates, chromates, fluorides, iodides, carbonates, nitrates, sulfates, titanates, tungstates, borates, respectively. , Phosphate, dihydrogen phosphate, formate, acetate, propionate, butyrate, valerate, laurate, stearate, oleate, glutamate, lactate, succinate, Malate, tartrate, maleate, citrate, oxalate, malonate, sebacate, benzoate, phthalate, salicylate, mandelate and the like can be used.

The calcium compound is contained in the stock solution of the cooling liquid at a concentration of 0.00005 to 0.02% by weight as a metal element concentration. If this amount is less than 0.00005% by weight, the rust-prevention properties suddenly decrease, and even if added in excess of 0.02% by weight, the effect is saturated and the amount of other components added is not preferred. Particularly preferably, it is in the range of 0.0002 to 0.01% by weight. When a calcium compound and a magnesium compound are used in combination, the amount of each added is set to 0.00005 to 0.02% by weight as the metal element concentration. In addition, the mixing ratio of the calcium compound and the magnesium compound in the case of the combined use is desirably that the calcium compound / magnesium compound = 1/2 by the metal element weight ratio.

By the way, the calcium compound and the magnesium compound may cause an increase in product cost due to excessive addition, and may form scale-like deposits. Therefore, the coolant composition of the present invention further contains at least one of polyphosphoric acid and carboxylic acid. As a result, even if the amount of the calcium compound or the magnesium compound is reduced, the same rust prevention performance can be obtained.

Examples of polyphosphoric acid include pyrophosphoric acid, tripolyphosphoric acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, phytic acid and the like. As the carboxylic acid, an oligomer or a polymer carboxylic acid is used, and examples thereof include polyacrylic acid, oligomaleic acid, and maleic acid / acrylic acid copolymer.

The addition amount of polyphosphoric acid and carboxylic acid is preferably in the range of 0.005 to 0.5% by weight in total of either or both. If the amount is less than 0.005% by weight, no effect is obtained. If the amount is more than 0.5% by weight, the effect is saturated, and the amount of other rust preventives added is undesirably reduced. The cooling liquid composition of the present invention usually contains 20 to 6
0% by volume is used as a mixture. Here, in the cooling liquid composition of the present invention, at least one of a calcium compound and a magnesium compound is contained in a predetermined range, and at least one of polyphosphoric acid and carboxylic acid is included, so the rust prevention property is improved for unknown reasons. . Compared with a conventional compound containing a magnesium compound, in the present invention, the same amount of the calcium compound or the magnesium compound is added as compared with the conventional case, and the same rust prevention performance can be obtained.

When a calcium compound and a magnesium compound are used in combination, the same rust-preventive performance as the conventional one can be obtained with a smaller amount of addition, and when the amounts are the same, the rust-preventive performance is remarkably improved.

[0017]

The present invention will be specifically described below with reference to examples and comparative examples. In addition,% described below means% by weight unless otherwise specified. (Example 1) As also shown in Table 1, monoethylene glycol 90.0%, water 1.9476%, sodium nitrate 0.4%, sodium molybdate 0.5%, benzotriazole 0.4%, sodium benzoate 5.0%, mercaptobenzothiazole 0.2
%, Orthophosphoric acid 0.8%, potassium hydroxide 0.7%, calcium nitrate tetrahydrate 0.0071%.
0012%), 0.0253% of magnesium nitrate hexahydrate (0.0024% as magnesium metal concentration) and 0.02% of 1-hydroxyethylidene-1,1-diphosphonic acid were mixed to obtain a cooling liquid composition of Example 1.

The cooling liquid composition was prepared according to ASTM D4340-8
4 (Corrosion of Cast AluminumAlloys in Engine Cool
A corrosion test was performed based on ants Under Heat-Rejecting Conditions (aluminum alloy heat transfer surface corrosion test), and the results of the corrosion amount measurement and the appearance judgment are shown in Table 1. Coolant concentration: 25% by volume Test piece: Aluminum alloy casting (AC-2A) Test piece temperature: 135 ° C or 170 ° C Liquid volume: 500ml Test time: 168Hr Cl ^- amount in test solution: 100ppm Pressurizing pressure: 193kPa In the ASTM test method, the temperature condition is only 135 ° C,
The same test was performed at a temperature of 170 ° C. to perform a more severe test. The pH of an aqueous solution containing 30% by volume of the cooling liquid composition was 7.3.

Example 2 Calcium nitrate tetrahydrate was added to 0.1%
Example 2 is the same as Example 1 except that 0213% (the concentration of metal calcium was 0.0036%) and no magnesium compound was used. The test was performed in the same manner, and the results are shown in Table 1. The pH of the aqueous solution containing 30% by volume of the cooling liquid composition was 7.
Was 3.

Example 3 Magnesium nitrate hexahydrate was used
The same as Example 1 except that 0.0759% (concentration of metal magnesium was 0.0072%) and no calcium compound was used. The test was performed in the same manner, and the results are shown in Table 1. In addition, p of an aqueous solution containing 30% by volume of this cooling liquid composition
H was 7.3.

Comparative Example 1 1-Hydroxyethylidene-
Example 1 is the same as Example 1 except that 1,1-diphosphonic acid is not used and a calcium compound and a magnesium compound are not included. The test was performed in the same manner, and the results are shown in Table 1. (Comparative Example 2) The same as Example 1 except that the calcium compound and the magnesium compound were not used. The test was performed in the same manner, and the results are shown in Table 1. The pH of the aqueous solution containing 30% by volume of the cooling liquid composition was 7.3.

Comparative Example 3 1-hydroxyethylidene-
Example 1 except that 1,1-diphosphonic acid and a magnesium compound were not contained, and the amount of calcium nitrate tetrahydrate was 0.0212% (0.0036% as a calcium metal concentration).
Is the same as The test was performed in the same manner, and the results are shown in Table 1.

Comparative Example 4 1-Hydroxyethylidene-
Example 1 is the same as Example 1 except that 1,1-diphosphonic acid was not used, and instead of the calcium compound, magnesium nitrate hexahydrate was used in 0.0759% (magnesium metal concentration: 0.0072%). The test was performed in the same manner, and the results are shown in Table 1.

Comparative Example 5 1-hydroxyethylidene-
Except that 1,1-diphosphonic acid was not used, calcium nitrate tetrahydrate was used at 0.0071% (calcium metal concentration: 0.0012%), and magnesium nitrate hexahydrate was used at 0.0253% (metal magnesium concentration: 0.0024%). Is Example 1
Is the same as The test was performed in the same manner, and the results are shown in Table 1.

Comparative Example 6 1-hydroxyethylidene-
Performed except that 1,213-diphosphonic acid was not used, and calcium nitrate tetrahydrate 0.0213% (0.0036% as metal calcium concentration) and 0.0759% of magnesium nitrate hexahydrate (0.0072% as metal magnesium concentration) were used. Same as Example 1. The test was performed in the same manner, and the results are shown in Table 1. In addition,
The pH of the aqueous solution containing 30% by volume of the cooling liquid composition was 7.3.

[0026]

[Table 1]

(Evaluation) From a comparison between Comparative Examples 1 to 6 and Examples 1 to 3, it was found that at least one of calcium and magnesium and 1-hydroxyethylidene-1,1-diphosphonic acid coexisted, so that a severe test was performed. It was also found that the amount of corrosion was reduced and the corrosion resistance was excellent, and a synergistic effect due to the coexistence of polyphosphoric acid and a calcium compound or a magnesium compound was apparent.

On the other hand, a comparison between Comparative Example 5 and Comparative Example 6 shows that the corrosion resistance is improved even when the calcium compound and the magnesium compound are increased, but in the case of Comparative Example 6, scale-like deposits are formed. Worry about In other words, by allowing the polyphosphoric acid to coexist with the calcium compound or the magnesium compound, the same anticorrosive property as when the amount of the calcium compound or the magnesium compound is reduced is obtained, so that the formation of scale-like deposits is prevented, The heat radiation of the engine can be maintained for a long time.

[0029]

According to the cooling liquid composition of the present invention, polyphosphoric acid or carboxylic acid coexists with at least one of a calcium compound and a magnesium compound, so that the amount of the calcium compound or the magnesium compound can be reduced. Thus, the same anticorrosion property as that of the related art can be obtained.
Therefore, the formation of scale-like deposits due to excessive addition of the calcium compound or the magnesium compound is suppressed, and the heat radiation of the engine can be maintained high for a long period of time. In addition, since the degree of freedom in the blending design increases, the coolant can be easily blended and designed according to various uses, and the man-hours required for commercialization are reduced and the cost is reduced.

When a calcium compound and a magnesium compound are used in combination, the same anticorrosion as before can be obtained even if the addition amounts of both are further reduced. Therefore, the formation of scale-like deposits is further suppressed, and the degree of freedom in the formulation design is further increased.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiki Ito 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Hideyuki Tami 813 Yoshikawa Yoshimizu City, Shizuoka Prefecture Nippon Chemical Industry Co., Ltd. (72) Inventor Yaeda Hitoshi 813 Yoshikawa, Shimizu City, Shizuoka Prefecture Inside Nippon Chemical Industry Co., Ltd. (56) References JP-A 1-318077 (JP, A) JP-A 51-75641 (JP, A) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) C09K 5/00 C23F 11/00 WPI / L (QUESTEL)

Claims (3)

(57) [Claims] 1. A melting point depressant selected from alcohols and glycols, phosphate, borate, nitrate, molybdate, benzoate, silicate, triazole,
At least one rust inhibitor selected from thiazoles, sebacic acid and octylic acid, and a metal element concentration of 0.0000
A coolant composition comprising 5 to 0.02% by weight of a calcium compound and at least one of polyphosphoric acid and carboxylic acid in an oligomer or polymer state. 2. A melting point depressant selected from alcohols and glycols, phosphate, borate, nitrate, molybdate, benzoate, silicate, triazole,
At least one rust inhibitor selected from thiazoles, sebacic acid and octylic acid, and a metal element concentration of 0.0000
A coolant composition comprising a calcium compound in an amount of 5 to 0.02% by weight, a magnesium compound having a metal element concentration of 0.00005 to 0.02% by weight, and at least one of polyphosphoric acid and an oligomer or a carboxylic acid in a polymer state. . 3. A melting point depressant selected from alcohols and glycols, phosphates, borates, nitrates, molybdates, benzoates, silicates, triazoles,
At least one rust inhibitor selected from thiazoles, sebacic acid and octylic acid, and a metal element concentration of 0.0000
5 to 0.02% by weight of magnesium compound and polyphosphoric acid
And a cooling liquid composition comprising: