JP2003342559A - Long-life radiator coolant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiator coolant having high exchange life to a radiator made of an aluminum alloy. <P>SOLUTION: The coolant comprises a water-soluble organic medium used for radiator made of an aluminum alloy as a main component and contains an aliphatic polybasic carboxylic acid containing ≥4 carboxylic acid groups and/or its salt. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long-life coolant (meaning refrigerant, cooling liquid, cooling water, antifreeze liquid, etc.) used for a radiator made of an aluminum alloy for transportation machines such as automobiles.

[0002]

2. Description of the Related Art In order to reduce the weight of vehicles such as automobiles, aluminum alloy materials are being increasingly applied to radiators instead of copper alloy materials that have been conventionally used. For the corrosion protection of the inner surface of the tubes of these aluminum alloy radiators, an aluminum alloy endothelial material containing Zn and having a sacrificial anode effect is generally used.

On the other hand, as a radiator coolant, a coolant having a water-soluble organic medium such as ethylene glycol as a main component and appropriately containing water and a commercially available rust preventive agent has been used.

A long life is required for these radiator coolants in order to reduce the frequency of coolant replacement. For example, radiator coolants for automobiles are required to have a replacement life of at least 5 years and at least 150,000 km.

However, when the radiator coolant contains the above-mentioned rust preventives such as phosphates, amines, silicates, borates, etc., deterioration of water-soluble organic medium such as ethylene glycol in the coolant may occur. Along with this, it is often observed that the concentrations of these rust preventive agents decrease, and finally the rust preventive agent concentration also becomes zero. As a result, the long-term rust preventive effect of these rust preventive agents cannot be expected, and actually, the replacement life of the radiator coolant is only about 2 years, and the high replacement life cannot be guaranteed.

Therefore, in the past, Japanese Patent Laid-Open No. 8-1137 has been used.
No. 71, JP-A No. 11-61117 and the like, typically citric acid, sebacic acid, succinic acid and / or salts thereof (aliphatic carboxylic acids containing two carboxylic acid groups and / or salts thereof). In addition, it has been proposed to add a carboxylic acid having an anticorrosive effect to an aluminum alloy material, such as paratersiabutylbenzoic acid and octenyl succinic acid, to a coolant, and some of them have been put into practical use.

[0007]

However, the water-soluble organic medium such as ethylene glycol in the coolant inevitably deteriorates (decomposes) with time and has corrosiveness with respect to the aluminum alloy material, such as glycolic acid and formic acid. It produces an acid.
Therefore, the sacrificial anode material, the aluminum alloy material such as the engine head, and the metal such as the steel material of the engine block inevitably elute into the coolant.

The above-mentioned carboxylic acids such as sebacic acid, paratershabutylbenzoic acid and octenylsuccinic acid have an anticorrosive effect on the aluminum alloy material, but have a property of easily reacting with the aluminum alloy dissolved and eluted in the coolant. Have. When a reaction with this aluminum alloy occurs, the aluminum salt, which is a reaction product, is insoluble in the radiator coolant, precipitates and adheres to the inner surface of the radiator pipe over time, and causes clogging of the radiator pipe. Leading to.

This clogging phenomenon significantly shortens the replacement life of the radiator or the radiator coolant, and a high replacement life cannot be guaranteed.

Therefore, the aluminum alloy radiator has the above-mentioned long exchange life, has an anticorrosive property against aluminum alloy materials and other members, and produces the aluminum alloy and the insoluble compound eluted in the coolant. There was a need for a difficult rust inhibitor.

The present invention has been made in view of such circumstances, and an object thereof is to provide a radiator coolant having a long exchange life especially for an aluminum alloy radiator.

[0012]

In order to achieve this object, a coolant containing a water-soluble organic medium as a main component, which is used in an aluminum alloy radiator, was invented. The present invention is a long-life radiator coolant containing an aliphatic polyvalent carboxylic acid containing 4 or more carboxylic acid groups and / or a salt thereof.

In the present invention, the above aliphatic means
Both aliphatic and alicyclic are included, and both aliphatic and alicyclic are also simply referred to as aliphatic.

The aliphatic polyvalent carboxylic acid containing 4 or more carboxylic acid groups and / or its salt has anticorrosion properties against aluminum alloy materials and other members in a radiator coolant containing a water-soluble organic medium as a main component. . Also, when an aluminum alloy is dissolved in the coolant due to glycolic acid or formic acid, it reacts with this eluted aluminum alloy to form a compound soluble in the coolant.
The formation of the precipitate is suppressed. As a result, by adding an aliphatic polyvalent carboxylic acid containing four or more carboxylic acid groups and / or a salt thereof, the exchange life of the aluminum alloy radiator or coolant can be increased.

The aliphatic polyvalent carboxylic acid containing four or more carboxylic acid groups and / or its salt is a surface potential (zeta potential) of the aluminum alloy material constituting the radiator.
Lower. Therefore, it has a function of weakening the electrostatic attraction force between the radiator material and a precipitate such as a dissolved aluminum alloy having a negative surface potential, or a function of electrostatically repelling. In other words, it is difficult to deposit the deposit on the surface of the aluminum alloy material, and suppress the deposition of the deposit on the inner surface of the radiator pipe, to prevent clogging of the radiator pipe, and the aluminum alloy radiator or the coolant. It also has the effect of increasing the replacement life.

Normally, the surface potential (zeta potential) of the aluminum alloy material forming the radiator is originally on the plus side. On the other hand, the surface of the precipitate derived from the eluted aluminum alloy has a negative surface potential. For this reason, electrostatic adsorption works between the surface of the aluminum alloy material and the surface of the precipitate, and the precipitate adheres more to the surface of the aluminum alloy material, which tends to cause clogging of the radiator pipe.

As described above, the radiator coolant of the present invention reacts with the aluminum alloy eluted in the coolant to form a compound soluble in the coolant, which is an action of hardly forming a precipitate, and the precipitate in the coolant is The exchange life of the aluminum alloy radiator or the coolant can be increased by a synergistic effect with the effect that the aluminum alloy material forming the radiator does not easily adhere to the surface.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The composition constituting the radiator coolant of the present invention will be described in detail below.

(Water-Soluble Organic Medium) The water-soluble organic medium of the radiator coolant of the present invention is a water-soluble and commercially available anticorrosive agent as well as the conventionally used water-soluble organic medium of this kind. When used for, it is preferable that the rust preventive has a property of solubilizing. In addition, it is preferable to have the effect of lowering the freezing point of water in order to make the coolant containing water into antifreeze liquid.

Examples of the water-soluble organic medium having these properties include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl alcohol, ethyl alcohol, propanol and glycerin, and one or more selected from these may be used alone. Or used in combination.

The water-soluble organic medium is selected from the composition range of 70 to 10% and 30 to 90%, and used as the main component of the radiator coolant.

(Aliphatic Polycarboxylic Acid) The aliphatic polycarboxylic acid, which is a characteristic additive of the radiator coolant of the present invention, must contain at least 4 carboxylic acid groups. Some aliphatic carboxylic acids having 3 or less carboxylic acid groups and / or salts thereof have a rust preventive effect on aluminum alloy materials. However, when the metal components such as iron, aluminum alloy, etc., engines, radiators, etc. are dissolved by the acid generated by the deterioration of the water-soluble organic medium which is the main agent of the coolant, they immediately react with these ions and become the coolant. Since an insoluble compound is generated, the generated precipitate easily adheres to the aluminum alloy material and causes clogging.

Examples of those having 3 or less carboxylic acid groups and having a rust preventive effect on an aluminum alloy material include octenyl succinic acid, benzoic acid, sebacic acid and salts thereof.

As the number of carboxylic acid groups increases, the product reacted with the eluted metal such as an aluminum alloy becomes
It is easily dissolved in the coolant and the action of making it difficult to form a precipitate becomes stronger. The aliphatic polyvalent carboxylic acid containing four or more carboxylic acid groups has a rust preventive effect on the aluminum alloy material and also has the property that no precipitate is formed even when it reacts with the eluted metal.

As the number of carboxylic acid groups increases by 4 or more, the surface potential of the aluminum alloy material constituting the radiator is further lowered, so that precipitates such as eluted aluminum alloy having a negative surface potential and the radiator material. The action of weakening the electrostatic attraction force of or with the action of repelling electrostatic becomes stronger, and the effect of suppressing the adhesion of the precipitate becomes greater.

In order to enhance these effects, it is preferable that the aliphatic polycarboxylic acid has a molecular weight of 400 or more in addition to the number of carboxylic acid groups. When the molecular weight is less than 400, the effect is not sufficiently exerted when the coolant usage conditions such as the coolant composition conditions, the coolant usage temperature and the stirring strength during circulation become severe, and the above-mentioned automobile radiator coolant is used for 5 years or more. Through 1
There is a possibility that the replacement life cannot be guaranteed during a mileage of 50,000 km or more.

4 having a carboxylic acid group having these functions
Examples of the aliphatic polycarboxylic acid containing one or more of them include polycarboxylic acid, a derivative in its carboxyl group, or a salt thereof.

Among these, as the polycarboxylic acid having a high effect and preferable, a polyene polycarboxylic acid represented by the following formula 2 or a derivative in the carboxyl group or a salt thereof is preferable.

[0029]

[Chemical 2] (In the formula, n means an integer of 1 to 5 and m means an integer of 1 or 2)

In the above formula 1, it is preferable that m = 2, n = 1, or m = 2, n = 2. These preferable compounds are particularly represented by the following formula 3 (3
Z, 8Z, 10E) -6-ethyl-3,8,10-tridecatriene-1,3,4,8,9-pentacarboxylic acid pentasodium salt or represented by the following formula 4 (3Z,
8Z, 13Z, 15E) -6,11-diethyl-3,
8,13,15-octadecatetraene-1,3,4,
One or two of 8,9,13,14-heptacarboxylic acid hepta sodium salt (polyene polycarboxylic acid salt)
It is illustrated to include a seed.

[0031]

[Chemical 3]

[0032]

[Chemical 4]

These compounds are compounds derived from fermentation products.
(Synthesis is also possible) as well as International Publication No. WO99 /
46231, etc., and the Journal of the Oil Chemistry Society of Japan, No. 48.
Vol. 9, No. 9 (1999, pages 903 to 909) and the like, which are abbreviations of CF2399 and CF2403, respectively, and are known as surfactants and dispersants, including production methods. However, the present invention is
It was made by discovering that these polyene polycarboxylic acid compounds have the above-mentioned novel action and effect of extending the life of the radiator coolant.

However, even if an aliphatic polycarboxylic acid other than those described above or a salt thereof is used, the carboxylic acid having the performance specified in the present invention is included in the scope of the present invention.

Then, the aliphatic polycarboxylic acid containing four or more carboxylic acid groups and / or a salt thereof is added to the radiator coolant composed of the water-soluble organic medium and water in a composition range of 0.1 to 20%. Select from and use.

It is an advantage of the coolant of the present invention that the radiator coolant may further contain the above-mentioned commercially available rust preventive agent, and that even if the above-mentioned commercially available rust preventive agent is contained, it will be effective. That is, not only the use mode using the novel radiator coolant of the present invention, but also an aliphatic polyvalent carboxylic acid containing 4 or more carboxylic acid groups and / or a salt thereof is added to a radiator coolant that has already been used or is in use. Then, even if it is used as a coolant, the life of the radiator coolant thereafter is greatly extended.

Further, even if the radiator coolant of the present invention is applied in advance to the surface of an aluminum alloy material used for a radiator or an engine head or used for a radiator or an engine head (a surface in contact with the coolant), The same effect can be obtained.

[0038]

EXAMPLES Next, examples of the present invention will be described. The performance of the coolant having the composition of the present invention was evaluated under the following three coolant conditions assuming the usage of the aluminum alloy radiator coolant. The coolant having the composition of the present invention includes CF2399 represented by the above formula 2 and CF24 represented by the above formula 3.
03 was used alone or in combination, and was further used in combination with sebacic acid. For comparison, a coolant having a conventional composition was also tested.

The performance of the coolant is evaluated by immersing the aluminum alloy test material in the coolant and elution amount of the aluminum alloy (mg) as a measure of erosion property, and amount of precipitate generated (mg in order to see the reactivity with the aluminum alloy). ), And the zeta potential (mV) of the surface of the aluminum alloy test material was measured as a measure of the ease with which precipitates adhere.

The first coolant condition simulated the initial use of the coolant and nothing was added to each test coolant. Table 1 shows the composition of these coolants and the results of each of the above tests.
Shown in.

The second coolant condition simulates that ethylene glycol in the coolant is deteriorated with time during use of the coolant to generate an acid such as glycolic acid or formic acid, which is corrosive to the aluminum alloy material, 2000ppm glycolic acid and 400ppm formic acid in each test coolant
Was added. Table 2 shows the composition of these coolants and the results of each of the above tests.

The third coolant condition is that the aluminum alloy such as the engine head, which is considered to be more likely to be eluted even if the radiator member aluminum alloy is not corroded during use of the coolant, elutes and the eluted aluminum alloy in the coolant is used. Simulating the case where the amount increased, 100 mg of aluminum ion (Al ³⁺ ) was added to 1 L of the test coolant.
Was added. Table 3 shows the compositions of these coolants and the results of the respective tests.

As the aluminum alloy test material, 20% each of aluminum alloy skin materials containing 2% Zn used in radiator tubes and JIS4343 aluminum alloy as a brazing material were used.
(Brazed material clad rate 10%) JIS3003 clad on both sides
Aluminum alloy plate (total thickness 0.3mm, 20 × 60mm, 10g)
Was used.

The test coolant composition was kept constant at 30% ethylene glycol, 65% water, and 5% addition amount of aliphatic carboxylic acid, and only the kind of aliphatic carboxylic acid was changed. When two kinds of aliphatic carboxylic acid are used, the addition amount of each is
It was set to 2.5%. However, for CF2399 and CF2403,
Since a 30% solids solution was used, the actual solid content conversion is 1.5% when used alone and 0.75% when used in combination with two types.

The test conditions are as follows:
The aluminum alloy test material was immersed in a test target coolant at 90 ° C for 480 hours (the coolant was stirred with a stirrer and the coolant surface was in contact with air), and then the aluminum alloy elution amount (test material reduction amount: mg), aluminum alloy The amount of precipitate produced (the amount of residual precipitate of coolant filtration; mg) and the zeta potential (mV / pH) of the surface of the aluminum alloy test material were measured.

The elution amount of the aluminum alloy was determined by measuring the weight of the test material before and after the test. If the amount of the test material was reduced from before the test, it was plus (+), and due to the deposition of precipitates, the amount of the test material was compared to that before the test. If the amount was increased, it was displayed as a minus (-).

The zeta potential on the surface of the aluminum alloy test material is measured by Japanese Patent Application No. 2000-73625 or Japanese Patent Application No.
The measurement was performed according to the method for measuring the zeta potential on the surface of the aluminum alloy plate described in the specification of No. 000-73626.

As is clear from Table 1, when Examples Nos. 1 to 5 and Comparative Examples Nos. 6 to 9 were compared, the first coolant condition was that nothing was added to each test coolant, Under the initial use conditions, the zeta potential on the surface of the aluminum alloy test material of the example is low, and the aluminum alloy elution amount and the aluminum alloy precipitate production amount are not so different.

On the other hand, under the second coolant condition in which the ethylene glycol in the coolant deteriorates with time and contains an acid such as glycolic acid or formic acid, as is clear from Table 2,
In Examples Nos. 10 to 14, the amount of aluminum alloy precipitate produced was significantly smaller than the amount of aluminum alloy eluted. On the other hand, in Comparative Examples Nos. 15 to 18, the amount of aluminum alloy precipitate produced was extremely large. In addition, Comparative Example No. 1
On the other hand, in 6 to 18, the weight of the aluminum alloy test material was conversely increased from that before the test, and it can be seen that the aluminum alloy precipitates eluted and generated were reattached. Then, in Examples No. 10 to 14, elution, the precipitate is difficult to reattach, the zeta potential of the aluminum alloy test material surface of Examples No. 10 to 14 is compared to Comparative Examples No. 15 to 18. It is also supported by the low price.

Under the third coolant condition in which a large amount of aluminum ions are contained in the coolant, as is clear from Table 3, Examples Nos. 19 to 23 are higher in aluminum content than Comparative Examples Nos. 24 to 27. The amount of alloy precipitate produced is significantly reduced.

Therefore, these results show that the radiator coolant of the present invention is not much different from the coolant having the conventional composition at the beginning of use of the coolant, but when the coolant is used, acids such as glycolic acid and formic acid are contained. When the coolant contains a large amount of aluminum ions, it is difficult to elute the aluminum alloy in the coolant, and even if it elutes, it is difficult to form a precipitate, and the precipitate in the coolant constitutes the radiator. It shows that there is a synergistic effect with the effect that it is difficult to adhere to the surface of the material.

Therefore, it is understood from these results that the radiator coolant of the present invention can extend the replacement life of the aluminum alloy radiator or coolant.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

According to the present invention, it is possible to provide a radiator coolant having a long exchange life for an aluminum alloy radiator. Therefore, the industrial value is great in that it is possible to reduce the weight of a transportation machine due to the spread of aluminum alloy radiators and to expand the aluminum alloy materials for radiator applications.

   ─────────────────────────────────────────────────── ─── Continued front page    (71) Applicant 592260310             Shinko Alcoa Transportation Equipment Co., Ltd.             5-9-12 Kitashinagawa, Shinagawa-ku, Tokyo (72) Inventor Mitsuo Hashiura             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Tomoko Ito             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Maki Shimizu             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Yoshihiko Kamiya             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Setsu Nishizawa             1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture             Kobe Steel Co., Ltd.Kobe Research Institute (72) Inventor Kazumi Yanagisawa             1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture             Kobe Steel Co., Ltd.Kobe Research Institute (72) Inventor Fumihiro Sato             15 Onigaoka, Moka City, Tochigi Prefecture Kobe, Inc.             Steel Works Moka Factory (72) Inventor Tsuruno Tsunehiro             15 Onigaoka, Moka City, Tochigi Prefecture Kobe, Inc.             Steel Works Moka Factory (72) Inventor Takashi Yoshiyasu             3-4-7 Doshomachi, Chuo-ku, Osaka-shi, Osaka Prefecture               Fujisawa Pharmaceutical Co., Ltd. (72) Inventor Toshihito Kakiuchi             3-4-7 Doshomachi, Chuo-ku, Osaka-shi, Osaka Prefecture               Fujisawa Pharmaceutical Co., Ltd.

Claims (5)

[Claims] 1. A coolant containing a water-soluble organic medium as a main component, which is used in a radiator made of an aluminum alloy,
A long-life radiator coolant comprising an aliphatic polyvalent carboxylic acid having 4 or more carboxylic acid groups and / or a salt thereof. 2. The water-soluble organic medium is ethylene glycol, diethylene glycol, propylene glycol,
The long-life radiator coolant excellent in corrosion resistance according to claim 1, which is one or more selected from dipropylene glycol, methyl alcohol, ethyl alcohol, propanol and glycerin. 3. The aliphatic polycarboxylic acid has a molecular weight of 40.
The long-life radiator coolant according to claim 1 or 2, which is 0 or more. 4. The long-life radiator according to any one of claims 1 to 3, wherein the aliphatic polycarboxylic acid is a polyene polycarboxylic acid represented by the following formula, a derivative in a carboxyl group thereof or a salt thereof. Coolant. [Chemical 1] (In the formula, n means an integer of 1 to 5 and m means an integer of 1 or 2) 5. The long-life radiator coolant according to claim 1, wherein the radiator coolant further contains a commercially available rust preventive agent.