JP2002030281A - Cooling liquid composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling liquid composition capable of enhancing corrosion inhibiting activity while keeping excellent cooling characteristics. SOLUTION: This cooling liquid composition consists essentially of an alkali metal salt of formic acid and water, and contains 0.5-15 wt.% aliphatic dicarboxylic acid, aliphatic monocarboxylic acid or alkali metal salt thereof as corrosion-controlling additive, and 0.01-1.5 wt.% phosphoric acids or 0.01-0.5 wt.% triazole compound. Preferably, the aliphatic dicarboxylic acid is succinic acid, malonic acid, glutaric acid or adipic acid, and the aliphatic monocarboxylic acid is valeric acid, caproic acid, caprylic acid or capric acid. The triazole compound is preferably tolyltriazole or benzotriazole.

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 used for cooling cooling equipment such as a refrigerator and an ice making machine, and a cooling system of an automobile engine.

[0002]

2. Description of the Related Art As a cooling liquid composition of this type, a freeze-resistant cooling fluid disclosed in JP-A-1-103684 has been known. This fluid comprises 3 to 6 parts by weight of water, 0.5 to 1.5 parts by weight of urea, at most 1.5 parts by weight of glycol, 1-2 parts by weight of sodium formate and 1-2 parts by weight Parts by weight of sodium acetate, or wherein the major components are 4 to 7 parts by weight of potassium acetate, at most 1.5 parts by weight of potassium formate and 3 to 9 parts by weight of water.

[0003] Further, the freeze-resistant cooling fluid may further include:
Preferably, it contains 0.1 to 1.0% by weight of an anticorrosion inhibitor. The anticorrosion inhibitor preferably contains at least one selected from benzoic acid, sodium benzoate, potassium benzoate and benzotriazole.

[0004] The freeze-resistant cooling fluid can be used, for example, in cooling towers of thermal power plants, industrial or household refrigerators and quick freezers, open and closed heat exchangers, solar heat collectors. Activating systems such as multipliers and autoclaves of the chemical industry can prevent freezing failure of the equipment during cooling. Furthermore, it is possible to constitute without containing glycol, and it is possible to improve durability without polluting the environment.

[0005]

However, the conventional freezing-resistant cooling fluid cannot exert a sufficient corrosion-preventing effect mainly on ferrous metals. When the system is operated for a long period of time, the metal constituting the heat exchanger, the pipes, and the connections thereof of the system is corroded to generate corrosion products, which block the pipes and the like. There was a fear.

The present invention has been made by paying attention to the problems existing in the prior art as described above. It is an object of the present invention to provide a coolant composition that can further enhance the corrosion prevention effect while maintaining excellent cooling characteristics.

[0007]

In order to achieve the above object, a coolant composition according to the present invention comprises an alkali metal salt of formic acid and water as main components and an anticorrosive additive. And 0.5 to 15.0% by weight of at least one aliphatic carboxylic acid selected from aliphatic dicarboxylic acids, aliphatic monocarboxylic acids and alkali metal salts thereof, and 0.01 to 1.5% by weight. Phosphoric acids or 0.01 to
And 0.5% by weight of a triazole compound.

[0008] The coolant composition of the invention according to claim 2 is
In the invention according to claim 1, the aliphatic dicarboxylic acid is malonic acid, succinic acid, glutaric acid or adipic acid, and the aliphatic monocarboxylic acid is valeric acid, caproic acid, caprylic acid or caproic acid. It is characterized by having.

[0009] The coolant composition of the invention according to claim 3 is:
The invention according to claim 1 or 2, wherein the triazole compound is tolyltriazole or benzotriazole.

[0010]

Embodiments of the present invention will be described below in detail. The cooling liquid composition contains, as main components, an alkali metal salt of formic acid and water, and as an anticorrosion additive, at least one kind of fat selected from aliphatic dicarboxylic acids, aliphatic monocarboxylic acids, and alkali metal salts thereof. It contains an aromatic carboxylic acid and a phosphoric acid or a triazole compound. The cooling liquid composition may have a
A low-temperature coolant liquid medium for cooling equipment such as a refrigerator and an ice machine used in a temperature range of about minus 55 ° C, or an automobile used at a relatively high temperature higher than the above temperature range and up to about 100 ° C It is suitably used as a vehicle engine cooling liquid medium for cooling a cooling system of a vehicle engine.

The alkali metal salt of formic acid is contained in the coolant composition as an antifreeze component. The aqueous solution in which the alkali metal salt of formic acid is dissolved can exert a very high freezing point depressing action, and can reduce the aqueous solution to minus -20.
It has the property that the viscosity of the solution does not increase so much even when it is cooled to a low temperature of about -55 ° C. The alkali metal salt of formic acid also functions to prevent the cooling liquid composition from freezing and destroying the cooling system of the automobile engine. Furthermore, this alkali metal salt of formic acid has little corrosive, volatile and flammable properties.

The alkali metal salt of formic acid preferably contains sodium formate or potassium formate because of its good solubility in water, and contains potassium formate because of its very high solubility in water. Most preferably. Alternatively, sodium hydroxide or potassium hydroxide may be added to the cooling liquid composition containing formic acid to adjust the pH, thereby making the alkali metal salt of formic acid.

The concentration of the formic acid alkali metal salt is appropriately determined depending on the temperature range in which the coolant composition is used, but is preferably contained in a concentration range of 30 to 60% by weight. If the concentration of this formate is less than 30% by weight, the cooling liquid composition may freeze when cooled to -15 ° C or lower. Conversely, 60% by weight
When it exceeds, the cooling liquid composition may not be in a liquid state.

On the other hand, the anticorrosive additive is used for the corrosion of the metal constituting the cooling system of the cooling system of the heat exchanger, the circulating pipe, the connecting parts thereof, and the metal constituting the cooling system of the automobile engine. It is included to prevent In addition, as the metal, cast iron, steel, copper, brass,
Aluminum, aluminum alloy, solder and the like can be mentioned.

Aliphatic dicarboxylic acids as anticorrosion additives,
Aliphatic monocarboxylic acids and their alkali metal salts (aliphatic carboxylic acids) have an excellent corrosion inhibitory effect mainly on iron-based, copper-based and aluminum-based metals. It also has a high corrosion prevention effect on solder.

As the aliphatic dicarboxylic acid and its alkali metal salt (hereinafter referred to as aliphatic dicarboxylic acids), those having 3 to 6 carbon atoms are preferably used. For example, malonic acid having 3 carbon atoms is used. And succinic acid having 4 carbon atoms, glutaric acid having 5 carbon atoms, adipic acid having 6 carbon atoms, and sodium or potassium salts thereof. When the number of carbon atoms of the aliphatic dicarboxylic acid is 2 or less, the effect of preventing corrosion of the metal is remarkably reduced, and when the number is 7 or more, the solubility is remarkably reduced.

As the aliphatic monocarboxylic acid and its alkali metal salt (hereinafter referred to as aliphatic monocarboxylic acids), those having 5 to 10 carbon atoms are preferably used, and those having 5 or 5 carbon atoms are preferable. Six are most preferably used. When the aliphatic monocarboxylic acid has 4 or less carbon atoms, it is difficult to handle because of high volatility.
In the case of 1 or more, the solubility is remarkably reduced, which is not preferable. Examples of the aliphatic monocarboxylic acids include valeric acid having 5 carbon atoms, caproic acid having 6 carbon atoms, caprylic acid having 8 carbon atoms, capric acid having 10 carbon atoms, and sodium or potassium salts thereof. Is mentioned.

These aliphatic carboxylic acids are used in an amount of 0.5 to 1
It is contained within the range of 5.0% by weight, more preferably 5.0% by weight.
It is contained within a concentration range of more than 0% by weight to 15.0% by weight. When the concentration of the aliphatic carboxylic acid is 0.5
If the amount is less than the weight percentage, a sufficient corrosion preventing effect cannot be exerted on the metal. 15.0% by weight
If it exceeds, it may not be completely dissolved in the cooling liquid composition.

Phosphoric acids as anticorrosion additives are mainly contained to prevent corrosion of iron-based, copper-based and aluminum-based metals, and include, for example, phosphoric acid, disodium phosphate,
Examples include dipotassium phosphate, sodium hydrogen phosphate, and potassium hydrogen phosphate. The phosphoric acids are contained in the coolant composition at a concentration of 0.01 to 1.5% by weight, more preferably at a concentration of more than 1.0% by weight to a concentration of 1.5% by weight. You. When the concentration of this phosphoric acid is 0.0
If the amount is less than 1% by weight, corrosion of iron-based, copper-based and aluminum-based metals cannot be sufficiently prevented. On the other hand, if it exceeds 1.5% by weight, it may not be completely dissolved in the cooling liquid composition.

The triazole compound as an anticorrosive additive is contained mainly to prevent corrosion of copper-based metals, and benzotriazole or tolyltriazole is preferably used. The triazole compound is contained in the coolant composition at a concentration of 0.01 to 0.5% by weight. If the concentration of the triazole compound is less than 0.01% by weight, corrosion of the copper-based metal cannot be sufficiently prevented. Conversely, if it exceeds 0.5% by weight, it may not be completely dissolved in the coolant composition.

Further, it is preferable that the coolant composition contains at least one anticorrosive additive selected from thiazole compounds, boric acids and molybdic acids. The thiazole compound is mainly contained in order to more effectively prevent corrosion of the copper-based metal, and examples thereof include mercaptobenzothiazole, and sodium or potassium salts of mercaptobenzothiazole. This thiazole compound is contained in the coolant composition in an amount of 0.01 to 1.0% by weight.
Is preferably contained at a concentration of When the concentration of the thiazole compound is less than 0.01% by weight, corrosion of the copper-based metal cannot be sufficiently prevented. Conversely, if it exceeds 1.0% by weight, it may not be completely dissolved in the cooling liquid composition.

Boric acids are mainly contained to more effectively prevent corrosion of iron-based metals, and examples thereof include boric acid, sodium borate, and potassium borate. The boric acids are present in the cooling liquid composition in an amount of 0.01 to 1.
It is preferably contained at a concentration of 0% by weight. If the concentration of the boric acids is less than 0.01% by weight, the corrosion of the iron-based metal cannot be sufficiently prevented. Conversely, if it exceeds 1.0% by weight, it may not be completely dissolved in the cooling liquid composition.

Molybdates are mainly contained to more effectively prevent corrosion of iron-based metals, and include, for example, molybdate, sodium molybdate and potassium molybdate. The molybdic acids are
It is preferably contained in the coolant composition at a concentration of 0.01 to 1.0% by weight. When the concentration of the molybdic acids is 0.
If it is less than 01% by weight, the corrosion of the iron-based metal cannot be sufficiently prevented. Conversely, if it exceeds 1.0% by weight, it may not be completely dissolved in the cooling liquid composition.

Further, it is preferable to add a dissolving agent for enhancing the solubility of the anticorrosive additive to the cooling liquid composition. As the dissolving agent, for example, ethylene glycol or propylene glycol is preferably used because it is easily available and hardly causes a decrease in cooling characteristics.
The concentration of this solubilizer is preferably 1 to 10% by weight, more preferably 1 to 5% by weight. If the concentration of this solubilizer is 1
When the amount is less than the weight percentage, the solubility of the anticorrosion additive cannot be sufficiently increased. Conversely, if it exceeds 10% by weight, the viscosity of the cooling liquid composition will increase.

Dyes for coloring the cooling liquid composition such as Food Yellow No. 4, Uranink, Acid Green 25, Phenol Red, etc .; silicone defoamers; polyether defoamers; It is also possible to add an appropriate combination of an antifoaming agent such as a foaming agent for preventing the generation of foam, or a bitter agent for preventing accidental ingestion such as denatonium benzoate.

Further, in order to enhance the corrosion preventing effect of the coolant composition, the pH of the coolant composition is preferably adjusted to 7 to 11. If the pH of the cooling liquid composition is less than 7, corrosion on the iron-based metal may be accelerated. Conversely, if the pH exceeds 11, there is a possibility that corrosion to the copper-based metal is accelerated. In addition, the salts contained in the cooling liquid composition are preferably alkali metal salts because insolubles are not easily generated.

The effects exerted by the above embodiment will be described below. -The cooling liquid composition contains, as main components, an alkali metal salt of formic acid and water, and as an anticorrosion additive, 0.5 to
15.0% by weight of at least one aliphatic carboxylic acid selected from aliphatic dicarboxylic acids, aliphatic monocarboxylic acids and alkali metal salts thereof, and 0.01 to 1.5% by weight of phosphoric acids or 0.1% by weight. And 0.1 to 0.5% by weight of a triazole compound.

The alkali metal salt of formic acid can exhibit a very high freezing point depressing action and has a remarkably small increase in viscosity of the solution at a low temperature, so that it is contained as an antifreeze component in the coolant composition. Very suitable to let. Therefore, this cooling liquid composition can exhibit excellent cooling characteristics due to the alkali metal salt of formic acid.

On the other hand, the alkali metal salt of formic acid is much less corrosive than calcium chloride which has been conventionally used as an antifreeze component, so that the metal constituting the cooling system is further corroded. Can be difficult. In addition, when compared with ethylene glycol or propylene glycol which has been conventionally used as an antifreeze component, the alkali metal salt of formic acid can significantly reduce the increase in viscosity of the solution, and therefore, the It can be circulated smoothly. For this reason, it is possible to reduce the mechanical load on the circulating pipes and the like that constitute the cooling system of the cooling equipment and the like, and to reduce the diameter of the circulating pipes (reduce the surface area). It is also possible to reduce the loss of a large amount of heat.

Further, since the alkali metal formic acid has biodegradability, it hardly pollutes the environment as compared with ethylene glycol and propylene glycol. In addition, the coolant composition of the present embodiment has a chemical oxygen demand (COD) and a biological oxygen demand (BOD) that are smaller than those of the coolant composition containing ethylene glycol or propylene glycol as a main component. ) Can be reduced to 1/20 or less, so that the effect of preventing environmental pollution is remarkably high.

In addition, since alcohol-based and fluorine-based compounds conventionally used as antifreeze components have extremely high volatility, it is necessary to frequently replenish the coolant composition in order to compensate for the loss due to volatilization. was there. On the other hand, since the alkali metal salt of formic acid has a remarkably low volatility, it is not necessary to frequently replenish the coolant composition and maintenance can be easily performed. Also, since the alcohol-based antifreeze component is very flammable,
When designing and manufacturing the cooling system, it was necessary to take sufficient measures against fire. On the other hand, the alkali metal salt of formic acid has almost no flammability, so that measures for fire are not required so much, and the design and production of the cooling system can be easily performed. Further, this alkali metal salt of formic acid can be obtained at a very low price as compared with a fluorine compound.

Further, the aliphatic carboxylic acids contained as anticorrosion additives have a high corrosion inhibiting effect on iron-based, copper-based, aluminum-based metals and solder.
Therefore, compared with the conventional freezing-resistant cooling fluid,
The effect of preventing corrosion on ferrous metals can be greatly enhanced. For this reason, the cooling system and the cooling system of the vehicle engine can be used for a long time with almost no trouble, and the labor and cost required for the maintenance can be reduced.

In addition, the aliphatic dicarboxylic acids have a high corrosion inhibiting effect particularly on aluminum and aluminum alloys in a cooling system under high temperature and high flow rate conditions, and prevent blackening of their metal surfaces. You can also. The aliphatic monocarboxylic acids have a high corrosion inhibiting effect on the metal, are available at a low cost, and are easy to handle because they are liquid.

Further, by adding a phosphoric acid or a triazole compound as an anticorrosion additive, a high corrosion inhibiting effect on iron-based, copper-based and aluminum-based metals can be exerted, and a cooling system composed of these metals can be provided. Corrosion can be more effectively prevented. For this reason, since corrosion products are not easily generated in the cooling liquid composition, it is possible to effectively prevent clogging of a circulation pipe and the like constituting the cooling system.

[0036] Malonic acid, succinic acid, glutaric acid, adipic acid and the like are contained as aliphatic dicarboxylic acids,
As aliphatic monocarboxylic acids, valeric acid, caproic acid,
By containing caprylic acid, capric acid, etc.,
The effect of preventing corrosion of the coolant composition can be easily and reliably increased while increasing the solubility. Further, by adding tolyltriazole or benzotriazole as the triazole compound, the solubility of the coolant composition can be more easily enhanced while the solubility is enhanced.

[0036]

EXAMPLES Examples and comparative examples which embody the above embodiment will be described below. The percentages described below are
Unless otherwise indicated, the percentages are by weight.

(Examples 1 to 8) The cooling liquid compositions of Examples 1 to 8 were prepared by mixing the components (%) shown in Tables 1 and 2. For these coolant compositions,
The corrosion amount (mg / cm ² ) of the metal test piece was measured according to the method described in JIS K 2234. The details of the test conditions are described below, and the results are shown in Tables 1 and 2.

Test piece: copper, solder, brass, steel, cast iron, aluminum casting Test temperature: 88 ± 2 ° C. Liquid volume: 750 ml Test time: 336 ± 2 hours Aeration condition: 100 ml / min

[0039]

[Table 1]

[0040]

[Table 2] (Comparative Examples 1 to 4) The cooling liquid compositions of Comparative Examples 1 to 4 were prepared by mixing the components (%) shown in Table 3.
For these coolant compositions, the corrosion amount (mg / cm ² ) of the metal test piece was measured in the same manner as in the tests of Examples 1 to 8 described above. Table 3 shows the results.

[0041]

[Table 3] From the results shown in Tables 1 to 3, the coolant compositions of Examples 1 to 8 are more likely to corrode copper, solder, brass, steel, cast iron and aluminum castings than the coolant compositions of Comparative Examples 1 to 4. The amount was shown to be significantly reduced.

The above embodiment can be modified as follows. The cooling liquid composition contains an alkali metal salt of formic acid, an aliphatic carboxylic acid, a phosphoric acid and a triazole compound. With this configuration, it is possible to further enhance the corrosion prevention effect while exhibiting excellent cooling characteristics.

Further, the technical ideas that can be grasped from the above embodiment will be described below. The cooling liquid composition according to any one of claims 1 to 3, wherein the formic acid alkali metal salt is contained at a concentration of 30 to 60% by weight. With this configuration, the cooling characteristics of the cooling liquid composition can be easily improved.

[0044] The aliphatic dicarboxylic acid is malonic acid, succinic acid, glutaric acid or adipic acid, and the aliphatic monocarboxylic acid is valeric acid or caproic acid. Coolant composition.

The cooling liquid composition according to claim 1, wherein the aliphatic carboxylic acids are contained in a concentration range of more than 5.0% by weight to 15.0% by weight. The cooling liquid composition according to claim 1, wherein the phosphoric acid is contained in a concentration range of more than 1.0% by weight to 1.5% by weight.

A composition containing an alkali metal salt of formic acid and water as main components, and 0.5 to 15.0 as an anticorrosive additive;
% Of at least one aliphatic carboxylic acid selected from aliphatic dicarboxylic acids, valeric acid, caproic acid and alkali metal salts thereof, and 0.01 to 0.5% by weight of a triazole compound. A coolant composition characterized by the following:

A mixture containing 0.5 to 15% by weight of an aliphatic dicarboxylic acid, an aliphatic monocarboxylic acid, and an alkali metal salt thereof as an anticorrosive additive, containing an alkali metal salt of formic acid and water as main components; 1. A coolant composition comprising at least one aliphatic carboxylic acid, 0.01 to 1.5% by weight of phosphoric acid, and 0.01 to 0.5% by weight of a triazole compound. .

[0048]

As described above in detail, according to the present invention, the following effects can be obtained. ADVANTAGE OF THE INVENTION According to the cooling liquid composition of the invention of Claim 1, while exhibiting excellent cooling characteristics, the corrosion prevention effect can be further enhanced.

According to the coolant composition of the second aspect of the present invention, in addition to the effect of the first aspect of the invention, it is possible to easily enhance the corrosion preventing effect of the coolant composition while improving the solubility. Can be.

According to the third aspect of the present invention, in addition to the effects of the first and second aspects of the present invention, the effect of preventing corrosion of the cooling liquid composition while improving the solubility is obtained. It can be more easily increased.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Sagasaki 1-3-1 Nagara Maiocho, Gifu City, Gifu Prefecture Showa Corporation F-term (reference) 4K062 AA03 BA08 CA05 DA01 DA10 FA05 GA01 GA08 GA10

Claims (3)

[Claims] 1. An anticorrosive additive containing 0.5 to 15.0% by weight of an aliphatic dicarboxylic acid, an aliphatic monocarboxylic acid, and an alkali metal thereof, which contain an alkali metal salt of formic acid and water as main components. A coolant containing at least one aliphatic carboxylic acid selected from salts and 0.01 to 1.5% by weight of phosphoric acid or 0.01 to 0.5% by weight of a triazole compound. Composition. 2. The aliphatic dicarboxylic acid is malonic acid,
The cooling liquid composition according to claim 1, wherein the cooling liquid composition is succinic acid, glutaric acid, or adipic acid, and the aliphatic monocarboxylic acid is valeric acid, caproic acid, caprylic acid, or caproic acid. object. 3. The cooling liquid composition according to claim 1, wherein the triazole compound is tolyltriazole or benzotriazole.