JPH11349935A - Coolant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coolant composition having excellent keeping of corrosion protecting property against pH buffering property, a waste treatment or bad water while keeping a cooling property and corrosion protecting property ranging to a long period of time. SOLUTION: This coolant composition contains glycols as an antifreezing component, 0.1-3.0 wt.%, preferably 0.4-2.0 wt.% of at least one kind of molybdate and tungstate, 0.1-8.0 wt.%, preferably 0.4-5.0 wt.% of at least one kind of succinic acid and its alkali metal salt and 0.01-1.0 wt.%, preferably 0.05-0.4 wt.% of at least one kind of triazoles, thiazoles or an alkali metal salt of thiazoles, as a corrosion protecting agent. Preferably, the molybdate, the tungstate, an alkali metal salt of the succinic acid or an alkali metal salt of the thiazoles is a sodium salt or a potassium salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coolant composition mainly used for cooling a cooling system of an automobile engine or the like.

[0002]

2. Description of the Related Art Conventionally, this type of coolant composition includes, in addition to glycols which are antifreeze components, amine salts, phosphates, silicates and borates as corrosion inhibitors for metals. And at least one of nitrites are known. Other corrosion inhibitors contained in the coolant composition include nitrates, benzoic acid, benzoic acid derivatives,
Aliphatic monobasic acids, aliphatic dibasic acids or their alkali metal salts are known.

[0003]

However, the corrosion inhibitor contained in the above-mentioned conventional coolant composition has various problems described below. In other words, while amine salts are effective corrosion inhibitors for iron-based metals in cooling systems, they are corrosive to copper-based metals, and are also subject to severe conditions such as high-temperature conditions in cooling systems. It was easy to be degraded and consumed by exposure to water. In addition, when nitrite was present at the same time, it was easy to cause a chemical reaction to generate nitrosamine, a carcinogen.

[0004] Phosphate reacts with hardness components such as calcium ions and magnesium ions contained in the dilution water of the cooling liquid composition to easily generate insolubles, which may cause clogging of the cooling system. Similarly, when the iron-based or aluminum-based metal constituting the cooling system corrodes, it reacts with these corrosion products to form insoluble iron phosphate or aluminum phosphate, thereby causing clogging of the cooling system. There was a fear. In addition, spills into rivers and seas could cause environmental pollution due to eutrophication.

[0005] Silicates are low in stability and are easily gelled by the influence of heat, a change in pH, coexistence with other additives, and the like, so that the silicate is liable to lower the corrosion prevention performance. In addition, since it easily accumulates on the mechanical seal of the circulating pump, there is a possibility that the abrasion of the seal may be accelerated to cause liquid leakage.

Although borate is an effective corrosion inhibitor for iron-based metals, it tends to promote corrosion of aluminum and aluminum alloys. Nitrite is liable to be deteriorated and consumed by being exposed to severe conditions such as a high temperature condition of a cooling system, and is liable to generate a carcinogenic substance by causing a chemical reaction with an amine salt.

[0007] The cooling liquid composition is commercially available in the form of a concentrated liquid, and is generally used after being diluted to a concentration of 25 to 60% by volume. And the like, or corrosive components such as chloride ions, sulfate ions, and carbonate ions in many cases. With conventional corrosion inhibitors, effective countermeasures against these bad waters were insufficient.

On the other hand, the above-mentioned other corrosion inhibitors cause a problem that a high pH buffering ability cannot be obtained, and, for example, glycol, which is an antifreeze component, is decomposed under severe conditions such as high temperature, and There was a possibility that the pH was lowered due to the generation of acid and formic acid, and the corrosion prevention performance was significantly reduced. Further, depending on the composition of the corrosion inhibitor, there is a possibility that the solubility of the corrosion inhibitor is reduced due to a decrease in pH due to these causes and an insoluble matter is generated.

The present invention has been made by focusing on the problems existing in the prior art as described above. It is an object of the present invention to provide a coolant composition which is excellent in pH buffering property, disposal treatment, corrosion prevention performance against bad water and maintenance of corrosion prevention performance over a long period of time while maintaining cooling performance. .

[0010]

In order to achieve the above-mentioned object, the coolant composition according to claim 1 comprises, in addition to glycols, which are antifreeze components, molybdate and molybdate as corrosion inhibitors. 0.1 at least one of tungstates
To 3.0% by weight, 0.1 to 8.0% by weight of at least one of succinic acid and its alkali metal salt, and 0.01 to 0.01% by weight of at least one of triazoles, thiazoles and alkali metal salts of thiazoles. To 1.0% by weight.

The cooling liquid composition according to the second aspect is the invention according to the first aspect, wherein the alkali metal salt of molybdate, tungstate, succinic acid and the alkali metal salt of thiazole are sodium salt. Or a potassium salt.

According to a third aspect of the present invention, in the cooling liquid composition according to the first or second aspect, the corrosion inhibitor comprises at least one of a molybdate and a tungstate in a range of 0.4 to 0.4. 2.0% by weight, 0.4 to 5.0% by weight of at least one of succinic acid and alkali metal salts thereof, and 0.05 to 0.05% by weight of at least one of triazoles, thiazoles and alkali metal salts of thiazoles. It is contained in the range of 0.4% by weight.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. The cooling liquid composition contains 0.1 to 3.0% by weight of at least one of molybdate and tungstate as a corrosion inhibitor in addition to glycols as an antifreeze component, succinic acid and an alkali metal salt thereof. Is contained in the range of 0.1 to 8.0% by weight, and at least one of triazoles and thiazoles is contained in the range of 0.01 to 1.0% by weight. Further, the coolant composition is substantially free of amine salts, phosphates, silicates, borates and nitrites conventionally used as corrosion inhibitors.

The antifreeze component is added to lower the freezing point of the coolant composition, and serves to prevent the coolant composition from freezing and destroying a cooling system such as an automobile engine. is there. Examples of the antifreeze component include glycols such as ethylene glycol, propylene glycol, 1,3-butylene glycol, hexylene glycol, diethylene glycol, and glycerin. Of these, it is preferable to use ethylene glycol or propylene glycol because they are easily available and inexpensive. The concentration of these antifreeze components is appropriately determined depending on the temperature of the environment, but is preferably used in the range of 25 to 60% by volume.

The corrosion inhibitor is added to prevent corrosion of metals containing aluminum, aluminum alloy, cast iron, steel, brass, solder, copper, etc. constituting a cooling system of an automobile engine or the like.

With respect to iron and aluminum-based metals, at least one of molybdate and tungstate is in the range of 0.1 to 3.0% by weight, preferably 0.4 to 2.
It is contained in the range of 0% by weight. This concentration is 0.1% by weight
If the amount is less than the above range, a sufficient corrosion preventing effect cannot be exerted on iron and aluminum-based metals. On the other hand, when the content exceeds 3.0% by weight, the effect of preventing corrosion is sufficiently exhibited, but it is not economical because a large amount of metal salt is used.

The molybdate and tungstate are preferably alkali metal salts, and more preferably sodium salts or potassium salts, since they do not easily form insolubles. Examples of such salts include sodium molybdate dihydrate, potassium molybdate dihydrate, sodium tungstate dihydrate, potassium tungstate dihydrate, and the like.

With respect to aluminum and the solder-based metal, at least one of succinic acid and its alkali metal salt is in the range of 0.1 to 8.0% by weight, preferably 0.4 to 8.0% by weight.
It is contained in the range of 5.0% by weight. If this concentration is less than 0.1% by weight, a sufficient corrosion preventing effect cannot be exerted on aluminum and solder-based metals. Conversely, if the content exceeds 8.0% by weight, the corrosion prevention effect is sufficiently exhibited,
It is not economical because a large amount of succinic acid or the like is used. As the alkali metal salt of succinic acid, a sodium salt or a potassium salt is preferable because insolubles are not easily generated,
Examples include disodium succinate or dipotassium succinate.

With respect to the copper-based metal, at least one of triazoles, thiazoles and alkali metal salts of thiazoles is in the range of 0.01 to 1.0% by weight, preferably 0.05 to 0.4% by weight. %. When the concentration is less than 0.01% by weight, the effect of preventing corrosion of the copper-based metal due to deterioration and consumption is not sufficiently exhibited. Conversely, 1.
When the content exceeds 0% by weight, corrosion of the copper-based metal is promoted, and azoles and the like are used in large amounts, which is not economical.

The triazoles include, for example, benzotriazole and tolyltriazole, and the thiazoles include mercaptobenzothiazole. As the alkali metal salt of a thiazole, a sodium salt or a potassium salt is preferable since insolubles are not easily generated, and examples thereof include a sodium salt of mercaptobenzothiazole and a potassium salt of mercaptobenzothiazole.

Further, the cooling liquid composition contains a nitrate such as sodium nitrate which is a commonly used corrosion inhibitor,
Benzoic acid derivatives such as benzoic acid and p- (t-butyl) benzoic acid; aliphatic monobasic acids such as octylic acid; aliphatic dibasic acids such as sebacic acid, dodecane diacid, octenyl succinic acid, and alkali metal salts thereof At least one of them can also be added.

Colorants for coloring the cooling liquid composition such as Food Yellow No. 4, Uranink, Acid Green 25, and Phenol Red, silicone-based antifoaming agents, polyether-based antifoaming agents, and high-molecular alcohol-based antifoaming agents 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.

The cooling liquid composition containing these components comprises:
Usually, after being manufactured as a concentrated solution, it is used after being diluted to 25 to 60% by volume. This concentrate contains 0.5 to 3.0% by weight, preferably 2.0 to 3.0% by weight of at least one of molybdate and tungstate in addition to the antifreeze component.
0% by weight, and 0.5 to 8.0% by weight, preferably 2.0 to 8.0% by weight, of at least one of succinic acid and its alkali metal salt.
8.0% by weight, and at least one of triazoles, thiazoles and alkali metal salts of thiazoles in an amount of 0.05 to 1.0% by weight, preferably 0.2 to 0.5% by weight. It is preferred that it is.

Further, the pH of the cooling liquid composition is 7.
It is preferably from 0 to 9.0, and if necessary, by adding sodium hydroxide or potassium hydroxide,
The pH of the solution can be adjusted. The coolant composition is used by being enclosed in a cooling system such as an automobile engine.

Next, the effects exerted by the coolant composition of the above embodiment will be described. In the coolant composition of the embodiment, at least one of molybdate and tungstate is 0.1 to 3.0% by weight as a corrosion inhibitor, and at least one of succinic acid and an alkali metal salt thereof is 0. 0.1 to 8.0% by weight and at least one of triazoles and thiazoles in the range of 0.01 to 1.0% by weight. Therefore, it is possible to effectively prevent corrosion of various metals constituting a cooling system of an automobile engine or the like. Furthermore, it can be excellent in pH buffering ability, waste treatment and corrosion prevention performance against bad water. According to the cooling liquid composition of the embodiment, since it does not substantially contain amine salts, phosphates, silicates, borates and nitrites which have been conventionally used as corrosion inhibitors, waste treatment and It has excellent corrosion prevention performance against bad water and can exhibit a high corrosion prevention effect. According to the cooling liquid composition of the embodiment, the salt contained as the corrosion inhibitor is an alkali metal salt, so that it is difficult to generate an insoluble matter and the corrosion prevention effect can be enhanced. Further, by using a sodium salt or a potassium salt among the alkali metal salts, the corrosion preventing effect can be further enhanced. According to the coolant composition of the embodiment, the corrosion inhibitory effect can be further enhanced by appropriately adding a generally used corrosion inhibitor. According to the cooling liquid composition of the embodiment, by preparing the concentrated liquid in advance, the amount of the component contained in a trace amount can be accurately added, and the cooling liquid composition having an arbitrary concentration can be easily prepared. Can be made. According to the cooling liquid composition of the embodiment, by adding sodium hydroxide or potassium hydroxide for pH adjustment, the pH can be surely adjusted and insoluble matter can be hardly generated.

[0026]

EXAMPLES Examples in which the coolant composition of the above embodiment is embodied will be described below. (Examples 1 to 8) Sodium hydroxide dissolved in ion-exchanged water was added to a solution in which ethylene glycol as an antifreeze component and a corrosion inhibitor shown in Table 1 were mixed, and for those requiring pH adjustment. Thus, a cooling liquid composition concentrate was prepared. In Tables 1 and 2, the blending amount of ethylene glycol is described by rounding off two decimal places, and sodium molybdate represents sodium molybdate dihydrate and sodium tungstate represents sodium tungstate dihydrate. . Table 1 shows the results of measuring the pH of the coolant composition obtained by diluting the coolant composition concentrate to 30% by volume.

[0027]

[Table 1] (Comparative Examples 1 to 9) Comparative Examples 8 and 9 were not substantially contained in the present invention in a solution in which the antifreeze component ethylene glycol and the corrosion inhibitor shown in Table 2 were mixed. Corrosion inhibitors were added. For Comparative Examples 2 to 9, sodium hydroxide or potassium hydroxide dissolved in ion-exchanged water was added for pH adjustment to prepare a cooling liquid composition concentrate. However, Comparative Example 1
Nos. To 9 do not contain at least one kind of corrosion inhibitor required in the present invention. Table 2 shows the results of measuring the pH of the coolant composition obtained by diluting the coolant composition concentrate to 30% by volume.

[0028]

[Table 2] (PH buffering capacity test) Regarding the pH buffering capacity of the cooling liquid composition concentrates of Examples 1 to 8 and Comparative Examples 1 to 9, JIS K
The test was carried out according to the preliminary alkalinity test method described in Section 7.6 of 2234-1994 antifreeze. In this test, the titer (ml) of 0.1 mol / liter hydrochloric acid required to lower 10 ml of the sample to pH 5.5 was measured, and the appearance of the liquid when the pH reached 5.5 was evaluated. Table 3 shows the results. In addition, in the evaluation of the appearance of the liquid, in the case where no abnormal change was particularly observed, a circle was marked.

[0029]

[Table 3] From the results shown in Table 3, the coolant compositions of Examples 1 to 8 are superior to the coolant compositions of Comparative Examples 2 to 8 in pH buffering capacity, and the pH was reduced to 5.5. Comparative Example 5
And it was shown that it did not become cloudy and the stability was high as in the case of Comparative Example 7. (Measurement of Insolubles Generation Rate by Hard Water) The cooling liquid composition concentrates of Examples 1 to 8 and Comparative Examples 1 to 9 were mixed with two kinds of hard waters for 3 times.
The cooling liquid composition diluted to 0% by volume was placed in a dark place at room temperature for 24 hours.
After standing for a period of time, the volume of the generated insoluble matter was measured to determine the insoluble matter generation rate (% by volume). The two types of hard water used here were obtained by diluting calcium chloride in ion-exchanged water at concentrations of 500 ppm and 1000 ppm. Table 4 shows the results.

[0030]

[Table 4] The results in Table 4 show that the cooling liquid compositions of Examples 1 to 8 had a very slight tendency to react with calcium ions to produce insolubles. (Metal Corrosion Prevention Performance Test) Examples 1 to 8 and Comparative Examples 1 to
Metallic corrosion prevention performance of a coolant composition obtained by diluting the coolant composition concentrate of No. 9 to 20% by volume with dilution water was measured according to JIS.
The test was carried out according to the metal corrosion test method described in 7.8 of K2234-1994 antifreeze. The dilution water contains chlorine ion, sulfate ion and hydrogen carbonate ion each at 100 pp.
m-containing ion-exchanged water.

The concentrates of the cooling liquid compositions of Examples 1 to 8 and Comparative Examples 1 to 9 were diluted to 25% by volume with ion-exchanged water, and sodium chloride was added to reduce the concentration of chlorine ions to 10%.
The metal corrosion inhibiting performance of the coolant composition adjusted to 0 ppm was determined according to ASTM D4340-1996 (Corr.
osion of Cast Aluminum Alloys in Engine Coolants
Under heat-rejecting conditions), the test was performed according to the test method for corrosion of a heat transfer surface of an aluminum casting.

Tables 5 and 6 show the test results.
In a test performed according to JIS K 2234, a mark was given when there was no abnormality in the appearance of the test piece, and a mark was given when there was abnormality (fail).

[0033]

[Table 5]

[0034]

[Table 6] From the results in Table 5, the cooling liquid compositions of Examples 1 to 8 were prepared for aluminum casting (described as aluminum in the table), cast iron, steel, brass, solder, and copper. It was shown that a high corrosion inhibiting effect was exhibited at a low concentration. Further, in the aluminum casting heat transfer surface corrosion test, it was shown that a high corrosion prevention effect was exhibited for the aluminum casting. However, this test was performed using a coolant composition diluted to 20% by volume, which is generally less than the concentration to be diluted, in consideration of the decrease in concentration due to replenishment of water or the like in the market. It was shown that metal corrosion could be prevented.

On the other hand, from the results shown in Table 6, the coolant compositions of Comparative Examples 1 to 6 which do not contain molybdate and tungstate, or succinic acid and its alkali metal salt, were found to be superior to aluminum casting, cast iron and steel. And noticeable corrosion was observed. Furthermore, the corrosion test on the heat transfer surface of an aluminum casting also showed that the corrosion prevention effect was not sufficiently exerted on the aluminum casting. Further, even in the case of Comparative Examples 2 to 6 containing a generally used corrosion inhibitor, the lack of molybdate and tungstate, or succinic acid and its alkali metal salt cannot be sufficiently compensated. It was shown that. (Effect test of corrosion prevention effect by bad water)
The metal corrosion inhibiting effect of the coolant compositions obtained by diluting the coolant composition concentrates of Examples 5 and 7 and Comparative Examples 3, 4, 5, 7 and 8 with bad water to 30% by volume was measured according to JIS K223.
The test was performed using a method substantially similar to the metal corrosion test method of No. 4. The bad water used here was 150 pp
m chloride ion, 100 ppm sulfate ion, 100p
pm, bicarbonate ion, 70 ppm calcium ion, 5 ppm iron ion, 5 ppm copper ion and 5 p
It is ion exchange water containing pm zinc ions. Table 7 shows the results.

[0036]

[Table 7] The results in Table 7 show that the coolant compositions of the examples exhibited a sufficient corrosion inhibitory effect even when diluted with bad water containing a corrosive substance. On the other hand, Comparative Examples 3 to 5 and 7
It was shown that the cooling liquid composition of No. could not sufficiently suppress the influence of corrosive substances in bad water.

Next, the technical ideas that can be grasped from the above embodiment will be described below. The cooling liquid according to any one of claims 1 to 3, further comprising at least one of a nitrate, a benzoic acid, a benzoic acid derivative, an aliphatic monobasic acid, an aliphatic dibasic acid, and an alkali metal salt thereof. Composition.

With this configuration, a more excellent corrosion prevention effect can be exhibited. At least one of a coloring agent for coloring, an antifoaming agent for preventing generation of bubbles, and a bitter agent for preventing accidental ingestion.
The coolant composition according to any one of claims 1 to 3, comprising a seed.

With this configuration, the handleability of the coolant composition can be further improved. -0.5 to 3.0% by weight of at least one of molybdate and tungstate as a corrosion inhibitor, and at least one of succinic acid and its alkali metal salt, in addition to glycols which are antifreeze components. From 0.5 to 8.0% by weight, and at least one of triazoles, thiazoles and alkali metal salts of thiazoles from 0.05 to 8.0% by weight.
A cooling liquid composition concentrate containing 1.0% by weight,
A method for producing a cooling liquid composition to be diluted with water.

With this configuration, the amount of the component contained in a trace amount can be added more accurately, and a coolant composition having an arbitrary concentration can be easily prepared. The cooling liquid composition according to any one of claims 1 to 3, wherein the pH of the solution is adjusted to 7.0 to 9.0 by further adding sodium hydroxide or potassium hydroxide as needed. .

With this configuration, the effect of preventing corrosion can be further improved. 0.1 to 3.0% by weight of at least one of molybdate and tungstate as a corrosion inhibitor, and at least one of succinic acid and an alkali metal salt thereof, in addition to glycols which are antifreeze components From 0.1 to 8.0% by weight, and at least one of triazoles, thiazoles and alkali metal salts of thiazoles from 0.01 to 8.0% by weight.
Cooling in which a cooling liquid composition containing 1.0% by weight is circulated through a cooling system composed of at least one metal of aluminum, aluminum alloy, cast iron, steel, brass, solder and copper. How to use the liquid composition.

In the case of such a structure, aluminum,
A high corrosion prevention effect can be exerted on metals constituting a cooling system containing at least one metal of aluminum alloy, cast iron, steel, brass, solder and copper. -It does not contain amine salts, phosphates, silicates, borates and nitrites as corrosion inhibitors in addition to glycols which are antifreeze components, and contains at least one of molybdate and tungstate. 0.1 to 3.0% by weight, and at least one of succinic acid and an alkali metal salt thereof is 0.1 to 3.0% by weight.
A cooling liquid composition containing 8.0% by weight and at least one of triazoles, thiazoles and alkali metal salts of thiazoles in a range of 0.01 to 1.0% by weight.

With this configuration, the corrosion prevention performance against bad water can be improved.

[0044]

The present invention is configured as described above, and has the following effects. According to the coolant composition of the first aspect, while maintaining the cooling performance, it is excellent in pH buffering property, disposal treatment, corrosion prevention performance against bad water, and maintenance of corrosion prevention performance for a long period of time.

According to the cooling liquid composition of the second aspect,
In addition to the effect of the first aspect of the present invention, the corrosion prevention performance can be maintained for a long period of time. According to the cooling liquid composition of the third aspect, in addition to the effects of the invention of the first or second aspect, a more excellent corrosion prevention effect can be exhibited.

Claims (3)

[Claims] 1. In addition to glycols, which are antifreeze components, 0.1 to 3.0% by weight of at least one of molybdate and tungstate as corrosion inhibitors, succinic acid and alkali metal salts thereof 0.1 to at least one of
A cooling liquid composition containing 8.0% by weight and at least one of triazoles, thiazoles and alkali metal salts of thiazoles in a range of 0.01 to 1.0% by weight. 2. The coolant composition according to claim 1, wherein the molybdate, tungstate, succinic acid alkali metal salt and thiazole alkali metal salt are sodium salts or potassium salts. 3. The corrosion inhibitor comprises 0.4 to 2.0% by weight of at least one of molybdate and tungstate, and at least one of succinic acid and an alkali metal salt thereof.
The composition according to claim 1, wherein the content of the seed is in the range of 0.4 to 5.0% by weight, and at least one of triazoles, thiazoles and alkali metal salts of thiazoles is in the range of 0.05 to 0.4% by weight. 3. The cooling liquid composition according to 2.