JP6970037B2 - Coolant composition - Google Patents

Description

The present invention relates to a coolant composition.

A coolant containing glycols such as ethylene glycol or alcohols is used as a freezing point depressant for imparting antifreeze as a coolant for cooling an internal combustion engine of an automobile, a hybrid system, or the like. For example, Patent Document 1 discloses a coolant composition containing a melting point lowering agent selected from alcohols and glycols as a main component. In addition to the melting point lowering agent, the coolant composition of Patent Document 1 comprises at least one of phosphoric acid and an alkali metal salt thereof, at least one of a calcium compound and a magnesium compound, and 2-phosphonobutane-1,2,4 tricarboxylic acid. And at least one of its alkali metal salts.

On the other hand, in Patent Document 2, the _{water-soluble liquid composition containing a mixture of C 1 to} C ₂ carboxylate and C _{3 to} C ₅ carboxylate shows a very low freezing point and uses glycol as a freezing point depressant. It is disclosed that it is superior in heat transferability to the composition containing the mixture.

Patent Document 3 _{discloses an aqueous coolant composition in which a C 6 to} C ₁₆ organic acid salt corrosion inhibitor and a C _{3 to} C ₅ carboxylate freezing point depression agent are combined.

Patent Document 4 includes a heat transfer fluid additive composition: about 10% by weight or more of a carboxylate based on the total weight of the composition; an azole compound; a base; and water; the base is a heat transfer. The heat transfer fluid additive composition is disclosed which is present in an amount sufficient to obtain a pH of about 7 to about 10.5 when the additive composition is diluted to 50% by volume with water.

Japanese Unexamined Patent Publication No. 2002-322467 Japanese Patent Publication No. 2003-505532 U.S. Patent Application Publication US2007 / 0158612A1 Japanese Patent Application Laid-Open No. 2015-528267

To date, coolant compositions whose main component is a base other than glycols have not been widely used despite their good heat transfer properties.

The conventionally provided coolant composition containing a carboxylate described in Patent Document 2 has good freeze resistance and heat transfer property. However, the coolant composition described in Patent Document 2 proposes a pH on the alkaline side. In recent years, since aluminum or an aluminum alloy is widely used for cooling system parts of automobile internal combustion engines, hybrid electric vehicles and the like for the purpose of reducing the weight of vehicles, there is a problem that metal corrosion easily progresses.

The present inventors have also found that a coolant composition containing a carboxylate as a main component of a freezing point depressant tends to deteriorate rubber.

The present inventors have conducted diligent research to provide a coolant composition containing propionate as a freezing point depression agent, which has low corrosion resistance to metals and does not easily deteriorate rubber without impairing freezing resistance. A coolant composition having the characteristics of the above was completed.

The present invention
A coolant composition containing water and propionic acid salt.
Aliphatic polyol compound;
nitrate;
Azole compound;
At least one selected from phosphoric acid and its salts;
Molybdate of 0.1 to 2.0% by weight in terms of sodium molybdate with respect to the total amount of the coolant composition;
At least one selected from calcium compounds, magnesium compounds and strontium compounds in a nitrate equivalent of 0.0001 to 0.2% by weight based on the total amount of the coolant composition; and phosphonobutanetricarboxylic acid based on the total amount of the coolant composition. Provided are a coolant composition further comprising at least one selected from a phosphonobutane tricarboxylic acid and a salt thereof, in terms of 0.01 to 1.0% by weight.

The coolant composition of the present invention is advantageous in that it has excellent freezing resistance and heat transferability by containing propionate as a freezing point depressant, has low corrosiveness to metals, and does not easily deteriorate rubber. be.

The coolant composition comprises, in a preferred embodiment, at least one selected from glycerin, propylene glycol and 1,3-propanediol as the aliphatic polyol compound.

The coolant composition according to the preferred embodiment can particularly remarkably suppress the deterioration of the rubber when it comes into contact with the rubber.

In another preferred embodiment, the coolant composition contains an aliphatic polyol compound in an amount of 1.0 to 10% by weight based on the total amount of the coolant composition.

In another preferred embodiment, the coolant composition contains nitrate in an amount of 0.01 to 0.5% by weight in terms of sodium nitrate with respect to the total amount of the coolant composition.

In another preferred embodiment, the coolant composition comprises 0.01-10% by weight of the azole compound with respect to the total amount of the coolant composition.

In another preferred embodiment, the coolant composition contains at least one selected from phosphoric acid and a salt thereof in an amount of 0.01 to 2.0% by weight in terms of phosphoric acid with respect to the total amount of the coolant composition.

The coolant composition according to each of the other preferred embodiments can particularly significantly suppress the corrosion of the metal when it comes into contact with the metal and the deterioration of the rubber when it comes into contact with the rubber.

The coolant composition containing the propionate of the present invention as a freezing point depressant has low corrosiveness to metals and does not easily deteriorate rubber.

Hereinafter, embodiments of the coolant composition of the present invention will be specifically described. The embodiments shown below do not limit the present invention.

The coolant composition of the present invention contains water and propionic acid salt, and further contains other components described below.

Propionic acid salt is compounded as the main component of the melting point lowering agent. A coolant composition containing propionic acid salt is preferable because it has good heat transfer properties and is less corrosive to metals as compared with a coolant composition containing acetate and formate.

As the propionic acid salt, an alkali metal salt of propionic acid can be preferably used. As the alkali metal salt, a potassium salt, a sodium salt and a lithium salt are preferable, and a potassium salt is particularly preferable. The propionic acid salt may be a mixture of a plurality of salts.

The content of the propionic acid salt is not particularly limited, but can be preferably 10 to 45% by weight, more preferably 15 to 40% by weight in terms of propionic acid with respect to the total amount of the coolant composition. In the following description, the content of a certain component is shown as a ratio (% by weight) to the total amount of the coolant composition. That is, the total amount of the coolant composition is 100% by weight, and the content of each component is represented.

The water content of the coolant composition of the present invention is not particularly limited, but may be preferably 40 to 80% by weight, more preferably 50 to 80% by weight, based on the total amount of the coolant composition.

The coolant composition of the present invention is characterized by further containing an aliphatic polyol compound in addition to propionic acid salt as a melting point lowering agent. A coolant composition containing only propionic acid salt as a melting point lowering agent tends to deteriorate the rubber when in contact with the rubber and reduce the tensile strength. On the other hand, a coolant composition further containing an aliphatic polyol compound is preferable because it does not easily deteriorate the rubber even though it contains propionic acid salt.

The aliphatic polyol compound may be an aliphatic hydrocarbon compound having two or more hydroxyl groups, but is typically an aliphatic having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, and more preferably 2 or 3 carbon atoms. It is a hydrocarbon compound, and the number of hydroxyl groups is typically 2 to 4, preferably 2 or 3. Specific examples of the aliphatic polyol compound include glycerin, propylene glycol (= 1,2-propanediol), 1,3-propanediol, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, and 1,5. -At least one selected from pentandiol and hexylene glycol, more preferably at least one selected from glycerin, propylene glycol and 1,3-propanediol.

The content of the aliphatic polyol compound in the coolant composition of the present invention is not particularly limited, but is preferably smaller than the content of propionic acid salt, and more preferably 1.0 to 1.0 with respect to the total amount of the coolant composition. It is 10% by weight, particularly preferably 2.0 to 8.0% by weight.

The coolant composition of the present invention further comprises a nitrate and an azole compound. Nitrate has the effect of suppressing pitting corrosion of aluminum. Azole compounds are effective in preventing copper from corrosion.
Examples of the nitrate include sodium nitrate and potassium nitrate.

The content of nitrate in the coolant composition of the present invention is not particularly limited, but is preferably 0.01 to 0.5% by weight in terms of sodium nitrate with respect to the total amount of the coolant composition, and more preferably 0. It is more preferably 05 to 0.4% by weight.

Examples of the azole compound include a triazole compound and a thiazole compound. Examples of the triazole compound include benzotriazole and triltriazole. Examples of the thiazole compound include benzothiazole and mercaptobenzothiazole sodium. The azole compound may be a combination of a plurality of types of azole compounds.

The content of the azole compound in the coolant composition of the present invention is not particularly limited, but is preferably 0.01 to 10% by weight, more preferably 0.05 to 5.0% with respect to the total amount of the coolant composition. More preferably, it is by weight.

The coolant composition of the present invention further comprises at least one selected from phosphoric acid and salts thereof. It may be a combination of two or more components selected from phosphoric acid and a salt thereof. Phosphoric acid and its salts greatly contribute to the suppression of corrosion of aluminum and aluminum alloys, and the corrosion resistance of aluminum under cavitation is greatly improved. As the phosphate, an alkali metal salt of phosphoric acid is preferable, and a potassium salt, a sodium salt and a lithium salt of phosphoric acid are more preferable.

The content of at least one selected from phosphoric acid and a salt thereof in the coolant composition of the present invention is not particularly limited, but is 0.01 to 2.0% by weight in terms of phosphoric acid with respect to the total amount of the coolant composition. It is preferably 0.05 to 0.5% by weight, and more preferably 0.05 to 0.5% by weight. When the content of at least one selected from phosphoric acid and a salt thereof is in this range, the corrosion resistance of the coolant composition is particularly high.

The coolant composition of the present invention further contains molybdate in an amount of 0.1 to 2.0% by weight in terms of sodium molybdate with respect to the total amount of the coolant composition. The coolant composition of the present invention is advantageous in reducing metal corrosion by containing this amount of molybdate.

The molybdate is preferably an alkali metal salt of molybdate, more preferably a sodium salt, a potassium salt or a lithium salt of molybdate, and particularly preferably sodium molybdate. The molybdate may be a mixture of a plurality of salts.

The content of molybdate in the coolant composition of the present invention is more preferably 0.2 to 2.0% by weight in terms of sodium molybdate with respect to the total amount of the coolant composition.

The coolant composition of the present invention further contains at least one selected from calcium compounds, magnesium compounds and strontium compounds in an amount of 0.0001 to 0.2% by weight in terms of nitrate with respect to the total amount of the coolant composition.

Calcium compounds, magnesium compounds and strontium compounds have the effect of greatly suppressing the corrosion of metals such as aluminum and aluminum alloys at high temperatures. Therefore, cavitation, erosion, and corrosion in metal members made of aluminum, aluminum alloys, and the like are prevented, and the heat transfer surface corrosion resistance at high temperatures is improved.

Examples of the calcium compound, magnesium compound and strontium compound include nitrate, oxide, hydroxide, permanganate, chromate, fluoride, iodide, carbonate, sulfate, titanate and tungstate, respectively. Borate, phosphate, dihydrogen phosphate, nitate, acetate, propionate, butyrate, valerate, laurate, stearate, oleate, glutamate, lactate, succinate Salts, malate, tartrate, maleate, citrate, oxalate, malonate, cevacinate, benzoate, phthalate, salicylate, mandelate and the like can be used. ..

The content of at least one selected from the calcium compound, magnesium compound and strontium compound in the coolant composition of the present invention is preferably 0.001 to 0.2% by weight in terms of nitrate with respect to the total amount of the coolant composition. , More preferably 0.002 to 0.1% by weight.

By the way, at least one selected from the calcium compound, the magnesium compound and the strontium compound may increase the product cost due to excessive addition and may form scale-like deposits in the cooling water flow path. Therefore, the coolant composition of the present invention further contains one or more selected from phosphonobutane tricarboxylic acids and salts thereof, which will be described later. As a result, although the content of at least one selected from the calcium compound, the magnesium compound and the strontium compound is reduced to 0.2% by weight or less, the content of these components is equal to or higher than the case where the content is larger. Anticorrosion performance can be obtained and the formation of deposits can be prevented.

The coolant composition of the present invention contains at least one selected from phosphonobutane tricarboxylic acid and a salt thereof in an amount of 0.01 to 1.0% by weight in terms of phosphonobutane tricarboxylic acid with respect to the total amount of the coolant composition. Further included.

The phosphonobutane tricarboxylic acid and its salt have an effect of improving the solubility of other components, improving the storage stability, and suppressing the corrosion of the heat transfer surface of the aluminum casting. If the amount of at least one selected from the phosphonobutane tricarboxylic acid and its salt is less than 0.01% by weight, it becomes difficult to exhibit the above-mentioned action, a precipitate is formed and the storage stability is lowered, or heat transfer of aluminum casting is performed. It becomes difficult to suppress surface corrosion. Further, if it is blended in excess of 1.0% by weight, the corrosion resistance of the solder becomes insufficient.

The coolant composition of the present invention is selected from at least one selected from phosphoric acid and a salt thereof, at least one selected from a magnesium compound and a strontium compound, and a phosphonobutane tricarboxylic acid and a salt thereof. By blending at least three components of at least one kind, a synergistic effect with each other is exhibited, and corrosion resistance to a metal member is greatly improved particularly at a high temperature.

Specifically, as the phosphonobutane tricarboxylic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid can be used.

The phosphonobutane tricarboxylic acid salt is typically an alkali metal salt of a phosphonobutane tricarboxylic acid, and can be one or more selected from, for example, a sodium salt, a potassium salt and a lithium salt.

The content of at least one selected from the phosphonobutane tricarboxylic acid and its salt in the coolant composition of the present invention is preferably 0.01 to 0 in terms of phosphonobutane tricarboxylic acid with respect to the total amount of the coolant composition. It is 5.5% by weight.

Furthermore, it is desirable that one embodiment of the coolant composition of the present invention does not contain amine salts, borates, nitrites or silicates.

Hereinafter, embodiments of the present invention will be specifically described based on examples. However, the present invention is not limited to the following examples. The% referred to below means% by weight unless otherwise specified.

<Experiment 1: Rubber tensile test>
(Test conditions)
Test piece: H-NBR (hydrogenated nitrile rubber)
Temperature: 120 ° C
Test time: 500 hours

(Test method)
A test piece made of H-NBR hollowed out in a dumbbell shape was immersed in a test solution having the composition of Example 1, Example 2 and Comparative Example 1 shown in Table 1, and the test was carried out at 120 ° C. for 500 hours.
The tensile strength of the test piece before and after immersion for 500 hours was measured. Tensile strength was measured according to JIS K 6251: 2010.
From the measured values of tensile strength, the rate of change in tensile strength was calculated from the following formula.

Table 1 shows the measurement results of the composition of each test solution and the rate of change in tensile strength.

Compared with the test solution of Comparative Example 1 which does not contain the aliphatic polyol compound propylene glycol or glycerin, the test solutions of Examples 1 and 2 containing the aliphatic polyol compound have the tensile strength of the H-NBR test piece. The effect of reducing the deterioration of was recognized.

<Experiment 2: Heat-Transfer Corrosion Test>
The amount of corrosion due to heat transfer of the aluminum test piece in each test solution having the composition shown in Table 2 was evaluated by a method according to ASTM D4340.
Each test solution having the composition shown in Table 2 was placed in an apparatus in which an aluminum test piece and a glass cell were assembled, and a pressure of 193 kPa was applied to heat the test piece to 135 ° C., and a test was carried out for 168 hours. The weight of the test piece before and after the test was measured, and the amount of corrosion was calculated by the following formula.

Table 2 shows the measurement results of the composition and the amount of corrosion of each test solution.

Compared with the test solution of Comparative Example 2 containing no phosphonobutane tricarboxylic acid, calcium, magnesium and strontium, the test solutions of Examples 1 and 4 containing phosphonobutane tricarboxylic acid, calcium and magnesium, and phosphonob It was confirmed that the test solutions of Examples 3 and 5 containing tantricarboxylic acid and strontium had an anticorrosion effect on the aluminum test piece.

Claims (6)

A coolant composition containing water and propionic acid salt.
Aliphatic polyol compound;
nitrate;
Azole compound;
At least one selected from phosphoric acid and its salts;
Molybdate of 0.1 to 2.0% by weight in terms of sodium molybdate with respect to the total amount of the coolant composition;
At least one selected from calcium compounds, magnesium compounds and strontium compounds in a nitrate equivalent of 0.0001 to 0.2% by weight based on the total amount of the coolant composition; and phosphonobutanetricarboxylic acid based on the total amount of the coolant composition. A coolant composition further comprising at least one selected from a phosphonobutane tricarboxylic acid and a salt thereof, which is 0.01 to 1.0% by weight in terms of conversion. The coolant composition according to claim 1, which comprises at least one selected from glycerin, propylene glycol and 1,3-propanediol as the aliphatic polyol compound. The coolant composition according to claim 1 or 2, wherein the aliphatic polyol compound is contained in an amount of 1.0 to 10% by weight based on the total amount of the coolant composition. The coolant composition according to any one of claims 1 to 3, wherein nitrate is contained in an amount of 0.01 to 0.5% by weight in terms of sodium nitrate with respect to the total amount of the coolant composition. The coolant composition according to any one of claims 1 to 4, wherein the azole compound is contained in an amount of 0.01 to 10% by weight based on the total amount of the coolant composition. The cooling according to any one of claims 1 to 5, wherein at least one selected from phosphoric acid and a salt thereof is contained in an amount of 0.01 to 2.0% by weight in terms of phosphoric acid with respect to the total amount of the coolant composition. Liquid composition.