JP2005113250A - Cooling liquid composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling liquid composition which can exhibit high corrosion preventiveness to an Mg alloy and Al alloy. <P>SOLUTION: The liquid composition contains a corrosion inhibitor containing a fluorine element, phosphorus element and silicon element in the form of a compound of one kind or a mixture composed of compounds of two or more kinds. The three kinds of elements are incorporated into the composition, by which the incorporation of the fluoride having a high effect of the corrosion preventiveness to magnesium in the state of suppressing the adverse influence thereof on the aluminum alloy is made possible and the high corrosion preventiveness to the magnesium and the aluminum can be exhibited. Here, the corrosion inhibitor is preferably the fluoride and a mixture composed of phosphoric acid and/or its salt and silicic acid and/or its salt. Namely, the fluorine element is preferably incorporated into the composition in the form of fluoride, the phosphorus element in the form of phosphoric acid and/or its salt and the silicon in the form of silicic acid and/or its salt. The preferable salt relating to the phosphoric acid and the silicic acid is an alkaline metal salt. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coolant composition, and in particular, has excellent anticorrosive properties against aluminum and aluminum alloys (hereinafter appropriately referred to as “aluminum etc.”) and magnesium and magnesium alloys (hereinafter appropriately referred to as “magnesium etc.”). Relates to a liquid coolant composition.

  Since various metals such as cast iron, steel, copper alloy, and aluminum are used in the cooling system of an internal combustion engine such as an automobile engine, the coolant composition can prevent corrosion regardless of the type of metal. It has been demanded.

  Conventionally, a coolant composition containing a melting point depressant such as alcohols and glycols as a main component has been added to the coolant of an automobile engine to prevent freezing in winter. However, alcohols and glycols have no rust-preventing action, and as such cannot prevent the corrosion of the metal constituting the coolant flow path. Therefore, various corrosion inhibitors are added to the coolant composition.

  By the way, there is a movement to consider adopting parts made of magnesium or the like in the cooling system for the purpose of saving resources and energy. Magnesium is the metal with the lowest density among practical metals and has excellent recyclability, but the standard oxidation-reduction potential is the lowest among practical metals and has low anticorrosion properties. There is a need. In order to improve the corrosion resistance of magnesium or the like used in the cooling system, it is conceivable to achieve it by the cooling liquid used in addition to improving the corrosion resistance of magnesium or the like.

As a conventional cooling liquid composition in consideration of anticorrosive properties against magnesium and the like, aluminum and the like, a selected group of an aliphatic or aromatic carboxylic acid or an alkali metal salt, ammonium salt or amine salt thereof, fluoride and / or A combination of fluorocarboxylates is disclosed (Patent Document 1).
Special table 2002-527619

  However, although the coolant composition to which fluoride is added has high anticorrosion properties against magnesium and the like, it has not been able to exhibit sufficient improvement in anticorrosion properties against aluminum and the like. This cannot be sufficiently solved only by adding an organic acid as disclosed in Patent Document 1.

  This invention is made | formed in view of the said situation, and makes it the subject which should be solved to provide the cooling fluid composition which can exhibit high anticorrosion property with respect to magnesium etc. and aluminum.

  In order to solve the above problems, the present inventors have studied the influence of fluoride on aluminum and the like, and as a result, fluoride has a particularly bad influence on aluminum and the like under cavitation and high-temperature heat transfer surfaces. It was discovered that the corrosion resistance of aluminum and the like cannot be improved. Therefore, when a means for containing a fluoride having a large anticorrosive effect against magnesium or the like in a state in which an adverse effect on aluminum or the like is suppressed is found, aluminum or the like is effectively obtained by containing phosphorus (compound) and silicon (compound). The inventors have found that the adverse effects on can be suppressed, and have completed the following invention.

  That is, the cooling liquid composition of the present invention is a cooling liquid composition mainly composed of a melting point depressant that is one or more compounds selected from the group consisting of glycols and alcohols. It contains a corrosion inhibitor containing the element and silicon element as one compound or a mixture of two or more compounds. By containing these three kinds of elements, high anticorrosive properties against magnesium and aluminum can be exhibited.

  Here, the corrosion inhibitor is preferably a mixture of fluoride, phosphoric acid and / or a salt thereof, and silicic acid and / or a salt thereof. That is, it is preferable to contain elemental fluorine as fluoride, elemental phosphorus as phosphoric acid and / or a salt thereof, and silicon as silicic acid and / or a salt thereof. The preferred salts for phosphoric acid and silicic acid are alkali metal salts.

  And when the whole composition is 100 mass%, it is preferable to make it contain 0.01%-2% in conversion of a fluorine element. The fluoride is preferably at least one of sodium fluoride, potassium fluoride and ammonium fluoride. Moreover, when the whole composition is 100 mass%, it is preferable to contain 0.01% to 0.1% in terms of phosphorus element and 0.01% to 0.1% in terms of silicon element, respectively.

  Furthermore, when the whole composition is 100% by mass, it contains 3 to 8% of one or more compounds selected from the group consisting of aliphatic dibasic acids having 9 to 12 carbon atoms and alkali metal salts thereof. It is preferable from the viewpoint of improving the anticorrosion property. Moreover, when the whole composition is 100 mass%, nitrate is 0.01% to 1.0%, triazole is 0.05% to 1.0%, and thiazole is 0.01% to 1.0%. % Each is preferable.

  Moreover, it is preferable that the cooling fluid composition of the present invention is used for a cooling fluid channel in which aluminum or the like, magnesium, or the like is exposed on at least a part of the surface in contact with the cooling fluid composition.

  Furthermore, the cooling fluid composition containing 20-60 volume% of any one of the above-mentioned cooling fluid composition with respect to the whole mass in use condition is preferable. Here, the “total mass in use state” refers to the mass in a state where the cooling liquid composition of the present invention is used in a cooling system. That is, the cooling liquid composition of the present invention can be used by appropriately diluting with a solvent such as water and the absolute content cannot be defined.

  The cooling liquid composition of the present invention has an effect of improving the corrosion resistance against aluminum and the like while maintaining high corrosion resistance against magnesium and the like by containing fluorine element, phosphorus element and silicon element in the composition.

  Hereinafter, the coolant composition of the present invention will be described in detail based on embodiments. The present cooling liquid composition is used by dissolving the cooling liquid composition in a solvent such as water in a cooling system. This cooling liquid composition is often produced and distributed in a state where it is mixed with water at a ratio of 20 to 60% by volume based on the whole as in the case of a general cooling liquid composition.

  The coolant composition of this embodiment has a melting point depressant and a corrosion inhibitor. The melting point depressant is one or more compounds selected from the group consisting of glycols and alcohols. Examples of glycol include ethylene glycol and propylene glycol. Examples of alcohols include methanol, ethanol, and 2-propanol. These alcohols and glycols can be used alone or in admixture of two or more.

  As a corrosion inhibitor, a fluorine element, a phosphorus element, and a silicon element are contained. Fluorine is preferably contained as a fluoride. The fluoride is not particularly limited. The fluorine element such as fluoride is preferably contained in an amount of 0.01% to 2% in terms of the elemental fluorine with respect to the total mass. Fluorine element exhibits corrosion resistance even outside this range, but if contained within this range, a sufficient effect can be exhibited.

  The fluoride is preferably a salt that can be dissolved in the cooling liquid composition (and water) within the above-mentioned preferred addition range, and is sodium fluoride, potassium fluoride, ammonium fluoride, lithium fluoride, sodium borofluoride. Examples thereof include ammonium borofluoride and lithium borofluoride. As the fluoride, a salt with an alkali metal such as sodium fluoride or potassium fluoride, or ammonium fluoride is particularly preferable.

  The phosphorus element is preferably contained as phosphoric acid and / or a salt thereof. As the phosphate, an alkali metal salt is preferable. Phosphorus element (especially phosphoric acid or a salt thereof) can largely suppress the corrosiveness of aluminum or the like, and can greatly improve the corrosion resistance of aluminum or the like under cavitation or at high temperatures. For example, when an aluminum housing is adopted for a water pump or the like, cavitation, erosion, and corrosion of the water pump can be effectively prevented. Moreover, the corrosion resistance of the high-temperature aluminum casting heat transfer surface is also improved.

  The phosphorus element such as phosphoric acid is preferably contained in an amount of 0.01% to 0.1% in terms of phosphorus element with respect to the total mass. Phosphorus element exhibits corrosion resistance even outside this range, but by adopting this range, it can exhibit sufficient corrosion resistance against aluminum, etc., and improve the corrosion resistance against aluminum etc. under cavitation and constitute a cooling system Reduction of adverse effects on other materials (for example, brass) can be achieved.

  The silicon element is preferably contained as silicic acid and / or a salt thereof. As the silicate, an alkali metal salt is preferable. Silicon element (especially silicic acid or a salt thereof) can suppress and reduce the influence of fluorine element on aluminum and the like, and can greatly improve the corrosion resistance of aluminum and the like under cavitation and at high temperatures.

  Silicon elements such as silicic acid are preferably contained in an amount of 0.01% to 0.1% in terms of silicon element when the entire composition is 100% by mass. Silicon element exhibits corrosion resistance even outside this range, but by adopting this range, sufficient corrosion resistance against aluminum or the like can be exhibited and improvement of aluminum corrosion resistance under cavitation can be achieved. In addition, when this range is adopted, the solubility can be increased and the storage stability is improved.

  Other corrosion inhibitors include borate, carbonate, sulfate, nitrate, molybdate, benzoate, benzotriazole, mercaptobenzothiazole sodium salt, and tolyltriazole. And triazoles such as triethanolamine salts and thiazoles. Thereby, corrosion resistance can be improved further. In particular, by adding an organic acid-based rust inhibitor, a high corrosion inhibition effect can be exhibited.

  For example, when one or more compounds selected from the group consisting of aliphatic dibasic acids having 9 to 12 carbon atoms and alkali metal salts thereof are 100% by mass of the entire composition, 3 to 8% are included. preferable. Preferred aliphatic dibasic acids having 9 to 12 carbon atoms are azelaic acid, sebacic acid and undecanedioic acid. An example is dodecanedioic acid. Moreover, when the whole composition is 100 mass%, nitrate is 0.01% to 1.0%, triazole is 0.05% to 1.0%, and thiazole is 0.01% to 1.0%. % Each is preferable.

  In addition, the corrosion inhibitor in the additive for the coolant composition can be added after the coolant composition is added to the cooling system of an automobile or the like, or disposed in advance in the cooling system. Then, the coolant composition may be added later so that the corrosion inhibitor such as fluoride is dissolved in the coolant composition. For example, the corrosion inhibitor may be granulated or tableted and later added to the cooling liquid composition, or may be applied and formed in layers on the surface of the cooling system component.

[Test 1: Corrosion test]
(Sample 1)
Potassium fluoride as a corrosion inhibitor is added to a commercially available cooling liquid composition (not containing fluorine, phosphorus and silicon) in which an organic acid-based anticorrosive agent as a corrosion inhibitor is added to ethylene glycol as a melting point depressant. 6000 ppm (0.6 mass%) in terms of fluorine element, 500 ppm (0.05 mass%) in terms of sodium metasilicate in terms of silicon element, and 600 ppm (0.06 mass%) in terms of orthophosphoric acid in terms of phosphorus element %) Was used as a coolant composition of the test sample.

(Sample 2)
600 ppm by converting orthophosphoric acid as a corrosion inhibitor into phosphorus element in a commercially available coolant composition in which an organic acid corrosion inhibitor as a corrosion inhibitor is added to ethylene glycol as a melting point depressant used in Sample 1 The composition contained (0.06% by mass) was used as the coolant composition of this test sample.

(Sample 3)
Conversion of potassium fluoride as a corrosion inhibitor to fluorine element in a commercially available coolant composition in which an organic acid-based anticorrosive agent as a corrosion inhibitor was added to ethylene glycol as a melting point depressant used in Sample 1 A composition containing 6000 ppm (0.6% by mass) and 600 ppm (0.06% by mass) of orthophosphoric acid in terms of phosphorus was used as the coolant composition of this test sample.

  That is, sample 2 contains only phosphorus element as a corrosion inhibitor, sample 3 adds fluorine element as a corrosion inhibitor to sample 2, and sample 1 further contains silicon element as a corrosion inhibitor with respect to sample 3. Added.

(Metal corrosion test)
Based on the JISK2234 metal corrosion test, the contact corrosion test of the magnesium alloy (AZ91D) and the aluminum alloy (AC2A) was performed. A plate made of magnesium alloy (AZ91D) (50 mm × 25 mm × 3 mm) and a plate made of aluminum alloy (AC2A) while maintaining 750 mL of an aqueous solution diluted to 50% by volume with ion-exchanged water for each sample described above at 90 ° C. The mass change before and after being immersed for 300 hours in the state where (50 mm × 25 mm × 3 mm) was stacked in the thickness direction was measured. During immersion, air was bubbled at a flow rate of 100 mL / min. The results are shown in Table 1.

In the magnesium alloy (AZ91D), a large mass change (−0.78 mg / cm ² ) was observed in the sample 2 not containing fluorine, but it was found that the anticorrosion properties were improved by the samples 1 and 3 to which fluorine was added. That is, it was found that the corrosion resistance of the magnesium alloy is improved by adding fluorine.

In the aluminum alloy (AC2A), the anticorrosion property was sufficient in the sample 2 not containing fluorine (and silicon), whereas the sample 3 containing fluorine showed a large mass change (−0.17 mg / cm ² ). Therefore, it was found that the corrosion resistance of the aluminum alloy is not sufficient when fluorine is simply added. It was found that Sample 1 containing silicon in addition to fluorine improves the corrosion resistance of the aluminum alloy. In other words, it was found that although the corrosivity of the aluminum alloy is increased by the presence of fluorine, fluorine can suppress the corrosion of the aluminum alloy by adding silicon.

  That is, in Sample 2 to which only phosphorus is added, the aluminum alloy can be prevented from corrosion, but the corrosion resistance of the magnesium alloy is not sufficient, but by adding fluorine (Sample 3), the corrosion resistance of the aluminum alloy is reduced, but the corrosion resistance of the magnesium alloy Can be improved. Furthermore, it was found that by adding silicon, the adverse effects of fluorine disappeared and both the corrosion resistance of both the magnesium alloy and the aluminum alloy can be achieved.

[Test 2: Corrosion test of aluminum alloy at high temperature]
A corrosion test at a high temperature was performed using Samples 1 to 3 described in Test 1 and Sample 4 which is a commercially available coolant composition used for Samples 1 to 3.

  The corrosion test of the aluminum alloy at a high temperature was performed in accordance with an aluminum casting heat transfer surface corrosion test specified in JISK2234. The heat transfer surface temperature was 170 ° C. Samples 1 to 4 were diluted with ion exchange water to 45% by volume and tested at a liquid temperature of 95 ° C. The results are shown in Table 2.

Sample 4 containing no F, Si and P shows a large mass change (−1.19 mg / cm ² ). It was found that the anticorrosive property of was not sufficient. In Sample 2 to which phosphorus was added, no mass change was observed and high anticorrosion properties were exhibited. From the results of Sample 3 in which fluorine was added to Sample 2, it was found that the corrosion resistance of the aluminum alloy was lowered by the addition of fluorine. It was found that Sample 1 in which silicon was further added to Sample 3 was able to exhibit sufficient corrosion resistance of the aluminum alloy again.

  That is, it was found that high corrosion resistance to an aluminum alloy can be exhibited by containing both fluorine and silicon even in a high temperature atmosphere.

[Test 3: Cavitation resistance test]
Samples 1 to 4 used in Test 2, Sample 5 containing 6000 ppm (0.6%) of potassium fluoride in terms of fluorine element with respect to Sample 4, and Sodium metasilicate to silicon element with respect to Sample 5 Cavitation resistance was examined using Sample 6 containing 500 ppm (0.05%) in terms of conversion.

  The cavitation resistance test is a test that evaluates the cavitation resistance of a sample by generating an ultrasonic cavitation environment on a metal test piece in a sample (cooling liquid), measuring the mass change of the metal test piece before and after the test. . Samples 1 to 6 were diluted with ion-exchanged water so as to be 50% by volume, before and after the test of aluminum alloy (AC2A) and magnesium alloy (AZ91D) at a liquid temperature of 80 ° C., a vibration amplitude of 40 μm, and a test time of 3 hours. Mass change was measured, and the magnitude of mass reduction per unit surface area was calculated. The results are shown in Table 3.

  Samples 1 to 3 are greatly different from Samples 6, 4 and 5 in that phosphorus is added. In addition, the result in magnesium alloy is not described about the samples 4-6, since the corrosion resistance with respect to an aluminum alloy is made into a problem in this test.

Result of the addition of phosphorus, mass change (-8.5mg / cm ²⁾ is the mass change of the sample 1 (F, Si and P added) samples 6 (F and Si added) (-5.0mg / cm ^2), Sample 5 (F addition) mass change (−19.5 mg / cm ² ) is sample 3 (F and P addition) mass change (−15.9 mg / cm ² ), and sample 4 (F, Si and P all) It was found that the mass change (−16.5 mg / cm ² ) of (no addition) decreased to the mass change (−11.5 mg / cm ² ) of Sample 2 (P addition). That is, it was found that corrosion resistance (cavitation resistance) can be improved regardless of whether fluorine and silicon other than phosphorus are added.

[Conclusion]
Summarizing the results of tests 1 to 3 described above, corrosion resistance is sufficiently high for both magnesium alloy and aluminum alloy by adding fluorine, silicon and phosphorus as corrosion inhibitors to the coolant composition. It turned out that it can exhibit sex.

Claims (9)

A coolant composition mainly comprising a melting point depressant, which is one or more compounds selected from the group consisting of glycols and alcohols,
A coolant composition comprising a corrosion inhibitor containing fluorine element, phosphorus element and silicon element as one compound or a mixture of two or more compounds.   The coolant composition according to claim 1, wherein the corrosion inhibitor is a mixture of fluoride, phosphoric acid and / or a salt thereof, and silicic acid and / or a salt thereof.   The cooling fluid composition according to claim 1 or 2 containing 0.01% to 2% in terms of fluorine element when the entire composition is 100% by mass.   The coolant composition according to claim 1, wherein the fluoride is at least one of sodium fluoride, potassium fluoride, and ammonium fluoride.   The composition according to any one of claims 1 to 4, which contains 0.01% to 0.1% in terms of phosphorus element and 0.01% to 0.1% in terms of silicon element when the entire composition is 100% by mass. A coolant composition according to 1.   When the total composition is 100% by mass, 3 to 8% of one or more compounds selected from the group consisting of aliphatic dibasic acids having 9 to 12 carbon atoms and alkali metal salts thereof are included. The coolant composition according to any one of 5.   When the total composition is 100% by mass, nitrate is 0.01% to 1.0%, triazole is 0.05% to 1.0%, and thiazole is 0.01% to 1.0%, respectively. The coolant composition according to claim 1, which is contained.   The coolant composition according to any one of claims 1 to 7, which is used for a coolant channel in which aluminum and magnesium are exposed on at least a part of the surface.   The cooling fluid composition which contains 20-60 volume% of the cooling fluid composition in any one of Claim 3 and 5-7 with respect to the whole mass in use condition.