JP2009256735A - Cooling liquid composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling liquid composition which has aluminum corrosion preventiveness and magnesium corrosion preventiveness in combination, and in which generation of a gel, deposition to a mechanical seal and generation of an insoluble fluoride are suppressed. <P>SOLUTION: The cooling liquid composition is composed of a melting point depressant selected from a group consisting of glycols and alcohols, and is characterized by including (a) one or more kinds of corrosion inhibitors selected from fluorides, (b) one or more corrosion inhibitors selected from alkaline earth metal compounds, and (c) an ion sealing agent, and does not contain a silicon compound. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a coolant composition that is added to cooling water of an internal combustion engine such as an automobile, and particularly relates to a coolant composition that is excellent in metal corrosion resistance.

  Conventionally, a cooling liquid mainly composed of a melting point depressant such as alcohols or glycols is added to the cooling water of an automobile engine to prevent freezing in winter. However, alcohols and glycols are not only rust-proof, but also oxidized when they come into contact with oxygen during circulation at high temperatures, and the resulting oxide promotes corrosion of the metals that make up the cooling water flow path. There is.

  Therefore, the coolant generally includes phosphate, borate, carbonate, sulfate, nitrate, molybdate, benzoate, silicate, benzotriazole, mercaptobenzothiazole sodium salt, tolyltriazole, A rust preventive agent selected from ethanolamine salts and the like is added to prevent corrosion of the metal when used in a predetermined amount mixed with cooling water.

  Since various metals such as cast iron, steel, and copper alloys are used for the cooling system of an internal combustion engine such as an automobile engine, it is required to prevent corrosion in the coolant regardless of the type of metal. . However, with the frequent use of aluminum parts for the purpose of resource saving and energy saving, it has become clear that the conventional cooling liquid has insufficient anticorrosion properties against aluminum-based metals.

  For example, borates have excellent anticorrosion properties for cast iron materials, but corrosive properties for aluminum-based metal materials. Triethanolamine phosphate has anticorrosive properties against both iron-based metals and aluminum-based metals. However, it can react with nitrite to produce toxic nitrosamines. In addition, the amine salt has a problem that the anticorrosion property against iron is rapidly lowered due to deterioration.

  Furthermore, there is a movement to consider adopting magnesium alloy parts in the cooling system for resource and energy saving purposes. However, magnesium has the lowest standard potential among practical metals and has low corrosion resistance, and it is necessary to consider corrosion resistance for practical use. In order to improve the corrosion resistance, in addition to improving the corrosion resistance of the magnesium alloy itself, it may be achieved by the cooling water used in the cooling system, but magnesium cannot be prevented by conventional coolant additives. .

Therefore, the following Patent Document 1, as a coolant which can anticorrosion magnesium, a) alkyl benzoate is selected from C ₅ -C ₁₅ monobasic acid and a C ₅ -C ₁₅ dibasic acids or salts thereof Disclosed is a corrosion inhibitor composition comprising 0.1 to 15% by weight of one or more inhibitors and b) 0.005 to 5% by weight of fluoride and / or fluorocarboxylic acid or salt thereof. Yes. However, fluoride has a high anticorrosion property against magnesium, but has a problem of adversely affecting aluminum alloys.

  Patent Document 2 below discloses that a coolant containing fluoride, phosphoric acid, and silicic acid has high anticorrosive properties against magnesium and aluminum. However, since the cooling liquid contains silicic acid, there is a concern about generation of gel or deposition on the mechanical seal.

Further, Patent Document 3 below discloses a cooling composition for magnesium or a magnesium alloy containing an alkaline earth metal (Ca, Mg, Sr) and a fluorine compound. However, since fluorides of alkaline earth metals (Ca, Mg, Sr) have very low solubility in water, there is concern that precipitation of CaF ₂ , MgF ₂ , SrF _2, etc. may occur. Precipitation can build up on the mechanical seal and clog in the engine cooling system.

JP-T-2002-527619 JP 2005-113250 A JP 2007-269854 A

  The present invention has been made in view of such circumstances, and has a coolant composition that combines aluminum corrosion resistance and magnesium corrosion resistance, and suppresses the generation of gels, deposition on mechanical seals, and generation of insoluble fluorides. The purpose is to provide.

  The present inventors have found that the above problems can be solved by using an ion sequestering agent in combination with a corrosion inhibitor, and have reached the present invention.

  That is, this invention is invention of the cooling fluid composition which has as a main component melting | fusing point depressant selected from the group which consists of glycols and alcohol, Comprising: (a) One or more types of corrosion selected from fluoride It contains an inhibitor, (b) one or more corrosion inhibitors selected from alkaline earth metal compounds, and (c) an ion sequestering agent, and does not contain a silicon compound.

  The cooling liquid composition of the present invention is excellent in aluminum corrosion resistance and magnesium anticorrosion properties, and is highly practical as a cooling liquid composition because generation of gel, deposition on a mechanical seal and generation of insoluble fluoride are suppressed. Is.

  As the ion sequestering agent used in the present invention, one or more selected from polymer carboxylic acid, polyphosphoric acid, and phosphono aliphatic carboxylic acid are preferably exemplified.

  Preferred examples of the alkaline earth metal compound used in the present invention include one or more selected from calcium compounds, magnesium compounds, and strontium compounds.

  As the fluoride used in the present invention, one or more selected from sodium fluoride, potassium fluoride and ammonium fluoride are preferably exemplified.

  The cooling liquid composition of the present invention preferably further contains, as an optional component, (d) one or more of aliphatic and aromatic tribasic acids having 6 to 20 carbon atoms and alkali metal salts thereof. Here, as an aliphatic and aromatic tribasic acid having 6 to 20 carbon atoms and an alkali metal salt thereof, 1,3,5-benzenetricarboxylic acid or an alkali metal salt thereof is preferably exemplified.

  Conventionally known additives can be added as appropriate to the coolant composition of the present invention. Specifically, 1 selected from nitrates, triazoles, thiazoles, phosphoric acid and alkali metal salts thereof, molybdates, aliphatic carboxylic acids and alkali metal salts thereof, and aromatic carboxylic acids and alkali metal salts thereof. More than one type of corrosion inhibitor can be included.

  The coolant composition of the present invention in which a specific corrosion inhibitor and an ion sequestering agent are added together has both aluminum corrosion resistance and magnesium corrosion resistance, and also generates gels, deposits on mechanical seals and insoluble fluorides. Therefore, it is a coolant composition that is suitably used for automobiles and the like that use lightweight materials such as aluminum alloys and magnesium alloys for engines and cooling systems.

  The melting point depressant, which is the main component of the coolant composition of the present invention, is conventionally known. Examples of the alcohols that are melting point depressants include those composed of one or a mixture of two or more selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol. Examples of glycols include one selected from ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, and hexylene glycol, or The thing which consists of 2 or more types of mixtures can be mentioned. These can be used alone or in admixture of two or more.

  As one or more types of corrosion inhibitors for fluoride added to the coolant composition of the present invention, water-soluble fluorides are preferred. Specific examples include hydrogen fluoride, fluorocarboxylic acid, alkali metal salts, ammonium salts thereof, soluble amine salts, borofluorides, and the like. Among these, sodium fluoride, potassium fluoride and ammonium fluoride are preferably exemplified from the viewpoint of workability and anticorrosive effect.

  The fluoride compounding amount is less than 0.01% by weight of fluoride, but the effect of adding fluoride is recognized, but the weight loss of aluminum alloy and magnesium alloy is large, and when the compounding amount exceeds 2% by weight, the effect of adding fluoride is reduced. Since a saturation phenomenon is observed, the blending amount of fluoride is preferably 0.01 to 2% by weight.

  One or more types of corrosion inhibitors selected from the alkaline earth metal compounds added to the coolant composition of the present invention include those composed of metals such as beryllium, magnesium, calcium, strontium, barium, or radium. And can be used in the form of any one or a mixture of two or more selected from these compounds.

  Among these, the metal constituting the compound is preferably made of magnesium, calcium, and strontium in view of excellent corrosion inhibition effect of magnesium or magnesium alloy. These compounds are further excellent in the corrosion inhibitory effect, and are excellent in handleability and availability.

  Specific examples of the compound composed of magnesium include, for example, magnesium oxide, magnesium chloride, magnesium hydroxide, magnesium carbonate, magnesium nitrate, magnesium sulfate, magnesium titanate, magnesium tungstate, magnesium borate, magnesium phosphate, magnesium dihydrogen phosphate. , Magnesium compounds of inorganic acids such as magnesium ammonium phosphate, magnesium chromate, magnesium permanganate, magnesium iodide, magnesium formate, magnesium acetate, magnesium propionate, magnesium butyrate, magnesium valerate, magnesium laurate, magnesium stearate, Magnesium oleate, magnesium glutamate, magnesium lactate, magnesium oxalate, magnesium malate, Magnesium tartrate, magnesium hydrogen tartrate, magnesium maleate, magnesium citrate, magnesium oxalate, magnesium malonate, magnesium sebacate, magnesium benzoate, magnesium phthalate, magnesium salicylate, magnesium mandelate, etc. Can be mentioned.

  Specific examples of compounds composed of calcium include calcium formate, calcium acetate, calcium propionate, calcium butyrate, calcium valerate, calcium laurate, calcium stearate, calcium oleate, calcium glutamate, calcium lactate, calcium succinate, apple Calcium oxide, calcium tartrate, calcium maleate, calcium citrate, calcium oxalate, calcium malonate, calcium sebacate, calcium benzoate, calcium phthalate, calcium salicylate, calcium mandelate, calcium oxide, calcium hydroxide, permanganese Calcium oxide, calcium chromate, calcium iodide, calcium carbonate, calcium nitrate, calcium sulfate, calcium titanate, tongue Calcium phosphate, calcium borate, calcium phosphate, phosphoric acid dihydrogen calcium can be cited.

  Specific examples of the compound composed of strontium include, for example, strontium oxide, strontium hydroxide, strontium chloride, strontium iodide, strontium sulfate, strontium nitrate, strontium titanate, strontium borate, strontium tungstate, strontium phosphate, diphosphate Strontium hydrogen, strontium formate, strontium acetate, strontium propionate, strontium butyrate, strontium valerate, strontium laurate, strontium stearate, strontium oleate, strontium glutamate, strontium lactate, strontium malate, strontium malate Strontium acid, strontium citrate, sputum Strontium, strontium malonate, strontium sebacate, strontium benzoate, phthalic acid strontium salicylate, strontium, and the like can be given mandelic acid strontium, among which may be mentioned in particular strontium nitrate, strontium sulfate, phosphate strontium.

  The content of the alkaline earth metal compound in the coolant composition of the present invention is 0.0001 as an alkaline earth metal with respect to 100% by mass of the base in order to ensure a sufficient corrosion inhibiting effect on magnesium or a magnesium alloy. It is desirable to be in the range of ˜5 mass%. When the content of alkaline earth metal compound is less than this range, it is not possible to obtain a sufficient corrosion inhibition effect on the aluminum heat transfer surface, and when the content of alkaline earth metal compound is larger than this range This is because the effect exceeding the range cannot be expected and it becomes uneconomical.

  One or more of aliphatic and aromatic tribasic acids having 6 to 20 carbon atoms and alkali metal salts thereof are preferably added to the coolant composition of the present invention from the viewpoint of metal corrosion resistance and solubility. Specifically, as the trivalent carboxylic acid compound, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2 , 4-naphthalenetricarboxylic acid, aromatic carboxylic acid such as pyromellitic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2- Aliphatic carboxylic acids such as methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, alicyclic carboxylic acids such as 1,2,4-cyclohexanetricarboxylic acid, and the like Examples include alkali metal salts. Of these, 1,3,5-benzenetricarboxylic acid or an alkali metal salt thereof is particularly preferred.

  The coolant composition of the present invention further includes 0.01 to 1.0% by weight of nitrate, 0.01 to 1.0% by weight of triazoles, 0.01 to 1.0% by weight of thiazoles, In addition, it is desirable to include one or more corrosion inhibitors selected from phosphoric acid and its alkali metal salt, molybdate, aliphatic carboxylic acid and its alkali metal salt, and aromatic carboxylic acid and its alkali metal salt. . Thereby, corrosion resistance improves further. Nitrate suppresses pitting corrosion of aluminum, and triazoles and thiazoles are effective in preventing copper corrosion. Each of these may be added alone, but it is more preferable to include all of these three types. Examples of nitrates include sodium nitrate and potassium nitrate, and examples of triazoles include benzotriazole and tolyltriazole. Examples of thiazoles include benzothiazole and mercaptobenzothiazole sodium.

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

  The coolant composition of the present invention is usually used by mixing 20 to 60% by volume in cooling water. Therefore, each component to be added to the cooling liquid composition of the present invention needs to be completely dissolved in cooling water at least when used, and a component that is difficult to dissolve is desirably blended as an easily soluble alkali metal salt. Examples of the alkali metal salt include Na salt and K salt. Further, from the viewpoint of storage stability and handleability, it is desirable that each component is completely dissolved in the stock solution state of the cooling liquid composition. Therefore, it is preferable that sodium hydroxide, potassium hydroxide and the like are further added to the cooling water composition of the present invention to improve the solubility and to adjust the pH optimally.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In the following, “%” means “% by weight” unless otherwise specified.

(Example 1 and Comparative Examples 1 to 4)
The coolant compositions of Example 1 and Comparative Example 1 were prepared with the blending amounts shown in Table 1 below. Here, an example (Example 1) where a fluoride, an alkaline earth metal compound and polyacrylic acid which is an ion sequestering agent are added together, and a case where no fluoride is added (Comparative Example 1), an alkaline earth metal compound The case where it is not added (Comparative Example 2), the case where a silicon compound is added (Comparative Example 3), and the case where polyacrylic acid which is an ion sequestering agent is not added (Comparative Example 4) are shown. Here, AZ91D is a magnesium alloy, and AC2A is an aluminum alloy.

  Using the cooling liquid composition, a metal corrosion test at the time of contacting a magnesium alloy and an aluminum alloy was performed by an AZ91D-AC2A contact corrosion test. Table 1 below shows the composition of each coolant and the test results.

In Table 1,
Note 1: KOH is blended in an amount that gives a pH of 7.8 after dilution to 50%.
Note 2: In the metal corrosion test, a contact corrosion test of a magnesium alloy (AZ91D) and an aluminum alloy (AC2A) was performed in accordance with the JISK2234 metal corrosion test. Each sample in the above table was diluted to 50% with ion-exchanged water and then immersed in 750 ml of an aqueous solution of 750 ml held at 88 ± 2 ° C. During the immersion, air was blown at a flow rate of 100 ml / min.
Note 3: The aluminum heat transfer surface test was conducted according to the JISK2234 aluminum cast heat transfer surface corrosion test. The heat transfer surface temperature was 170 ° C. The samples in the above table were diluted to 45% with ion exchange water and tested at a liquid temperature of 95 ° C.
Note 4: Stability is determined by diluting the above-mentioned meter to 50% with ion-exchanged water and keeping it at −200 ° C. × 24 h → 50 ° C. × 24 h → −20 ° C. × 24 h → 50 c × 24 h → room temperature × 72 h. The residual rate was calculated by analyzing the concentration of calcium and magnesium by ICP analysis.

  From the results in Table 1, the following can be understood. Example 1 containing calcium, magnesium, and sequestering agent (polyacrylic acid) in the fluoride improves the anticorrosion property of AZ91D and contains fluoride compared to Comparative Example 1 that does not contain fluoride. It turns out that the aluminum heat-transfer surface performance is improving compared with the comparative example 2 which does not contain calcium, a magnesium, and an ion sequestering agent. Further, Comparative Example 3 in which silicic acid is blended with Comparative Example 2 improves the aluminum heat transfer surface performance, but there is a possibility of gel generation as shown in SAE Technical Paper Series 852327. In addition, when calcium and magnesium are used without using an ion sequestering agent, not only the corrosion resistance of the aluminum heat transfer surface cannot be improved, but also the stability (decreased residual ratio) is poor, and insoluble calcium and magnesium It is thought to settle as fluoride.

  As described above, in order to achieve the present invention, it is essential that at least one of fluoride and an alkaline earth metal compound and an ion sequestering agent are contained and no silicon compound is contained.

  The coolant composition of the present invention in which a specific corrosion inhibitor and an ion sequestering agent are added together has both aluminum corrosion resistance and magnesium corrosion resistance, and also generates gels, deposits on mechanical seals and insoluble fluorides. As a result, a coolant composition in which the above was suppressed was obtained. It has become possible to promote weight reduction of automobiles and the like by using this coolant composition for automobiles and the like using lightweight materials such as aluminum alloys and magnesium alloys for engines and cooling systems.

Claims (7)

  A coolant composition comprising as a main component a melting point depressant selected from the group consisting of glycols and alcohols, wherein (a) one or more corrosion inhibitors selected from fluorides, (b) alkaline earth A coolant composition comprising at least one corrosion inhibitor selected from a metal group compound, and (c) an ion sequestering agent, and no silicon compound.   The coolant composition according to claim 1, wherein the sequestering agent is at least one selected from high-molecular carboxylic acid, polyphosphoric acid, and phosphonoaliphatic carboxylic acid.   The coolant composition according to claim 1 or 2, wherein the alkaline earth metal compound is at least one selected from a calcium compound, a magnesium compound, and a strontium compound.   The coolant composition according to any one of claims 1 to 3, wherein the fluoride is one or more selected from sodium fluoride, potassium fluoride, and ammonium fluoride.   5. The coolant composition according to claim 1, further comprising (d) one or more of aliphatic and aromatic tribasic acids having 6 to 20 carbon atoms and alkali metal salts thereof. object.   The said C6-C20 aliphatic and aromatic tribasic acid and its alkali metal salt are 1,3,5-benzenetricarboxylic acid or its alkali metal salt, The Claim 5 characterized by the above-mentioned. Coolant composition.   Further, at least one selected from nitrates, triazoles, thiazoles, phosphoric acid and alkali metal salts thereof, molybdates, aliphatic carboxylic acids and alkali metal salts thereof, and aromatic carboxylic acids and alkali metal salts thereof. The coolant composition according to any one of claims 1 to 6, wherein a corrosion inhibitor is contained.