JPS58164792A - Corrosion preventing liquid for aluminum engine - Google Patents

Abstract

PURPOSE:To provide the titled low-pollution corrosion preventing liq. having a sufficient corrosion preventing effect and contg. specified amounts of phosphoric acid, polyphosphoric acid or a salt thereof, molybdic acid, tungstic acid, vanadic acid, a salt thereof or a heteropolyacid salt of Mo, W or V, and benzotriazole, tolyptriazole or a salt thereof. CONSTITUTION:This corrosion preventing liq. contains 500-30,000ppm of >=1 kinds among component (1) selected from phosphoric acid, polyphosphoric acid and salts thereof, 50-500ppm of >=1 kinds among component (2) selected from molybdic acid, tungstic acid, vanadic acid, salts thereof and heteropolyacid salts of Mo, W and V, and 5-500ppm of >=1 kinds among component (3) selected from benzotriazole, polyltriazole and salts thereof. It is known that each of the components 1-3 has a corrosion preventing effect on a specified metal. By blending the components 1-3 at said concns., the corrosion of a Cu-solder-Al contact system as well as a stee-cast iron-Al contact system can be prevented thoroughly. The preventing liq. also inhibits the corrosion of the heating surface of Al.

Description

[Detailed Description of the Invention] A variety of anticorrosive agents have been proposed for metals used in cooling systems, and many products are commercially available. In the case of cooling systems for related internal combustion engines, the metals used are copper, solder, brass,
There are many types such as steel, cast iron, Al-1-Rum alloy, etc.
Nyanda, cast iron, and aluminum alloys are prone to contact corrosion with dissimilar metals, and to prevent this, tertiary acid-based corrosion inhibitors are used as an extremely effective anti-corrosion agent. However, as awareness of environmental pollution has increased in recent years, the use of kutamic acid-based corrosion inhibitors has become more and more difficult. However, it has actually become difficult.

For these reasons, there is a strong desire to develop anticorrosive agents that have excellent anticorrosion effects and are non-polluting or low-polluting.

Furthermore, in recent years, aluminum alloys have been used as materials for engines with the aim of reducing the weight of a car body, but in this case, the problem of aluminum heat transfer surface corrosion has become more prominent, and aluminum alloys There is a need for the development of anticorrosive agents that exhibit excellent anticorrosion effects.

In response to these demands for anticorrosive agents, various non-tamic acid anticorrosive agents have been developed, such as anticorrosive agents based on phosphoric acid, nitrous acid, acene, etc. Some products satisfy the Ic-22s4 (antifreeze) standard test. However, even if the m standard is
Even if an anticorrosive agent is added, severe corrosion occurs in the heat transfer surface corrosion test of these commercially available anticorrosion m□1i and alkaline.
In cases where aluminum is used for heat transfer surfaces, such as in aluminum engines, it has the essential drawback that it cannot withstand use. In particular, it has been reported that conventional anticorrosive agents based on phosphoric acid, which has anticorrosion effects on various metals, increase corrosion of heat transfer surfaces of aluminum when the phosphoric acid concentration exceeds approximately 500%. , cannot be used for aluminum engines.

Based on the current situation as described above, the above-mentioned J Engineering S
There is a strong desire to develop an anticorrosive agent that exhibits an anticorrosion effect that satisfies the standards and also suppresses corrosion on the heat transfer surface of aluminum.

In view of the current situation, the present inventors have developed a low-pollution material that exhibits a sufficient corrosion prevention effect against contact corrosion between dissimilar metals, particularly between cast iron and solder to aluminum alloys and other dissimilar metals. As a result of intensive research to develop a corrosion inhibitor that not only is a tetra-acid-based corrosion inhibitor, but also suppresses corrosion on heat transfer surfaces of aluminum in the cooling system of internal combustion engines using aluminum engines.
(1) One or more selected from the group consisting of phosphoric acid, polyphosphoric acid, and salts thereof as the r component.

~50s000]i1!111, (2) One or more selected from the group consisting of molybdic acid, tungstic acid, vanadate, their acids, and molybdenum-1-tungsten, palladium, and sodium carbonate polysates. of! By using an aluminum engine corrosion inhibitor containing at least 50 to 5000 ppm+% and (8) one or more selected from the group consisting of benzocyriazole, tolyltriazole, and their salts at a PFI of 5 to 500, We have discovered a new fact that the above object can be easily achieved, and have completed the present invention.Remarkable features of the corrosion-inhibiting liquid for Altaka engines of the present invention include (4) to (to), etc. ◎In other words, (A) It not only provides corrosion protection for the cooling system of internal combustion engines that use aluminum, but also provides sufficient corrosion protection for a wide variety of different metals other than aluminum; (2)) Aluminum In an internal combustion engine using an engine,
(0) It is low pollution and does not rot due to bacteria, etc., and (D) The liquid phase of the droplet used is stable and does not cause sedimentation. There is almost no carbonization over time, such as formation of carbon or deterioration of active ingredients.

The features of the present invention will be explained in more detail.

The agents (1) to (11) above, which are used as the effective main components of the corrosion-inhibiting liquid for aluminum engines of the present invention, are f
It is known that it has an anticorrosive effect on certain metals. That is, some cooling systems are used under special conditions, such as cooling systems in chemical factories and thermal power plants, where the types of metals that can be used are relatively limited.

However, these agents cannot be used alone in extremely harsh corrosive environments, such as in the cooling system of internal combustion engines, where a wide variety of metals are used and there is a high risk of contact corrosion between dissimilar metals. In this case, it is not possible to expect a sufficient corrosion protection effect on metals with only one surface. For example, phosphates have a certain degree of corrosion protection effect in steel or cast iron alone, but in a steel-cast iron-aluminum contact system, the corrosion protection against steel and cast iron is lower than that of steel or cast iron alone. Unfortunately, it is significantly lower than before. The same trend holds true for aluminum. In addition, molybdic acid, tungstic acid, vanadate, their salts, or their heteropolyacid salts, when used alone on steel, cast iron, etc., exhibit a certain degree of corrosion-preventing effect, and vanadium praise etc. Ni alone is effective, but in a steel-cast iron-aluminum contact system, steel, cast iron, aluminum
This is lower than when using only minium. 11. However, when these known active ingredients are combined in a corrosion-inhibiting solution at the specified concentration and used in combination, they can prevent corrosion not only in steel-cast iron-alium contact systems but also in copper-solder-brass contact systems. The present inventors have discovered a surprising new fact that can also be completely prevented.

Also, as mentioned above (it has been reported that when the phosphoric acid concentration exceeds about 500P%, corrosion of the heat transfer surface of aluminum becomes more likely to occur;
In the general corrosion test specified in the standard, there is a conflicting fact that the corrosion protection effect on not only cast iron and steel but also aluminum etc. is weak, and the phosphoric acid concentration needs to be 50GPpm1 or more. It was thought that it would be impossible to create an ideal anticorrosion agent using

Furthermore, the present inventors have discovered and found a new fact that even in formulations containing a large amount of phosphoric acid, corrosion of aluminum heat transfer surfaces can be suppressed by adjusting - to around neutrality. Furthermore, in general, when one tone is near neutral, the corrosion resistance of iron, steel, etc. decreases111, and for aluminum, although the amount of corrosion is small, pores
It has been known that metal corrosion tends to occur more easily, but by incorporating the above-mentioned active ingredients in the above-mentioned specific range as in the present invention, these problems can be solved at once. They discovered that the liquid could be provided and completed the present invention.

Furthermore, many of the anticorrosive agents commercially available to date are susceptible to decay due to bacteria, but the corrosion inhibiting liquid for aluminum engines of the present invention does not suffer from decay due to such factors.

Furthermore, the corrosion-inhibiting liquid of the present invention has a stable liquid phase, and there is almost no change over time such as formation of precipitates, separation of active ingredients, or deterioration due to deterioration, and therefore it is sufficient for actual use. We can withstand it.

The corrosion-inhibiting liquid for aluminum engines of the present invention was developed based on the above-mentioned new discoveries.

In the present invention, specific examples of salts of phosphoric acid or borylic acid among the components (1) include orthophosphoric acid,
Suitable examples include sodium salts and potassium salts of diphosphoric acid, tripolyphosphoric acid, metaphosphoric acid, tetrametaphosphoric acid, and hemometaliphosphoric acid. Also, the above (2
) Among the components, specific examples of molybdic acid salts or molybdenum hetate salts include sodium salts, potassium salts, or phosphomolybdic acid, sodium salts of silicomolybdic acid or boromolybdic acid, and potassium salts of molybdic acid. Examples include salt. Specific examples of tungstic acid salts or tungsten heteropolyarates include sodium and potassium salts of tungstic acid, and sodium and potassium salts of silicotungstic acid, borotungstic acid, and phosphotungstic acid. Specific examples of vanadate salts or vanadium heteropolyacid salts include sodium salts, potassium salts, silvanadate, borovanadate or phosphovanadate salts, potassium salts, etc. can be given. Furthermore, among the components (8) above, specific examples of benzotriazole salts or tolyltriazole salts include sodium salts and potassium salts of benzotriazole or silyltriazole. , at least one or two or more selected from the group consisting of (1) phosphoric acid, polyphosphoric acid, and salts thereof as active ingredients in an amount of 500~jsO*
ooops (one or two selected from the group consisting of polymolybdic acid, tungstic acid, vanadate acid, salts thereof, and polysaccharides of molybdenum, tungsten, and vanadium)
60 to 5 seeds or more. 11Ii or 2 selected from the group consisting of OOOppms and (8) benzo)lyazole, tolyltriazole and salts thereof.
It is used by adding 6 to 5007% □ of seeds or more. -2 If the amount of the component (1) added is less than 500P%, the anticorrosive effect on the cast iron-Fulminiram contact system will be weakened, and it will be undesirable, especially since aluminum will be severely corroded.
*Even if the concentration exceeds 0OOPP11, the effect will not be improved and it is not desirable from an economical point of view. If the concentration of the above component is less than 50 ppm, the corrosion protection effect on steel and cast iron will be insufficient. becomes sufficient, while S*0OOx-
If it is used in excess of this amount, it is undesirable because it will have a negative effect on the contact corrosion of aluminum. Said (3
) If the concentration of the component is less than h-, the anticorrosion effect on steel and brass will be insufficient, while if it is used in excess of 500 ya, the concentration of 0 in the wastewater will be high, resulting in pollution problems. undesirable.

In addition to the above-mentioned active ingredients (1) to (8), other conventionally known antirust ingredients can also be used in the anticorrosion liquid of the present invention. For example, by adding carboxylic acid III (fatty carmenic acid, aromatic carboxylic acid), which is well known as a rust-inhibiting ingredient, it has the same or more effective than that
1 is expressed.

When actually using the corrosion-inhibiting liquid of the present invention, it is sufficient to bring the solution in which the concentration of the active ingredient is adjusted to within the above range into contact with the metal.However, from two aspects of on-site management, Usually, high-concentration water droplets or liquid with a compounding ratio corresponding to the above range are diluted with cooling water and used. The total concentration of active ingredients in this highly concentrated aqueous solution is subject to change as appropriate, but is usually in the range of 20 to 60% by weight.
In addition, the corrosion-inhibiting liquid of the present invention □ is
If it is adjusted to a range of 6.0 to 8.0, it will preferably exhibit its excellent anti-corrosion effect.However, in the cooling system of an internal combustion engine using aluminum, heat transfer surface corrosion of aluminum In order to more effectively prevent...
It is more preferable to adjust - to a range of 7.0 to 7.5.

Furthermore, in the cooling system of an internal combustion engine, anti-freeze agents are added in winter for the purpose of preventing freezing, and the corrosion-inhibiting liquid for aluminum engines of the present invention can be used together with these anti-freezing agents. In this case, the anti-corrosion liquid for aluminum engines of the present invention may contain an anti-freeze agent (such as ethylene glycol) in addition to the above-mentioned active ingredients. It is convenient for practical use to use it in a blended state.Also, of course, the corrosion inhibitor of the present invention can also be used in general internal combustion engines other than aluminum engines. The corrosion-inhibiting liquid for aluminum engines of the present invention will be explained in more detail by way of examples, but the present invention is not limited to these examples.

Example 1 Sodium chloride, sodium sulfate, and sodium hydrogen carbonate were added to distilled water to obtain concentrations of chloride ions, sulfuric acid 5 ions, and hydrogen carbonate ions of 100-
A synthetic corrosive solution was prepared.

Next, each component of the metal corrosion prevention solution was added to the synthetic corrosion solution so that the concentration thereof was as shown in Table 1, and a test liquid 5 was prepared. Note that - of each test solution was adjusted to a predetermined value using an alkaline agent shown in Table 1.

Then, using each of the test solutions A1 to A5 obtained, zrnx-
In accordance with the metal corrosion test method specified in 22M (Antifreeze)-1981, six metal test pieces made of aluminum alloy castings, cast iron, steel, brass, solder, and copper made in accordance with the test method were tested at 88±2 A continuous test was carried out for 666 hours (14 days) at a temperature of 10°C while blowing dry air at a rate of 100±10°C.

The degree of corrosion of each metal was evaluated based on the amount of change in mass (0) obtained from the following calculation formula.

(In the formula, O is the amount of change in mass (Ill/Q-/'), W
is the mass of the metal test piece before the test (■), W' Gt is the metal after the test, 1.・5′.

The mass of the test piece (!ap), S is the total surface area (OwP) of the metal test piece before the test. ) The results observed are shown in Table 2.

Comparative Example 1 ゛As shown in Comparative test liquids A1 to i in Table 1, the temperature of each component of the metal corrosion prevention liquid was lower than the specified amount of the present invention, or the types of components were insufficient than the specified amount of the present invention. I prepared it exactly as I did. A metal corrosion test was conducted on each test liquid in the same manner as in Example 1.

The results observed are shown in Table 2.

Comparative Example 2 A commercially available metal corrosion inhibitor containing phosphoric acid as the main component (hereinafter referred to as Mu), a commercially available metal corrosion inhibitor containing nitrous acid as the main component (hereinafter referred to as 1), and a A commercially available metal corrosion inhibitor (hereinafter referred to as O) was added to the same synthetic corrosive solution used in Example 1 at an optimum concentration of 6 to 6% (v/v). A test solution was prepared. The obtained test liquid was subjected to metal corrosion tests in the same manner as in Example 1. The selected results are shown in Table 2.

Example 2 Test solutions 600- of M1 to M5 shown in Table 1 were applied to an aluminum test piece with a removable bottom (material m H-52).
02), placed in a cylindrical stainless steel container (made of solid material, diameter 50 cm, height 70 cm) equipped with a circulation cooling device, and heated the 4 aluminum test pieces at the bottom with an electric heater. At the same time, the test solution was circulated. While keeping the temperature near the surface of the arsenium test piece at 110±5°o1 and the temperature of the test solution at 75±5'O, the contact area between the aluminum elastomer test piece and the test solution is 2001/! A heat transfer surface corrosion test was conducted for 20 hours, and the change in mass of the aluminum test piece was determined. The results obtained are shown in Table 2. □Comparative Example 3 For each of the comparative test solutions A1 to A6 obtained in Comparative Example 1, the same heat transfer surface corrosion test as in Example 2 was conducted, and the mass change of the aluminum component test piece was measured. I asked for it. The results obtained are shown in Table 2. .

The same heat transfer surface corrosion test as in Example 2 was conducted on each of the commercially available solutions of Mu, 1 and 0 obtained in Comparative Example 2, and the mass change of the Al 1-Ram test piece was determined.
The results observed are shown in Table 2.

Example 1 Example 1 except that the same synthetic corrosive liquid as that used in Example 1 above was used, and a synthetic corrosive liquid prepared by further containing J$0.
Metal corrosion test solutions A6-10 were prepared in the same manner as above. A metal corrosion test was conducted on each of the test liquids in the same manner as in Example 1. The results obtained are shown in Table 3.

Comparative Example 5 Commercially available antifreeze containing phosphoric acid as the main component (hereinafter referred to as D)
, a commercially available antifreeze solution containing nitrous as a main component (hereinafter referred to as 1), and a commercially available antifreeze solution containing amine as a main component (hereinafter referred to as 1).
1) was added to the same synthesis-nutrient solution used in Example 1 at 80% (≠
) A metal corrosion test was conducted on each test solution in the same manner as in Example 1. The results are shown in Table 6. Example 4 Regarding the test solutions A6 to 10 found in Example 6,
An aluminum heat transfer surface corrosion test was conducted in the same manner as in Example 2. The results obtained are shown in Table 6.

Comparative Example 6 An aluminum heat transfer surface corrosion test was conducted in the same manner as in Example 2 for each of the commercially available test solutions F, 1, and ν obtained in Comparative Example 5. The results obtained are shown in Table 6.

When evaluating the performance of anticorrosive agents or antifreeze, one of the major criteria was to satisfy Japanese Industrial Standard nB K-22114 (antifreeze)-1981.
As is clear from the results of the comparative examples shown in Tables 2 and 6, although conventional commercially available products are corrosion inhibitors that pass the JxB standard, they are not suitable for aluminum engines, which have been upgraded in recent years. There is virtually no substance found that inhibits corrosion of the heat transfer surface of aluminum in the cooling system of the internal combustion engine used.6 On the other hand, as is clear from Table 2, the anti-corrosion liquid for aluminum engines of the present invention is It exhibits a sufficient corrosion-preventing effect to satisfy the standards and at the same time suppresses corrosion on the heat transfer surface of aluminum. Also, as is clear from Table 6, in particular, the present invention's 7□ Corrosion-inhibiting liquid for Ruse engines When used in combination with an antifreeze agent such as monotylene glycol, it exhibits a sufficient antifreeze effect as well as anticorrosive effect.
! It can be seen that it is also sufficiently effective in the heat transfer surface corrosion test of /C.

Claims (1)

[Claims] 1. As active ingredients, (1) one or more selected from the group consisting of phosphoric acid, polyphosphoric acid, and salts thereof; 500~! ios
ooOppm. (2) One or more selected from the group consisting of molybdic acid, tungstic acid, vanadate acid, their salts, and molybdenum, tungsten, and vanadium polysaccharides in 50 to 5*0OOppl s and ( 8) A corrosion-inhibiting liquid for aluminum engines containing at least 5 to 500 pPl of one or more selected from the group consisting of benzotriazole, tolyltriazole, and salts thereof. 2. The corrosion-inhibiting liquid according to claim 1, which has a pH in the range of 6.0 to 8.0.