JP6364149B1 - Automotive coolant base material, coolant additive, coolant and coolant testing equipment - Google Patents

Abstract

An object of the present invention is to provide an automotive coolant having excellent cooling performance, improved rust prevention performance against metals, and having a long life. A vehicle coolant base material comprising water of less than 50% and the balance of ethylene glycol and a small amount of diethylene glycol, which contains monovalent carboxylic acid and divalent carboxylic acid as additives, molybdic acid Automobile coolant that contains soda, fluorosurfactant, phosphoric acid organic polymer compound, and a transparent pipe between the flow meter and the heating tank. An automotive coolant testing apparatus characterized by the above. [Selection] Figure 1

Description

  TECHNICAL FIELD The present invention generally relates to a coolant for cooling an automobile engine, a base material for the coolant, and an additive for the coolant, and in particular, a coolant excellent in rust prevention, a base material for the coolant, and the coolant. Relating to additives.

  Now that the drastic changes in the global environment are becoming a serious problem, earthlings must seriously work on protecting the global environment. However, it should be explored to maintain the living environment as much as possible. Under such circumstances, fuel cells are ideal for automobiles, but for the time being, in addition to hybrid cars, performance improvement is continuously required for automobiles using conventional engines.

  Such an improvement in engine performance is directly linked to an increased burden on the cooling system. Thus, it is desired to improve the performance of the coolant used in the cooling system.

  As such a coolant, Patent Document 1 discloses a technical concept of a coolant containing an aliphatic polyvalent carboxylic acid containing a water-soluble organic medium as a main component and containing four or more carboxylic acid groups and / or a salt thereof. ing. According to this, the radiator coolant which has a high exchange life with respect to the radiator made from an aluminum alloy can be provided.

JP 2003-342559 A

  However, the coolant disclosed in Patent Document 1 has a problem that it is difficult to satisfy demands required for various coolants.

  That is, as the cooling system becomes highly functional, the necessity for uniformly cooling all parts of the cooling system increases. In addition, the higher the performance and lighter the engine, the higher the frequency vibrations of each part of the engine, and countermeasures are required.

  The components used in the engine cooling system are iron and its alloys, copper, brass, aluminum, aluminum alloys, synthetic rubber, and various plastics. Static electricity is generated by high-frequency vibration generated by engine vibration. . The generated static electricity has a different potential depending on each part.

  That is, the occurrence of a potential difference in the cooling system immediately leads to the occurrence of galvanic corrosion, which is a severe condition for rust prevention. In particular, in iron, when high frequency vibration is increased, sufficient rust prevention measures must be taken into account.

  Therefore, an object of the present invention is to provide an automotive coolant that has excellent cooling performance, improves rust prevention performance against metals, and has a long life.

  1st this invention is a base material of the coolant for motor vehicles for solving the said subject, Comprising: Water shall be less than 50%, and the remainder is between 15: 1 and 53: 1 with ethylene glycol and diethylene glycol. It is characterized by the ratio.

  Here, it is the ratio before the additive is added, and is different from the ratio in the automotive coolant after the additive is added.

  According to this, the antifreezing effect by glycols can fully be exhibited, and furthermore, by suppressing the ratio of water, evaporation of water alone can be suppressed, and metal oxidation can be prevented.

  The second aspect of the present invention is an additive for an automotive coolant for solving the above-described problems, and includes a monovalent carboxylic acid and a divalent carboxylic acid.

  This is preferably added to the coolant base material of the first invention, but is not limited thereto, and may be added to a coolant base material that is generally used. The same applies to the following additives.

  The ratio of monovalent carboxylic acid to divalent carboxylic acid is preferably about 1: 1, but is not limited thereto.

  According to this, these carboxylic acids are generally used for preventing corrosion of metals, and when added to the coolant, a rust prevention effect can be obtained.

  A third aspect of the present invention is an additive for an automotive coolant for solving the above-described problems, and includes sodium molybdate.

  According to this, by adding an appropriate amount of sodium molybdate to the place where the metal is used in combination, the occurrence of abnormal metal corrosion is almost completely eliminated.

  The fourth aspect of the present invention is an additive for an automotive coolant for solving the above-described problems, and includes a fluorine-based surfactant.

  According to this, the polymer fluorosurfactant has a great effect of significantly lowering the surface tension at the liquid-solid interface. A high-performance engine is like a nest of high-frequency vibrations, and numerous vacuums are generated on the cooling surface. As a method for avoiding the damage due to this phenomenon to the utmost limit, the surface tension of the liquid is lowered by a fluorine-based polymer surfactant to greatly suppress the chance of metal oxidation.

A fifth aspect of the present invention is an additive for an automotive coolant for solving the above-described problems, and includes an organic phosphate compound having a large molecular weight .

According to this, by adding a phosphoric acid organic compound having a high molecular weight, such as an organic phosphate ester , that has a low phosphoric acid content, iron reacted with phosphoric acid is moved to the side of the phosphoric acid organic compound having a large molecular weight. Because it is attached, iron phosphate (electrically non-conductive) is not generated on the metal surface side. This produces an effect of preventing metal corrosion by preventing potential difference from occurring.

  The sixth aspect of the present invention is an additive for an automobile coolant for solving the above-described problems, and includes an antifoaming agent.

  In particular, those having an action of eliminating bubbles generated at 80 ° C. or higher are desirable.

  A seventh aspect of the present invention is an automotive coolant for solving the above-described problems, and the coolant additive according to the second to sixth aspects of the present invention is added to the coolant base material of the first aspect. It is characterized by adding an agent.

  According to this, the effects of the coolant base material and coolant additive which have been described so far can be exhibited together.

  An eighth aspect of the present invention is an automotive coolant according to the seventh aspect of the present invention for solving the above-mentioned problems, and is characterized by a fixed prescription without dilution.

  This is because the conventional antifreeze standard specifies the properties of the stock solution. In actual use, the stock solution is diluted with water. However, the recent severe environmental problems and severe engine operating requirements Then, since the required property with respect to coolant (cooling liquid) became severe and the coolant containing the fixed water was desirable, it was set as the fixed prescription which is not diluted.

  However, the stock solution may be diluted so that the final ratio is obtained as long as the dilution is appropriately managed.

  The ninth aspect of the present invention is the automotive coolant testing apparatus according to the seventh or eighth aspect of the present invention for solving the above-mentioned problems, and has a transparent pipe between the flow meter and the heating tank. It is characterized by.

  If it does in this way, in the case of the test of the coolant for motor vehicles, the magnitude | size of a bubble can be confirmed visually and evaluation of coolant will become easy.

  According to the automotive coolant substrate, automotive coolant additive, or automotive coolant of the present invention, it is possible to provide a long-life automotive coolant that has excellent cooling performance, improves rust prevention performance against metals.

It is a block diagram of the coolant test apparatus of one Embodiment of this invention.

  The most preferred blend of automotive coolant of the present invention is as follows.

As a condition of automotive coolant, weight percent
Standard Optimal range Suitable range Water 45 42-47 40-49
Ethylene glycol 49 47-51 45-53
Diethylene glycol 2 1.5-2.5 1-3
Various additives 4 3.5-4.5 3-5
In this state, in the standard configuration of the coolant base material excluding the additive, water is 46.9% and ethylene glycol: diethylene glycol is 24.5: 1.

Next, the ratio of various additives is defined as 100 for the total additive.
Standard Optimum range Suitable range Monovalent synthetic carboxylic acid 27 22-32 18-36
Divalent synthetic carboxylic acid 27 22-32 18-36
Caustic soda 20 16-24 12-28
Anticorrosive for copper 10 6-14 2-18
Mixed antioxidant 10 6-14 2-18
Sodium molybdate 2 1.4-2.6 1.0-3.0
High molecular weight phosphoric acid organic compound 2 1.4-2.6 1.0-3.0
Fluorosurfactant 1 0.6-1.4 0.2-1.6
Antifoam 1 0.6-1.4 0.2-1.6
Is desirable.

  Here, the antifreeze standard specifies the properties of the undiluted solution, and in actual use, it is specified that the antifreeze solution is diluted with water to a concentration of 30% to 55%. With the requirements of the engine, the requirement for coolant has become stricter and the need for coolant with fixed water has increased.

  In other words, in recent coolants, especially for diesel engines, the anti-freezing effect is only part of the effect expected of the coolant, maintaining the optimum temperature as an engine cooling system, and the engine cooling surface that can be said to be the nest of high-frequency vibrations Must be maintained and the performance to maximize the cooling effect must be maintained.

  Accordingly, a coolant having a fixed blending ratio containing water that is not diluted is desirable. Here, it is known that the water content is 47.4% (that is, less than 50%), and it is known that the freezing point (freezing point) of ethylene glycol is significantly lowered by adding water. In addition to suppressing the ratio of water, the opportunity to evaporate only water and become water vapor is suppressed. Thereby, the opportunity to oxidize the metal surface is greatly suppressed. In particular, in order to suppress the evaporation of water alone, it is desirable that the water ratio clearly falls below 50%.

Diethylene glycol can improve the solubility with respect to ethylene glycol of water by adding a small amount. As a result, the freezing point of the coolant can be lowered.

Next, a specific manufacturing process will be described.
Step A: A monovalent synthetic carboxylic acid is dissolved with a small amount of ethylene glycol.
Step B: Dissolve sodium molybdate transparently with a small amount of water Step C: Dissolve the antifoaming agent with a small amount of butyl triglycol ether.
Step D: A phosphoric acid organic compound having a large molecular weight is dissolved in ethylene glycol or water.
Step E: Dissolve the fluorosurfactant with ethylene glycol or water.
Step F: The mixed antioxidant is dissolved with ethylene glycol or water.
Process G: Caustic soda is put into the remaining water, and after a predetermined time has passed, a copper anticorrosive agent is added.
Step H: The products of Step A to Step F are added to the product of Step G.
Step I: Charge the remaining ethylene glycol with divalent synthetic carboxylic acid and diethylene glycol.
Step J: The product of Step H is gradually mixed into the product of Step I.

  Like so-called water-in oil, in which the ratio of glycols (ethylene glycol + diethylene glycol) is "glycol rich", which is greater than that of water, and by mixing in such a process, water is taken into the glycols. Can be realized.

Next, the characteristics and effects of each additive will be described.
The monovalent synthetic carboxylic acid is preferably isonanoic acid (C ₉ H ₁₈ O ₂ ) (trade name Kyowanoic-N), but is not limited thereto. The divalent synthetic carboxylic acid is
Dodecanoic acid C ₁₂ H ₂₂ O ₄ or HOOC (CH ₂ ) ₁₀ COOH or sebacic acid C ₁₀ H ₁₈ O ₄ or HOOC (CH ₂ ) ₈ COOH
Therefore, it is preferable to use dodecanedioic acid and sebacic acid in approximately equal amounts, and the side effects disappear. This is because sebacic acid has different isomers and may work differently, so sebacic acid alone may not achieve the desired purpose, but it is preferable to add dodecanedioic acid, but it is not limited to this. Not what you want.

  Synthetic carboxylic acids are generally widely used as a general rust preventive agent for metals, and an antirust effect can be obtained by adding them to a coolant base material. However, considering the use conditions of the engine coolant, there is a risk of causing metal corrosion. In particular, since the frequency of reaction with copper ions is high, it is desirable not to use more than a certain amount. The combination of monovalent and divalent synthetic carboxylic acids in equal amounts was adopted from the analysis of experimental results.

  Regarding copper anticorrosives, benzotriazole and tolyltriazole are widely used as copper anticorrosives. However, when experiments are repeated under the conditions of engine coolant use, in the case of benzotriazole, depending on the conditions, On the other hand, an event in which aggression is intense is confirmed.

  In that case, in the instrumental analysis, a reaction indicating the presence of alkanolamine may appear, and such a phenomenon is unlikely to occur when only tolyltriazole is used. From the above results, only tolyltriazole was adopted as a rust preventive for copper.

  For the mixed antioxidant, butylated hydroxytoluene (BHT) is preferred, but is not limited thereto. As the operating condition of the engine coolant, the temperature on the inner surface of the cooling system is very high and the flow rate of the coolant is fast.

  Antioxidants are self-sacrificing types, and there are concerns about side effects the higher the temperature is. Since the liquid temperature is 105 ° C. or less even in the current mainstream pressure type, BHT (butylated hydroxytoluene) is considered as the main component.

  If the antioxidant is added more than necessary, there is a great concern that the antioxidant will decompose more than necessary and cause harm to the main body. Therefore, since an antioxidant cannot be added in a certain amount or more at a time, it is necessary to add it periodically.

  When sodium molybdate is added to the place where metal is used in combination, the occurrence of abnormal metal corrosion is almost eliminated.

  Here, using an appropriate amount of sodium molybdate has the effect of protecting the surface of iron and aluminum, but since the range of the appropriate amount is narrow, it cannot be specified when diluting with a stock solution type. It is difficult to use, but it can be easily used for fixed prescription types that do not require dilution.

Although sodium molybdate has been pointed out to cause environmental pollution, if it is a long-life coolant, it will not cause environmental problems by being careful during disposal.

  As for the caustic soda, the inorganic alkali generally includes caustic soda and caustic potash, but caustic soda is used. Regarding caustic potash, there are many cases in which abnormal values occur in practical experiments, and the cause analysis cannot be identified in many cases. On the other hand, in general, caustic potash is said to have a lower surface tension than caustic soda when there is little water. However, in this coolant, there is no problem with caustic soda because there is enough water.

  The purpose of adding caustic soda is to neutralize since most of the additives described so far are weakly acidic.

  As the fluorosurfactant, Surflon (registered trademark, AGC Seimi Chemical Co., Ltd.) is suitable, but is not limited thereto. The fluorine-based surfactant has a great effect of significantly reducing the surface tension at the liquid-solid interface.

  In recent years, high-performance engines are in a state of high-frequency vibration, and an infinite number of vacuums are generated on the cooling surface. As a method of avoiding the damage due to this phenomenon to the utmost, the surface tension of the liquid is lowered by the fluorine-based polymer surfactant and the concentration of water contained in the coolant base material is suppressed to less than 50%. By selecting only substances that have a high affinity with water, the opportunity to evaporate only water and become water vapor is minimized. This measure greatly reduces the chance of metal oxidation.

For phosphoric acid organic compounds having a large molecular weight , organic phosphate esters such as Chelex TD (triisodecyl phosphite) and Chelex OL (trioleyl phosphite) from SC Organic Chemical Co., Ltd. are suitable, but are not limited thereto. It is not something. The mass of phosphoric acid in the phosphoric acid organic compound having a large molecular weight is preferably 1/10 or less, more preferably 1/20 or less.

  Heretofore, iron rust prevention in coolant has been dealt with by forming a thin film of iron phosphate uniformly on the surface of iron metal, but it is extremely difficult to form a thin film of iron phosphate uniformly. It was difficult and often caused a potential difference.

In the present invention, by using a phosphoric acid organic compound having a large molecular weight and containing a small amount of phosphoric acid, iron reacted with phosphoric acid is bound to the phosphoric acid organic compound side having a large molecular weight instead of the metal surface side. I made it.

  In practical experiments, there was no trace of iron phosphate on the metal surface, and very slight precipitation was observed on the liquid side, but there was no effect on the performance of the coolant.

  The antifoaming agent is preferably one that can eliminate the foam generated at 80 ° C. or higher, and Plurnik L-61 (trade name) is preferable, but is not limited thereto.

  Although not included in the composition described above, a small amount of sodium nitrate may be added as an additive. The addition of sodium nitrate is effective for stably protecting aluminum and aluminum alloys.

  There are various types of rust prevention of aluminum, but there are many difficult conditions in the case where the film formation has a large potential difference from aluminum, whether it is anodized or nitridized, and the fluid contacts the cooling system etc. The method of adding a small amount of sodium nitrate is the most reliable in practical experiments.

  Special considerations in the present invention are based on the premise that as a method of extending the service life, a method of forming a rust-preventive coating on the metal on the inner surface of the cooling system is not used, and a contact is made as close as possible to the interface to avoid oxygen contact Devised a prescription.

However, in reality, it is impossible to reduce the oxygen contact to zero, and iron is bound to a small amount of phosphoric acid with a large molecular weight on the premise of the production of a very small amount of iron ions. A method of adding a phosphoric acid organic compound (surfactant) and collecting it on the coolant side was adopted.

  When formulating from this point of view, there are additives that must be added regularly (eg every 3 years or every 5 years) during use. Antioxidants are self-sacrificing type agents, and the amount that can be added at one time is small, and if the amount added is large, harmful effects will also appear. Therefore, the amount added at one time should be as small as possible. preferable.

  Carboxylic acid is considered to be durable for about 10 years in the amount originally prescribed.

  Copper rust preventives (tolyltriazole, etc.) are also highly consumed additives due to their ability to form complexes with other copper substances. Therefore, it is an additive that needs to be periodically added.

Sodium molybdate and organic phosphoric acid compound (surfactant) with large molecular weight do not need to be replenished for 4 to 5 years. The method is preferred.

<Experimental result>
Fluorine-based surfactants are formulated because the engine cooling inner surface inevitably contains some air, so minimizing the air particles makes the air in direct contact with the cooling surface. You can avoid things. This can increase the cooling effect.

  More specifically, it takes away latent heat when the liquid becomes a gas. The gas in the liquid will be in a bubble state, and the more bubbles there are, the more it will collapse, so it will take away a lot of its heat. In order to make a lot of bubbles generated in the coolant, it is preferable to add a fluorinated surfactant.

  Furthermore, the structure of the current radiator is a pressurization type around 1.5 atm, and the pressure is adjusted by a valve at the reserve tank. The temperature of the engine combustion chamber is high, and in the coolant in contact with the engine combustion chamber, gas is generated in the liquid due to the heat of the engine. As described above, it is preferable that the bubble particles generated in the cooling liquid be small, and therefore it is preferable to add a fluorosurfactant.

  Actually, it was decided to verify the effect of the coolant of the present invention by remodeling the circulating corrosion test apparatus in the current antifreeze standard (JIS K2234).

  FIG. 1 shows a coolant test apparatus 1 according to the present invention, which is an improved version of the apparatus shown in JIS.

  Although the details of this test apparatus 1 are based on JIS, the coolant circulates through the radiator 12, the water pump 13, and the flow meter 14 from the heating tank 11 in which an assembly test piece (not shown) is incorporated. Between the total 14 and the heating tank 11, a tempered glass pipe 15. And / or a pipe 16 made of heat-resistant glass is installed. Furthermore, these pipes are made transparent so that the inside can be observed. The transparent member is not limited to glass.

  When a test liquid (equivalent to coolant) is flowed under various conditions with such an apparatus and the temperature and flow rate are changed and observed, the liquid formulated with the fluorosurfactant has a smaller bubble diameter. Coloring becomes darker and the temperature of the thermometer attached to the testing machine decreases. In this test, when the liquid is circulated, bubbles are always observed in the liquid.

  As a specific test method, a motor (not shown) that circulates the test liquid is equipped with a transmission (not shown), and after operating for 55 minutes at 500 rpm for 1 hour within the test time of 8 hours per day, It is preferable to operate the transmission for 5 minutes to make 1,000 rotations, and after 5 minutes, return to 500 rotations, and repeat this for 8 hours. It is possible to change the operating condition as a future possibility.

  The focus was on fluorine-based surfactants, when other surfactants were formulated, there were many variations in the results of repeated tests, and there was a problem with heat resistance, and the effective concentration was fluorine-based. This is because there is a case where a phenomenon that is considered to be a side effect may occur anew because it is 10 times or more that when a surfactant is used.

  Furthermore, in the metal corrosion test, it is considered that the influence of the test in which the test is repeated for 90 hours to 120 days after heating for 8 hours and 16 hours is more realistic than the standard test (continuous heating test).

  In a current internal combustion engine, forming a rust-preventive coating on the engine inner surface in a state where static electricity is generated results in a galvanic corrosion that feels like creating a potential difference department store on the engine inner surface.

For iron, a phosphate organic compound with a large molecular weight is prescribed for the purpose of covering it with a carboxylate and catching it to the liquid side in the unlikely event that iron ions are generated.

  As an evaluation method of the coolant (coolant) prescribed in accordance with this, various ideas were considered and a laboratory method was tried. As a result, the following conclusion was obtained.

  1) In the test method of the official standard such as JIS standard, the continuous heating method and the continuous air blowing method are adopted as the result promotion method, and the test solution has a volume of corrosive liquid specified by the sample. The liquid diluted to 30% in the ratio is to be used.

  This time, it is a test of the liquid that is used as it is without being diluted, and the structure of the current radiator is a type in which all the radiators are pressurized types and the air is shut off. Decided to delete.

  As a test method, the method of continuous heating is adopted in the JIS standard, but this is not possible in actual use. This time, it is repeatedly heated for 8 hours and left for 16 hours. In the conventional JIS standard, LLC ( Long Life Coolant) is 720 hours, but this time, a test was conducted with a test period of 2 months, 3 months, 4 months, and 5 months, and compared with the test method of JIS method .

  As a result, it was judged that there was no significant difference in the results after 3 months. However, although it is not possible to prove whether this test method covers all formulations, stable results were obtained with a formulation that approximated this formulation.

2) The point of view that this prescription has an advantage over the conventional prescription is that it is a rust prevention method against iron, as a characteristic of the current engine, and is a high-frequency vibration nest that is very prone to static electricity. Since it has the properties that can be said, rust prevention by making a film is not problematic if the potential difference is electrochemically the same as that of the metal of the fabric, but it is not possible in reality.

  In particular, if iron does not satisfy the conditions, it will become a nest of galvanic corrosion, resulting in significant damage and the engine being unable to be repaired.

  In addition, although the Example demonstrated so far is a mixing | blending ratio used as the reference | standard of a coolant base material and a coolant additive, it is not limited to this ratio, respectively, If it is an optimal range, respectively, it will have a substantially equivalent effect. If it is played and it is in a suitable range, there will be a certain effect.

  Moreover, the kind of additive may be decreased or increased, and in that case, the blending ratio may naturally vary.

DESCRIPTION OF SYMBOLS 1 Coolant test apparatus 11 Heating tank 12 Radiator 13 Water pump 14 Flow meter 15 Tempered glass pipe 16 Heat-resistant glass pipe 17 Motor

Claims (7)

42-47% by weight of water,
Ethylene glycol 47-51% by weight,
Diethylene glycol 1.5-2.0% by weight,
An automotive coolant comprising 3.5 to 4.5% by weight of various additives,
For the total amount of the various additives,
A motor vehicle characterized in that it is a fixed prescription without dilution, comprising 1.4 to 2.6% by weight of a compound which is an organic compound of phosphoric acid and the mass of phosphoric acid in the compound is 1/10 or less. For coolant. 42-47% by weight of water,
Ethylene glycol 47-51% by weight,
Diethylene glycol 1.5-2.0% by weight,
An automotive coolant comprising 3.5 to 4.5% by weight of various additives,
For the total amount of the various additives,
A coolant for automobiles characterized by being a fixed formulation containing 1.4 to 2.6% by weight of an organic phosphate ester and not diluted. Furthermore, the monovalent | monohydric synthetic carboxylic acid 22-32 weight% and the bivalent synthetic | combination carboxylic acid 22-32 weight% are included with respect to the total amount of the said various additives, The Claim 1 or Claim 2 characterized by the above-mentioned. Antifreeze for automobiles. The automotive coolant according to claim 1 or 2, further comprising 0.6 to 1.4% by weight of a fluorosurfactant based on the total amount of the various additives. Furthermore, the automotive coolant of Claim 1 or Claim 2 containing 1.4-2.6 weight% of sodium molybdate with respect to the total amount of the said various additives. Furthermore, 0.6 to 1.4 weight% of antifoamers which can eliminate the foam | bubble which generate | occur | produces at 80 degreeC or more with respect to the total amount of the said various additives are included. The coolant for automobiles described in 1. The automotive coolant test apparatus according to any one of claims 1 to 6 , further comprising a transparent pipe between the flow meter and the heating tank. apparatus.

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