JPH0473476B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water removal agent for fuel oil for diesel engines. More specifically, it relates to a water removal agent that prevents rust from accumulating in fuel supply systems such as diesel engine fuel tanks, fuel oil piping, filters, and injection pumps, and efficiently disperses and dissolves water in fuel oil. be. The water solubility of hydrocarbon oils such as fuel oil for diesel engines is low, ranging from several tens to 100 ppm.
Its saturation solubility increases or decreases with temperature. Diesel gas oil often comes into contact with water during its production, transportation, storage, etc., and generally dissolves water close to its saturated solubility. Even after it is refueled into the fuel tank of a diesel engine, its solubility varies due to temperature changes between day and night, causing water to separate, settle, and accumulate at the bottom of the fuel tank. In addition, the air layer in the fuel tank changes depending on the fuel usage conditions, and especially during humid periods such as the rainy season, the moisture in the air in the fuel oil tank condenses into water droplets due to changes in outside air temperature between day and night, causing the fuel oil to Instead of dissolving, it separates, settles, and accumulates at the bottom of the fuel tank. It is difficult for the water collected in this way to completely dissolve into the fuel oil again.
If moisture is drawn up from the fuel tank through the suction pipe and supplied, it may corrode the fuel supply system, cause the rust to peel off and block filters, or in extreme cases, the injection pump may become damaged. Separated water may flow into the engine and cause engine malfunction. Conventionally, it is well known that in order to prevent such troubles caused by water, a water solubilizing agent for diesel light oil containing isopropyl alcohol or the like as a main component is used. However, conventional water-soluble agents mainly composed of alcohols such as isopropyl alcohol have the following drawbacks in practical use. That is, the first problem is that it lowers the flash point of fuel oil. The flash point of isopropyl alcohol alone is low at 12°C, and even if it is added to diesel light oil, which has a flash point of 65°C, at just 1% by volume, the flash point will be extremely low to about 25°C. Therefore, an explosive mixture will exist in the fuel tank. The fuel tank of a typical diesel engine has
Since the oil level gauge has electrical contacts, there is a drawback that there is a risk of explosion due to sparks. The second problem lies in both the drainage effect and economic efficiency. The water solubilizing performance of a water solubilizer mainly composed of isopropyl alcohol or the like is very small when added at about 1% by volume to light oil, and it is not possible to satisfy both a sufficient water removal effect and economical efficiency. A third problem is that alcohol-based water-soluble agents, such as isopropyl alcohol, do not have corrosion-preventing properties. The fuel system, from the fuel tank to the injection nozzle, includes metal parts made of iron, aluminum alloy, and the like, and these parts corrode when they come into contact with moisture. As described above, conventional alcohol-based water solubilizers have various drawbacks and cannot be put to practical use. Also, as a water solubilizer for fuel oil, (A) carbon number 3 to 6
A mixture containing a monohydric alcohol and/or glycol ether and (B) a nonionic surfactant of polyoxyethylene alkyl ether and/or polyoxyethylene alkyl phenyl ether has been proposed (especially Kaisho 59-8788
issue). However, the above-mentioned method is not necessarily satisfactory. In other words, it is considered to be characterized by containing polyoxyethylene alkyl ether or polyoxyethylene alkyl phenyl ether as a non-ionic surfactant, but a low molecular weight alcohol is used as a mixing solvent. Insofar as they are concerned, they exhibit the same drawbacks as the above-mentioned water-solubilizing agents mainly composed of alcohols. SUMMARY OF THE INVENTION In view of the above-mentioned circumstances of the conventional method, the present invention aims to provide a safe and effective water removal agent for diesel light oil. For the above-mentioned purpose, the present inventor has worked diligently to develop a product that does not lower the flash point of diesel light oil, can exhibit an extremely superior water removal effect than conventional products, and has the effect of preventing metal corrosion. As a result of repeated studies, we found that a specific nonionic surfactant consisting of an ester bond between sorbitan and a fatty acid.
It has been found that materials with an HLB value are not only safe, but also have excellent water removal effects and metal corrosion prevention properties. In other words, the present invention is fundamentally different from conventionally known water solubilizers that dissolve water, and uses the emulsifying effect of a nonionic surfactant with a specific HLB value to dissolve water. The purpose is to remove moisture efficiently and economically by incorporating it into diesel light oil. In practical terms, the product of the present invention is stable in a mixed state, has no danger of ignition or explosion, has excellent metal corrosion prevention performance, and has been completed with new effects that are economically beneficial. It is a water removing agent. The nonionic surfactants referred to in the present invention generally contain several hydroxyl groups (OH-) and ether bonds (-O-) in the molecule, making the hydrophobic groups water-soluble. Moreover, since the active molecule does not contain any ionizable atoms or atomic groups, the aqueous solution is completely ionically unrelated and exhibits surface-active properties. Commonly used and relatively inexpensive nonionic surfactants include (A) surfactants having ester-type bonds made by condensing ethylene oxide with aliphatic higher alcohols, alkylphenols, and fatty acids; Examples include (B) a polymeric surfactant with a polypropylene glycol group as a hydrophobic group and a polyethylene glycol group as a hydrophilic group, and (C) a surfactant formed by an ester bond between sorbitan and various fatty acids. These numerous nonionic surfactants are
The performance of the surfactant can be estimated by the HLB value. In other words, those with an HLB value of 1.5 to 3 are antifoaming agents;
It is said that those with numbers 3 to 7 are highly effective as W/O type emulsifiers, and those with numbers 8 to 18 are highly effective as O/W type emulsifiers. In the present invention, the HLB value refers to HLB (Hydrohile-
Lipophile Balance), as discussed in the Journal of the Society of Cosmetic Chemistry, page 419, December 1948.
In the present invention, nonionic surfactants having both lipophilicity and hydrophilicity and having an HLB value in the range of 3 to 7 are suitable. When the HLB value is 3 or less, the ability of the surfactant to dissolve in the diesel fuel oil is high, but the ability to trap moisture, that is, the emulsification ability, tends to be poor. When the HLB value is 7 or more, the surfactant has a high solubility in water, but on the contrary tends to have poor oil solubility, and is not preferred alone in the present invention. Therefore, in the present invention, the water drainage effect,
In other words, a nonionic surfactant with an HLB value of 3 to 7 is essential in order to maximize the performance of entrapping separated water into oil and emulsifying it. The present inventors used various nonionic surfactants with HLB values in the range of 3 to 7, and as a result of detailed studies on the solubility in diesel light oil and the water emulsification property, that is, the water removal effect, we found that sorbitan and various nonionic surfactants It was discovered that a nonionic surfactant consisting of an ester bond with a fatty acid and with an HLB value in the range of 3 to 7 also has metal corrosion prevention properties and has extremely excellent water removal performance. did. In particular, sorbitan monooleate, sorbitan monostearate, sorbitan monopalmitate, sorbitan sesquioleate, and sorbitan distearate have very good compatibility with diesel light oil, and have a greater water removal effect than the other inventions mentioned above. is outstanding. Although nonionic surfactants having an HLB value of 3 to 7 have been mentioned above, in the present invention, the above surfactants can be used alone or in combination of two or more types. be. That is,
Mix appropriate amounts of two or more types of nonionic surfactants other than those with an HLB value of 3 to 7, and after mixing
It has been found that if the HLB value falls within the range of 3 to 7, it can also be used. For example, sorbitan trioleate (HLB
After homogeneously mixing and stirring 70% by volume of polyoxyethylene (4) sorbitan trioleate (HLB value 1.8) and 30% by volume, the HLB value was measured and found to be 4.6. This product was tested in the same manner as in the Examples shown later, and as a result, it was confirmed that it had an excellent water removal effect. Therefore, the nonionic surfactant that can be used in the present invention is (A) one type, or a mixture of two or more types, which is composed of an ester bond between sorbitan and a fatty acid and has an HLB value in the range of 3 to 7. , (B) A nonionic surfactant consisting of an ester bond between sorbitan and a fatty acid with an HLB value outside the range of 3 to 7.A mixture of two or more types with an HLB value of 3 after mixing.
(C) A mixture of the above (A) and (B) with an HLB value adjusted to a range of 3 to 7, which can be used in either case. The surfactant used in the present invention can be dissolved in a hydrocarbon solvent and/or an oxygen-containing solvent. In that case, sufficient consideration must be given to the selection of a solvent and the amount used within a range that does not affect the flash point and other practical performance of diesel light oil. In the water removal agent for diesel light oil according to the present invention, the amount of surfactant added as an active ingredient to diesel light oil is at least 0.01 part by volume, preferably at least
0.05 volume part is required. If the amount added is 0.01 part by volume or less, it is also related to the water content in the fuel tank, but if there is a lot of water,
It becomes difficult to obtain sufficient water drainage effect. Conversely, the upper limit of the amount added depends on the balance between the water content in the fuel tank and the economic cost of the water removal agent to be added. For example, if a large amount of separated water accidentally enters the fuel tank, the large amount of water can be removed by letting it stand and then draining the tank. The upper limit of the amount added when removing water generated in the tank under normal conditions or water mixed in during the transportation process, etc., will slightly affect the cetane number of diesel light oil if it is dissolved with the above-mentioned solvent. Therefore, it must not cause a decrease in the cetane number. Therefore, when considering the surfactant alone, it is preferably 1.0 part by volume or less per 100 parts by volume of diesel light oil. As mentioned above, the nonionic surfactant of the present invention having an HLB value of 3 to 7 is oil-soluble and has an emulsifying effect to entrain moisture if present. Looking at this phenomenon from the perspective of its working structure, water on the metal surface is replaced by the polar groups of the surfactant, and the polar groups are adsorbed to the metal, forming a protective film that prevents corrosion. On the other hand, water is surrounded by polar groups and becomes emulsified in oil. In this way, surfactants not only have the effect of entrapping water but also have the effect of preventing metal corrosion. In particular, sorbitan-based nonionic surfactants have excellent anti-corrosion properties. Conventional alcohol-based water-dissolving agents, mainly consisting of isopropyl alcohol, do not have this corrosion-preventing performance, and will lead to corrosion or rust unless some measure is taken. As mentioned above, the surfactant according to the present invention has superior corrosion prevention performance compared to alcohol-type surfactants. It is also possible to add an inhibitor, and a synergistic effect can be exerted by using this together. Note that many of the corrosion inhibitors generally used in petroleum products are oil-soluble, such as organic acid-based and amine-based ones. The surfactants to be used according to the invention and the metal corrosion inhibitors described above generally have a viscous liquid form;
When these are mixed into diesel light oil as a water removal agent, it is convenient to use a hydrocarbon oil or an oxygen-containing compound as a solvent in order to improve the handling and compatibility. Examples of the solvent include kerosene and aromatic solvents, but in actual use, it is preferable to use a solvent with a relatively high flash point. These uses are not intended to limit the scope of the invention. When actually using the product of this invention, for example, 40
It is preferable to add and mix 0.05% by volume or more, that is, 20ml or more, with respect to the diesel light oil being filled. Even immediately after addition and mixing, it traps moisture at the bottom of the fuel tank and emulsifies it. Particularly when the diesel engine is a self-propelled type such as an automobile, the product of the present invention is sufficiently stirred with the diesel light oil, and the effect of entrapping moisture is increased. Diesel light oil that has absorbed water passes through the filter paper of the fuel filter, but the water is not separated here and is sent to the injection pump. Since the water is not separated until it is burned, it will not have any negative effect on the metal parts of the fuel system. As mentioned above, it is a nonionic surfactant composed of an ester bond between sorbitan and a fatty acid, and
By using a water removal agent mainly composed of surfactants with an HLB value in the range of 3 to 7, water generated or mixed in the fuel tank can be emulsified, without changing the general properties of diesel light oil. Moisture can be carried out of the system. Furthermore, the metal parts within the fuel system are protected by the polar groups of the surfactant and the corrosion inhibitor, thereby providing long-term corrosion prevention performance. As explained in detail above, the present invention is a nonionic surfactant formed by an ester bond between sorbitan and a fatty acid, and the present invention is a diesel light oil characterized by containing a nonionic surfactant having an HLB value in the range of 3 to 7. Concerns water removal agents, and applies to all fields where water removal agents are used, especially diesel passenger cars, diesel trucks, agricultural tractors with diesel engines, agricultural machinery, construction machinery, and all industrial applications that use diesel light oil as fuel. Can be used for machines. Next, typical examples of diesel light oil according to the present invention and comparative examples with conventional products will be described, but the present invention is not limited thereto. Examples and Comparative Examples (1) Drainage performance evaluation Diesel light oil in a 100ml graduated cylinder with a stopper
Take 100 ml, add 0.5 ml and 2.0 ml of each of the seven types of water removal agents shown in Table 1, shake and mix, add 3 ml of water, shake vigorously, and leave overnight. Table 1 shows the results of measuring the water content of the oil layer by the Karl Fischer method. A similar method was used to test diesel light oil alone, and the water content was 116 ppm. Comparison of each sample was shown with this quantity set as 1.0. These results show that it has a water removal effect that is slightly less than 2 times to over 12 times that of conventional water removal agents whose main ingredients are alcohols.

[Table] (2) Rust prevention evaluation when kerosene is used as a solvent Place a mild steel plate (50 x 25 x 1 mm) at the bottom of a 200 ml beaker, add 100 ml of diesel light oil to a stoppered graduated cylinder, and use Table 2. Add 0.5 ml of each of the 10 types of water removal agents shown below, mix by shaking, then add 0.2 ml of water and 0.5 ml of water.
ml was added, shaken vigorously, poured into a beaker containing a test piece, and allowed to stand at room temperature. The appearance of the test piece was observed for two months, and the weight change of the test piece after two months was measured. The results are shown in Table 2. The same method was used for diesel oil alone, and the results after the test were shown. These results show that the alcohol-type conventional product shows a tendency for red rust to increase as moisture is added, whereas the product of the present invention shows no change in appearance and no change in the weight of the mild steel plate. .

[Table] Note: ○ mark indicates no change.
(3) Rust prevention evaluation when aromatic hydrocarbon oil is used as a solvent Place a light steel plate (50 x 25 x 1 mm) at the bottom of a 200 ml beaker, add 100 ml of diesel light oil to a stoppered measuring cylinder, and 0.5 ml of each of the six types of water removal agents shown in Table 3 were added, and after mixing by shaking, 0.5 ml of water was added and vigorously shaken, and the mixture was poured into a beaker containing a test piece and allowed to stand at room temperature. The appearance of the test piece was observed for 50 days, and the change in weight of the test piece after 50 days was measured. The results are shown in Table 3. The same method was used for diesel light oil alone and aromatic solvents, and the results after the tests were shown. Compared to the conventional alcohol type, the combination of an aromatic solvent with a slightly lower boiling point than kerosene and various rust preventives does not change the appearance or change the weight of the mild steel sheet.

[Table] Note 3: ○ indicates no change
(4) Water drainage performance actual vehicle test In order to evaluate water drainage performance using a method close to actual usage conditions, we conducted a fuel tank for trucks (capacity: 56 cm).
) 13 units were fixed on the loading platform of a truck, and the water removal effect of mixing and stirring during refueling and the water removal effect of vibrations during driving were investigated. Fill each fuel tank with 10 oil as bottom oil and 50 oil with water.
Six sets each of 150 ml and 150 ml were prepared, and the water removal agent according to the present invention and the conventional product were added. Sorbitan monooleate according to the invention 20ml
(Example 8), sorbitan monostearate 20ml
(Example 9), and as comparative examples, 20 ml of polyethylene glycol decyl phenyl ether (Comparative example 4), 200 ml of isopropyl alcohol (Comparative example 6), 20 ml of polypropylene glycol polyethylene glycol ether (Comparative example 7), 20 ml of polyethylene glycol oleyl ether ( Comparative example 8)
35% of diesel oil at a gas station
Immediately after refueling (step 1), the amount in stock is 45
After running for about 1.5 hours (step 2) and after running for about 2 hours with the tank amount reduced to 20% (step 3), light oil was sampled and its water content was measured using the Karl Fischer method. The results are shown in Table 4. As is clear from Table 4, the diesel light oil to which sorbitan monooleate and sorbitan monostearate, which are products of the present invention, have been added, has a water content that significantly increases with the passage of time, approximately 2
After running for several hours, it was found that the water content was approximately 1.5 to 4 times that of polyethylene glycol decyl phenyl ether, polyethylene glycol oleyl ether, and polypropylene glycol polyethylene glycol ether, which were cited as comparative examples. was found to have very good performance.

【table】 The properties of Example 8 are shown in Table 5.

【table】

Claims (1)

[Claims] 1. A nonionic surfactant formed by an ester bond between sorbitan and a fatty acid, whose HLB value is 3.
A water removal agent for diesel light oil, characterized in that it contains a substance in the range of 7 to 7. 2. The water removal agent for diesel light oil according to claim 1, wherein the nonionic surfactant is sorbitan monooleate, sorbitan monostearate, sorbitan monopalmitate, sorbitan sesquioleate, or sorbitan distearate. . 3 2 nonionic surfactants with different HLB values
A water removal agent for diesel light oil that has an HLB value as set forth in claim 1 by mixing two or more types. 4. The water removal agent for diesel light oil according to claims 1 to 3, characterized in that the water removal agent also contains a metal corrosion inhibitor used in general petroleum products. 5. The diesel light oil according to claims 1 to 3, wherein the water removal agent also contains a hydrocarbon oil and/or an oxygen-containing compound as a solvent for a nonionic surfactant. Water removal agent. 6. Claims 1 to 4, characterized in that the water removal agent contains a nonionic surfactant and a hydrocarbon oil and/or an oxygen-containing compound as a solvent for a metal corrosion inhibitor. Water removal agent for the diesel light oil listed.