JPH1192773A - Lubricating additive for gas oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating additive to prevent beforehand problems caused by lowered sulfur content in gas oil. SOLUTION: The following compounds are used as a lubricating additive for gas oil: (1) a 20-30C aliphatic hydroxycarboxylic acid represented by the formula R1(COOH)n (wherein R1 is a 1-29C straight chain or branched alkyl or alkenyl group having one or more hydroxyl groups; and n is 1 or 2) (1,2- hydroxystearic acid or the like), (2) a condensate of an aliphatic hydroxycarboxylic acid (ricinoleic acid dimer or the like), (3) an ester compound of a hydroxycarboxylic acid and an aliphatic alcohol having 1-6 hydroxyl groups (an ester compound of 1,2-hydroxystearic acid), and (4) an ester compound of a hydroxycarboxylic acid condensate and an aliphatic alcohol (an ester compound of ricinoleic acid dimer or the like).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light oil lubricating additive, and more particularly to a light oil lubricating additive for reducing friction and wear generated in a fuel supply system of a diesel engine using low sulfur. It is.

[0002]

2. Description of the Related Art Exhaust gas regulations for diesel vehicles have begun on a global scale. Germany has banned the use of diesel oil containing more than 0.05% by weight of sulfur, and Scandinavia has also introduced ultra-low sulfur diesel oil with a sulfur content of less than 0.002% by weight. It is known that natural sulfur contained in mineral oil exhibits good extreme pressure performance.Therefore, in the field of fuel oil, there is a concern that low sulfur content will cause wear of fuel supply equipment and seizure of engines. . In fact, in Europe, abnormal wear of fuel injection pumps due to Swedish class 1 gas oil (sulfur content 0.001% by weight or less) has been reported.
Immediate action is needed. In Japan as well, the environmental government has set the sulfur content of diesel fuel to 0.1 to 0.2 since October 1997.
It has been determined that the weight percent is restricted to 0.05% by weight or less. Automakers are more aware of the dangers of fuel pumps malfunctioning due to friction and wear caused by low-sulfur diesel fuel, such as the engine being unable to deliver sufficient power due to the timing lag of fuel injection. Is also expected. For the time being, petroleum manufacturers will use additives to reduce gas oil sulfur. As these additives, esters of unsaturated dicarboxylic acid (JP-A-8-199178), esters of carboxylic acid (JP-A-8-505893), and esters of carboxylic acid and glycerin (JP-A-9-30552) JP-A-96 / 18707), esters of carboxylic acids and ethylene copolymers (WO 96/18708), esters of carboxylic acids with polyoxyalkylenes (such as polyethylene glycol) (WO 96/18707), esters and Content with nitrogen compounds (amine salts, amides, etc.) (International Publication WO96 / 187)
No. 06 publication) and the like.

[0003]

As mentioned above, some lubricating additives for low sulfur gas oil have already been developed. However, many of them are manufactured by foreign additive and petroleum manufacturers, and mainly target foreign gas oils. The properties of diesel oil vary from country to country, and it is likely that they will greatly affect the solubility and stability of the additive. We believe that the development of additives should be based on the target gas oil. In Japan, it is expected that the reduction of sulfur in diesel oil will continue. Therefore, it is important to quickly develop a new additive that is more excellent in lubricating effect than the existing additives. The present invention provides a lubricating additive (anti-wear additive) for obviating a problem due to low sulfur content of light oil, that is, a novel light oil lubricating additive having excellent wear resistance, Provided is a novel light oil lubricating additive which is added to light oil (diesel engine fuel) and has excellent wear resistance.

[0004]

Means for Solving the Problems The present inventors have added various compounds to domestic low sulfur gas oil (without additives) and studied the lubricating performance in detail. As a result, hydroxycarboxylic acids and their condensates, and their ester compounds,
It has been found that, at lower concentrations, a superior antiwear effect is exhibited at a lower concentration than other aliphatic carboxylic acids and known carboxylic acid esters. The lubricating additive for gas oil of the first invention is characterized by containing an aliphatic hydroxycarboxylic acid having 2 to 30 carbon atoms represented by the general formula (1). The lubricating additive for gas oil of the second invention is characterized by containing the condensate of the aliphatic hydroxycarboxylic acid shown in the first invention. The lubricating additive for gas oil of the third invention comprises 1 to 6 (1 of them) of the hydroxycarboxylic acid shown in the first invention.
Means one. ) And an aliphatic alcohol having a hydroxyl group. The lubricating additive for gas oil according to the fourth invention comprises 1 to 6 (of which 1 to 6) the hydroxycarboxylic acid condensate shown in the second invention.
Means one. ) And an aliphatic alcohol having a hydroxyl group. The lubricating additive for gas oil of the fifth invention is a dimer of 12-hydroxystearic acid, ricinoleic acid, an ester compound of the 12-hydroxystearic acid and an aliphatic alcohol having one hydroxyl group, and the ricinol It is characterized by containing at least one ester compound of an acid dimer and an aliphatic alcohol having one hydroxyl group. The lubricating additive for gas oil of the sixth invention is characterized in that it is added to low sulfur gas oil having a sulfur content of 0.05% by weight or less.

In the above-mentioned "aliphatic hydroxycarboxylic acid", the number of "COOH" groups is 1-2, and when it is 3 or more, polar groups are dispersed and the number of adsorption points increases, but the molecular chains are strongly aligned. It is not preferable because it becomes difficult to form a suitable adsorption film. "R1" has 1 to 29 carbon atoms;
If it is 30 or more, the solubility of the carboxylic acid in light oil is excessively increased, and the adsorptivity to the metal surface (friction surface) is inhibited, which is not preferable. Further, the number of hydroxyl groups is one or more (for example, 1 to 4 or the like), and usually one or two are used. Specific examples of the hydroxycarboxylic acid include ricinoleic acid (the position where the hydroxyl group is bonded to the 12-position),
α-hydroxypartiminic acid, β-hydroxypartiminic acid, 12-hydroxypartimidic acid, α-hydroxystearic acid, β-hydroxystearic acid, 12-hydroxystearic acid, and the like. Among them, 12-hydroxystearic acid and ricinoleic acid are particularly preferable as shown in the fifth invention. All of these are excellent in performance, particularly the former is excellent in stability of performance against the fluctuation of the added amount, and the latter is preferable in view of economic efficiency. In addition, it is preferable that the position where the hydroxyl group is bonded is 12 or more, and that the hydroxyl group is distant to some extent from the carboxy group.

The "condensate of hydroxycarboxylic acid" described in the second, fourth to sixth inventions is a product obtained by dehydrating and condensing two or more hydroxycarboxylic acids and having a hydroxycarboxylic acid having an ester group therein. Is an acid. The condensate is preferably a dimer or tetramer (particularly a dimer).
It may be a mixture such as a trimer or trimer. The dimer to tetramer is preferable because a multimer of pentamer or more has a wide molecular weight distribution (a multimer having a different degree of condensation other than the desired multimer is produced as a by-product), and purification for obtaining the desired product is performed. This requires complicated steps and costs. Of these, ricinoleic acid dimer is preferred because of excellent performance.

The "aliphatic alcohols" described in the third to sixth inventions have 1 to 9 carbon atoms. If the number exceeds 10, the solubility of the obtained esterified product becomes excessively high, and the adsorbability to the friction surface is increased. Is undesirably reduced. Further, the number of hydroxyl groups is 1 to 6 (preferably 1), and when the number exceeds 6, the solubility of the obtained esterified product in light oil is reduced, which is not preferable. Specific examples of the aliphatic alcohol include methanol, ethanol, butanol, ethylene glycol, propylene glycol, 1.4-butanediol, glycerin and the like. Considering the ease of the esterification reaction with the aliphatic hydroxycarboxylic acid and the stability of dissolving the esterified product in light oil, methanol, ethanol and butanol are preferred. Examples of the ester compound of the present invention include ester compounds of 12-hydroxystearic acid and an aliphatic alcohol having one hydroxyl group, and ester compounds of a dimer of ricinoleic acid and an aliphatic alcohol having one hydroxyl group. (Refer to the fifth invention).

Further, the content of the additive of the present invention in the gas oil composition is 10 to 500 ppm (particularly 30 to 200 PP).
m) is preferable. If this is less than 10 ppm, sufficient abrasion resistance may not be obtained in some cases.
This is because even if the content exceeds 00 ppm, the performance is saturated.
In particular, in the case of 50 to 200 ppm, even if the kind of the additive is changed, stable performance can be obtained, so that it is particularly preferable. Furthermore, the dimer of 12-hydroxystearic acid and ricinoleic acid is 10 to 500 ppm (or 10 to 2 ppm).
00 ppm), especially 30 to 200 ppm. The 12-hydroxystearic acid and 1
Also, an ester compound with an aliphatic alcohol having one hydroxyl group and an ester compound with a dimer of the ricinoleic acid and an aliphatic alcohol having one hydroxyl group are also 50%.
Excellent performance is shown even at 500 ppm, especially 50 to 200 ppm. Further, an additive such as the aliphatic hydroxycarboxylic acid and the esterified product thereof shown in the present invention may be further used in combination with an ethylenic copolymer. This ethylenic copolymer can be a copolymer comprising ethylene and one or more vinyl monomers (eg, vinyl acetate, etc.).

By using the lubricating additive for light oil of the present invention,
Compared to a simple carboxylic acid having no hydroxy group and a simple carboxylic acid ester having no hydroxy group, the abrasion resistance is excellent. The reason is considered as follows. That is, generally, carboxylic acid type oiliness improvers (lubricating additives)
Is said to exert load-bearing capacity and anti-friction effect by orienting its lipophilic group densely and chemically adsorbing it on the metal surface. The hydroxyl group added to the lipophilic group of hydroxycarboxylic acid theoretically hinders the orientation of such an adsorbed film due to steric hindrance. However, practical diesel oil contains many organic substances other than pure hydrocarbons,
It is presumed that since they cause a competitive reaction with the oiliness improver, the phenomenon that only the above-mentioned hydroxyl group has a significant adverse effect did not appear.

[0010] Hydroxycarboxylic acids also have properties as so-called friction polymers. That is, when the frictional state deteriorates for some reason, dehydration condensation occurs between the carboxyl group and the hydroxyl group by a tribochemical reaction on the frictional surface. As a result, the formed low molecular weight polymer prevents a metal-to-metal contact as a stronger lubricating film. Generally, ester compounds are often used as additives for lubricating oils or fuel oils.
This is because the carboxylic acid may cause a corrosive action due to a strong adsorption force. However, corrosion actually occurs when excess (high concentration) carboxylic acid is placed under severe friction conditions, and under relatively mild friction conditions such as a fuel supply system, low concentration Is very unlikely to have a corrosive effect on ordinary steel pump parts.

Each ester compound of the hydroxycarboxylic acid of the third invention or the hydroxycarboxylic acid condensate of the fourth invention is one in which the solubility of hydroxycarboxylic acid in light oil is further improved. Since the ester group has a lower adsorptivity than the carboxyl group, the lubricity is slightly lower than that of the original hydroxycarboxylic acid. However, this hydroxycarboxylic acid ester or condensate ester is clearly superior in lubricity as compared with other simple aliphatic carboxylic acid esters.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples. A composition was prepared by adding the additives shown in Table 2 to the low sulfur gas oil shown in Table 1 in an amount of 0.001 to 0.01% by weight based on the low sulfur gas oil. Each of these compositions was subjected to a reciprocating vibration friction test under the friction conditions shown in Table 3 to examine the effect of preventing wear. The results of the friction test are shown in Table 2, FIG. 1 and FIG.

[0013]

[Table 1]

[0014]

[Table 2] Incidentally, ricinoleic acid (ricinoleic acid) has 18 carbon atoms and 1
It is an unsaturated linear hydroxycarboxylic acid having a hydroxyl group at the 2-position and double bonds at the 9- and 10-positions.

[0015]

[Table 3]

As shown in Table 2 and FIG. 1, the hydroxycarboxylic acids [(A), (C) and (D)] and the ricinoleic acid dimer (B) were prepared from a simple carboxylic acid having no hydroxy group [ (E) stearic acid], and is excellent in abrasion resistance. In particular, any hydroxycarboxylic acid may be used in an amount of 0.1 to less than 0.01% which is usually applied.
At an addition amount of 005%, the abrasion resistance is remarkably superior to that of the simple carboxylic acid [(E)]. Among them, particularly, the ricinoleic acid dimer of (B) and the 12-hydroxystearic acid of (D) are further reduced to 0.003% and 0.1%.
Even with the addition amount of 001%, the abrasion resistance did not decrease so much. Even with the small addition amount of 0.003%, the same abrasion resistance as 0.01% of the simple carboxylic acid (E) was exhibited. Furthermore, the ricinoleic acid dimer (B) and the 12-hydroxystearic acid (D) were added to the IS
It can satisfy the performance of the wear scar diameter of 450 μm or less required by the O standard, and exhibits remarkably excellent economic effect. These additives [(A) to (D)] can be sufficiently expected as additives for further reducing sulfur of gas oil expected in the future.

Further, as shown in Table 2 and FIG. 2, the esters of hydroxycarboxylic acids [(F) and (H)] and the esters of ricinoleic acid dimer (G) are simple carboxylic acids having no hydroxy group. Compared with the ester [(I) ethyl stearate], the abrasion resistance is excellent at the addition amount of 0.01%, and it is remarkably excellent as compared with the case of no addition (J). In particular, ricinoleic acid 2
With the monomeric ester (G) and 12-hydroxystearic acid methyl ester (H), even if the addition amount is 0.005%, it is almost the same as 0.01% and the wear scar diameter required by the ISO standard is 450 μm or less. Can be fulfilled, and exert a great economic effect. These additives [(F) (G) (H)] can be sufficiently expected as additives for further reducing sulfur of light oil expected in the future.

It should be noted that the present invention is not limited to the specific embodiments described above, but may be other examples and modifications in which various modifications are made within the scope of the present invention in accordance with the purpose and application. it can. That is, the additives such as the aliphatic hydroxycarboxylic acid and the esterified product thereof shown in the present invention are further added with a metal corrosion inhibitor (1,3,4-thiadiazolyl-).
2,5-bisdialkyldithiocarbamate, benzotriazole, etc.), antioxidants (2,6-di-tert-
Butyl-4-methylphenol, 2,6-di-tert
Other additives such as -butylphenol and cetane number inhibitor (octyl nitrate, butyl peroxide and the like) can also be added depending on the purpose and use. This does not cause a decrease in lubrication performance.

[0019]

The aliphatic hydroxycarboxylic acid of the first invention, the condensate of the aliphatic hydroxycarboxylic acid of the second invention, the ester compound of the hydroxycarboxylic acid of the third invention, and the ester compound of the fourth invention When the ester compound of the hydroxycarboxylic acid condensate is used as a lubricating additive for light oil, it has excellent abrasion resistance as compared with a simple carboxylic acid having no hydroxyl group and a simple carboxylic acid ester having no hydroxyl group, and has no It is remarkably superior to the case of addition. These additives can be expected as additives for further reducing sulfur of gas oil expected in the future.

The dimer of 12-hydroxystearic acid (D) and ricinoleic acid (B) shown in the fifth invention,
An ester compound of the 12-hydroxystearic acid with an aliphatic alcohol having one hydroxyl group [eg, (H)], and an ester of the dimer of ricinoleic acid with an aliphatic alcohol having one hydroxyl group When at least one of the compounds [for example, (G)] is contained, the amount of 0.001% is usually smaller than 0.01% of the added amount.
Even at 5% and 0.003% addition, the wear resistance hardly decreases, and even at a very small addition amount of 0.005%, the performance of the wear scar diameter 450 μm or less required by the ISO standard is obtained. It can be satisfied, has excellent performance stability, and has excellent economic effects. In particular, the above 12
2-hydroxystearic acid (D) and ricinoleic acid
In the case of the monomer (B), even with a very small addition amount of 0.001%, the required performance of a wear scar diameter of 450 μm or less can be satisfied, the performance stability is extremely excellent, and the economic effect is extremely excellent. Also demonstrate.

Each of the lubricating additives for light oils according to the first to fourth inventions is added to a low sulfur gas oil having a sulfur content of 0.05% by weight or less as shown in the sixth invention. Then
In particular, it is particularly useful because there is no problem of corrosion of steel and the like.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of a wear resistance test of hydroxycarboxylic acid and ricinoleic acid dimer.

FIG. 2 is a graph showing the results of an abrasion resistance test of an ester of hydroxycarboxylic acid and an ester of ricinoleic acid dimer.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tosumi Muto 1580 Tabata, Samukawa-cho, Koza-gun, Kanagawa Prefecture

Claims (6)

[Claims] 1. A compound having 2 to 2 carbon atoms represented by the following general formula (1):
30. A lubricating additive for gas oil, comprising 30 aliphatic hydroxycarboxylic acids. R1 (COOH) n (1) wherein R1 is an alkyl or alkenyl group having at least one hydroxyl group and having a linear or branched structure having 1 to 29 carbon atoms. Or 2.) 2. A lubricating additive for light oil, comprising the condensate of the aliphatic hydroxycarboxylic acid shown in claim 1. 3. A lubricating additive for gas oil, comprising an ester compound of the hydroxycarboxylic acid shown in claim 1 and an aliphatic alcohol having 1 to 6 hydroxyl groups. 4. A lubricating additive for light oil, comprising an ester compound of the hydroxycarboxylic acid condensate shown in claim 2 and an aliphatic alcohol having 1 to 6 hydroxyl groups. 5. A dimer of 12-hydroxystearic acid and ricinoleic acid, an ester compound of the 12-hydroxystearic acid and an aliphatic alcohol having one hydroxyl group, and a dimer of ricinoleic acid and 1 A lubricating additive for light oil, comprising at least one ester compound with an aliphatic alcohol having a hydroxyl group. 6. The lubricating additive for gas oil according to claim 1, which is added to a low sulfur gas oil having a sulfur content of 0.05% by weight or less.