JP3292549B2 - Flame retardant hydraulic oil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic lubricating oil having a high flash point, a low pour point, and excellent thermal oxidative stability and lubricity. Particularly, there is a risk of fire such as a rolling mill and a die casting machine. The present invention relates to a flame-retardant hydraulic oil based on synthetic oil, which is suitable for a part.

[0002]

2. Description of the Related Art The properties required of a flame-retardant hydraulic fluid include good fluidity and temperature-viscosity characteristics in terms of pressure and power transmission, good high-temperature oxidation stability in terms of long life, and lubricity. Is high, and the flash point is high because it is used in places where there is a risk of fire. From such a point, flame-retardant hydraulic oils based on synthetic oils have been used instead of mineral oils. Examples of the synthetic hydraulic oil include a water-glycol type, a phosphate ester type, and a fatty acid ester type.

The water-glycol type has problems in stability, lubricity, etc., and the phosphate ester type has excellent fire resistance and abrasion resistance, but has poor temperature-viscosity characteristics and has a problem in hydrolytic stability. is there. On the other hand, fatty acid esters are excellent in temperature-viscosity characteristics, fluidity, lubricity and the like, and have well-balanced performance.

At present, an oleic acid ester of neopentyl polyol disclosed in Japanese Patent Application Laid-Open No. Sho 53-136170 is one of the fatty acid ester compounds widely used. This ester has an unsaturated bond in the molecule. Since it has many, there is a problem in thermal oxidation stability. JP-A-63-125598 discloses a method for improving the thermal oxidation stability of oleic acid ester of neopentyl polyol, but it cannot be said to be an essential solution.

In order to solve this problem, it is conceivable to use a fatty acid having no unsaturated bond instead of oleic acid. However, when a long-chain saturated carboxylic acid such as stearic acid is used instead of oleic acid, The ester has a high melting point. On the other hand, in order to improve the fluidity, there is a method of forming an ester of a short-chain saturated carboxylic acid such as heptanoic acid or octanoic acid or an ester of a long-chain saturated branched carboxylic acid such as 2-heptylundecanoic acid or methylheptadecanoic acid. The former ester has a lower flash point, and the latter ester has a lower viscosity index.

[0006] As a method of having a high viscosity index while keeping the pour point low and increasing the flash point, Japanese Patent Application Laid-Open No. 2-2147 discloses a method.
No. 95, as described in JP-A-3-21697, polybasic acids such as adipic acid were introduced,
Complex esters with a higher molecular weight have also been developed, but have problems with lubricity.

[0007]

As described above,
The fatty acid ester-based hydraulic oil in the prior art is
Although it has favorable properties such as temperature-viscosity characteristics, pour point, and high flash point, it does not impair those properties and does not satisfy both thermal oxidation stability and lubricity.

Accordingly, the main object of the present invention is to provide a fatty acid ester-based flame-retardant hydraulic oil having temperature-viscosity characteristics, pour point, high flash point, excellent thermal oxidation stability and excellent lubricity. To provide.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the above object, and as a result, have precisely controlled the carbon number distribution and the branched component of the monocarboxylic acid component constituting the complex ester. By doing so, it is possible to obtain a fatty acid ester having excellent temperature-viscosity characteristics, pour point, high flash point, excellent thermal oxidation stability, excellent lubricity, and useful as a flame-retardant hydraulic oil. And completed the present invention.

That is, the present invention relates to a) a) 10 to 50% by weight of all carboxylic acid components.
The following saturated dicarboxylic acids having 5 to 14 carbon atoms or derivatives thereof; b) The amount of the linear monocarboxylic acid component having 16 to 18 carbon atoms is not less than 1.8 equivalent% and not more than 10 equivalent% based on all carboxylic acid components. 5 to 18 carbon atoms, wherein the straight-chain unsaturated monocarboxylic acid component having 18 carbon atoms is contained in an amount of 0.2 equivalent% or more and 5 equivalent% or less based on all carboxylic acid components.
C) 50 equivalent% or less of the total carboxylic acid component, a monocarboxylic acid having a branch at the α-position and 5 to 18 carbon atoms or a derivative thereof, and d) a total alcohol component And an iodine value (Img / 100g) of 10 or less, a flash point of 280 ° C or more and a pour point of -20 ° C or less, which was synthesized from a neopentyl polyol containing 70 equivalent% or more of trimethylolpropane. An object of the present invention is to provide a flame-retardant hydraulic oil characterized by containing a complex ester.

The complex ester used in the present invention uses neopentyl polyol containing trimethylolpropane as a main component as an alcohol component, and a fatty acid or a derivative thereof having the above-mentioned specific composition as an acid component. Obtained by Here, as the acid derivative, for example, a lower alcohol ester such as an acid anhydride, a methyl ester and an ethyl ester is suitably used. Hereinafter, these are simply referred to as “acids” for simplicity, but in the present invention, they mean “acids or acid derivatives”.

In the present invention, the "component" in the expressions such as "acid component" and "alcohol component" is used to describe the structure of the residue portion of the ester relating to the flame-retardant hydraulic oil.

The role of the saturated dicarboxylic acid component of component a) in the present invention is to crosslink alcohols. The average molecular weight is controlled by its proportion in the total carboxylic acid component, whereby the viscosity and the flash point are adjusted. Contributing to the rise.
The amount of these saturated dicarboxylic acids used is determined by the desired viscosity, and this amount also affects the flash point. The base oil for flame-retardant hydraulic oil has a viscosity of 20 cSt at 40 ° C.
To 150 cSt, it is preferable that the content of the saturated dicarboxylic acid component is in the range of 10 to 50 equivalent% based on the total carboxylic acid component. That is, if less than 10 equivalent%, the viscosity is too low,
An ester having an appropriate viscosity cannot be obtained, and a flash point cannot be increased. On the other hand, when the content is more than 50 equivalent%, the viscosity is too high, so that an ester having an appropriate viscosity cannot be easily obtained.

The saturated dicarboxylic acid used in the present invention for the above purpose must have 5 to 14 carbon atoms, preferably 5 to 10, more preferably 5 to 8. If the number of carbon atoms is less than 5, the thermal stability of the ester will be poor.
If the number of carbon atoms exceeds 14, the molecular weight distribution of the produced ester is widened, so that the viscosity becomes too high. If the proportion of the dicarboxylic acid is reduced to avoid this and the viscosity is adjusted to an appropriate value, the proportion of the low molecular weight ester becomes too large, and the flash point is lowered.

The saturated dicarboxylic acid having 5 to 14 carbon atoms used in the present invention includes, for example, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10 -Decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,
12-dodecanedicarboxylic acid, dimethylmalonic acid, 2,
2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid,
3,3-dimethylglutaric acid, trimethyladipic acid,
2,2-dimethyladipic acid and the like. From the viewpoint of viscosity index, straight-chain is more preferable than branching. Above all, adipic acid is particularly preferable in consideration of the balance among viscosity, pour point and flash point.

The linear monocarboxylic acid of the component (b) in the present invention has 5 to 18 carbon atoms. If the number of carbon atoms is less than 5, the obtained ester has a low flash point and has more than 18 carbon atoms. And its pour point increases. Further, among these linear monocarboxylic acids, it is necessary to use a linear monocarboxylic acid having 16 to 18 carbon atoms in an amount of 1.8 equivalent% or more and 10 equivalent% or less based on all carboxylic acid components. It is from 1.8 equivalent% to 8 equivalent%, more preferably from 1.8 equivalent% to 5 equivalent%. This carbon number 1
When the amount of the linear monocarboxylic acid of 6 to 18 is less than 1.8 equivalent%, the obtained ester has poor lubricity, and when it is more than 10 equivalent%, the pour point becomes poor.

Furthermore, in order to improve lubricity, it is desirable to add a linear unsaturated monocarboxylic acid as a part of the component (b). Among the linear unsaturated monocarboxylic acids, those having 14 to 18 carbon atoms are preferable, and those having 18 carbon atoms are particularly preferable. The content of the linear unsaturated monocarboxylic acid is preferably from 0.2 to 5 equivalent%, more preferably from 0.2 to 3 equivalent%, based on all carboxylic acid components.
It is as follows. If the content of this linear unsaturated monocarboxylic acid is less than 0.2 equivalent%, the effect of its addition cannot be obtained, and if it is more than 5 equivalent%, the thermal oxidation stability of the obtained ester tends to be reduced.

The straight-chain monocarboxylic acids having 5 to 18 carbon atoms used in the present invention include straight-chain saturated monocarboxylic acids and straight-chain unsaturated monocarboxylic acids. Folic acid, caproic acid, enanthic acid,
Caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid and the like, and as the linear unsaturated monocarboxylic acid,
2-pentenoic acid, 4-pentenoic acid, 2-hexenoic acid, 3
-Hexenoic acid, 6-heptenoic acid, 2,6-heptadienoic acid, 2-octenoic acid, undecylenic acid, lindelic acid, myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, linoleic acid, linoleic acid and the like.

Further, by adding a branched monocarboxylic acid component of c) as a carboxylic acid component as required, the hydrolysis resistance of the obtained ester can be improved. The component c) must have a branch at the α-position and have 5 to 18 carbon atoms in view of the stability of the resulting ester to hydrolysis. Preferably those having 7 to 14 carbon atoms, more preferably 7 to 1 carbon atoms
0. If the number of carbons is less than 5, the obtained ester has a low flash point, and if the number of carbons is more than 18, the viscosity becomes too high. If the proportion of the dicarboxylic acid component is reduced to avoid this and is adjusted to an appropriate viscosity, the proportion of the low-molecular-weight ester becomes too large, and the flash point is undesirably lowered.

The monocarboxylic acids having a branch at the α-position and having 5 to 18 carbon atoms used in the present invention include, for example, isovaleric acid, 2-methylbutyric acid, trimethylacetic acid and 2-methylbutyric acid.
Methylvaleric acid, 2,2-dimethylbutyric acid, 2-ethylbutyric acid, 2,2-dimethylpentanoic acid, 2-ethylpentanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid,
2,2-dimethylhexanoic acid, 2-methylheptanoic acid,
2-propylpentanoic acid, 2,2-dimethylheptanoic acid, 2-methyloctanoic acid, 2-ethylheptanoic acid,
-Ethyl-2,3,3-trimethylbutyric acid, 2,2,4
4-tetramethylpentanoic acid, 2,2-diisopropylpropionic acid, 2,4-dimethyloctanoic acid, 2,2-
Examples include dimethyloctanoic acid, isotridecanoic acid, 2-heptylundecanoic acid, and isomiristinic acid, isopalmitic acid, and isostearic acid manufactured by Nissan Chemical. These branched monocarboxylic acids may be used singly or as a mixture of two or more, but as described above, α
If the carbon number of the branched monocarboxylic acid is short, the flash point decreases,
If the length is long, the viscosity increases and the flash point decreases, so that the most well-balanced one is one having 8 carbon atoms. Among them, 2-ethylhexanoic acid is superior to 2-methylheptanoic acid in terms of hydrolysis resistance,
It is more preferable than 2,2-dimethylhexanoic acid in terms of ease of reaction during production and availability, and is most preferable.

In order to exhibit the effect of hydrolysis resistance of the α-branched monocarboxylic acid, 1 to 1
It is desirable to add 0 equivalent% or more. However, on the one hand, the viscosity index of the resulting ester deteriorates, so in that case no more than 50 equivalent% should be added.

As the alcohol of component d) in the present invention, neopentyl polyol is preferred from the viewpoint of the heat resistance of the ester, and trimethylolpropane is most suitable.
In the present invention, neopentyl polyol is represented by the formula

[0023]

Embedded image

A polyol having at least one group represented by the formula: Neopentyl polyols other than trimethylolpropane include neopentyl glycol and pentaerythritol, as well as dimers and trimers thereof.When neopentyl glycol is used, the molecular weight of the resulting ester is small, so the flash point Can not be higher. In addition, when pentaerythritol is used, the pour point is high, and since it is a tetrahydric alcohol, compared to trimethylolpropane, when a dicarboxylic acid is introduced and a complex ester is formed, the molecular weight tends to increase, and the viscosity increases. Become. If the viscosity is adjusted by reducing the amount of the dicarboxylic acid to be used, the ratio of the low molecular weight increases and the flash point decreases, which is not preferable. In the present invention, pentaerythritol or neopentyl glycol may be mixed with trimethylolpropane.However, in order to lower the flash point or increase the pour point for the reasons described above, the mixing ratio of these components is based on the total alcohol component. It is necessary that the content be less than 30 equivalent%, and it is preferable that substantially all of the alcohol component consists of trimethylolpropane.

After the esterification reaction, the complex ester of the present invention can be purified by a general purification step such as deacidification, washing with water and adsorption treatment. The iodine value (Img / 100g) of the resulting complex ester must be less than 10. Beyond this, the thermal oxidative stability of the esters becomes significantly impaired. Further, in the complex ester of the present invention, even if the composition as described above is selected, since a part has a flash point equivalent to that of the prior art, a part of the complex ester is used to achieve the object of the present invention. Requires a further requirement that the flash point of the hydraulic oil be 280 ° C. or higher. In addition, increasing the flash point also increases the pour point, so it is important to keep this below -20 ° C.

These values can be obtained by controlling the composition of the acid component and the alcohol component of the ester. Further, although not essential for the present invention, the higher the hydroxyl value of the obtained ester, the lower the flash point. However, it should be noted that if the acid value is too high, the thermal oxidation stability may deteriorate or the flash point may decrease. Also, if the acid value is too high,
Wear resistance may be impaired. For this reason, in the complex ester of the present invention, the acid value after purification is preferably 1 mgKOH / g or less, more preferably 0.5 mgKOH / g or less. Similarly, the hydroxyl value is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less.

The ester used as a base oil of the flame-retardant hydraulic oil of the present invention can be used as it is,
Further, lubricating oil additives such as antioxidants, extreme pressure agents, rust preventives, defoamers, demulsifiers and the like which are usually used can also be used. The complex ester of the present invention is used not only as a flame retardant hydraulic oil, but also as an engine oil, a gear oil,
It can also be used as refrigerating machine oil and other industrial lubricants.

[0028]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A 1-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydrating tube equipped with a condenser. In this flask, 131 g of trimethylolpropane, 50 g of adipic acid, 126.6 g of caprylic acid, and 12 parts of capric acid
5.0 g, lauric acid 73.2 g, myristic acid 27.
4 g, palmitic acid 13.7 g, stearic acid 4.6
g, 10.7 g of oleic acid, 230 g under nitrogen stream
Esterification was performed at 10 ° C. for 10 hours. As an esterification catalyst, tin oxide was used in an amount of 0.1% by weight based on the total charged amount. After completion of the reaction, filtration was performed to obtain an ester having a composition shown in Table 1. Table 1 shows the physical property values of the obtained ester.

Examples 2 to 7 In the same manner as in Example 1, various esters having the compositions shown in Table 1 were obtained. Table 1 shows the physical property values of the obtained ester.

Example 8 A 1-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydrating tube equipped with a condenser. 131 g of trimethylolpropane, 43.7 g of adipic acid, 13.1 g of caprylic acid, 102.2 g of 2-ethylhexanoic acid, 154.4 g of capric acid, 78.0 g of lauric acid, 29.4 g of myristic acid, and 15 of palmitic acid 0.0 g, stearic acid 5.0 g, oleic acid 1
1.6 g was taken and esterified at 230 ° C. for 10 hours under a nitrogen stream. As an esterification catalyst, tin oxide was used in an amount of 0.1% by weight based on the total charged amount. After completion of the reaction, filtration was performed to obtain an ester having a composition shown in Table 1. Table 1 shows the physical property values of the obtained ester.

Examples 9 to 16 In the same manner as in Example 8, various esters having the compositions shown in Table 1 were obtained. Table 1 shows the physical property values of the obtained ester.

Comparative Examples 1 to 9 In the same manner as in Example 1 or 8, various esters having the compositions shown in Table 2 were obtained. Table 2 shows the physical property values of the obtained ester.

[0034]

[Table 1]

[0035]

[Table 2]

The abbreviations in Tables 1 and 2 have the following meanings. TMP; trimethylolpropane, PET; pentaerythritol, NPG; neopentyl glycol, nCm; linear monocarboxylic acid having m carbon atoms, nC18F; linear unsaturated monocarboxylic acid having 18 carbon atoms, 2EH; 2-ethylhexane Acid, AA: adipic acid, SA: sebacic acid, V40; kinematic viscosity at 40 ° C (cSt), VI;
Viscosity index, PP; pour point (° C), FP; flash point (° C), IV;
Iodine value (Img / 100g) The thermal oxidation stability and lubricity of the ester of the present invention obtained in Examples 1 to 16 and the ester of the comparative product obtained in Comparative Examples 1 to 5 were evaluated by the following methods. did. The hydrolysis stability of the esters of Examples 8 to 15 and Comparative Examples 1 to 4 was evaluated by the following method. Tables 3 and 4 show the results.
Shown in

(Thermal Oxidation Stability) According to JIS K2514, 250 ml of sample oil was added in the presence of copper and a steel catalyst in the presence of 1 ml.
The test was conducted for 72 hours while maintaining the temperature at 65.5 ° C., and the increase in total acid value and the change in viscosity were examined.

(Lubricity) Using a high-speed four-ball type abrasion tester, the test was conducted under the conditions of a rotation speed of 1800 rpm, a load of 30 kg and a time of 30 minutes, and the wear scar diameter was measured.

(Hydrolysis stability) 25 g of water was added to 75 g of the sample.
Was added, and the mixture was stirred in a sealed state at 93 ° C. for 48 hours in the presence of a copper catalyst, and then the acid values of the oil layer and the aqueous layer were measured.

[0040]

[Table 3]

[0041]

[Table 4]

With respect to the thermal oxidation stability, as shown in Comparative Example 4, the content of the linear unsaturated monocarboxylic acid was large, and the iodine value was 10%.
Those having a high value as described above show that, as a result of the thermal oxidation stability test, the acid value and the viscosity were significantly increased, and the thermal oxidation stability was clearly poor. Regarding the lubricity, as shown in Comparative Example 1, when a linear monocarboxylic acid component having 16 to 18 carbon atoms was not contained, the lubrication test showed that the wear scar diameter was large and the lubricity was poor. The hydrolysis stability was determined in Comparative Examples 1 and 4.
When only linear carboxylic acid is used as shown in
It can be seen that the acid value increases sharply after the test and the stability is poor. Therefore, as shown in Comparative Examples 2 and 3, in order to improve the hydrolytic stability, when a large amount of a branched carboxylic acid is introduced, the stability is improved, but the viscosity index, which is one of the important physical properties as a lubricating oil, is increased. It is low and not suitable.

As shown in Comparative Examples 6 and 7, when pentaerythritol was used as the alcohol component, problems such as poor fluidity and high viscosity occurred. When glycol is used, problems such as a lower flash point occur, so that it is understood that trimethylolpropane is optimal. Also,
When trimethylolpropane and pentaerythritol are mixed and used, as can be seen from Comparative Example 9 and Example 16, when the ratio of pentaerythritol is more than 30 equivalent% with respect to all alcohol components, problems such as deterioration of fluidity are caused. Occurs. However, even when trimethylolpropane is used, as shown in Comparative Example 5, the use of a large amount of a straight-chain monocarboxylic acid having 16 to 18 carbon atoms increases the pour point. Therefore, it is conceivable to introduce a branched monocarboxylic acid to lower the pour point, but as shown in Comparative Example 2, the viscosity index becomes worse.

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Claims (3)

(57) [Claims] (1) a) not more than 10 equivalent% based on all carboxylic acid components;
A saturated dicarboxylic acid having 5 to 14 carbon atoms or a derivative thereof having a maximum of 50 equivalent% or less , and b) a linear monocarboxylic acid component having 16 to 18 carbon atoms is at least 1.8 equivalent% to 10 equivalent% based on all carboxylic acid components. And a linear unsaturated monocarboxylic acid component having 18 carbon atoms is contained in an amount of 0.2 equivalent% or more and 5 equivalent% or less based on all carboxylic acid components.
C) 50 equivalent% or less of the total carboxylic acid component, a monocarboxylic acid having a branch at the α-position and 5 to 18 carbon atoms or a derivative thereof, and d) a total alcohol component And an iodine value (Img / 100g) of 10 or less, a flash point of 280 ° C or more and a pour point of -20 ° C or less, which was synthesized from a neopentyl polyol containing 70 equivalent% or more of trimethylolpropane. A flame-retardant hydraulic oil characterized by containing a complex ester. (2) a) the component is adipic acid or a derivative thereof, and (d)
2. The composition of claim 1, wherein the component is substantially trimethylolpropane.
Flame retardant hydraulic fluid as described. 3. The flame-retardant hydraulic oil according to claim 1, wherein the component (c) is 2-ethylhexanoic acid or a derivative thereof, and the component (d) is substantially trimethylolpropane.