JP2019014855A - Hydraulic oil composition - Google Patents

Abstract

To provide a hydraulic oil composition having excellent sealant compatibility and lubricity (wear resistance).SOLUTION: The hydraulic oil composition contains an ester compound A and an alkyloxirane derivative B, where the alkyloxirane derivative B is contained in an amount of 1.0-30.0 pts.mass relative to 100 pts.mass of the ester compound A. The (A) is an ester compound of a neopentyl polyol with 5-10 carbon atoms and an alcohol valence of 3-6, and a fatty acid with 6-22 carbon atoms. The (B) is an alkyloxirane derivative represented by formula 1, and satisfies a relationship of formula 2. RO-(AO)n-H (1) (Ris a C1-22 hydrocarbon group; AO is a C3 oxyalkylene group; and n is an integer of 25 or more). 0.35≤M/M≤0.75 (2) (Mand Mare obtained from a chromatogram obtained by a gel permeation chromatography measurement).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic fluid composition used as a power transmission medium in a hydraulic device. More specifically, the present invention relates to a hydraulic fluid composition that is excellent in sealing material compatibility and lubricity (wear resistance).

  The hydraulic fluid is a fluid used as a power transmission medium in various hydraulic devices, and has functions such as lubrication and cooling in addition to power transmission.

  In recent years, esters are often used as base oils for hydraulic fluids. By using esters as base oils, hydraulic fluids having features such as flame retardancy and biodegradability can be obtained. However, when ester is used as the base oil, there is a tendency to swell the sealing material, and the sealing material may swell excessively, which may lead to problems such as leakage of hydraulic oil and malfunction of the hydraulic system. There is.

  In order to solve this problem, for example, in Patent Document 1, a part of a fatty acid portion of a polyol ester composed of a fatty acid having 9 carbon atoms is replaced with a fatty acid having 10 to 16 carbon atoms, and the structure is optimized to swell rubber. It discloses that a refrigerator lubricating oil capable of appropriately suppressing the above is obtained. However, this refrigerating machine lubricating oil is not suitable for hydraulic equipment in terms of kinematic viscosity and lubricity, and is difficult to use as a hydraulic hydraulic oil.

  Further, for example, Patent Document 2 discloses a hydraulic fluid composition that improves sealing material compatibility by mixing paraffin oil and naphthenic oil with ester.

JP, 2006-190892, A JP2016-14091A

  However, although the hydraulic fluid composition described in Patent Document 2 has a high compatibility with a sealing material, since the blending amount of the ester is small, the original characteristics of the ester are impaired.

  On the other hand, since the hydraulic fluid is a lubricating oil used under high pressure, if the lubricity (wear resistance) is insufficient, the sliding portion may be worn. Therefore, it is necessary to consider lubricity (wear resistance).

  An object of the present invention is to provide a hydraulic fluid composition that is excellent in sealing material compatibility and lubricity (wear resistance).

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have a hydraulic pressure comprising an ester compound (A) of a specific neopentyl polyol and a specific fatty acid and a specific alkyloxirane derivative (B). It has been found that the hydraulic oil composition has excellent lubricity (wear resistance) in addition to good sealant compatibility.

That is, the present invention is as follows.
[1] The following ester compound (A) and the following alkyl oxirane derivative (B) are contained, and the alkyl oxirane derivative (B) is added in an amount of 1.0 to 30.0 mass with respect to 100 parts by mass of the ester compound (A). A hydraulic fluid composition characterized by containing a part.

(A) An ester compound of a neopentyl polyol having 5 to 10 carbon atoms and 3 to 6 valences of alcohol and a fatty acid having 6 to 22 carbon atoms

(B) An alkyloxirane derivative represented by the following formula (1) and satisfying the relationship of the formula (2):

R ¹ O— (AO) n—H (1)

(In the formula (1),
R ¹ represents a hydrocarbon group having 1 to 22 carbon atoms,
AO represents an oxyalkylene group having 3 carbon atoms,
n represents a number of 25 or more. )

_{0.35 ≦ M L / M H ≦} 0.75 ···· (2)

(On the chromatogram where the length of the perpendicular from the maximum point K at which the refractive index intensity on the chromatogram obtained by gel permeation chromatography measurement is maximum to the base line B is L and the refractive index intensity is L / 2) Of the two points, the earlier elution time is designated as point O, the later elution time is designated as point Q, and the intersection of the straight line G connecting point O and point Q and the perpendicular drawn from the maximum point K to the base line when is P, a distance between the point O and the intersection P and M _H, the distance between the point Q and the point of intersection P and M _L.)

[2] The hydraulic fluid composition according to [1], wherein the alkyloxirane derivative (B) satisfies the relationship of the formulas (3) and (4).

As = W _1/2 / W _5% (3)
0.30 ≦ As ≦ 0.70 (4)

(Of the two points on the chromatogram where the refractive index intensity is L / 20, the earlier elution time is point R, the later elution time is point S, and the straight line H connecting point R and point S is (The intersection point between the maximum point K and the perpendicular drawn from the maximum point K to the base line B is T, the distance between the point R and the intersection point T is W _1/2 , and the distance between the point R and the point S is W _5% .)

  The hydraulic fluid composition of the present invention has good compatibility with the sealing material and is excellent in lubricity (wear resistance).

It is a model figure of the chromatogram obtained by the gel permeation chromatography of an alkyl oxirane derivative. It is a model figure of the chromatogram for demonstrating the calculation method of As.

  Hereinafter, the hydraulic fluid composition of the present invention will be described in more detail. In addition, the numerical value range prescribed | regulated using the symbol "~" in this specification shall contain the numerical value of the both ends (upper limit and lower limit) of "~". For example, “2 to 5” represents 2 or more and 5 or less.

[Ester compound (A)]
The ester compound (A) in the present invention is an ester compound of a neopentyl polyol having 5 to 10 carbon atoms and a valence of 3 to 6 alcohols and a fatty acid having 6 to 22 carbon atoms.

  As a raw material for the ester compound (A), neopentyl polyol having 5 to 10 carbon atoms and 3 to 6 valences of alcohol is used. The neopentyl polyol having 5 to 10 carbon atoms and 3 to 6 valences of alcohol is, for example, trimethylolpropane, pentaerythritol, or dipentaerythritol.

  The neopentyl polyol is preferably trimethylolpropane or pentaerythritol, and more preferably trimethylolpropane.

  The fatty acid having 6 to 22 carbon atoms used as the raw material for the ester compound (A) is a straight-chain saturated fatty acid having 6 to 22 carbon atoms, a saturated fatty acid having a branched chain having 6 to 22 carbon atoms, or 6 to 22 carbon atoms. It is a straight chain unsaturated fatty acid. If the number of carbon atoms is less than 6, the lubricity (wear resistance) may be lowered. Therefore, the number is 6 or more, but more preferably 8 or more. Further, when the number of carbon atoms is more than 22, there is a risk of deterioration of fuel consumption caused by energy loss due to internal resistance of the lubricating oil itself due to high viscosity, and the generated ester may become a solid and cannot be used as a lubricating oil. 22 or less, more preferably 18 or less.

  Specific examples of the linear saturated fatty acid having 6 to 22 carbon atoms include caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid. . Specific examples of the saturated fatty acid having a branched chain having 6 to 22 carbon atoms are 2-methylpentanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, and neodecanoic acid. Specific examples of the linear unsaturated fatty acid having 6 to 22 carbon atoms are palmitoleic acid, oleic acid, linoleic acid, linolenic acid, and erucic acid.

  Among the above fatty acids, caproic acid, caprylic acid, capric acid, lauric acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, oleic acid, linoleic acid, and linolenic acid are more preferable, and capryl is more preferable. Acid, capric acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid and oleic acid.

[Alkyloxirane Derivative (B)]
The alkyloxirane derivative (B) in the present invention is a compound represented by the formula (1).

R ¹ O— (AO) n—H (1)

In the formula (1), R ¹ is a hydrocarbon group having 1 to 22 carbon atoms, and AO is an oxyalkylene group having 3 carbon atoms. n is an average addition mole number of the oxyalkylene group AO and is 25 or more.

In the formula (1), the hydrocarbon group having 1 to 22 carbon atoms represented by R ¹ is a functional group composed of carbon and hydrogen, and is selected from an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group. Preferably an alkyl group or an alkenyl group, more preferably an alkyl group or alkenyl group having 1 to 14 carbon atoms, still more preferably an alkyl group or alkenyl group having 1 to 6 carbon atoms, and 1 to carbon atoms. Most preferred is an alkyl group of 6. The alkyl group having 1 to 6 carbon atoms may be linear or branched, but is more preferably linear. Examples of the linear alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. The hydrocarbon group having 1 to 22 carbon atoms represented by R ¹ may be only one type or two or more types.

  AO is an oxyalkylene group having 3 carbon atoms. N is an average added mole number of the oxyalkylene group AO and is 25 or more. If n is less than 25, the viscosity is low and the lubricity (abrasion resistance) may be insufficient, so n is 25 or more, more preferably 50 or more.

  Also, the viscosity increases as n increases. From the viewpoint of ease of blending when blended with the lubricating oil, n is preferably 150 or less, and more preferably 120 or less.

The alkyloxirane derivative (B) of the present invention is defined by a chromatogram obtained by using a differential refractometer in gel permeation chromatography (GPC). This chromatogram is a graph showing the relationship between refractive index intensity and elution time. In the alkyloxirane derivative of the present invention, the chromatogram is asymmetrical and satisfies the relationship of formula (2). In addition, the shape of a chromatogram becomes left-right symmetric, so that M _L / _MH becomes a value close to 1.

_{0.35 ≦ M L / M H ≦} 0.75 ···· (2)

  Here, FIG. 1 is a model diagram of a chromatogram obtained by gel permeation chromatography of an alkyloxirane derivative. The horizontal axis represents the elution time, and the vertical axis represents the refractive index strength obtained using a differential refractometer. Show.

  When a sample solution is injected into a gel permeation chromatograph and developed, elution starts from the molecule with the highest molecular weight, and the elution curve increases as the refractive index intensity increases. Thereafter, when the maximum point K at which the refractive index intensity is maximum is passed, the elution curve is lowered.

  Further, in the gel permeation chromatography of the alkyloxirane derivative of the present invention, when there are a plurality of refractive index intensity maximum points in the chromatogram, the point having the highest refractive index intensity is set as the maximum point K. Further, when there are a plurality of local maximum points having the same refractive index intensity, the longer elution time is set as the local maximum point K of the refractive index intensity. At this time, the peak due to the developing solvent used in the gel permeation chromatography and the pseudo peak due to the fluctuation of the baseline due to the column or apparatus used are excluded.

M _L and _MH are calculated from the chromatogram as follows.
(1) A perpendicular line is drawn from the maximum point K of the refractive index intensity on the chromatogram to the base line B, and the length of the perpendicular line is L.
(2) Of the two points on the chromatogram having a refractive index intensity of L / 2, the point with the earlier elution time is designated as point O, and the point with the later elution time is designated as point Q.
(3) Let P be the intersection of a straight line G connecting point O and point Q and a perpendicular drawn from the local maximum point K of the refractive index intensity to the base line B.
(4) point O and the intersection point P distance _{M H} of the distance of an intersection P and the point Q and _{M L.}

In the alkyloxirane derivative of the present invention, M _L / M _H satisfies 0.35 ≦ M _L / M _H ≦ 0.75. When M L _/ M _H is greater than 0.75, resulting a decrease in the viscosity of the alkyl oxirane derivatives, which when blended with a lubricating oil, there is a possibility that the lubricity (abrasion resistance) is insufficient. From this viewpoint, M _L / _{MH is set} to 0.75 or less, and more preferably 0.62 or less.

Further, as M _L / M _H becomes smaller, the bias on the high molecular weight side in the molecular weight distribution becomes larger, and an increase in viscosity derived therefrom is observed. When M _L / _MH is smaller than 0.35, the viscosity becomes too high, and it becomes difficult to blend in, for example, a lubricating oil. From this point of view, M _L / _MH is 0.35 or more, and more preferably 0.36 or more.

In a preferred embodiment, in gel permeation chromatography, the chromatogram represented by the refractive index intensity and the elution time obtained using a differential refractometer is asymmetrical, and the chromatogram obtained as shown below is used. The asymmetry value As of the gram peak satisfies the following expressions (3) and (4).

As = W _1/2 / W _5% (3)
0.30 ≦ As ≦ 0.70 (4)

The method for calculating As will be further described with reference to the model diagram of the chromatogram in FIG. The horizontal axis represents the elution time, and the vertical axis represents the refractive index intensity obtained using a differential refractometer.
When a sample solution is injected into a gel permeation chromatograph and developed, elution starts from the molecule with the highest molecular weight, and the elution curve increases as the refractive index intensity increases. After that, the maximum point where the refractive index intensity is maximum is passed, and the elution curve is lowered.

(1) A perpendicular line is drawn from the maximum point K of the refractive index intensity on the chromatogram to the base line B, and its length is set to L.
(2) Of the two points on the chromatogram where the refractive index intensity is L / 20, point with the earlier elution time as point R and point with the later elution time as point S.
(3) Let T be the intersection of a straight line H connecting point R and point S and a perpendicular drawn from the maximum point K of the refractive index intensity to the base line B.
(4) The distance between the point R and the intersection T is W _1/2 , and the distance between the point R and the point S is W _5% .

  In a preferred embodiment, As satisfies 0.30 ≦ As ≦ 0.70. By setting As to 0.70 or less, the viscosity is improved, and the lubricity is improved when the alkyloxirane derivative is blended with the lubricating oil. From this viewpoint, it is more preferable that As is 0.65 or less.

  Moreover, as As becomes smaller, the deviation of both sides of the polymer in the molecular weight distribution becomes larger, and an increase in viscosity derived therefrom is observed. By setting As to 0.30 or more, it is possible to suppress the viscosity from becoming too high and to easily mix it with the lubricating oil. In this respect, As is more preferably 0.57 or more.

In the present invention, gel permeation chromatography (GPC) for determining M _L , _MH and As is a system dedicated to SHODEX (registered trademark) GPC101GPC as a system, SHODEX RI-71s as a differential refractometer, and SHODEX KF as a guard column. -G, 3 columns of HODEX KF804L were installed continuously, column temperature was 40 ° C, tetrahydrofuran as a developing solvent was flowed at a flow rate of 1 ml / min, and 0.1 ml of 0.1 wt% tetrahydrofuran solution of the obtained reaction product was injected. Then, using the BORWIN GPC calculation program, a chromatogram represented by the refractive index intensity and the elution time is obtained.

  When producing the alkyloxirane derivative (B) of the present invention, preferably, an alkylene oxide having 3 carbon atoms, that is, in the presence of a double metal cyanide catalyst (hereinafter abbreviated as DMC catalyst) as an initiator, Ring-opening addition of methyloxirane. In the reaction vessel, an initiator having at least one hydroxyl group in the molecule and a DMC catalyst are added, and methyl oxirane is added continuously or intermittently under stirring in an inert gas atmosphere to perform addition polymerization. Methyloxirane may be added under pressure, or may be added under atmospheric pressure.

At this time, the average supply rate of methyloxirane is not limited, but it is preferable to change the average supply rate of methyloxirane. Speed between Specifically supplies 20 to 50 wt% speed (supply amount per unit time) of V _1, the total supply amount of methyl oxirane between supplying 5 to 20 wt% of the total feed amount of methyl oxirane the _{V 2,} when the speed between the supplying 50～100Wt% of the total feed amount of methyl oxirane was _{V 3, V 1 / V 2} = 1.1~2.0, V 2 / V 3 = 1. It is preferable to control the average supply rate of methyloxirane so as to be 1 to 1.5.

  Moreover, 50 to 150 degreeC is preferable and, as for reaction temperature, 70 to 110 degreeC is more preferable. If the reaction temperature is higher than 150 ° C, the catalyst may be deactivated. When reaction temperature is lower than 50 degreeC, reaction rate is slow and it is inferior to productivity.

As the initiator of the present invention, in formula (1), it may be used a monohydric alcohol having a hydrocarbon group having 1 to 22 carbon atoms represented by R ^1.

  The amount of water contained in the initiator and methyloxirane is not particularly limited, but the amount of water contained in the initiator is preferably 0.5 wt% or less, and methyloxirane is preferably 0.01 wt% or less. .

  Although the usage-amount of a DMC catalyst is not restrict | limited in particular, 0.0001-0.1 wt% is preferable with respect to the alkyl oxirane derivative to produce | generate, 0.001-0.05 wt% is more preferable. The DMC catalyst may be introduced into the reaction system all at once, or may be introduced in divided portions. After completion of the polymerization reaction, the composite metal complex catalyst is removed. The catalyst can be removed by a known method such as filtration, centrifugation, or treatment with a synthetic adsorbent.

As the DMC catalyst used in the present invention, a known one can be used. For example, it can be represented by the formula (5).

Ma [M′x (CN) y] b (H ₂ O) c · (R) d (5)

In formula (5), M and M ′ are metals, R is an organic ligand, a, b, x and y are positive integers that vary depending on the valence and coordination number of the metal, and c and d are metals It is a positive integer that varies depending on the coordination number.

  As the metal M, Zn (II), Fe (II), Fe (III), Co (II), Ni (II), Al (III), Sr (II), Mn (II), Cr (III), Examples thereof include Cu (II), Sn (II), Pb (II), Mo (IV), Mo (VI), W (IV), W (VI), etc. Among them, Zn (II) is preferably used.

  As the metal M ′, Fe (II), Fe (III), Co (II), Co (III), Cr (II), Cr (III), Mn (II), Mn (III), Ni (II) , V (IV), V (V), etc., among which Fe (II), Fe (III), Co (II), and Co (III) are preferably used.

As the organic ligand R, alcohol, ether, ketone, ester and the like can be used, and alcohol is more preferable. Preferred organic ligands are water-soluble, and specific examples include tert-butyl alcohol, n-butyl alcohol, iso-butyl alcohol, N, N-dimethylacetamide, ethylene glycol dimethyl ether (glyme), diethylene glycol dimethyl ether ( Diglyme). Particularly preferred is Zn ₃ [Co (CN) ₆ ] ₂ coordinated with tert-butyl alcohol.

  In this invention, 1.0-30.0 mass parts of alkyl oxirane derivatives (B) are contained with respect to 100 mass parts of ester compounds (A). When the content is less than 1.0 part by mass, the compatibility with the sealing material may not be sufficient, so the content is 1.0 part by mass or more, and more preferably 5.0 parts by mass or more. On the other hand, when the content of the alkyloxirane derivative (B) exceeds 30.0 parts by mass, the entire hydraulic fluid composition becomes highly viscous, and there is a risk of deterioration in fuel consumption resulting in energy loss due to internal resistance of the lubricating oil itself. Therefore, it is 30.0 parts by mass or less, but is more preferably 20.0 parts by mass or less.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited by these examples.

[Synthesis of ester compounds]
(Synthesis Example 1)
748 g (5.58 mol) of trimethylolpropane, “NAA-82” manufactured by NOF (industrial caprylic acid: caprylic acid content) in a 5 L four-necked flask equipped with a thermometer, nitrogen introducing tube, stirrer and air cooling tube 9912) was charged with 1512 g (10.5 mol) and “NAA-102” (industrial capric acid: capric acid content 99%) was added 1237 g (7.18 mol), and the reaction water was distilled off at 240 ° C. under a nitrogen stream. The ester I was obtained by reacting at normal pressure while performing distillation purification after the reaction.

(Synthesis Example 2)
Into a 5 L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirrer and an air cooling tube, 640 g (4.70 mol) of pentaerythritol, NOA "NAA-82" (industrial caprylic acid: caprylic acid content 99 %) 1121 g (7.77 mol), “NAA-102” (industrial capric acid: capric acid content 99%) 233 g (1.35 mol), 2-ethylhexanoic acid 1483 g (10.3 mol) were charged, nitrogen Ester II was obtained by making it react at normal pressure, distilling off reaction water at 240 degreeC under airflow, and performing distillation refinement | purification after reaction.

[Synthesis of alkyloxirane derivatives]
(Reference synthesis example: Synthesis of double metal cyanide complex catalyst)
15 ml of an aqueous solution containing 0.84 g of potassium hexacyanocobaltate K3Co (CN) 6 was dropped into 2.0 ml of an aqueous solution containing 2.1 g of zinc chloride over 15 minutes while stirring at 40 ° C. After completion of dropping, 16 ml of water and 16 g of tert-butyl alcohol were added, the temperature was raised to 70 ° C., and the mixture was stirred for 1 hour. After cooling to room temperature, a filtration operation (first filtration) was performed to obtain a solid. To this solid, 14 ml of water and 8.0 g of tert-butyl alcohol were added and stirred for 30 minutes, followed by filtration (second filtration) to obtain a solid.

  Further, 18.6 g of tert-butyl alcohol and 1.2 g of methanol were added to this solid again, and the mixture was stirred for 30 minutes and then filtered (third filtration). The obtained solid was dried at 40 ° C. under reduced pressure for 3 hours. As a result, 0.7 g of a double metal cyanide complex catalyst was obtained.

(Synthesis Example 3)
A stainless steel 5L pressure vessel equipped with a thermometer, pressure gauge, safety valve, nitrogen gas blowing pipe, stirrer, vacuum exhaust pipe, cooling coil, steam jacket, 200g of n-butanol and the composite metal cyanide complex catalyst of the reference synthesis example 0.2 g was charged. After nitrogen substitution, the temperature was raised to 110 ° C., and 243 g of methyloxirane (manufactured by Sumitomo Chemical Co., Ltd., LOT.151212D) was charged over 16 hours from a nitrogen gas blowing tube under a condition of 0.3 MPa or less. At this time, changes in pressure and temperature in the reaction tank over time were measured.

  After 16 hours, the pressure in the reaction vessel suddenly decreased. Thereafter, while maintaining the inside of the reaction vessel at 110 ° C., methyloxirane was gradually introduced from the nitrogen gas blowing tube under the condition of 0.6 MPa or less, and 3,270 g of methyloxirane in total was continuously added with stirring. Pressure was applied. At this time, the time required for introducing 987 g of methyloxirane was 60 minutes, the time required for introducing 2,470 g was 180 minutes, and the time required for introducing 3,270 g was 270 minutes.

  After completion of the addition, the mixture was reacted at 110 ° C. for 1 hour. 2220 g was withdrawn from the reaction tank, the residue in the reaction tank was heated to 110 ° C., and 1,110 g of methyloxirane was added from a nitrogen gas blowing tube over 2 hours under the condition of 0.6 MPa or less. After completion of the addition, the mixture was reacted at 110 ° C. for 1 hour. Again, 1.044 g was extracted from the reaction vessel, the temperature in the reaction vessel was raised to 110 ° C., and 312 g of methyloxirane was added from the nitrogen gas blowing tube over 40 minutes under the condition of 0.6 MPa or less. After completion of the addition, the reaction was carried out at 110 ° C. for 1 hour, and filtration was performed after reducing the pressure at 75 to 85 ° C. and 50 to 100 Torr for 1 hour while blowing nitrogen gas.

The obtained alkyloxirane derivative I was measured by gel permeation chromatography.
For gel permeation chromatography, a system exclusively for SHODEX GPC101GPC is used as a system, SHODEX RI-71S as a differential refractometer, SHODEX KF-GS as a guard column, three HODEX KF804L as columns, and column temperature 40 ° C., developing solvent Then, 0.1 ml of a 0.1 wt% tetrahydrofuran solution of the obtained reaction product was poured at a flow rate of 1 ml / min, and a chromatograph represented by refractive index intensity and elution time was calculated using a BORWIN GPC calculation program. Got gram.
When obtaining the _M L / _{M H} from the chromatogram, is 0.52, _{A s} was 0.58.

(Synthesis Example 4)
Molecular weight 1,290 obtained by reaction with methyloxirane in a stainless steel 5L pressure-resistant reactor equipped with a thermometer, pressure gauge, safety valve, nitrogen gas blowing pipe, stirrer, vacuum exhaust pipe, cooling coil, steam jacket 250 g of polyoxypropylene butyl ether and 5.4 g of potassium hydroxide were charged. At 100 ° C., 2322 g of methyl oxirane was reacted, and the remaining methyl oxirane was removed under reduced pressure at 0 ° C. for 30 minutes. The reaction product was transferred to a 5 L eggplant flask, promptly neutralized with 1N hydrochloric acid, and in a nitrogen gas atmosphere. After dehydration, filtration was performed to obtain alkyloxirane derivative II.
The obtained alkyloxirane derivative II was measured by gel permeation chromatography.

For the alkyloxirane derivatives I and II obtained above, Table 1 shows the values of _ML / _MH and As obtained from the chromatogram, and the characteristics of the compounds.

[Preparation of lubricating oil composition]
About the ester compound obtained above, the additive was mix | blended in the following procedures, and the lubricating oil composition of Examples 1-3 and Comparative Examples 2-4 was prepared. Comparative Example 1 was ester I alone, and Comparative Example 5 was ester II alone.

  In a 5 L four-necked flask equipped with a thermometer, nitrogen inlet tube, stirrer, and Dimroth condenser, the ester compound and alkyloxirane derivative synthesized above were stirred and mixed at room temperature for 1 hour in the amounts shown in Table 2. To obtain a hydraulic fluid composition.

  These hydraulic fluid compositions were subjected to viscosity, rubber immersion test and lubricity test (SRV test) by the methods described below, and the results are shown in Table 2.

<Viscosity>
The measurement was performed according to Japanese Industrial Standard JIS K 2283.
<Rubber immersion test>
The temperature of each lubricating oil composition was set to 80 ° C., and a butyl rubber test piece (20.0 × 30.0 × 2.0 mm) was immersed in it for 14 days (336 hours). The weight change rate was measured.
Based on the value of the weight change rate, the swelling suppression effect for Comparative Example 1 was calculated by the following formula. The higher the value of the swelling suppression effect, the higher the compatibility with the sealing material. 50% or more was evaluated as ◎, 10% or more and less than 50% as ○, and less than 10% as x.
Swelling suppression effect (%) = (1− “weight change rate of target” / “weight change rate of Comparative Example 1”) × 100
(In the case of Example 1)
Swelling suppression effect (%) = (1− “weight change rate of Example 1” / “weight change rate of Comparative Example 1”) × 100

<Lubricity test (SRV test)>
The test was performed with a ball-on-disk, and test pieces manufactured by SUJ-2 were used. The test conditions were a test temperature of 40 ° C., a load of 100 N, an amplitude of 1 mm, and a vibration frequency of 50 Hz, and the wear scar diameter (μm) after a test time of 25 minutes was measured. The smaller the wear scar diameter (μm), the better the lubricity.

  From the results shown in Table 2, the hydraulic fluid compositions of Examples 1 to 3 in which an alkyl oxirane derivative having a specific molecular weight distribution is blended with a specific ester of the present invention are suitable for sealing material, lubricity (wear resistance). It turns out that all are excellent.

  From the results in Table 2, the ester I of Comparative Example 1 was inferior in sealing material compatibility and lubricity (wear resistance) because it did not contain an alkyloxirane derivative.

In the hydraulic fluid compositions of Comparative Examples 2 to 4, since the values of M _L / M _H and As of the alkyl oxirane derivative II are high and the alkyl oxirane derivative having a wide molecular weight distribution on the low molecular weight side is blended, The property (abrasion resistance) was inferior. Furthermore, compared with the case where the same amount of alkyl oxirane derivative I was blended, the sealing material compatibility was inferior.

  The composition of Comparative Example 5 uses ester II, but does not contain an alkyloxirane derivative, so that the kinematic viscosity value is equivalent to that of Example 3, but lubricity (wear resistance) ) Was inferior, and the compatibility with the sealing material was also inferior.

According to the present invention, it is possible to provide a hydraulic fluid composition having good compatibility with a sealing material and excellent lubricity (wear resistance).

Claims (2)

The following ester compound (A) and the following alkyl oxirane derivative (B) are contained, and the alkyl oxirane derivative (B) is contained in an amount of 1.0 to 30.0 parts by mass with respect to 100 parts by mass of the ester compound (A). A hydraulic fluid composition characterized by that.

(A) An ester compound of a neopentyl polyol having 5 to 10 carbon atoms and 3 to 6 valences of alcohol and a fatty acid having 6 to 22 carbon atoms

(B) An alkyloxirane derivative represented by the following formula (1) and satisfying the relationship of the formula (2):

R ¹ O— (AO) n—H (1)

(In the formula (1),
R ¹ represents a hydrocarbon group having 1 to 22 carbon atoms,
AO represents an oxyalkylene group having 3 carbon atoms,
n represents a number of 25 or more. )

_{0.35 ≦ M L / M H ≦} 0.75 ···· (2)

(On the chromatogram where the length of the perpendicular from the maximum point K at which the refractive index intensity on the chromatogram obtained by gel permeation chromatography measurement is maximum to the base line B is L and the refractive index intensity is L / 2) Of the two points, the earlier elution time is designated as point O, the later elution time is designated as point Q, and the intersection of the straight line G connecting point O and point Q and the perpendicular drawn from the maximum point K to the base line when is P, a distance between the point O and the intersection P and M _H, the distance between the point Q and the point of intersection P and M _L.)
The hydraulic fluid composition according to claim 1, wherein the alkyloxirane derivative (B) satisfies the relationship of the formulas (3) and (4).

As = W _1/2 / W _5% (3)
0.30 ≦ As ≦ 0.70 (4)

(Of the two points on the chromatogram where the refractive index intensity is L / 20, the earlier elution time is point R, the later elution time is point S, and the straight line H connecting point R and point S is (The intersection point between the maximum point K and the perpendicular drawn from the maximum point K to the base line B is T, the distance between the point R and the intersection point T is W _1/2 , and the distance between the point R and the point S is W _5% .)

Images