JPH03285988A - Hydraulic operating fluid - Google Patents

Abstract

PURPOSE:To provided the subject hydraulic oil expressing stable hydraulic response especially over a long period by employing a hydraulic oil comprising an olefinic oligomer and a polyol ester in a specific ratio. CONSTITUTION:The subject hydraulic oil preferably having a viscosity of 4-8cSt (100 deg.C) and a low temperature flowability of 500-2500mPa (-40 deg.C) comprises (A) 75-90wt.% of an olefin oligomer and (B) 10-25wt.% of a polyol ester. The component A is prepared from the (co)polymer of a 2-14C olefinic hydrocarbon which may have a (preferably 4-12C) branch, and the component B is synthesized from a 5-9C polyol and a 4-18C fatty acid.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a hydraulic fluid suitable for use in various hydraulic mechanisms for automobiles, and in particular to a hydraulic fluid that has stable hydraulic response over a long period of time. The present invention relates to hydraulic fluid for automobiles.

More specifically, the present invention relates to a synthetic lubricating oil-based hydraulic fluid for automobiles having excellent hydraulic responsiveness and having a base oil base consisting of an olefin oligomer and a polyol ester.

(Prior Art) Automobiles are equipped with various hydraulic mechanisms, but the performance of the hydraulic fluid used in these hydraulic systems is becoming increasingly demanding. For example, PSE (power steering fluid), 5AF (shock absorber fluid)
Performance requirements for hydraulic fluids such as automatic transmission fluid and automatic transmission fluid are becoming increasingly strict.

Recently, as a support device (suspension) for automobile bodies, hydraulic rams have been installed in place of spring dampers installed near the four wheels, and hydraulic rams have been installed in place of the spring dampers installed near the four wheels. There is a hydraulic mechanism that drives the ram to stably control the attitude of the vehicle body, but the required performance of the hydraulic fluid used in this mechanism is also severe.

Taking into consideration the harsh usage environment of automobiles, the basic characteristics of the hydraulic fluid used in the various hydraulic mechanisms of automobiles mentioned above are particularly good viscosity characteristics on the high temperature side and good low-temperature flow on the low temperature side. properties, that is, good viscosity-temperature properties, and furthermore, excellent oxidation stability.

Hitherto, hydraulic fluids based on mineral oil base oils have been known as hydraulic fluids used for this type of use. In other words, a high molecular weight PH
A (Polymethacrylate) type viscosity index improver is blended in a large amount to provide desired viscosity-temperature characteristics.

(Problems to be Solved by the Invention) However, in the case of the conventional mineral oil-based hydraulic fluid described above, although the viscosity-temperature characteristics are satisfactory, other characteristics are insufficient. More specifically, in order to obtain the desired viscosity-temperature characteristics, the base oil viscosity must be approximately 2.
When a large amount of PHA is added as a viscosity index improver to mineral oil at centistokes (100°C) to make it approximately 6 centistokes (100°C), (1) the flash point is as low as 100 to 140°C; (ii) )
Poor oxidation stability, (ut) high i-induced loss of 15-35%, (b) poor anti-seizure properties due to low base oil viscosity, (V)
Shear stability, that is, low viscosity stability of hydraulic oil due to shear force (viscosity decreases due to shear force in piston pump sliding parts, shock absorber piston nozzles, etc.) This is due to low shear stability). That is, in the above-mentioned hydraulic fluid made of mineral oil and PHA, it is extremely difficult to maintain various properties of the hydraulic fluid over a long period of time, especially to maintain stable hydraulic response over a long period of time.

The present invention solves the drawbacks of the above-mentioned mineral oil-based automotive hydraulic fluid, and provides an automotive hydraulic fluid with excellent hydraulic response based on a synthetic lubricating oil system, particularly a base oil consisting of an olefin oligomer and a polyol ester. The purpose is to provide oil.

[Structure of the invention]

(Means for Solving the Problems) To summarize the present invention, the present invention provides a synthetic lubricating oil type hydraulic oil in which the base oil base is composed of an olefin oligomer component and a polyol ester component, The present invention relates to a hydraulic fluid for automobiles that is characterized by containing a lubricating oil additive such as an index improver and has excellent hydraulic responsiveness.

Hereinafter, the configuration of the present invention will be explained in detail.

Although the automobile hydraulic fluid of the present invention is applied to a wide range of hydraulic systems, the severity of its performance requirements will be examined in the context of the above-mentioned attitude control system. That is, as mentioned above, in hydraulic systems that use hydraulic pressure to control the attitude of the vehicle body, rather than the conventional suspension mechanism using spring dampers, advances in microprocessor technology have enabled thousands of sensors to collect road surface information. /second, for example, 3000 pieces/second, and the posture is controlled in accordance with this. Therefore, for accurate attitude control, the hydraulic fluid must respond stably over a long period of time to hydraulic drive instructions of several i ooo times/second.

The present inventors have generally found that hydraulic fluids used for this type of use have good viscosity properties on the high temperature side, specifically 4 to 8 centistokes (100 cm °C), good low-temperature fluidity on the low temperature side, specifically 500 to 2500 milliPascal seconds (mPa
s) having a viscosity-temperature characteristic of (-40°C);
In other words, we have a basic understanding that it is preferable for hydraulic oil to have a viscosity index (V, I) of 230 or more.

However, as mentioned above, the basic properties of this type of hydraulic fluid must be comprehensively excellent in terms of flammability, oxidation stability, evaporation, anti-seizure properties, and shear stability. It's a no-brainer.

The present invention aims to prepare a hydraulic oil for automobiles having the above-mentioned required performance by using a specific synthetic lubricating oil from one based on mineral oil. That is, the automotive hydraulic oil of the present invention is characterized in that the base oil base is composed of an olefin oligomer component and a polyol ester component. Further, the present invention is characterized in that lubricating oil additives are blended into the synthetic lubricating oil blend base oil in order to further improve various properties of the hydraulic oil.

Each component used in the automobile hydraulic fluid of the present invention will be explained in detail below.

The olefin oligomer component used in the present invention is any one kind of homopolymerized or two or more kinds of olefin hydrocarbons with or without branching in the range of 2 to 14 carbon atoms, preferably 4 to 12 carbon atoms. It is obtained by copolymerization of
Preferably it is 1.5 to 25 cS1. In addition, the average molecular weight is about 100 to about 2000, preferably about 2
00 to about 1000, with particular preference given to products with unsaturated bonds removed by hydrogenation. Preferred olefin oligomer components include, for example, α-
There are olefin oligomers, ethylene/α-olefin oligomers, etc. As α-olefin oligomer,
A mixture of α-olefins having 6 to 12 carbon atoms obtained by trimerization to hexamerization of hydrocarbons or lower olefins, such as 25% to 50% by weight of hexene-1 and octene-1.
A copolymerized mixture of 30% to 40% by weight of 1 and 25% to 40% by weight of decene-1 can be used. Also suitable are oligomers obtained from single polymers such as decene. Furthermore, as an ethylene/α-olefin oligomer, ethylene is 40% by weight or more.
A mixture of 90% by weight monomers and 10% to 60% by weight of other α-olefins, such as propylene, can be used.

These olefin oligomers can be produced using a Friedelta raft type catalyst such as aluminum chloride or boron fluoride, a Ziegler catalyst, or an oxide catalyst such as chromium oxide. Hydrogenation of the olefinic oligomer can also be carried out by removing the catalyst from the reaction product and then bringing it into contact with a hydrogenation catalyst such as nickel-molybdenum/alumina under heating and pressure.

Polyol esters, which are components of other hydraulic fluids used in the present invention, include polyols having 5 to 9 carbon atoms and 4 to 4 carbon atoms.
It is synthesized from ~18 fatty acids.

The polyols having 5 to 9 carbon atoms used in the synthesis of the polyol ester of the present invention include neopentyl glycol (hereinafter referred to as NPG), trimethylolpropane (hereinafter referred to as THP), pentaerythritol (hereinafter referred to as THP), and pentaerythritol (hereinafter referred to as THP).
Hereinafter, it will be referred to as PE. ), 2-methyl-2-propylpropane-1,3-diol, 2,2-diethyl-propane-diol, trimethylolethane, trimethylolhexane, and the like. In addition, examples of the fatty acids having 4 to 18 carbon atoms include n-butanoic acid, isobutanoic acid,
n-pentanoic acid, isopentanoic acid, rhohexanoic acid, 2
-ethylbutanoic acid, cyclohexanoic acid, n-hebutanoic acid, isohebanoic acid, methylcyclohexanoic acid, n-octanoic acid, dimethylhexanoic acid, 2-ethylhexanoic acid,
2.4.4-i-limethylbentanoic acid, isooctanoic acid, 3.5.5-trimethylhexanoic acid, n-nonanoic acid, isononanoic acid, isodecanoic acid, isoundecanoic acid,
These include 2-butyloctanoic acid, tridecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid; preferred are heptanoic acid, 0-octanoic acid, and 2-ethylhexanoic acid.

Next, specific examples of the polyol esters used in the present invention are listed below.

NPG G (heptanoate), NPG G (
2-ethylbutyrate), NPG-G (cyclohexanoate), NPC-G (isoheptanoate), NPG-G (octylate), NPG-G (2-ethylhexanoate), NPC-C (iso-octanoate) Noate), NPG G (isononylate),
NPC・G (isodecanoate), NPG・G
[Mixture (hexanoate, heptanoate)], NPG
・G [mixture (hexanoate, octanoate)
], NPG-G [mixture (hexanoate, nonylate)], NPG-G [mixture (heptanoate, octanoate)], NPG-G [mixture (heptanoate, nonylate)], NPG-G [mixture (
heptanoate, isooctanoate)], NPG-G [mixture (heptanoate, innonylate)], NP
G.G [mixture (isooctanoate, isononylate)], NPG.G [mixture (butanoate, tridecanoate)], NPG.G [mixture (butanoate, tetrazocaate)], NPG.G [mixture (butanoate, tridecanoate)] hexadecanoate)], NPG
・G [mixture (butanoate, octadecanoate)
], NPC・G [mixture (hexanoate, isooctanoate, isononylate)], NPG・G [
Mixture (hexanoate, isooctanoate, isodecanoate)], NPG sea [mixture (heptanoate,
isooctanoate, isononylate) ], NPC
・Sea [mixture (heptanoate, isooctanoate,
isodecanoate)], NPG-G [mixture (octanoate, isononylate, isodecanoate)],
TMP ・Tori (pentanoate), Ding HP ・Tri (hexanoate), THP ・Tri = (heptanoate), Ding HP ・Tori (octanoate), TM
P-tri(nonylate), THP-tri(isopentanoate), THP-tri(2-ethylbutyrate), DHP-tri(isopentanoate)
, THP/Tree (isooctanoate), D) IP/
Tri(2-ethylhexanoate), HP Tri(isononylate), THP Tri(isodecanoate), THP Tri(mixture(butyrate,
octadecanoate)], THP・Tree [mixture (hexanoate, hexadecanoate)], T'
MP・Tree [mixed (heptanoate, tridecanoate)], TMP・Tree [mixed (octanoate, decanoate)], T)4P・Tree [mixed (octanoate, nonylate)], DingHP・Tree [mixed (butyrate, heptanoate, octanoate)] decanoate)], THP-tree [mixture (pentanoate, heptanoate, tridecanoate)-)], T)
IP・Tree [mixture (hexanoate, heptanoate, octanoate)], PE・tetra (pentanoate), PE・tetra (hexanoate), PE・
Tetra (isopentanoate), PE Tetra (2-
PE/tetra(isoheptanoate), PE/tetra(isooctanoate), PE/tetra(2-ethylhexanoate), PE/tetra(isononylate), and PE with carbon number 4~ 8 with a mixture of linear or branched carboxylic acids, etc. Particularly preferred among these are THP tree (
octanoate) and NPC・G(isooctanoate). Also, the viscosity range is 1.0 to 100cSt
, preferably 1.5 to 22C3t.

The base oil base of the automotive hydraulic oil of the present invention is composed of the above-mentioned olefin milligomer component and polyol ester component, and from the viewpoint of effectiveness, the base oil base preferably contains 75% of the olefin oligomer component. ~
90% by weight, 10-2% polyol ester hydraulic fluid
5% by weight, particularly preferably 75 to 85% by weight of the olefin oligomer component, and 15 to 2% by weight of the polyol ester component.
It is composed of 5%. At this blending ratio,
In addition to the above-mentioned performance requirements for hydraulic fluids, that is, good viscosity-temperature characteristics, evaporability, shear stability, etc., which have a contradictory relationship with improvement of the viscosity-temperature characteristics, are effectively improved, and furthermore, oxidation stability is improved. will also be improved. If the polyol ester component exceeds 25% by weight in the blending ratio, the low-temperature viscosity deteriorates and the rubber members constituting the hydraulic system tend to swell, so care must be taken. Furthermore, if the olefin oligomer component exceeds 90% by weight, there is a tendency for the rubber member to become hard, so care must be taken.

In the present invention, it goes without saying that various additives may be added to the blended base oil of the olefin oligomer component and polyol ester component described above in order to improve the properties of the hydraulic fluid. be.

This type of additive will be explained below.

(i) Viscosity index improver: As described above, high molecular weight PHA is used in conventional mineral oil-based hydraulic fluids.

In the present invention, since the synthetic lubricant-based blended base oil itself exhibits good viscosity-temperature characteristics, it has a weight average molecular weight of 30,000 to 100,000, which has better shear stability than a high molecular weight one. By blending a PHA-based viscosity index improver with a low molecular weight, preferably from 30,000 to 80,000, the properties of the hydraulic fluid can be further improved.

In addition to the PHA system, PIB (polyisobutylene), EPC (ethylene-propylene copolymer), 5p
c (styrene-butadiene hydrogenated copolymer), etc. are used. The amount used is 5 to 25% by weight.

(11) Anti-wear agent: In the hydraulic fluid of the present invention, an anti-wear agent such as a phosphate ester or a phosphite ester is used in order to improve friction characteristics and anti-wear characteristics.

The above-mentioned phosphoric esters are used especially to improve initial low friction properties and anti-wear properties, and phosphorous esters are used to ensure especially low friction properties over a long period of time. be. Conventional antiwear agents such as these phosphoric acid compounds may be used, and the amount used is 0.05 to 2.0% by weight from the viewpoint of effectiveness.

(Xun Ashless dispersant: This is used for the purpose of dispersing oil deterioration products, phosphorus-based anti-wear agents, etc. in oil. For example, succinimide-based, amide-based, benzylamine-based, and ester-based These are used in a proportion of 0.05 to 0.5% by weight.

倚 Metal deactivators: These are used to prevent corrosion of metals due to oxidation and heat deterioration products of oil and to prevent metals from leaching into base oil.For example, thiadiazole-based and triazole-based It is used in a proportion of 0.01 to 0.3% by weight.

(V) Antioxidant: In the present invention, commonly used antioxidants such as amine antioxidants and phenolic antioxidants are used. For example, examples of amine antioxidants include alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated α-naphthylamine, and examples of phenolic antioxidants include 2,6-di-t-butyl-4
-Methylphenol, 4,4'-methylenebis(2,6
-di-t-butylphenol), etc., and these are usually used in a proportion of 0.05 to 0.5% by weight.

In the present invention, other antifoaming agents such as dimethylpolysiloxane and polyacrylate; rust preventive agents such as alkyl succinic acids or partial esters thereof; and Ca-sulfonate and Hq- Sulfonate, Ba-sulfonate, Ca-phenate,
Metal detergents such as Ba-phenate can be used if desired.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples.

Examples 1 to 5/Comparative Examples 1 to 2 Various automotive hydraulic fluids were prepared using the base oil components and additive components shown in Table 1 (the proportions of each component used are shown in parts by weight). ing).

In addition, each component means the following; PAO
...1-decene α-olefin oligomer viscosity is 2.3 cSt (Note 1), 1.7 cS at 100°C
t (Note 2), 2.4cSt (Note 3) 2.2cSt
(Note 4) was used.

Polyol ester: Trimethylolpropane trioctanoate.

One with a viscosity of 4.0C8t used.

Mineral oil: A viscosity of 2.0 cSt (100°C) was used.

Ashless dispersant: Alkenylsuccinic acid polyalkylene polyimide Antioxidant: (phenolic) 2,6-di-t-butyl-4-methylphenol antioxidant: (Amine-based) Bis(P-octylphenyl) Amine metal deactivator...Benzotriazole-based viscosity index improver...Polymethacrylate low molecular weight (
Weight average molecular weight 35,000.70.000.80,
000) High molecular weight (weight average molecular weight 120,0DD) anti-wear agent (
phosphoric acid ester)... Monooleyl phosphate Dioleyl phosphate anti-wear agent (phosphite)... Dioleyl phosphite antifoaming agent... Dimethylpolysiloxane Next, the performance of each hydraulic fluid was evaluated.

The results are also shown in Table 1. (In addition, oxidation stability is
According to JIS Section 25143.3. ) (Hereinafter in the margin) [Effects of the Invention] The synthetic lubricating oil-based hydraulic fluid based on the olefin oligomer-based hydraulic fluid and ester-based hydraulic fluid of the present invention has excellent viscosity-temperature characteristics, and flammable,
It also has excellent oxidation stability, evaporation properties, anti-seizure properties, and shear stability.

Therefore, the hydraulic fluid of the present invention is useful for various hydraulic systems installed in automobiles, and is characterized by excellent hydraulic response over a long period of time.

Claims (3)

[Claims] (1) Hydraulic oil for automobiles, characterized in that the hydraulic oil for automobiles consists of a hydraulic fluid composed of 75 to 90% by weight of olefin oligomer and 10 to 25% by weight of polyol ester. (2) The hydraulic oil for automobiles is characterized in that the hydraulic oil for automobiles consists of a hydraulic fluid composed of 15 to 90% by weight of olefin oligomer and 10 to 25% by weight of polyol ester, and a lubricating oil additive. . (3) Hydraulic fluid is 4 to 8 centistokes (100℃
The automotive hydraulic fluid according to claim 1 or 2, which has a viscosity of 500 to 2500 mPas (-40°C) and low-temperature fluidity of 500 to 2500 mPas (-40°C).