JPH03285989A - Hydraulic operating fluid for automobile - Google Patents

Abstract

PURPOSE:To provided the subject hydraulic oil expressing stable hydraulic response especially over a long period by employing a hydraulic fluid comprising an olefin oligomer, a specific diester and a polyol ester in a specific ratio. CONSTITUTION:The subject hydraulic oil especially having a viscosity of 4-8cSt (100 deg.C) and a low temperature flowability of 500-2500Pas (-40 deg.C) comprises (A) 70-90wt.% of an olefin oligomer, (B) a diester prepared from the condensation of a 4-14C aliphatic dibasic acid with a 4-14C alcohol and (C) 1-29wt.% of a polyolester.

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. This invention relates to automobile hydraulic fluid used in valves.

More specifically, the present invention relates to a synthetic lubricating oil based on an olefin oligomer, a diester, and a polyol ester, and has an excellent hydraulic response.

(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, performance requirements for hydraulic fluids such as PSE (power steering fluid), 5AF (shock absorber fluid), and ATF (automatic transmission fluid) are becoming increasingly strict. Recently, as a support device (suspension) for an automobile body, a hydrolink ram has been installed in place of the spring damper installed near the four wheels, and the ram is powered by hydraulic pressure from a pressure accumulator. drive the
There is a hydraulic mechanism that attempts to stably control the attitude of a 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 (ioo°C), (1) the flash point is as low as 100 to 140°C; 1) Poor oxidation stability, (iii) High evaporation loss of 15-35%, (
2) Poor anti-seizure properties due to low base oil viscosity; (1)
/) Shear stability, that is, low viscosity stability of hydraulic fluid due to shear force (viscosity decreases due to shear force in the sliding parts of piston pumps, nozzles of shock absorber pistons, etc.), mainly due to high molecular weight This is due to the low shear stability of PHA. 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, particularly to maintain stable hydraulic responsiveness over a long period of time.

The present invention solves the drawbacks of the above-mentioned mineral oil-based automotive hydraulic oils, and provides synthetic lubricating oils, especially automotive oils with excellent hydraulic response based on base oils consisting of olefin oligomers, diesters, and polyol esters. The purpose is to provide hydraulic fluid.

[Structure of the invention]

<Means for Solving Problem n> To summarize the present invention, the present invention is characterized in that the base oil base is (1) an olefin oligomer component (70 to 90 wt%), <i
i>Specific diester component (1 to 29 wt%), and (
Hydraulic oil characterized by being composed of a synthetic lubricating oil-based hydraulic oil consisting of a polyol ester component (1 to 29 wt%), and further containing a lubricating oil additive such as a viscosity index improver. This invention relates to hydraulic fluid for automobiles with excellent responsiveness.

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

Although the automotive 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 at several thousand times per 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);
To put it bluntly, we have a basic understanding that it is preferable that the viscosity index (V, I) of hydraulic oil be 230 or higher.

In addition, it goes without saying that the basic properties of this type of hydraulic fluid must be comprehensively excellent in terms of flammability, evaporability, oxidation stability, anti-seizure properties, shear stability, etc. as mentioned above. There is no such thing.

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 fluid of the present invention is characterized in that the base oil base is composed of an olefin oligomer component, a diester 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.

(1) Olefin oligomer component: The olefin oligomer component used in the present invention is any one selected from olefin hydrocarbons having 2 to 14 carbon atoms, preferably 4 to 12 carbon atoms, with or without branching. It is obtained by homopolymerization of different types or copolymerization of two or more types, and the viscosity ranges from 1.0 to 130C3t, preferably from 1.5 to 25C8t. In addition, the average molecular weight is about 100 to about 2000, preferably about 200 to about 1
000 products, with particular preference given to those from which unsaturated bonds have been removed by hydrogenation. Preferred olefin oligomer components include, for example, α-olefin oligomers, ethylene/α-olefin oligomers, and the like. The α-olefin oligomer is 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 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 the ethylene/α-olefin oligomer, ethylene is 40% to 90% by weight.
, other α-olefins such as propylene are 10
A mixture of monomers in a proportion of 60% by weight and polymerized 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.

(ii) Diester component: The diester hydraulic fluid used in the present invention has a carbon number of 4.
It is obtained by condensation of an aliphatic dibasic acid having 4 to 14 carbon atoms and an alcohol having 4 to 14 carbon atoms.

Preferred aliphatic dibasic acids having 4 to 14 carbon atoms include succinic acid, glutaric acid, adipic acid, pimelic acid,
Speric acid, azelaic acid, sebacic acid, undecanol, dodecanoic acid, brassicic acid, and tetradecanoic acid can be mentioned, and among these, particularly preferred are adipic acid, azelaic acid, and sebacic acid, and the most preferred are is necessary for adipic acid and sebacic acid.

Among the alcohols having 4 to 14 carbon atoms, preferred are n-butanol, isobutanol, 0-amyl alcohol, isoamyl alcohol, n-hexanol, 2-ethylbutanol, cyclohexanol, n-
heptatool, isoheptatool, methylcyclohexanol, n-octatool, dimethylhexanol, 2
-Ethylhexanol, 2゜4.4-trimethylpentanol, isooctatool, 3.5.5-trimethylhexanol, isononanol, isodecanol, isoundecanol, 2-butyloctatool, tridecanol and isote1-radecanol, etc. Particularly preferred among these are 2-ethylhexanol and isodecanol.

Next, specific examples of the diester component used in the present invention are listed below.

Di(1-ethylpropyl)adipate, Di(3-methylbutyl)adipate, Di(1,3-methylbutyl)adipate, Di(2-ethylhexyl)adipate, Di(isononyl)adipate, Di(isodecyl)
Adipate, Di(undecyl)adipate, C(tridecyl)adipate, Di<isotetradecyl>adipate, Di(2,2゜4-trimethylpentyl)adipate, Di[mixed (2-ethylhexyl, isononyl)]adipate, Di( 1-ethylpropyl) azelate, di-(3-methylbutyl) azelate, di(2-
Ethylbutyl) azelate, C(2-ethylhexyl) azelate, Di(isooctyl) azelate, Di(isononyl) azelate, Di(isodecyl) azelate, Di(tridecyl) azelate, Di[Mixed(2-ethylhexyl)
-ethylhexyl, isononyl)] azelate, di[
Mixed (2-ethylhexyl, decyl)] azelate, mixed (2-ethylhexyl, isodecyl) coazelate, di[mixed (2-nitylhexyl, 2-propylheptyl)] azelate, di(n-butyl) sebacate, di( isobutyl) sebacate, di(1-ethylpropyl) sebacate, di(1,3-methylbutyl)
Sebacate, di(2-methylbutyl) sebacate, di(2-ethylhexyl) sebacate, di(2-(2
-Ethylbutoxy)ethylbutyrate, di(2°2.
4-trimethylbenzyl) sebacate, di-(isononyl) sebacate, di-(isodecyl) sebacate, di-(isoundecyl) sebacate, di-(tridecyl) sebacate, di-(isotetradecyl) sebacate, di [mixed (2-ethylhexyl, isononyl)] Sebacate, C(2-ethylhexyl)glutarate, Di(
These include isoundecyl) glutarate and di(isotetradecyl) glutarate.

The diester component described above has a viscosity of 2 at 100°C.
to 7C3t, preferably 2.2 to 7.0CSt
belongs to. If the viscosity is lower than this, there will be problems with flammability, volatility, and load resistance, and if it is higher than this, the effect of mixing will not be obtained and the viscosity at low temperatures will become too large.

Polyol ester component: The polyol ester component, which is a component of the third hydraulic fluid used in the present invention, is synthesized from a polyol having 5 to 9 carbon atoms and a fatty acid having 4 to 18 carbon atoms.

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 TMP), and pentaerythritol (hereinafter referred to as TMP).
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, impentanoic acid, n-hexanoic acid,
2-ethylbutanoic acid, cyclohexanoic acid, n-hebutanoic acid, isohbutanoic acid, methylcyclohexanoic acid, n-octanoic acid, dimethylhexanoic acid, 2-ethylhexanoic acid, 2,4.4-trimethylpentanoic acid, isooctanoic acid , 3.5.5-trimethylhexanoic acid, n-nonanoic acid,
Isononanoic acid, isodecanoic acid, isoundecanoic acid, 2-
These include butyloctanoic acid, tridecanoic acid, tetradecanoic acid, hexadecanoic acid and octadecanoic acid; preferred are heptanoic acid, n-octanoic acid, and 2-ethylhexanoic acid.

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

NPG-C ('V7ri/I-to), NPG
・C (2-ethylbutyrate), NPG・G (
cyclohexanoate), NPG C (isoheptanoate), NPG C (octylate), NP
G.G. (2-ethylhexanoate), NPG.C. (isooctanoate), NPC.C. (innonylate), NPG.G. (isodecanoate), NP
G・G [mixture (hexanoate, heptanoate)
],,NPG・G [mixture (hexanoate, octanoate)],NPC・C [mixture (hexanoate, octanoate)]
nonylate) ], NPG・G [mixture (heptanoate, octanoate)], NPC・G [mixture (heptanoate, nonylate)], NPC・G [mixture (heptanoate, isooctanoate)], HPG・
G [Mixture (heptanoate, isononylate)]
, NPG-G [mixture (isooctanoate, isononylate)], NPG-G [mixture (butanoate,
tridecanoate) ], NPG・G [mixture (butanoate, tetrazocaate)], HPG・C [
Mixture (butanoate, hexadecanoate)], N
PG・C [mixture (butaneate, octadecanoate)], NPG・G [mixture (hexanoate, isooctanoate, isononylate)], NPC・G [mixture (hexanoate, isooctanoate, isononylate)]
Mixture (Hexanoate, Isooctanoate, Isononylate)], NPG Sea [Mixture (Heptanoate, Isooctanoate, Isononylate)],
NPC・G [mixture (heptanoate, isooctanoate, isodecanoate)], NPC・G [mixture (octanoate, isononylate, isodecanoate) co, DingHP・Tree (pentanoate), THP
・Tori (hexanoate), THP ・Tori (
heptanoate), THP-tree (octanoate), THP-tree (nonylate), THP-tree
Tory (isopentanoate), Ding HP・Tory (2
-ethyl butyrate), Ding MP/Tori (isopetanoate), Ding HP/Tori (isooctanoate), T
HP ・Tori (2-ethylhexanoate), TH
P-tree (isononylate), THP-tree (isodecanoate), THP-tree [mixture (butyrate, octadecanoate)], THP-tree [mixture (hexanoate, hexadecanoate)]
, THP-tree [mixture (heptanoate, tridecanoate)], DHP-tree [mixture (octanoate, decanoate)], THP-tree [mixture (octanoate, nonylate)], THP-tree [mixture (butyrate, heptanoate, octadeca)] Noate)], THP/Tree [Mixture (pentanoate, heptanoate, tridecanoate)]
, THP・Tree [mixed (hexanoate, heptanoate, octanoate)], PE・tetra (pentanoate), PE・tetra (hexanoate),
PE・tetra(isopentanoate), PE・tetra(
2-ethylbutyrate), PE・tetra(isoheptanoate), PE・tetra(isooctanoate), PE
-Tetra (2-ethylhexanoate), PE-tetra (isononylate), and esters of PE and mixtures of linear or branched carboxylic acids having 4 to 8 carbon atoms.

Among these, particularly preferred are d)IP.tri(octanoate) and NPC.cy(isooctanoate). Also, the viscosity range is from 1.0 to 100
cSt, preferably 1,5 to 22 CSt.

The base oil base of the automotive hydraulic oil of the present invention is composed of the above-mentioned (1) olefin oligomer component, (ii) diester component, and (iii) polyol ester component, and these base oil bases are From the viewpoint of effectiveness, preferably (i) the olefin oligomer component is 70 to
90% by weight, Xun) diester component is 1-29% by weight, (
iii) Polyol esters are used in proportions of 1 to 29% by weight. Particularly preferably, (i) the olefin oligomer component is used in a proportion of 75 to 85% by weight, (No. 1) the diester component is used in a proportion of 5 to 20% by weight, and (iii) the polyol ester component is used in a proportion of 5 to 20% by weight. . At this blending ratio, the above-mentioned performance requirements for hydraulic fluids, that is, not only good viscosity-temperature properties, but also evaporation properties, shear stability, etc., which are contradictory to improvements in viscosity-temperature properties, are effectively improved. Furthermore, oxidative stability is also improved. When the total amount of (ii) and (iii) exceeds 30% by weight, the low-temperature viscosity deteriorates and the rubber members forming 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, various additives are added to the blended base oil consisting of the above-mentioned (1) olefin oligomer component, (ii) diester component, and (i) mepolyol ester component in order to improve the properties of the hydraulic fluid. It goes without saying that they may be combined.

This type of additive will be explained below.

(1) Viscosity index improver: As described above, high molecular weight PHA is used in 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 above-mentioned PHA type, we also have PIB (polyisobutylene), EPC (ethylene-propylene copolymer), 5PC
(styrene-butadiene hydrogenated copolymer), etc. are used. The amount of these used is 5 to 20% by weight, which is sufficient.

(ii) Anti-wear agent: Anti-wear agents such as phosphate esters and phosphite esters are used in the hydraulic oil of the present invention in order to improve frictional properties and anti-wear properties.

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 from the viewpoint of effectiveness, 0.05 to 2.0% by weight is sufficient.

(ii9 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, succinimide-based, benzylamine-based, and ester-based These are used in a proportion of 0.05 to 0.5% by weight.

2. Metal deactivators: These are used for the purpose of preventing corrosion of metals caused by oxidation and heat deterioration products of oil and preventing elution of metals into base oil. For example, thiadiazole-based and triazole-based It is used in a proportion of 0.01 to 0.3% by weight.

(%/) Antioxidant: In the present invention, commonly used antioxidants such as amine antioxidants and phenolic antioxidants are used. For example, examples of amine-based antioxidants include alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated-α-naphthylamine, and examples of phenolic antioxidants include 2,6-ditobutylphenol and 4.4-di-butylphenol. -methylenebis(2,6-di-t-butylphenol), etc., and these are usually 0.05 to 0.
．． It is used in a proportion of 5% by weight.

In the present invention, other antifoaming agents such as dimethylpolysiloxane and polyacrylate; rust preventive agents such as alkenylsuccinic acid or its partial ester; and Ca-sulfonate and 8g-sulfonate for neutralizing oxidative deterioration products of oil. , 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 7/Comparative Examples 1 to 3 To prepare various automotive hydraulic fluids 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 2.2C8t (Note 1) at 100℃, 2.4
cSt (Note 2) and 2.3C3t (Note 3) were used.

Diester (to DO)... Di(2-ethylhexyl)adipate. The one used had a viscosity of 2.3 cSt at 100°C.

Diester (DiDA)...Di(isodecyl)adipate. The one used had a viscosity of 3.6 C8t at 100°C.

Polyol ester: Trimethylolpropane trioctanoate. The one used had a viscosity of 4.0C3t at 100°C.

Ashless dispersant...Alkenyl succinic acid polyalkylene polyimide Antioxidant...-(phenolic) 2.6-di-t-butyl-4-methylphenol antioxidant...Beametsu System) Bis(P-octylphenyl) Amine total bending deactivator...Benzotriazole-based viscosity index improver...Polymethacrylate (weight average molecular weight 35,000) (weight average molecular weight 80 .000) Anti-wear agent (phosphate ester)... Monooleyl phosphate 10 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 blank) [Effects of the invention] The olefin oligomer component and diester component of the present invention,
Synthetic lubricating oil based on polyol ester component and polyol ester component has excellent viscosity-temperature characteristics, as well as flammability, oxidation stability, evaporation property, anti-seizure property,
It also has excellent 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 is obtained by condensation of (i) 70 to 90% by weight of olefin oligomer, (ii) aliphatic dibasic acid having 4 to 14 carbon atoms, and alcohol having 4 to 14 carbon atoms. 1 to 29% by weight of diester, (iii)
A hydraulic fluid for automobiles, characterized in that the hydraulic fluid is composed of 1 to 29% by weight of polyol ester. (2) Hydraulic oil for automobiles is obtained by condensation of (i) 70 to 90% by weight of olefin oligomer, (ii) aliphatic dibasic acid having 4 to 14 carbon atoms, and alcohol having 4 to 14 carbon atoms. 1 to 29% by weight of diester, (iii)
A hydraulic fluid for an automobile, comprising a hydraulic fluid comprising 1 to 29% by weight of a 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).