JP5378632B2 - Hydraulic fluid - Google Patents

Description

  The present invention relates to a hydraulic fluid.

WO 93/03121 relates to a hydraulic fluid with improved wet filterability and zinc loss resistance when exposed to water. These hydraulic fluid compositions comprise (A) a metal salt selected from the group consisting of sulfonate, phenolate, carboxylate and mixtures thereof; (B) an aliphatic group having at least 20 carbon atoms in the aliphatic group A carboxylic acid group comprising a group carboxylic acid or anhydride, or derivative thereof, and optionally (C); (C) (I) at least one organic phosphorous acid, or (C) (I) at least one organic A combination of a metal salt of phosphorous acid and a mixture of (C) (II) at least one carboxylic acid group, and optionally (D) a triazole. In one embodiment, the carboxylic acid of (A) is an aromatic carboxylic acid. These aromatic carboxylic acids, particularly zinc, calcium and magnesium salts of salicylic acid are preferred. Both magnesium salicylate and zinc dithiophosphate, which are themselves mentioned, do not teach the use of these compounds in combination.
WO 89/04358 describes (A) neutral or basic metal salts of acidic organic compounds, (B) metal deactivators, preferably optionally substituted benzotriazoles, and (C); ) A phosphorus-containing amide, (C-2) a phosphorus-containing ester, (C-3) a sulfur-coupled dithiocarbamate, (C-4) a sulfur selected from the group consisting of a sulfur-containing compound of formula (I) and / or Or relates to a composition comprising a phosphorus-containing compound. Particularly preferred metals for the metal salt (A) are sodium, magnesium, calcium or a mixture of two or more thereof. A wide range of examples of other compounds that can be present include zinc dialkyldithiophosphates. Both magnesium salicylate and zinc dithiophosphate, which are themselves mentioned, do not teach the use of these compounds in combination.

EP-A-604218 contains a large amount of lubricating viscous oil, at least one metal salt of thiophosphoric acid, a zinc salt of salicylic acid, and a rust inhibitor and is basic with a dispersant content of less than about 1% by weight. Functional fluids are described in which the sulfonate content is less than about 1% by weight. The most common thiophosphoric acid is dihydrocarbyl dithiophosphoric acid and the most preferred metal is zinc. This document only teaches the use of zinc salicylate.
US-A-4,627,928 describes a basic magnesium salicylate which may be characterized in that the magnesium content is 150% or more and 500% or less with respect to the theoretical equivalent of magnesium based on the total amount of acid present. A manufacturing method is described. The obtained magnesium salt is generally described as being suitable for use as an additive, more specifically as an additive for various lubricating oils and fuels such as gasoline and diesel fuel. These particular magnesium salicylates state that they can be used in combination with a wide range of other compounds. There is no disclosure or teaching about the combined application of zinc dithiophosphate and zinc salicylate in the hydraulic fluid.

The hydraulic fluid needs to meet two special requirements of smoothing and transferring pressure. In order to meet these requirements, the hydraulic fluid contains additives. Generally, the hydraulic fluid contains an antiwear / extreme pressure additive. In a vane pump in which a vane tip slides on a casting at high speed and high temperature under high load, the conditions for the working fluid are particularly difficult. In addition, modern hydraulic equipment with ever higher operating temperatures requires a heat-stable liquid to avoid deposition and sludge formation and to prevent corrosion of both ferrous and non-ferrous metals. The reason why good thermal stability is required for hydraulic fluids containing antiwear additives is that these additives are often used in combination with detergents. However, commonly applied calcium salts of alkylbenzene sulfonates, alkyl naphthalene sulfonates, petroleum sulfonates, alkyl phenolates, alkyl sulfurized phenolates or alkyl salicylates increase wear. The increase in wear is particularly noticeable in vane pumps, and more particularly in low load conditions. Low load conditions occur during pump idle operation.
WO-A-97 / 10318 describes a lubricant that improves acid neutralization characteristics in a continuous (Seq.) 5E test and exhibits excellent sludge / wear performance. The lubricant uses a detergent system containing at least one alkali or alkaline earth metal of an oil-soluble organic acid selected from the group consisting of sulfonic acid, phenol, sulfurized phenol and carboxylic acid (including salicylic acid). It is formed. Here, at least one metal salt is excessively basified, and inorganic salts and organic salts present in the detergent system expressed as TBN from inorganic salts (for overbasing) to total molar organic salts. The weight ratio of is at least 2500.
US-A-5558802 describes multi-grade lubricants for crankcases that have good low temperature pumpability and low volatility.
US-A-5558802 states that neutral and overbased calcium salts of organic acids have been found to increase in low-temperature high-shear viscosity when measured with a low-temperature crank rotation simulator (CCS).
US-A-5558802 also provides a lubricant with a high shear rate and low CCS viscosity (ie, facilitating engine cranking at low temperatures and thus improving engine startability at low ambient temperatures). States that these salts should not be used at all, or that calcium salts should be used in a molar amount of 0.0007 or less per 100 g of lubricant.
WO-A-96 / 37582 describes lubricating oil compositions used for internal combustion engines, automatic transmission gearboxes, dampers, power steering units and the like.
The lubricating oil described in WO-A-96 / 37582 contains a sulfothiomolybdate dithiocarbamate having a specific alkyl group, a zinc dialkyldithiophosphate having a specific alkyl group, a specific alkyl salicylate, and, if desired, a boron Each of the succinimides contains a specific amount in the lubricant base material.
US-A-4462918 contains a large amount of lubricating oil and a small amount of each group II dithiophosphate metal salt and the formula: R ¹ O.I. CO. CR ² (NR ³ R ⁴ ). CR ⁶ R ⁷ . CO. OR ⁵ (wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are hydrogen or a hydrocarbon residue having 1 to 30 carbon atoms, and R ³ or R ⁴ is And a composition having hydrogen, independently selected from hydrocarbon residues having 1 to 30 carbon atoms and acyl having 1 to 30 carbon atoms.

It has now been surprisingly found that hydraulic fluids containing a combination of magnesium salicylate and zinc dithiophosphate show superior performance at low loads compared to combinations containing calcium salicylate. Furthermore, this combination has also been found to improve thermal stability. When the hydraulic fluid of the present invention is tested in the Cincinnati Milacron thermal stability test, sludge and sediment formation is low.
The present invention provides a hydraulic fluid comprising a lubricant base oil in combination with (a) 0.001 to 5% by weight of magnesium salicylate and (b) 0.01 to 8% by weight of zinc dithiophosphate. These amounts are based on the total amount of hydraulic fluid.

  The magnesium salicylate used in the present invention may be neutral or excessively basified. The expression “over-basic” refers to “basic”, “super-basic”, “hyper-basic” and “salts with high metal content”. These magnesium salicylates contain an excess of metal compared to the amount of metal present according to the stoichiometry of the metal and the salicylic acid reacted with the metal. Methods for making such neutral and basic metal salts are well known in the art. Neutral salts heat a mineral oil solution of an acidic organic compound with a theoretical equivalent of a metal neutralizer, such as a metal oxide, hydroxide, carbonate, bicarbonate or sulfide, at a temperature above 50 ° C. Then, it is made by filtering the resulting mass. Basic salts are made in the same way except that a theoretical excess of the metal is used.

Preference is given to using an overbased magnesium salicylate. These compositions are characterized by their total basic number (TBN). This total base number is at least 100 mg KOH / g, more preferably at least 200 mg KOH / g, most preferably at least 300 mg KOH / g. This total base number is preferably at most 600 mg KOH / g. Another way to characterize overbased magnesium salicylate is by magnesium content relative to the theoretical equivalent of magnesium, based on the total amount of acid present. The magnesium content of the overbased magnesium salicylate that can be used in the present invention is preferably more than 500%, more preferably at least 550%, based on the theoretical equivalent of magnesium based on the total amount of acid present.
The salicylate may be substituted or unsubstituted. Suitable substituents include aliphatic groups having 1 to 40 carbon atoms, optionally containing one or more oxygen and / or nitrogen atoms and a hydroxyl group. Preferred substituents are alkyl groups having 6 to 30 carbon atoms, preferably 12 to 20 carbon atoms. The substituent is preferably linear. The salicylate can contain 1 to 4, preferably 1 to 3, and most preferably 1 or 2 substituents. Most preferred salicylates are those substituted with one linear alkyl group having 14 to 18 carbon atoms.

In general, monoalkyl salicylic acid is produced by alkylation of phenol and subsequent carboxylation. Thus, small amounts (generally at most 20 mol%) of dialkyl salicylates and unsubstituted salicylates may be present in the monoalkyl salicylates.
Magnesium salicylate that can be used in the present invention can be obtained as a commercial product. A suitable commercial product is SAP 007 (from Infineum). This magnesium salicylate is usually supplied in combination with mineral oil. The amounts referred to in this document relate to the compound itself without mineral oil.
A method by which suitable magnesium salicylate can be produced is described in US-A-4,627,928.

Zinc dithiophosphate is well known in the art. A preferred zinc dithiophosphate used in the present invention has the following formula:
(Wherein R ⁸ and R ⁹ may be hydrogen or an aliphatic group)
It is represented by A preferred aliphatic group is a hydrocarbyl group. Hydrocarbyl groups optionally contain acid groups, hydroxyl groups and / or ester groups. Preferred hydrocarbyl groups are alkyl groups having 12 or fewer carbon atoms and optionally containing acid groups, hydroxyl groups and / or ester groups. The hydrocarbyl-substituted dithiophosphate may contain one or two aliphatic groups or may be a mixture of a dithiophosphate having one aliphatic group and a dithiophosphate having two aliphatic groups. It's okay. A preferred zinc dithiophosphate is zinc dialkyldithiophosphate.

The substituted dithiophosphate is bonded to the oxygen atom via a first, second and / or third aliphatic group, ie a carbon atom bonded to 1, 2 or 3 further carbon atoms, respectively. Substituents can be included. In the present invention, it is preferred that at least 60% by weight of the aliphatic substituent, preferably the alkyl substituent, of the zinc dithiophosphate is the first aliphatic substituent. More preferably, at least 80% by weight of the aliphatic substituents are first aliphatic substituents.
Suitable commercially available zinc dithiophosphates include Elco 108 (manufactured by Elco Corporation), Lz 1375 (manufactured by Lubrizol), OLOA 4269Q (manufactured by Oronite) and HITEC 680 (manufactured by Ethyl).

The amount of magnesium salicylate present is preferably at most 1% by weight, more preferably at most 0.5% by weight and most preferably at most 0.3% by weight, based on the total composition. The amount of magnesium salicylate present is preferably at least 0.001 wt%, more preferably at least 0.005 wt%, more preferably at least 0.01 wt%, and most preferably at least 0.015 wt%. The amount of zinc dithiophosphate present is preferably at most 5% by weight, more preferably at most 3% by weight and most preferably at most 1% by weight, based on the total composition. The amount of zinc dithiophosphate present is preferably at least 0.05% by weight, more preferably at least 0.7% by weight, and most preferably at least 0.1% by weight.
The hydraulic fluid further comprises (c) a rust inhibitor, preferably a compound having a total carbon number of 4 to 70 containing a carboxylic acid, ester, amide or imide, more preferably a dicarboxylic acid or a mono- or di-ester thereof or The mono-amide, di-amide or imide, more preferably dicarboxylic acid or its ester, amide or imide may be contained in an amount of 0.001 to 5% by weight based on the total composition. The more preferable carbon number of this compound is 20-40. Preferred compounds are aliphatic succinimides or succinic diamides. Such compounds are described in EP-A-776964.

Most preferred (c) is 0.001 to 5% by weight of the compound of formula I below.
Wherein R ₁ and R ₂ are each hydrogen, or alkyl or hydroxyalkyl having 1 to 30 carbon atoms, and R ₃ , R ₄ and R ₅ are each hydrogen, or alkyl or hydroxy having 1 to 4 carbon atoms Alkyl, X is CH or N, and R ₆ and R ₇ are each hydrogen, alkyl or alkenyl having 1 to 30 carbon atoms, or an acyl group derived from a saturated or unsaturated carboxylic acid having 30 or less carbon atoms. It is. Preferably, R ₁ and R ₂ are each alkyl having 3 to 6 carbon atoms, R ₃ , R ₄ and R ₅ are each hydrogen, X is N, and R ₆ and R ₇ are each 15 carbon atoms. Or an acyl group derived from an alkyl group having ˜20 or a saturated or unsaturated dicarboxylic acid having 4 to 10 carbon atoms, provided that at least one of R ₆ and R ₇ is an acyl group. Particularly preferred is aspartic acid, that is, N- (3-carboxy-1-oxo-2-propenyl) -octadecyl-bis (2-methylpropyl) ester. Such aspartic acid esters are commercially available. A method for producing such compounds is described in EP-A-434464.

  The weight ratio at which the compounds of the invention are present can vary widely. The hydraulic fluid is magnesium salicylate, zinc dithiophosphate and optionally a rust inhibitor, the weight ratio of magnesium salicylate to zinc dithiophosphate is 1: 5 to 1: 100 and the weight ratio of magnesium salicylate to rust inhibitor is 1. : It is preferable to contain in the quantity which will be 0-1: 50.

  The lubricant base oil present in the hydraulic fluid of the present invention may be any base fluid as long as it is suitably used for the hydraulic fluid. The base oil may be a natural or synthetic lubricant base oil or a mixture thereof. Natural oils can be animal or vegetable oils such as lard oil or castor oil, or liquid oils and paraffinic, naphthenic or paraffinic / naphthenic mixed systems that can be further refined by hydrocracking and hydrofinishing and hydrofinishing processes and / or dewaxing. It may be a mineral lubricating oil treated with a solvent or acid. Synthetic lubricating oils include hydrocarbon oils such as polymerized or copolymerized olefins and halogen-substituted hydrocarbon oils. Suitable base oils contain poly-α-olefins such as polydecene. A preferred base oil is a hydrocarbon base oil. Further preferred base liquids are mineral oils having an aromatic content measured according to DIN 51378 of less than 10% by weight, preferably less than 5% by weight and most preferably less than 3.0% by weight. The base oil preferably has a sulfur content measured according to ASTM D 4045, calculated as elemental sulfur, preferably less than 0.1% by weight, more preferably less than 0.05% by weight. Such mineral oil can be produced by a strict hydrogenation process. The kinematic viscosity of the lubricating oil at 40 ° C. is preferably in the range of 5 to 220 cSt, more preferably 10 to 200 cSt, and most preferably 20 to 100 cSt.

The hydraulic fluid of the present invention can further contain additives such as pour point depressants, antifoaming agents and demulsifiers that are usually present in the hydraulic fluid. Pour point depressants are generally high molecular weight polymers such as alkyl aromatic polymers and polymethacrylates. As the antifoaming agent, silicone polymers and / or polymethacrylates are generally used. A commonly applied demulsifier is a polyalkylene glycol ether. Further, detergents such as sulfonates and phenolates, metal deactivators, phenolic compounds, antioxidants such as diphenylamine and phenylnaphthylamine, anti-ash and anti-ash agents such as succinimide, and / or ash Can be present.
The hydraulic fluid of the present invention contains magnesium salicylate. For certain applications, it may be advantageous for the hydraulic fluid to include a combination of calcium salicylate and magnesium salicylate.
The components of the present invention may be added to the lubricating oil itself, or may be mixed before being added to the lubricating oil to form an additive package. This additive package for producing a hydraulic fluid is preferably magnesium salicylate, zinc dithiophosphate, and optionally a total of 4 to 70 carbon atoms, dicarboxylic acid or mono- or di-ester thereof or mono-amide or di-acid thereof. -Containing an amide or imide, the weight ratio of magnesium salicylate to zinc dithiophosphate being from 1: 5 to 1: 100, and magnesium salicylate and dicarboxylic acid or its mono- or di-ester or its mono-amide, di- The weight ratio of amide or imide is 1: 0 to 1:50.

【Example】
[0016]
A formulation containing the following additives was prepared.
Magnesium salicylate: total base number is 337 mg KOH / g (SAPINE from INFINEUM), magnesium content is about 750% with respect to the theoretical equivalent of magnesium based on the total amount of acid, and contains 40% by weight of mineral oil. Highly overbased calcium alkylsalicylate calcium salicylate: overbasic calcium alkylsalicylate with a total base number of 168 mg KOH / g (INFINEUM SAP 001) and containing 40 wt% mineral oil The salicylic acid described in Table 1 The amount of metal is the amount of metal salicylate itself without mineral oil.
Zinc dithiophosphate: zinc di (ethylhexyl) dithiophosphate (Elco 108 from Elco corporation)
Compound of formula I: Aspartic acid, ie N- (3-carboxy-1-oxo-2-propenyl) -N-octadecyl, bis (2-methylpropyl) ester

These compounds have an aromatic content of less than 1.0% by weight, a sulfur content of less than 0.05% by weight calculated as elemental sulfur, and a kinematic viscosity of 32 cSt (at 40 ° C.) Added to (ISO viscosity grade 32) lubricant base oil.
The resulting compositions are listed in Table 1. The indicated amount is the amount of the compound itself without mineral oil.
Compositions 1 and 2 were used for the Vickers V104C vane pump test. A new pump cartridge was used for each test. The test time was 250 hours, the liquid temperature was about 66 ° C., the liquid outlet pressure was 35 bar (3.5 MPa), and the pump speed was 1450 rpm. The results are listed in Table 1.

[Table 1]
Table 1
Composition 1 Composition 2
Magnesium salicylate 0.06% wt −
Calcium salicylate-0.06% wt
Zinc dithiophosphate 0.37% wt 0.37% wt
Compound of formula I 0.10% wt 0.10% wt
Lubricant base oil Remainder remaining Weight loss of low load test ring (mg) 13 96
Vane weight loss (mg) 2 1
Total weight loss (mg) 15 97

  As is clear from Table 1, the antiwear property is better in the composition (1) containing magnesium salicylate than in the composition (2) containing calcium salicylate. The weight loss of the ring and the overall weight loss are much less with composition 1 than with composition 2. The weight loss of the vanes is comparable for both compositions.

Claims (10)

In order to improve the wear performance at low load in the hydraulic fluid, the lubricant base oil (a) 0.001 to 5% by weight of magnesium salicylate,
(B) Zinc dithiophosphate 0.01-8% by weight
Use of a composition comprising a combination of
2. The composition according to claim 1, further comprising (c) 0.001 to 5 wt% of a dicarboxylic acid or a mono- or di-ester thereof or a mono-amide, di-amide or imide thereof having a total carbon number of 4 to 70. Use of the composition.
(C) is represented by the following formula I
[Chemical 1]


Wherein R ₁ and R ₂ are each hydrogen, or alkyl or hydroxyalkyl having 1 to 30 carbon atoms, and R ₃ , R ₄ and R ₅ are each hydrogen, alkyl having 1 to 4 carbon atoms or alkyl or Hydroxyalkyl, X is CH or N, and R ₆ and R ₇ are each hydrogen, alkyl or alkenyl having 1 to 30 carbon atoms, or acyl derived from a saturated or unsaturated carboxylic acid having 30 or less carbon atoms Base)
Use of the composition according to claim 2 which is a compound of
Magnesium salicylate, zinc dithiophosphate and optionally a compound of formula I with a weight ratio of magnesium salicylate to zinc dithiophosphate of 1: 5 to 1: 100 and a weight ratio of magnesium salicylate to the compound of formula I of 1: Use of a composition according to any one of claims 1 to 3 comprising in an amount such that 0 to 1:50.
Use of the composition according to any one of claims 1 to 4, wherein the composition further comprises a pour point depressant, an antifoaming agent and / or a demulsifier.
In order to produce a hydraulic fluid with improved wear performance at low loads, magnesium salicylate, zinc dithiophosphate, and optionally a total of 4 to 70 carbon atoms, dicarboxylic acid or mono- or di-ester thereof or mono- thereof Containing amide, di-amide or imide, the weight ratio of magnesium salicylate to zinc dithiophosphate being from 1: 5 to 1: 100, and magnesium salicylate and dicarboxylic acid or mono- or di-ester thereof or mono- thereof Use of a combination of additives in which the weight ratio of amide, di-amide or imide is 1: 0 to 1:50.
(A) 0.001 to 5% by weight of magnesium salicylate in the lubricant base oil,
(B) 0.01-8% by weight zinc dithiophosphate, and (c) the following formula I
[Chemical 2]


Wherein R ₁ and R ₂ are each hydrogen, or alkyl or hydroxyalkyl having 1 to 30 carbon atoms, and R ₃ , R ₄ and R ₅ are each hydrogen, alkyl having 1 to 4 carbon atoms or alkyl or Hydroxyalkyl, X is CH or N, and R ₆ and R ₇ are each hydrogen, alkyl or alkenyl having 1 to 30 carbon atoms, or acyl derived from a saturated or unsaturated carboxylic acid having 30 or less carbon atoms Base)
A hydraulic fluid comprising a combination of 0.001 to 5% by weight of the above compound.
Magnesium salicylate, zinc dithiophosphate and the compound of formula I are used in a weight ratio of magnesium salicylate to zinc dithiophosphate of 1: 5 to 1: 100 and a weight ratio of magnesium salicylate to the compound of formula I of 1: 0. The hydraulic fluid according to claim 7, which is contained in an amount so as to be 1:50.
The hydraulic fluid according to claim 7 or 8, wherein the hydraulic fluid further contains a pour point depressant, an antifoaming agent, and / or a demulsifier.
The additive is magnesium salicylate, zinc dithiophosphate, and
[Chemical Formula 3]



Wherein R ₁ and R ₂ are each hydrogen, or alkyl or hydroxyalkyl having 1 to 30 carbon atoms, and R ₃ , R ₄ and R ₅ are each hydrogen, alkyl having 1 to 4 carbon atoms or alkyl or Hydroxyalkyl, X is CH or N, and R ₆ and R ₇ are each hydrogen, alkyl or alkenyl having 1 to 30 carbon atoms, or acyl derived from a saturated or unsaturated carboxylic acid having 30 or less carbon atoms Base)
The weight ratio of magnesium salicylate to zinc dithiophosphate is 1: 5 to 1: 100, and the weight ratio of magnesium salicylate to the compound of general formula I is 1: 0 to 1:50. Additive for hydraulic fluid production.