JP2837947B2 - Zinc dialkyldithiophosphate and lubricating oil composition containing the same - Google Patents

Description

The present invention relates to a zinc dialkyldithiophosphate and a lubricating oil composition containing the same, and more particularly to a lubricant, a functional fluid, a fuel, a grease, a plastic or a paint, etc. The present invention relates to a zinc salt of a dialkyldithiophosphate useful as an additive of the present invention, and a lubricating oil composition containing this salt and having excellent metal corrosion resistance and heat stability.

[Problems to be solved by conventional technology and invention]

In recent years, performance requirements for lubricants and functional fluids used have become higher with the improvement of mechanical devices. In particular, there is a demand for improved heat resistance to cope with a rise in temperature due to severe environmental and operating conditions and a longer life for maintenance-free operation.

In order to improve the heat resistance and extend the life, metal salts of dialkyldithiophosphoric acids, particularly zinc salts, are effective as antioxidants and extreme pressure agents and are widely used.

By the way, as a problem often observed in recent years, there is corrosion of a metal part by a lubricant, particularly corrosion of a copper part. Further, when used at high temperatures, there is a problem that the deterioration of the metal salt is precipitated and the lubricating oil is deteriorated, thereby impairing the lubrication performance.

As a method for producing dialkyldithiophosphates that cause less corrosion of metal parts of machines, especially copper parts, by lubricants, Japanese Patent Publication No. Sho 62
No. -24115 discloses a method of treating with phosphite. However, when these salts are used, corrosion to the copper part is reduced, but there is a problem in thermal stability. Further, needless to say, a complicated operation of phosphite treatment is required. If this treatment is not carried out, the copper portion is corroded.

On the other hand, as a zinc dialkyldithiophosphate which has good oil solubility in lubricating oil and does not crystallize on standing,
No. 32005 discloses that 3 to 14 heteroalkyl groups (R)
And a mixed basic zinc salt having an average carbon number of 3.5 to 4.5 [(RO) ₂ PSS] ₃ Zn ₂ OH and a mixed neutral zinc salt [(RO) ₂ PSS]
A mixture of ₂ Zn is described. However, these salts also lack thermal stability, leaving problems such as precipitation of degraded metal salts, deterioration of lubricating oil, and corrosion of copper.

The above basic zinc salt is analyzed by P ³¹ -NMR and the like [Chemd, Tech (Leipzig) 38 (4) 169-17.
2 1986], which report the structures of [(RO) ₂ PSS] ZnOH and [(RO) ₂ PSS] ₃ Zn ₂ OH. on the other hand,
[(RO) ₂ PSS] _{6 for} [Lubrication oil 25 (2) 95-96,1980]
The structure of Zn ₄ O has also been reported.

As described above, the structure of the basic zinc salt has not yet been sufficiently specified, and there are many unclear points.

The present inventors have developed a new dialkyldithiophosphate which has no risk of causing metal corrosion when used as a lubricant or an additive thereof, has excellent thermal stability, and does not precipitate metal salt degradation products at high temperatures. Intensive research to develop.

[Means for solving the problem]

As a result, the specific basic zinc salt and the neutral zinc salt defined by the nuclear magnetic resonance ( ³¹ P-NMR) spectrum of phosphorus are mixed at a certain ratio, and the alkyl group contained has an average carbon number of 4.6 or more. It has been found that zinc dialkyldithiophosphate, which is a primary alkyl group, can achieve the above object. The present invention has been completed based on such findings.

That is, the present invention is a zinc dialkyldithiophosphate having a primary alkyl group having an average carbon number of 4.6 or more,
Its composition by the peak area ratio of the signals of the nuclear magnetic resonance of phosphorus ⁽³¹ P-NMR) is (a) of ³¹ P-NMR signal 103.3 to 1
60-85% of basic zinc salt appearing at 04.1 ppm, (b) 20-0% of basic zinc salt appearing at 102.5-103.2 ppm of ³¹ P-NMR signal and (c) 15-40% of neutral zinc salt It is intended to provide a zinc dialkyldithiophosphate salt characterized by comprising: The present invention also provides a lubricating oil composition comprising a lubricating base oil and the above-mentioned zinc dialkyldithiophosphate.

The zinc dialkyldithiophosphate of the present invention (Zn DTP)
Is a primary alkyl group having an average carbon number of 4.6 or more, preferably 4.6 to 18, particularly preferably 4.6 to 8 as an alkyl group (that is, an alkyl group having a primary carbon atom as a bonding site).
It has. Here, when the average carbon number of the alkyl group is less than 4.6, thermal stability is poor and discoloration and precipitation are liable to occur. Further, even a secondary alkyl group or a tertiary alkyl group is inferior in thermal stability and is liable to cause discoloration and precipitation.

The primary alkyl group is composed of a straight-chain or branched-chain alkyl, and a branched-chain alkyl is particularly preferable. Specific examples of such an alkyl group include n-butanol; isobutanol; n-pentanol; 2-methyl-1-butanol; 3-methyl-1-butanol; and 2,2-dimethyl. Propanol; n-hexanol; 2-
Methyl-1-pentanol; 2-methyl-1-butanol; 4-methyl-1-pentanol; 3-methyl-1-pental; n-heptanol; 1,1-diethyl-1-propanol; n-octanol; Isooctanol (for example, 2-
Ethyl-1-hexanol), and linear or branched decyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, octadecyl alcohol, and the like.

The zinc dialkyldithiophosphate of the present invention contains a primary alkyl group as described above, and the primary alkyl group may be one kind or a mixture of plural kinds. Further, as described above, the carbon number of the primary alkyl group is 4.6 or more on average, and the average carbon number is calculated as follows. That is, as an alkyl group, 2
When only -ethylhexyl group is contained, the average carbon number is naturally 8; however, when it contains 70 mol% of isobutyl group and 30 mol% of 2-ethylhexyl group, the average carbon number is calculated to be 5.2.

Meanwhile, the composition of the zinc dialkyl dithiophosphate salts of the present invention, as described above, basic zinc salts in peak area ratio of the signal of ³¹ P-NMR is (a) of ³¹ P-NMR signal appears at 103.3～104.1Ppm 60 (B) 20 to 0%, preferably 10 to 0%, of a basic zinc salt whose ³¹ P-NMR signal appears at 102.5 to 103.2 ppm; and (c) a neutral zinc salt. It is selected in the range of 15 to 40%, preferably 20 to 30%.

In the zinc dialkyldithiophosphate of the present invention, if the proportion of each of the zinc salts (a), (b) and (c) deviates from the above range, the thermal stability becomes insufficient, which is not preferable. The zinc dialkyldithiophosphate of the present invention contains the above zinc salts (a), (b) and (c) as main components, but may further contain small amounts of other components. .

The zinc dialkyldithiophosphate of the present invention can be produced by various methods. Generally, one or two or more of the above-mentioned primary alcohols are reacted with diphosphorus pentasulfide (P ₂ S ₅ ). First, a dialkyldithiophosphoric acid is produced. Here, diphosphorus pentasulfide may be either a highly reactive product or a slow reactive product, but a slow reactive product is preferred because the reaction can be easily controlled. Further, those purified by distillation can be suitably used.

The proportion of the alcohol and diphosphorus pentasulfide used is not particularly limited, but is usually 5 to 20 mol% excess of the theoretical amount (4 mol) of the alcohol to diphosphorus pentasulfide (1 mol), preferably It is selected so as to be in excess of about 5 mol%. The reaction temperature may be appropriately determined usually in the range of 40 to 100 ° C.
Unreacted diphosphorus pentasulfide can be removed by filtration or the like.

Further, in the reaction between the above alcohol and diphosphorus pentasulfide, the reaction can be promoted by using a nitrogen-containing compound disclosed in JP-A-49-87632, for example, ε-caprolactam, as a cocatalyst. The amount used is not particularly limited, but is usually 1% by weight or less, preferably about 0.5% by weight, based on diphosphorus pentasulfide. If too much of this cocatalyst is used, it adversely affects the thermal stability of the zinc dialkyldithiophosphate.

In the presence of a promoter such as ε-caplactam,
By reacting the distilled and purified diphosphorus pentasulfide with the above-mentioned excess amount of alcohol, diphosphorus pentasulfide can be completely reacted, and as a result, unreacted diphosphorus pentasulfide is removed by filtration. Operation can be omitted.

Next, the dialkyldithiophosphoric acid thus obtained is mixed with a mineral oil or a solvent as a diluent, if necessary, and reacted with zinc oxide, whereby the intended zinc salt of dialkyldithiophosphate can be produced. . Use of a mineral oil is preferred because the composition of the basic zinc salt as the components (a) and (b) can be easily controlled. This amount of mineral oil is
It is 10 to 30% by weight, preferably about 15% by weight, of the zinc dialkyldithiophosphate to be produced. If necessary, water can be added for the reaction.

Further, instead of zinc oxide, zinc compounds such as zinc hydroxide and zinc carbonate can be used, but zinc oxide is most preferable. The amount of zinc oxide used is 0.75 mol or more, preferably about 1 mol, per 1 mol of dialkyldithiophosphoric acid.

The amount of water used is 0 to 1 mol, preferably about 0.5 mol, per 1 mol of dialkyldithiophosphoric acid.

The method for producing the zinc dialkyldithiophosphate of the present invention described above will be described more specifically as follows. That is, first, 1 mol of diphosphorus pentasulfide is dissolved in about 4 mol of alcohol together with ε-caprolactam (about 0.5% by weight of diphosphorus pentasulfide) and reacted at 20 to 100 ° C. to stop generation of hydrogen sulfide. Hold at this temperature for 1-4 hours until The mixture is then cooled and, if diphosphorus pentasulfide remains, filtered off.

 The reaction in this process proceeds according to the following equation.

4ROH + P ₂ S ₅ → 2 (RO) ₂ PSSH + H ₂ S (wherein, R represents a primary alkyl group.) When using highly reactive diphosphorus pentasulfide, the pentasulfide in alcohol at 60 to 100 ° C. Add diphosphorus and hold for about 2 hours. On the other hand, when using slowly reactive diphosphorus pentasulfide,
Diphosphorus pentasulfide is added to an alcohol at 60 ° C. for about 1 hour.
For about 2 hours.

Subsequently, into the obtained dialkyldithiophosphoric acid, about 15% by weight of mineral oil of the zinc dialkyldithiophosphate produced and about 0.3 mol of water (based on 1 mol of dialkyldithiophosphoric acid) are added. Next, zinc oxide is added at 30 ° C. or lower and the temperature is maintained for about 1 hour, and thereafter, the temperature is maintained at 60 to 100 ° C. for 1 to 4 hours. Preferably, the temperature is maintained at about 70 ° C. for about 2 hours. Thereafter, unreacted alcohol and water are removed by vacuum distillation, a filter aid is added, and pressure filtration is performed to obtain a liquid product.

 The reaction in this process proceeds according to the following equation.

2 (RO) ₂ PSSH + 2ZnO → basic zinc salt (a) + (b) + [(RO) ₂ PSS] ₂ Zn + H ₂ O The filter aid is preferably 0.1 to 5% by weight, based on the zinc dialkyldithiophosphate. Is added in the range of 0.5 to 3% by weight. The filter aid includes diatomaceous earth, supercell, filter cell and the like, and diatomaceous earth is particularly preferable.

At the time of the above filtration, the temperature of pressure filtration is 20 to 100 ° C., preferably 70 ° C., and the pressure is 1 to 10 kg / cm ² , preferably 3
Is a ~5kg / cm ^2.

The ratio of the basic zinc salts (a) and (b) in the produced zinc dialkyldithiophosphate can be adjusted by changing the temperature and the temperature at which zinc oxide is added to the dialkyldithiophosphoric acid.

The zinc dialkyldithiophosphate of the present invention obtained by the above method can be used as a lubricating oil composition in addition to the lubricating base oil. The amount of the zinc dialkyldithiophosphate added in the lubricating oil composition is not particularly limited and may be appropriately selected depending on various circumstances.
It is 5% by weight, preferably 0.05 to 1% by weight (particularly when used as an engine lubricating oil).

As the lubricating base oil in the lubricating oil composition, various oils can be mentioned, and any of mineral oil, vegetable oil, animal oil, and synthetic oil may be used, or a mixture thereof may be used. Further, the applications of the lubricating oil composition are varied, such as for spark-ignition and compression-ignition internal combustion engines such as automobile and truck engines, two-stroke engines, aircraft piston engines, marine and railway engines, etc. And other crankcase lubricants. It can also be used as a lubricant for gas engines, quantitative engines, turbines, and the like. Further, it can be used for transmission bearing lubricants, gear lubricants, metalworking lubricants and other lubricating oils and grease compositions, as well as functional fluids such as pressure fluids and automatic transmission fluids.

Mineral oil-based lubricating base oils include liquid petroleum or base oils obtained by solvent or acid treatment of paraffinic, naphthenic or mixed paraffinic-naphthenic mineral oils. Oils having a lubricating viscosity derived from coal and shale are also useful base oils. Synthetic oil-based lubricating base oils include polymerized olefins (eg, polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly (1-hexanes), poly (1-octenes), (1-decenes) and the like and mixtures thereof) and halo-substituted hydrocarbon oils,
Alkylibenzenes (for example, dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di- (2
-Ethylhexyl) -benzenes, etc.), polyphenyls (eg, biphenyls, terphenyls, alkylated polyphenyls, etc.), alkylated diphenyl ethers and alkylated diphenyl sulfides, and derivatives, analogs and There are homologues.

Polymers and copolymers of alkylene oxide, further,
Those derivatives whose terminal hydroxyl groups have been modified by esterification, etherification, etc. are also suitable as synthetic oil-based lubricating base oils. Examples thereof include oils obtained by polymerization of ethylene oxide and propylene oxide, alkyl and aryl ethers of these polyoxyalkylene polymers (for example, methyl-polyisopropylene glycol ether having an average molecular weight of 1,000, and a molecular weight of 500 to 1,000). Diphenyl ether of polyethylene glycol, molecular weight 1000
Diethyl ether of polypropylene glycol 1500, etc.), or their mono- and polycarboxylic esters thereof, for example, acetic acid esters, are C ₁₂ Oxo acid diester of mixed resin fatty ester or tetraethylene glycol having 3 to 8 carbon atoms .

Other examples of synthetic oil-based lubricating base oils include dicarboxylic acids (eg, phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, Linoleic acid dimer, malonic acid, alkylmalonic acids, alkenylmalonic acids, etc.) and various alcohols (for example, butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-
Esters with ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, and propylene glycol). Specific examples of these esters include dibutyl adipate, di (2-ethylhexyl) sebacate, dinormalhexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, and didecyl phthalate. , Dieicosyl sebacate, 2-ethylhexyl diester of linoleic acid dimer, and complex ester obtained by reacting 1 mol of sebacic acid with 2 mol of tetraethylene glycol and 2 mol of 2-ethylcaproic acid.

Esters useful as synthetic oil-based lubricating base oils further include those produced from monocarboxylic acids having 3 to 12 carbon atoms and polyols, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol. And polyol ethers such as tripentaerythritol.

Silicon-based oils such as polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils are also suitable as synthetic oil-based lubricating base oils (for example, tetraethyl silicate,
Tetraisopropyl silicate, tetra (2-ethylhexyl) silicate, tetra (4-methyl-2-ethylhexyl) silicate, tetra (para-tert-butylphenyl) silicate,
Hexa (4-methyl-2-pentoxy) disiloxane,
Poly (methyl) siloxanes, poly (methylphenyl)
Siloxanes).

Other synthetic lubricating base oils include liquid esters of phosphorus-containing acids (eg, tricresyl phosphate, trioctyl phosphate, diethyl ester of decyl phosphonic acid, etc.), and polymerized tetrahydrofuran.

Unrefined, refined and rerefined oils, of the above-mentioned types, natural and synthetic, or mixtures of any two or more thereof are useful as the base oil of the lubricating oil composition of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without purification treatment. For example, unrefined oils which are used directly without reprocessing, such as syre oil obtained directly by retorting, petroleum oil obtained directly from distillation or ester oil obtained directly from the esterification process. Refined oils are the same as the unrefined oils except that they have been subjected to one or more purification treatments.

Such purification methods are known, and examples thereof include solvent extraction, acid or base extraction, and filtration percolation. Rerefined oil is obtained by subjecting a once used refined oil to the same operation as for obtaining a refined oil. Such rerefined oils are also known as reclaimed oils, which are further processed in a manner used to remove used additives and oil breakdown products.

The lubricating oil composition of the present invention is basically composed of the above zinc salt of dialkyldithiophosphate and a lubricating base oil, but may further contain various additives as necessary. Such other additives include rust preventives, detergents / dispersants (metal-based detergents / ashless detergents / dispersants), viscosity index improvers, pour point depressants, flow improvers, antioxidants , Extreme pressure agents, antifoaming agents, friction modifiers, coloring agents, fragrances, demulsifiers, oil agents and the like.

Here, as the rust inhibitor, triaryl or trialkyl phosphates, for example, tributyl phosphate,
Tricresyl phosphate, aryl or alkyl phosphites, alkyl phenol sulfides, P ₂
S ₅ - terpene addition compounds, further benzotriazole,
Phenothiazine, bisoctyldithiathiadiazole,
Examples thereof include phenyl-1-naphthylamine, aliphatic carboxylic acids, aliphatic dicarboxylic acids, and sulfonates.

Next, as a metal-based cleaning and dispersing agent, alkaline earth metal salts of petroleum sulfonic acid, alkaline earth metal salts of alkylbenzenesulfonic acid, carboxylate, salicylate,
There are overbased compounds of alkaline earth metal salts of carbonic acid such as naphthenates, and the like, and alkaline earth metal salts of phosphorus sulfided hydrocarbons and sulfided alkylphenols.

Examples of the ashless detergent / dispersant include alkenyl succinimides and bisimides having about 50 or more carbon atoms or borides thereof, and carboxylic acids having at least about 34, preferably at least about 54 carbon atoms (or derivatives thereof). ) And a nitrogen-containing compound such as an amine, a reaction product of an organic hydroxy compound such as phenol or alcohol and / or a basic inorganic substance [carboxylic dispersant], a relatively high molecular weight aliphatic or alicyclic halide and an amine A reaction product of an alkylphenol having an alkyl group having about 30 or more carbon atoms with an aldehyde (especially formaldehyde) and an anne (especially a polyalkylene polyamide). Mannich dispersant], carboxylic acid, amine or Mannich Products obtained by treating dispersants with urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides, boron compounds, phosphorus compounds, and methacrylic Polymer of oil-solubilizing monomer such as decyl acid, vinyl decyl ether and high molecular weight olefin and monomer having polar substituent (for example, aminoalkyl acrylate or acrylamide or polyoxyethylene-substituted acrylate) [Polymer dispersant ] Etc. can be given.

Further, as the viscosity index improver, an acrylate polymer, a methacrylate polymer or a polymer derived from N-vinylpyrrolidone, diethyl methacrylate or fumaric acid, furthermore, a polyisobutylene, an ethylene-propylene copolymer And hydrogenated styrene-diene copolymers.

Pour point depressants and fluidity improvers include ethylene-vinyl acetate copolymers, alkenyl succinamide compounds, ethylene-alkyl acrylate polymers, and other condensates of chlorinated paraffins and naphthalenes, and chlorinated paraffins. And phenol, polyalkyl methacrylate.

Examples of the antioxidant include phenol-based, amine-based antioxidants (for example, hindered phenol and naphthylamine), and sulfurized olefins.

As extreme pressure agents, sulfur extreme pressure agents, phosphorus extreme pressure agents, halogen extreme pressure agents, organometallic extreme pressure agents (for example, lead naphthenate, Mo-dithiocarbamate, Mo-dithiophosphate)
Etc.

In addition, anti-foaming agents include polysiloxanes (for example, dimethyl polysiloxane), and friction modifiers include carboxylic acids, esters, amines, molybdenum compounds, and boron compounds.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. This example shows a specific embodiment of the present invention, but the scope of the present invention is not limited thereby. In Examples and Comparative Examples, the ratio of a basic salt to a neutral salt was determined by ³¹ P-NMP. Note that ³¹ P−N
The MR measurement conditions and the thermal stability test method are as follows. ³¹ P-NMR measurement conditions Measurement solvent: CDCl ₃ Sample concentration: 6 wt% / vol% Measurement temperature: room temperature Pulse width: 45 degrees Repetition: 5 seconds Repeat count: 250 times Observation frequency: 110 MHz Internal standard: orthophosphoric acid (for adjustment ) Thermal stability test method 0.5% by weight of a sample (zinc dialkyldithiophosphate) was dissolved in mineral oil to prepare an evaluation sample.

Into a glass container containing 4.4 g of this evaluation sample, put a metal rod of Cu, Fe, Al having a diameter of 2 mm and a length of 2 cm polished with a No. 150 abrasive, put this in a dryer having a built-in rotary table, and put it in a dryer.
C. for 5 days.

The evaluation was performed with the color of the evaluation sample (10 points, colorless 1 point, yellow 3 points, brown 5 points, black 10 points) and with or without precipitation (×) and no metal corrosion (○).

Example 1 (Production of zinc dialkyldithiophosphate) 1 equipped with a stirrer, a thermometer and a reflux condenser connected to a sodium hydroxide solution trap for absorbing the generated hydrogen sulfide.
Of mixed alcohol (111.9 g of isobutanol, 30.0 g of 2-methyl-1-pentanol, n-
Hexanol 17.1 g and 2-ethylhexanol 16.4 g)
Was charged and nitrogen was bubbled at 100 ml / min.

111 g of mildly reactive diphosphorus pentasulfide purified by distillation at room temperature to 60 ° C. over 30 minutes was charged into the four-necked flask over 30 minutes with stirring.

Thereafter, the temperature was maintained at 60 ° C. for 2 hours, and further maintained at 75 ° C. for 3 hours. The resulting mixture was cooled to 25 ° C. to remove any remaining unreacted diphosphorus pentasulfide. As a result, 260 g of dialkyldithiophosphoric acid was obtained. The alkyl group in this dialkyldithiophosphoric acid contains 72 mol% of isobutyl group,
-Methyl-1-pentyl group was 14 mol%, n-hexyl group was 8 mol%, and 2-ethylhexyl group was 6 mol%, and the average carbon number was 4.7.

Next, 266 g of the above dialkyldithiophosphoric acid was placed in one round bottom flask equipped with a stirrer, thermometer and reflux condenser.
(1 mole), 9 g of water and 43.9 g of mineral oil. At 30 ° C., 60.8 g (0.75 mol) of zinc oxide was charged over 30 minutes while stirring. Subsequently, the temperature was maintained at 30 ° C. for 1 hour, and further maintained at 70 ° C. for 3 hours. Thereafter, the produced water and unreacted alcohol were removed by vacuum distillation. Charge 11g diatomaceous earth,
Then, the mixture was filtered under pressure at 5 kg / cm ² to obtain 285 g of an oily liquid product (zinc dialkyldithiophosphate). ³¹ P of this one
Table 1 shows the analysis results by NMR and the results of the thermal stability test.

Example 2 and Comparative Examples 1 to 3 The same operation as in Example 1 was performed except that the addition temperature and the amount of zinc oxide were changed as shown in Table 1.
The results are shown in Table 1.

Example 3 In Example 1, after charging the alcohol at the time of producing the dialkyldithiophosphoric acid, ε-caprolactam was further added to 0.1 ml.
56g was charged. As a result of the same reaction as in Example 1 below,
No unreacted diphosphorus pentasulfide remained. Therefore, the operation for removing diphosphorus pentasulfide was not performed.

Next, in the production stage of the zinc dialkyldithiophosphate, the same operation as in Example 1 was performed, except that 81 g of zinc oxide was charged at 25 ° C. instead of 60.8 g of zinc oxide at 30 ° C. The results are shown in Table 1. Also, of the obtained product
FIG. 2 shows ³¹ P-NMR.

Comparative Example 4 The same operation as in Example 1 was performed, except that the addition temperature of zinc oxide was changed to 60 ° C instead of 30 ° C. The results are shown in Table 1.

Comparative Example 5 The same operation as in Example 1 was performed, except that zinc oxide was charged and immediately heated to 70 ° C. and kept at 70 ° C. for 3 hours. The results are shown in Table 1.

Example 4 In Example 2, except that no water was added.
The same operation as in Example 2 was performed. The results are shown in Table 1.

Example 5 The same operation as in Example 3 was performed, except that a highly reactive diphosphorus pentasulfide was used instead of the mildly reactive diphosphorus pentasulfide. The results are shown in Table 1.

Comparative Example 6 Table 1 shows the evaluation results of the thermal stability test of a commercially available zinc dialkyldithiophosphate. Also, ³¹ P-NMR of this product
Is shown in FIG. The alkyl group contained 64 mol% of an isobutyl group, 24 mol% of a pentyl group, 12 mol% of a 2-ethylhexyl group, and had an average carbon number of 4.72.

Comparative Examples 7 to 10 The zinc dialkyldithiophosphate prepared in Example 3 and a commercially available zinc dialkyldithiophosphate were dissolved in n-hexane and injected and adsorbed on a silica gel column chromatograph.
The product was eluted with n-hexane to remove mineral oil.

Next, the mixture was successively desorbed with petroleum ether and toluene, and the solvent was distilled off to obtain each fraction.

Table 2 shows the results of analysis of each fraction by ³¹ P-NMR and the results of the thermal stability test.

Example 6 In Example 3, the alcohol was replaced with isobutanol 111.
9 g, n-hexanol 47.1 g and 2-ethylhexanol 1
The same operation as in Example 3 was performed except that the amount was changed to 6.4 g. The results are shown in Table 3.

Example 7 In Example 3, 132 g of alcohol was used.
And the same operation as in Example 3 except that the amount was changed to 41.0 g of 2-ethylhexanol. The results are shown in Table 3.

Example 8 In Example 3, the alcohol was replaced with 108.8 g of isobutal.
And the same operation as in Example 3 except that the amount was changed to 81.9 g of 2-ethylhexanol. The results are shown in Table 3.

FIG. 3 shows ³¹ P-NMR of the obtained product.

Example 9 The same operation as in Example 3 was performed, except that the alcohol was changed to 273 g of 2-ethylhexanol. The results are shown in Table 3.

Comparative Example 11 In Example 3, the alcohol was replaced with isobutanol 139.
The same operation as in Example 3 was performed, except that the amount was changed to 9 g and 27.3 g of 2-ethylhexanol. The results are shown in Table 3.

Comparative Example 12 In Example 3, the alcohol was changed to isopropanol 7
5.6 g and 85.7 g of 4-methyl-2-pentanol,
The same operation as in Example 3 was performed, except that 48.8 g of zinc oxide was used. The results are shown in Table 3.

Examples 10 to 12 and Comparative Example 13 (Performance evaluation of lubricating oil composition containing zinc dialkyldithiophosphate) Examples 6, 8, and 9 were added to mineral oil (ISO VG32 paraffinic base oil).
A lubricating oil composition was prepared by blending the zinc dialkyldithiophosphate produced in the above step or a commercially available zinc dialkyldithiophosphate and various additives at the concentrations shown in Table 4.
Table 4 also shows the desirable usable range of the prepared composition.

Table 5 shows properties and performance results of the lubricating oil composition (engine oil).

As shown in Table 5, from the oxidation stability and the panel coking test, the lubricating oil composition containing any of the zinc dialkyldithiophosphates of Examples 6, 8, and 9 contains a commercially available zinc dialkyldithiophosphate. It turns out that it is excellent in oxidation stability and heat stability compared with the lubricating oil composition.
In addition, from the Falex and shell four-ball wear test,
It can be seen that the product of Example 11 is more excellent in load-bearing wear performance than the product containing a commercial product, and the products of Examples 10 and 12 show equivalent load-wear performance.

〔The invention's effect〕

As described above, the zinc dialkyldithiophosphate of the present invention does not corrode metals, particularly copper, has excellent thermal stability, and does not deposit metal salt deterioration even at high temperatures. Therefore, the zinc dialkyldithiophosphate of the present invention is expected to be effectively used as a lubricant, a functional fluid, a fuel, a grease, a hydrocarbon composition, a plastic, a resin, a paint, or the like or an additive thereof.

In addition, the lubricating oil composition containing the zinc dialkyldithiophosphate has excellent thermal stability, does not corrode copper and other metals, and includes engine oil, refrigeration oil, turbine oil, cylinder oil, and bearing oil. It is widely used as various lubricating oils such as oil and gear oil.

[Brief description of the drawings]

Figure 1 is a ³¹ P-NMR spectrum of a commercial zinc dialkyl dithiophosphate salts used in Comparative Example 6, ³¹ P-NMR in Fig. 2 zinc dialkyldithiophosphate salt obtained in Example 3
FIG. 3 is a ³¹ P-NMR spectrum of the zinc dialkyldithiophosphate obtained in Example 8.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C10M 137/10 C07F 9/17

Claims (2)

(57) [Claims] 1. A zinc salt of a dialkyldithiophosphate having a primary alkyl group having an average carbon number of 4.6 or more, wherein the composition is represented by (a) ³¹ which is a peak area ratio of a nuclear magnetic resonance ( ³¹ P-NMR) signal of phosphorus. 60-85% of a basic zinc salt whose P-NMR signal appears at 103.3-104.1 ppm, (b) 20-0% of a basic zinc salt which appears at 102.5-103.2 ppm of ³¹ P-NMR signal, and (c) neutral A zinc dialkyldithiophosphate comprising 15 to 40% of a zinc salt. 2. A lubricating oil composition comprising a lubricating base oil and a zinc dialkyldithiophosphate according to claim 1.