DE1097606B - Lubricating oils - Google Patents

Description

The invention relates to lubricating oils containing zinc salts of mixed diesters of dithiophosphoric acids, the organic constituents of the esters of two different alcohols, e.g. B. of butyl and hexyl alcohol, are derived.

It is known that the zinc salts of dialkyldithiophosphoric acids, whose alkyl groups are derived from one and the same alcohol, the oxidation of Inhibit lubricating oils, the alkyl groups of the zinc dialkyl dithiophosphate being high or low May have molecular weight. Zinc dialkyl dithiophosphates, the alkyl groups of which are identical and Containing less than 6 (e.g. 4) carbon atoms each are considerably cheaper than those with each other the same alkyl groups are derived from higher alcohols. Nevertheless, these have zinc dialkyldithiophosphates with alkyl groups derived from lower alcohols (e.g. those with 4 carbon atoms) as Lubricating oil additives have not found widespread use in the trade. The main reason for this is the fact that the Zinc salts of the lower dialkyl-dithiophosphoric acids are not sufficiently oil-soluble to take them in the form of a to be able to produce a concentrated solution in oil and put it on the market. The impossibility of being focused Sending oil solutions of these zinc salts, because of their oil insolubility under normal storage conditions, has the advantage of the cheapness of these compounds largely nullified.

There is already a large number of salts of oil-soluble esters of dithiophosphoric acid, which are used to improve the Properties of lubricants are known. Generally esters are suggested to have the same ester groups exhibit; Only zinc salts of diesters of dithiophosphoric acid are known, although they are different Have ester groups, but are characterized by a greater number of carbon atoms than the ester groups the zinc salts according to the invention. From the comparative tests listed below, it can be seen that the zinc salts of mixed esters of dithiophosphoric acid proposed according to the invention as lubricating oil additives, in which the ester groups contain 4 or 6 carbon atoms, are not only significantly more effective than Mixtures of two different symmetrical zinc dialkyl dithiophosphates, but also more effective than that known above-mentioned zinc dithiophosphates.

The invention proposes a lubricating oil containing zinc salts of mixed diesters of phosphorodithioic acid before, which is characterized in that the zinc salt is a compound of the general formula Lubricating oils

R ₁ O _n
Ro O ^y

■ S - Zn - S - Ρ:

, OR ₁

OR ,,

Applicant:

California Research Corporation,
San Francisco, Calif. (V. St. A.)

Representative: Dr.-Ing. H. Ruschke, Berlin-Friedenau,

and Dipl.-Ing. K. Grentzenberg,
Munich 27, Pienzenauer Str. 2, patent attorneys

Claimed priority:
V. St. v. America March 29, 1951

Paul K. Mulvany, San Francisco, Calif. (V. St. Α.),
has been named as the inventor

in which R _{1 is derived} from an aliphatic alcohol containing 4 carbon atoms and R _{2 is derived} from an aliphatic alcohol containing 6 carbon atoms, the molar ratio of R ₁ to R _{2 being} between 0.5: 1 and 5, 0: 1, preferably between 2: 1 and 4: 1. A preferred embodiment of the invention also consists in that R _{1 is derived} from a secondary butyl alcohol and R ₂ is derived from a methyl isobutyl carbinol. The zinc salts proposed according to the invention are already _{oil-soluble at -29 ° C. to at least 35 ° / 0} , which makes it possible to incorporate these zinc salts of the mixed diesters of dithiophosphoric acids into the lubricating oils in a higher concentration than was previously possible. It has also been found that the zinc salts of mixed esters of dithiophosphoric acids containing two different organic groups significantly extend the effective life of lubricating oils.

According to the invention, zinc salts are used in the lubricating oils as zinc salts of mixed esters of dithiophosphoric acids of those compounds added by reacting phosphorus pentasulfide with two different Alcohols are obtained.

The one alcohol that is used in the production of the mixed dithiophosphoric acid esters is used contains up to 4 carbon atoms, such as. B. methyl, ethyl, propyl, Isopropyl, butyl, secondary butyl, and tertiary butyl alcohol. For the sake of simplicity, consider this alcohol group hereinafter referred to as Rj alcohols.

The others in the production of the dithiophosphoric acid mixed esters The alcohols used contain 6 carbon atoms. This group includes methyl isobutyl carbinol, Ethyl isopropyl carbinol and hexyl alcohol. Of the

009 699/464

3 4

For the sake of simplicity, this alcohol group is used in the following for the preparation of the

referred to as R ₂ alcohols. Zinc salts are not used in the context of the present invention

The R ₁ - and R ₂ alcohols need in the reaction protection claimed,
do not mix in equimolecular amounts

be. Depending on the type of base oil and the application, 5 examples

purpose, the cheapest Molverhältms between _R} - _{χ zinc salt of the reaction produc} t _e s of isopropyl alcohol,

and R ₂ alcohols within the range of 1: 2 to ■ * ,, -, ■, · ■ ,, ■, -, ·, ■■ -r. ^

can be varied to 5: 1. - Methyhsobutylcarbinol and P ₂ S ₅

As oils with a viscosity suitable for lubrication purposes, a mixture is placed in a glass reaction vessel

A variety of lubricating oils can be used, e.g. B. Mineral oils of 252 parts by weight (67 mol percent) of isopropyl alcohol on a naphthene, paraffin or mixed basis, and 206 parts by weight (33 mol percent) of methyl isobutyl and other hydrocarbon lubricants such as Al-carbinol 333 _{parts by weight of P 2} S _{5 are} added and the kylene polymers ( eg the polymers of propylene, mixture heated for 2 hours to 77 ° C. The reaction butylene etc. and mixtures thereof), polymers of the mass is cooled and nitrated to remove a small amount of alkylene oxide, dicarboxylic acid ester and liquid 15 of unreacted P ₂ S ₅ to remove.
Esters of various phosphoric acids. 650 g of the acidic intermediate thus obtained

Among the synthetic oils in the group of 130 parts by weight of an alkylene oxide-type polymer for dilution are the alkylene oxide-containing petroleum (with a viscosity of 300 SSU for polymers themselves (e.g. the propylene oxide polymers) and 37.8 ° C), then their derivatives are gradually named at 54.5 ° C., in particular those alkylene 20 122 parts by weight of zinc oxide are added. The mixture is oxide polymers, stirred by polymerization of alkylene for 3 hours at 54.5 ° C and then the neutral oxides (z. B. propylene oxide) in the presence of water sationwasser removed with calcium sulfate. The oil solution or alcohols are obtained as well as esters of such the zinc salt has after filtration a _pH value alkylenoxydartiger polymers, eg. , Acetylated propylene of 6.7 and containing 9.96 ° / ₀ Zinc, 9.43 ° / ₀ phosphorus and oxydpolymere obtained by acetylating hydroxyl 19.42 25 ° / ₀ sulfur.

group-containing propylene oxide _{polymers obtained 2 Zhlksalz of the} reaction product from butyl alcohol. »,“ ,. ·,, -,. ,,, -. ~

Among the synthetic oils in the group of dicarbon methyhsobutylcarbinol and P ₂ S ₅

acid esters include those obtained by esterification of a mixture of 237 parts by weight (77 mole percent)

Dicarboxylic acids, e.g. B. adipic, azelaic, cork, sebacic, secondary butyl alcohol, 98 parts by weight (23 mol alkenyl succinyl, fumaric, maleic acid, etc., with aiko percent) get methyl isobutyl carbinol and 222 parts by weight, such as butyl, hexyl -, 2-ethylhexyl, dodecyl alcohol P2S5 will be obtained in a reaction vessel for 2 hours at 76.7 ° C. etc. As examples of such synthetic stirred. The reaction mass is cooled and filtered, dicarboxylic ester oils are dibutyl adipate, dihexyl to remove a small amount of unreacted P ₂ S ₅ to adipate, di-2-ethylhexyl sebacate, di-n-hexyl fumarate poly. The butylmethyl isobutyl carbinol merisate obtained, etc. are listed. dithiophosphate is a dark excrement green liquid with the

The synthetic oils in the group of liquid neutralization number 193 (mg KOH / g), a viscosity of esters of various phosphoric acids, include: the ortho 35.7 SSU at 37.8 ° C (that's 1.21 ° Engler) and one Dense phosphoric acid esters, for example tricresyl phosphate; the phosphate of L, 04undenthält24,0 _^0/0 Schwefelundll, 9 ° / ₀ phosphorus. phonic acid esters, e.g. B. Decanphosphonsäurediäthylester, 40 The above reaction mass is heated 87 parts by weight, and those esters are added by reaction of alkyl .Zinkoxyd and the whole under stirring phosphonylchbriden containing hydroxyl groups with 4 hours at 54.5 ° C until the _pH value 6 , 7 is. Compounds such as phenols and aliphatic alcohols, After removal of the neutralization water which contains or Olefinoxyden such as propylene oxide, oil solution obtained 7.6 ° / ₀ zinc, 7.2 ° / ₀ phosphorus and 15.0 ° / ₀ are. 45 sulfur.

The zinc salts of the dithiophosphoric acid mixed esters The oil solubility of a mixed diester of a dithio-

According to the invention, oils with a given molar ratio are normally added to the lubricating phosphoric acid in a sufficient amount to prevent oxidation between the two ester groups and the oil solubility of the oil used. Preferably the corresponding zinc salt is significantly greater than 0.05 to 2.0% based on the weight of the oil solubility of a mixture with the same mole composite of finished lubricant employed. ratio of two dithiophosphoric acid diesters, but you can also use lubricating oil concentrates with one each containing only one type of the two alkyl radicals occurring in a content of 50 percent by weight or even more of these above mixed esters. Making salts. So begins z. As a 35 ° / _o strength oil solution of a mixture

The zinc salts used according to the invention are prepared from zinc di (sec. Butyl) dithiophosphate and zinc dia from mixed esters of dithiophosphoric acids, (methylisobutylcarbinol) dithiophosphate in a mol-die by reacting phosphorus pentasulfide (P ₂ S ₅ ) with a ratio of 3.35: 1 to crystallize out of the solution in the course of 2 days with a mixture of two different alcohols at a temperature of -29 ° C. In contrast, temperatures of about 50 to 95 ° C can be obtained. Should a 81 ° / _o oil solution (in the same oil as above), for example, dithiophosphoric acid Mischester under encryption 60 of zinc-sec. butyl-methyHsobutylcarbinol-dithiophos turn of methyl and hexyl alcohol prepared according to Example 2, also after, 4 mol of the alcohols (for example 3 mol .30 days at -29 ° C) are left clear. A methyl alcohol also begins. dithiophosphate 1 between methyl and hexyl and zinc di- (methyhsobutylcarbinol) alcohol) with 1 mole of P ₂ S ₅ at temperatures: and 1 mol of hexyl alcohol, corresponding to an 8 ° / _0-owned oil solution of a mixture of Zinkdiisopropyl molar ratio of 3 of about 65 dithiophosphate in a molar ratio of 2: 1 react within 50 to 85 ° C until the formation of the methylhexyl dithiophosphate crystallized from the solution for 3 days at -1 ° C is complete. Sieren for obtaining, during a 85 ° / _o sodium petroleum solution (prepared, for example, Example 1 zinc isopropyl-methylisobutyl Zinkmethylhexyl dithiophosphate.) According to the zinc salts of the mixed-dialkyl dithiophosphates the phosphates are carbinol-dithiophosphate even after 34 days at - Reacted with zinc oxide at 1 ° C at around 20 to 80 ° C. 70 shows no signs of crystallization yet.

lubricant Total- Ver Weight search loss after No. Oil "A" ¹ ) 20 hours, Oil "A" + 0.52 percent by weight zinc mg 1 butyl-methylisobutylcarbinol-dithio- 558 2 phosphate (according to example 2) Oil »B« ² ) Oil "B" + 0.81 percent by weight zinc 36 3 di- (cetylphenyl) dithiophosphate .... 1102 4th Oil "B" + 0.81 percent by weight zinc di (cetylphenyl) dithiophosphate 50 5 + 0.091% sulfurized alkyl-substituted tuated calcium phenate Oil »Β« + 0.69 percent by weight zinc butyl-methylisobutylcarbinol-dithio- 344 6th phosphate (according to Example 2) +0.091 ° / ₀ sulfurized alkyl substituted calci umphenat 76

¹ J oil "A" (experiments 1 and 2) is a Californian paraffin-based oil with an SAE value of 30 (viscosity 5.3 to 7.3 ° Engler at 55 ° C), which is refined with solvent and 0, Contains 80 percent by weight of a calcium alkyl sulfonate and 0.97 percent by weight of a sulfurized, alkyl-substituted calcium phenate.

² ) Oil "B" (tests 3 to 6) is an oil with an SAE value of 30 (viscosity 5.3 to 7.3 ° Engler at 55 ° C), which comes from the central part of the North American continent.

Furthermore, the effectiveness of the zinc salts of mixed diesters of dithiophosphoric acids as an agent for extending the oxidation resistance of lubricating oils is determined on a medicinally pure paraffin oil. This property is expressed in the form of the time span (in hours) in which 100 g of the oil sample consume 1000 ecm of oxygen at 171 ° C. With medically pure paraffin oil, this is less than 0.1 hour. If the same oil 0.19 ° / ₀ of the zinc salt may be added in accordance with Example 2, the period of time is 4.2 hours.

The zinc salts according to the invention can also be added to lubricating oils, which already others known additives to improve z. B. the oiliness, the fluorescence, the viscosity index, the pour point or for peptizing or grease thickeners.

Other lubricating oil additives used in conjunction with the zinc salts according to the invention are, for example, phenates (such as calcium cetylphenolate), sulfonates, phosphates, thiophosphates, sulfur-containing Paraffins.

The following table contains values from which the effectiveness of the zinc salts of dithiophosphoric acid mixed esters as a means of reducing the corrosion of metal parts as a result of the oxidation of lubricating oils during the operation of internal combustion engines emerges. These values are determined on an ordinary Chevrolet engine, only two connecting rods are modified to accommodate copper-lead bearing inserts in place of the usual soft metal bearings of the Chevrolet engine. These are weighed before being installed in the engine. The Chevrolet engine is operated at 3150 revolutions per minute, the cooling jacket temperature being kept ^{at 95 °} C. and the oil temperature in the crankcase at 138 ^{° C.} After 36 hours of operation, the engine is disassembled and the bearing inserts are weighed after being thoroughly solvent washed to remove oil.

The following comparative tests show the

Superiority of the zinc salts of mixed diesters of dithiophosphoric acid proposed according to the invention compared to zinc salts of other dithiophosphoric acid esters known from the art as lubricating oil additives:

Experiment No. 1

The oxidation resistance of the lubricating oil compositions mentioned below is tested. That

ίο The test procedure was similar to that in »Industrial and Engineering Chemistry ", 28 (1936), p. 26, described, wherein the amount of oxygen absorbed by the lubricating oil as Measure of its resistance to oxidation. The pure oxygen is at a pressure of 1 at in finely divided state passed through the oil. The test temperature is 171 ° C. That of 100 g of oil for Absorption of 1 liter of oxygen required time in hours is called the "inhibition time"; her end represents represents the point in time at which the oil sample begins to oxidize.

Table A.

1. 30th 3. Lubricating oil composition Inhibition 2. Time 25th Base oil (in hours) Base oil with an addition of 15 mmol 0.2 per kg of the physical mixture Zinc dibutyl dithiophosphate and zinc dihexyl dithiophosphate *) Base oil with an addition of 15 mmol 17.0 every kg of zinc salt produced after present embodiment 2 *) .. 22.3

*) The molar ratio of the butyl radical to the hexyl radical was 3: 1.

Experiment No. 2

A zinc dithiophosphate with the following formula is used as a comparison substance:

R-R-

Zn

where R is an alkyl group derived from a polybutene having an average of 12 carbon atoms derives. This compound is referred to in Table B as "Dithiophosphate A".

To test the lubricating oil additives, tests are carried out with regard to the wear of valve lifters, in a Chevrolet Power Glide engine. The valve spring pressure is when the valve is fully open 108.8 kg. Under these conditions, an oil with poor properties will perform in extreme pressures 24 hours for the formation of seizure spots on the bottom of the valve lifter.

Table B.

1. Base oil

2. Base oil with an addition of 6 mmol
per kg of "dithiophosphate A"

3. Base oil with an addition of 6 mmol
per kg of zinc salt produced according to the

present embodiment 2 ...

number of

damaged

Valve lifter

9 9

Experiment No. 3

Zinc nonylphenyl-2-ethylhexyl-dithiophosphate (Stand der Technik) is used with the zinc butylhexyl dithiophosphate compared according to the present invention. A Californian, solvent 5 used refined oil. The evaluation of the lubricating oil compositions is carried out according to an SAE extreme pressure test method, with the two Timken cups that rotate constantly at 1000 revolutions per minute, be exposed to various loads. The numbers in kilograms indicate the loads at which Failure occurs.

Table C.

Composition (weight percent) A. B. Base oil 92.0
4.0
4.0
108.86
95.25
104.33 91.32
4.68
4.0
31.75
22.68
27.22 Zinc butylhexyl dithiophosphate
(according to the present invention)
Zinc nonylphenyl-2-ethylhexyl-dithio-
phosphate (according to the state of the art)
Chlorinated wax (40 percent by weight)
Test properties (kilograms Bela
performance on failure)
Exam No. 1
Exam # 2
Exam No. 3

Claims (3)

PATENT KITCHEN: 1. Lubricating oil with a content of zinc salts of mixed diesters of dithophosphoric acid, characterized in that the zinc salt is a compound of the general formula - S - Zn - S— R ₂ O OR ₁ OR ₂ in which R _{1 is} an aliphatic alcohol having 4 carbon atoms and R _{2 is} an aliphatic alcohol having 6 carbon atoms, the molar ratio of R ₁ to R _{2 being} between 0.5: 1 and 5.0: 1. 2. Lubricating oil according to claim 1, characterized in that the molar ratio of R ₁ to R _{2 is} between 2: 1 and 4: 1. 3. Lubricating oil according to claim 1 or 2, characterized in that R _{1 is} a secondary butyl alcohol and R _{2 is} methyl isobutyl carbinol. Considered publications: U.S. Patents Nos. 2,063,629, 2,343,213,
361,746, 2,466,408, 2,540,084;
British Patent No. 645,345;
French patents nos. 968 565, 976 342. © 009 699/464 1.61