DE1090361B - Lubricant additives for internal combustion engines - Google Patents

Description

iSUl> JJJEiOJ

GERMAN

Recent changes to internal combustion engines have deficiencies in the properties of those previously used Reveal zinc salts of phosphorodithioic acids as lubricants. The slightly higher operating temperatures Modern engines subject the lubricating oil to correspondingly higher temperatures. Under these under more severe conditions, the zinc phosphorodithioate has a tendency to decompose, so that the lubricant the moving metal surfaces no longer protect against corrosion.

It has now been found that a mixture of at least two different zinc salts of dithiophosphoric acids the structure

E ₁ O, S

Lubricant additives
for internal combustion engines

Applicant:

The Lubrizol Corporation,
Cleveland, Ohio (V. St. A.)

Representative:

Dr. W. Beil and A. Hoeppener, lawyers,
Frankfurt / M.-Höchst, Antoniterstr. 36

Claimed priority:

V. St. v. America January 22, 1957

R ₂ O '

SH

in which R ₁ and R ₂ mean the same or different primary aliphatic hydrocarbon radicals, namely low-molar radicals with 1 to 4 carbon atoms and higher- 'molar radicals with at least 5 carbon atoms, which are characterized in that the molar ratio of the radicals of low molecular weight to those of higher molecular weight in the zinc salt mixture is 1: 1 to 3: 1, acts particularly advantageously.

When used in lubricants, these zinc salt mixtures give the moving metal surfaces of the Motors provides unprecedented protection against corrosion. Lubricants containing small amounts of the foregoing Containing zinc salt mixtures are able to withstand the higher operating temperatures of today's engines to an extent to withstand that with previous lubricants, but not has been achieved *

To the primary aliphatic hydrocarbon groups low molecular weight with 1 to 4 carbon atoms are primarily isobutyl, n-butyl and n-propyl groups; However, ethyl and methyl groups are also suitable »

To the higher molecular weight primary aliphatic hydrocarbon groups with at least 5 carbon atoms primarily include the primary amyl residues: n-Amyl, primary isoamyl, 2-methyl-i-butyl and 2,2-dimethylpropyl. These primary amyl radicals are preferred for economic reasons also because of the particular usefulness of these zinc salts. In any zinc phosphorodithioate can use the higher molecular weight primary aliphatic

■ Hydrocarbon residues from one. 'Mixture of such There are leftovers, each of which has at least 5 carbon

■ substance contains atoms. Such a mixture can, for example from 40 mole percent n-arnyi and 60 mole percent primary isooctyl residues, whereby it should be noted that William Albert Higgins and William Monroe LeSuer, Cleveland, Ohio (V. St. A.),

have been named as inventors

that such zinc phosphorodithioate also has a sufficient amount of lower primary aliphatic Must contain hydrocarbon residues in order to reduce the ratio of low-molar residues to high-molar ones Keep residues within the range given above. A particularly preferred mixture of primary aliphatic hydrocarbon radicals with at least 5 carbon atoms is a mixture of n-amyl, primary isoamyl and 2-methyl-1-butyl radicals.

Zinc phosphorodithioates, which contain this mixture of higher molar aliphatic hydrocarbon radicals, are particularly valuable both for reasons of economy and for efficiency of use.
The mixtures according to the invention of at least two different zinc salts of dithiophosphoric acids can be prepared by mixing together different zinc salts of these acids. However, they can also be prepared from a mixture of at least two different phosphorodithioic acids, or they can

Be zinc salts of dithiophosphorus, obtained from the corresponding alcohol mixtures have been prepared. The mixtures of different zinc salts are made prepared in the usual way by one of the individual Manufactures zinc phosphorodithioates separately and then mixes the two different salts. Such salt mixtures can be prepared, for example, by Zmk-di-n-hexylphosphorodithioate and Zinc di-n-propylphosphorodithioate is produced separately and ■ the two different salts are mixed in such "quantities"

009 610/374

³ 4

that the molar ratio of_n ^ propyl to ri-hexyl radicals. agents that are resistant to high temperatures,

is adhered to as defined above. The zinc creates is not revealed there.

salts of mixtures of different phosphorodithio-

acids are converted by phosphorus ... Example 1

pentasulfide mixed with a suitable mixture of n-butyl 5 to a mixture of 536 g (6MoI)

alcohol and n-octyl alcohol for the production of the primary amyl alcohols (65% n-amyl, 3% isoamyl

speaking phosphorodithioic acid and subsequent and 32% 2-methyl-l-butyl alcohol) and 1332 g (18MoI)

Neutralization of the acid by the mixed oxide of zinc isobutyl alcohol was gradually added at 60 to 7O ⁰ C.

explained. ■. within 4.5 hours 1332 g (6 mol) of phosphorus

The special process by which the invention io pentasulfide added. The mixture became wider

zinc salts are prepared according to 2 hours not ^{heated to 60 to 70 0} C, then filtered and

Content of the invention. All of the above resulted in a clear liquid filtrate. A suspension of

procedures can be used. There were 358 g (4.4MoI) of zinc oxide in 1796 g of mineral oil

it is only necessary that the zinc salt contains the above within 2.5 hours at 75 to 77 ° C 2080 g (8MoI)

described primary aliphatic hydrocarbon i _{5 of} the above filtrates were added. The water and

contains residues in the specified ratio. other volatiles were obtained from the

The zinc salt mixtures according to the invention are obtained by mixing by heating at 85 to 95 ° C./120 mm

marked two main features. That removed. The mixture was filtered to give a

The first characteristic is that the aliphatic hydrocarbons are clear filtrate with the following analysis result:

Scraps of fabric must be primary. The second feature is, 20 _p

that these residues are both low-molar and higher- _ς ο, U J ₀

must contain molar residues. The special heat- ~ '''' : ar o / °

resistance of the new zinc phosphorodithioates should be ⁿ 0.0 / ₀

be due to the first feature. It has that

It appears that the attachment of a - ■ CH ₂ group to Example 2

Oxygen of the phosphorodithioate is more stable than the A mixture of 1644 g (6 mol) of diisobutyl

similar bond of a phosphorodithioic acid and 588 g (2 mol) of diamylphosphorus

dithioic acid, which is produced by the reaction of phosphorus penta-

I sulfide with a mixture of amyl alcohols (65%

- CH or - C group. 30 n-amyl, 3% isoamyl and 32% 2-methyl-l-butyl

I [alcohol) had been made, made and after

and after at 75 to 77 ° C within 2 hours one

It also appears that this difference is a suspension of 358 g (4.4 mol) of zinc oxide in 864 g

in the resistance is enough to add the zinc-phosphorus mineral oil. The mixture became another

dithioate mixtures satisfactory as corrosion protection - held at 75 ° C for 35 hours and then reduced to a final temperature

Medium to work under conditions heated under temperature from 85 to 95 ° C / 120 mm. The residue

those found with the previous zinc phosphorodithioates was filtered and resulted in a clear filtrate with the following

Showed deficiency. Analysis result:

The second characteristic feature of the present ρ 8Ό ° /

Zinc phosphorodithioate is the special distribution of 40 g '^' g ₀ (°

lower and higher aliphatic hydrocarbon ^ _n * "'''''" 8 5 ⁰ l °

xeste within the zinc salt. There are two obvious " '

opposing requirements that make a good corrosion resistance. .

Protective means should distinguish themselves. It should be oil-soluble, -Example 0

however, it should also be cheap at the same time. Oil Solubility 45 The zinc salt of diisobutylphosphorodithioic acid can be obtained through the use of hydrocarbon residues by reacting isobutyl alcohol with phosphorus of higher molecular weight. The sources are pentasulphide and the subsequent neutralization of the acid held for such high molecular weight hydrocarbon residues is produced by zinc oxide. However, at 447 g are relatively expensive alcohols. The cheaper alcohols (0.36 mol) of an oil solution of this salt were 149 g of lower molecular weight to give low 50 (0.12 mol) of a zinc molecular hydrocarbon radical prepared in a similar manner, which was added to a phosphorus salt of a phosphorodithioic acid, which by dithioate molecule none give sufficient oil solubility. Reaction of phosphorus pentasulphide with the oil-soluble zinc phosphorodithioate which has been produced which is satisfactory for a mixture of primary alcohols mentioned in Example 1. The invention shows that it is nevertheless possible. This mixture had to produce the following analysis result, which is economical from cheap alcohols;
can be produced. ρ _ 5 ^ 0 /
■ The essence of the present invention is based on '' °
the molar ratio of the hydrocarbon radicals in each of the zinc salt mixtures of dithiophosphoric acid prepared in the preceding examples. Zinc salts Zinc salts were ^{tested by heating dithiophosphoric acids at 120 °} C. for 8 hours, the alkyl aryl groups being tested. In every FaE, the salt was retained after this experiment or its organic residues of ether groups were completely clear, which means that it is known to be heat-resistant. Also one has already suggested it has been proven. Furthermore, in each case only one zinc salt of dithiophosphoric acids, which contain little or no release of hydrogen sulfide groups with 1 to 25 carbon atoms, was found to be lubricating during the experiment.
Medium additives should be used, but the alkyl radicals are 65 A mixture of the zinc salts of the diisobutylphosphorus. no primary aliphatic hydrocarbon radicals, dithioic acid and di-n-hexylphosphorodithioic acid (mol and the molar ratio of the low molecular weight carbon ratio 75:25), a mixture of the zinc salts of the hydrogen radicals to the higher molecular weight radicals is not taken into account of the diamylphosphorodithioic acid of Example 2. The new and technically advanced di-n-butylphosphorodithioic acid (molar ratio 50:50), progressive of the present; Invention, which lubricant 70 a mixture of the zinc salts of diisobutylphosphorus

1 090 3rd Ö1

dithioic acid and the diamylphosphorodithioic acid des Example 2 (molar ratio 50:50) and a mixture the zinc salts. diisobutylphosphorodithioic acid and di-u-hexylphosphorodithioic acid (molar ratio 50:50) were all after. in the example described -5 Process made. It was found that too each of these salt mixtures exhibited a high level of heat resistance when tested by heating for 8 hours possessed at 121.1 ° C. Each of these salt mixes was clear and none of them by the time this experiment was completed developed hydrogen sulfide during the test. Instead of isobutyl alcohol, n-butyl alcohol can also be used used to produce di-n-butylphosphorodithioic acid.

The heat resistance of the zinc salt compositions according to the invention is also demonstrated by data which were obtained in a so-called “Panel Coke Test”. It is the one in a publication by Pratt-Whitney Aircraft Corp. with the title "Panel Coking Test" from 1952 described experiment. In this test method, a sample of the oil to be tested is vigorously stirred at room temperature so that an oil mist is formed which rises and comes into contact with a heated aluminum plate suspended above the oil container. The temperature of the aluminum plate is kept at 298 ^° C .; the duration of the experiment is 3 hours. The heat resistance of the oil sample to be examined is measured by examining the deposits accumulated on the aluminum plate. A rating of 10.0 in the complete absence of any deposits and 0.0 in the complete coverage of the aluminum plate by such deposits is given for the aluminum plate.

The inventive compositions were-30 Ö1 SAE examined in a Central American solvent-extracted, which in each case 0.67 ° / ₀ of a carbonated basic barium sulfonate (as sulfate ash) and 0.06 ° / ₀ (as phosphorus) of each particular to be examined Zinkphosphordithioat -Composition included. The results of these tests are listed below:

Further evidence of the superiority of the compositions according to the invention is available in the form of the results; obtained from tests in a Buda diesel engine. These tests were carried out with an engine speed of 1815 to .1820 revolutions per minute, a water jacket temperature of 79.4 to 82.2 ° C, an oil temperature of 62.8 to 65.6 ° C under a load of 3000 watts and using a at least 1% sulfur-containing fuel carried out. In any case it concerned with the lubricant used to thicken a solvent SAE 30 Ö1 from Central America, the 0.67 ° / ₀ (as sulfate ash) of a carbonated basic barium sulfonate and / to be tested 0.06 ° ₀ (as phosphorus) of Zinc phosphorodithioate composition.

The results of the experiment were noted after 100 hours and again after 150 hours of operation under the above conditions. The piston was generally checked for cleanliness and the lubricant tested was rated on a scale in which 0 means completely dirty and 100 means completely clean. A further evaluation was carried out according to the extent to which the upper annular groove of the piston was filled with deposits. This latter rating is given as a percentage so that the values are between _{0 and} 100 ° / 0.

These experiments have the following results:

Zinc phosphorodithioate

1. Zinc salt of a phosphorodithioic acid mixture, produced by reaction a mixture of 962 g of isobutanol and 624 g of amyl alcohol mixture from Example 1 with phosphorus pentasulfide ..

2. Zinc salt according to Example 2, in which the molar ratio of the isobutyl radicals to the primary amyl residues is not 65:35, but 75:25

3. Zinc di (4-methylpentyl-2) phosphorodithioate

4. Zinc salt of a mixture of di- (4-methylpentyl-2) -phosphorodithioic acid and diisopropylphosphorodithioic acid (molar ratio 60:40)

5. Zinc dimethyl cyclohexyl phosphorodithioate

valuation

Zinc phosphorodithioate 100 hours.,. 100 hours ... total
clean
ability of
Piston Percent
tuale
filling
the upper one
Ring groove 1. Zinc salt of a mixture of di- 150 hours ... 150 hours ... (4 - methylpentyl - 2) - phosphordi 2. Zinc salt of the composition thioic acid and diisopropylphos of example 3 phordithioic acid (molar ratio 60:40) 83 16 78 16 96 0 95 1

9.5

9.5 5.5

6.8 1.5

45 From the above data it can be seen that the products according to the invention have a much higher heat resistance than the previously known zinc phosphorodithioates.

Claims (2)

Patent claims: 1. Lubricant additives for internal combustion engines, consisting of a mixture of at least two different zinc salts of a mixture of dithiophosphoric acids of the structure 60 R ₂ O ' SH It should be noted that each of the zinc phosphorodithioates No. 3, 4 and 5 contain secondary alkyl groups, so that the rating of each of these three compositions is significantly worse than the rating that the corresponds to the compositions according to the invention. in which R ₁ and R _{2 are} identical or different primary aliphatic hydrocarbon radicals, namely low- molar radicals with 1 to 4 carbon atoms and higher-molar radicals with at least 5 carbon atoms, characterized in that the molar ratio of the radicals of low molecular weight to those of higher molecular weight in the zinc salt mixture is 1: 1 to 3: 1. 7 8 2. Lubricant additives as claimed in claim 1, _{characterized in that the publications which are taken into consideration are} : characterized in that the low molecular weight radicals are butyl radicals, preferably isobutyl radicals, and German patents No. 832030, 862 206; the higher molecular weight residues amyl residues, U.S. Patents Nos. 2,501,731, 2,501,732; preferably a mixture of 65 ° / ₀ n-amyl, 5 British Patents Nos 658 182.658183, 723,133. 3% isoamyl and 32% 2-methyl-1-butyl radicals. French patents nos. 976 342, 976343. © 009 610/374 9.60