DE1808492B2 - ZINC DITHIOPHOSPHORIC ACID ESTERS AND THEIR USE AS A LUBRICANT ADDITIVE - Google Patents

Description

R ² O OR ²

in which R ¹ (3,5-di-tert-butyl-4-hydroxybenzyl) propyl and R ² (3,5-di-tert-butyl-4-hydroxybenzyl) propyl, 4-methylpentyl-2 or Means cetyl.

2. Lubricant, characterized in that it contains a compound according to claim 1.

It is known that zinc dialkyldithiophosphates can be used as additives for lubricating oils since these compounds give lubricants a high resistance to oxidation and good anti-wear properties and impart anti-corrosion properties.

It is also known that hindered phenolic compounds, z. B. 2,6-di-tert-butyl-p-cresol as anti Oxidation additives can be used. In addition, it is known that some mixtures of zinc dialkyl dihiophosphates and hindered phenols due to the synergism between both classes of lubricants give a high resistance to oxidation.

The subject matter of the invention is defined in more detail in the claims.

Such a lubricant has anti-wear and anti-corrosion properties about as good as the well-known lubricants with bis (n-alkyl) zinc dithiophosphate additives, however, has better resistance to oxidation and is also such lubricants in terms of resistance to oxidation consider having a mixture of bis (n-alkyl) zinc dithiophosphates and contain sterically hindered phenols as additives.

The zinc dithiophosphoric acid esters according to the invention can by reacting P ₂ S ₅ with suitable alcohols in an approximate molar ratio of 1: 4 at an elevated temperature, generally at a temperature of 50 to 200 ^° C., preferably from 80 to 120 ^° C., and subsequent neutralization of the obtained diphosphonic acid can be obtained with zinc oxide.

The invention is illustrated in more detail by the following examples.

Example 1 Production of bis - [(3,5-di-tert-butyl-4-hydroxy-benzyl) propyl] zinc dithiophosphate

tert-butyl

- CH ₂ CH ₂ -CH ₂ -O-

\ tert-butyl

Zn

4 moles of (3,5-di-tert-butyl-4-hydroxy-benzyl) propanol were reacted with 1 mole of P ₂ S ₅ , suspended in benzene, at the boiling point of benzene. The reaction was complete in about 2 hours. The benzene was filtered and distilled off under reduced pressure. The resulting phosphorodithioic acid was heated with ZnO in the presence of an inert solvent which forms an azeotrope with water, in this case toluene, in order to neutralize the product. Then the inert solvent was evaporated.

and it became solid, resinous, orange-yellow in color Product obtained in a yield of 95%. The analysis of the product is the following Values:

45 Calculated ... P 4.56, Zn 4.79. S 9.42:
found ... P 4.51, Zn 4.70. S 9.38.

The infrared spectral analysis confirmed the presence of a dithiophosphate group.

Example 2 Preparation of (4-methyl-pentyl-2) [(3,5-di-tert-butyl-4-hydroxy-benzyl) propyl] zinc dithiophosphate

tert-butyl

HO- <f \ -CH ₂ -CH ₂ -CH ₂ -CH ₂ -O ■
ten-butyl

Ρ — S —Zn —S-P-

CH ₃
-Ο — CH-CH ₂ -CH-CH ₃

CH,

A mixture of 2 moles of (3,5-di-tert-butyi-4-hydroxyphenyl) propanol and 2 moles of 4-methylpentanol-2 was allowed to react _{with 1 mole of P 2} S _{5 under the same conditions as in Example 1,} and the product was similarly neutralized with ZnO to give a liquid, viscous, brown-orange colored product in 97% yield.

The analysis
Values:

of the final product gave the following

P 6.19. Zn 6.53. S 12.82:
P 6.13. Zn 6.50. S 12.73.

Calculated
found

The infrared spectral analysis confirmed the presence of a dithiophosphate group.

example

Production of cetyl-Cia.S-di-terL-butyl- ^ hydroxy-benzyl ^ propyO-zinc dithiophosphate tert-butyl

^ V-CH ₂ -CH ₂ -CH ₂ -CH

tert-butyl

Ρ— S — Zn — S— P —fO— (

S- CH ₃ ),

CH ₃ - (CHj) ₁₅ -O

A mixture of 1 mol of (3,5-di-tert-butyl-4-hydroxy-benzyl) propanol and 3 mol of cetyl alcohol was allowed to react with 1 mol of P ₂ S _{5 in a} manner similar to that described in Example 1 . After the neutralization with zinc oxide to obtain a solid, waxy, yellow-orange colored product in a yield of 96%.

The analysis of this product resulted in the following values:

P 4.93, Zn 5.15, S 10.01; P 4.80, Zn 5.10, S 9.95.

Calculated
found

Infrared spectral analysis of the product confirmed the presence of a dithiophosphate group.

Comparative examples

To prove the technical achieved according to the invention Progress over the prior art known on the priority date of the present invention Technique, the experiments described below were carried out:

1. Determination of the antioxidant properties of the lubricant additive according to the invention in comparison to known lubricant additives

With a paraffinic SAE 30 mineral oil with a high viscosity index, which contained additives according to the invention or known additives, became the known Staeger oxidation tests were carried out and the results obtained are as follows Table I given.

The test consisted of the oil containing the additives being tested in a kept at 110 ° C thermostatic oven has been heated. In the oil it was

Table I.

Additive to SAE 30 mincral oil

Zn-bis-butyldithiophosphate

Bis (4-methyl-2-pentyl) Zn dithiophosphate

Bis-cetyl-Zn-dithiophosphate

Bis-butyl-Zn-dithiophosphate 1

2,6-di-tert-butyl-p-cresol J.

Bis - [(3,5-di-tert-butyl-4-hydroxy-benzyl) propyl] -

Zn dithiophosphate

Bis (4-methyl-2-pentyl) -Zn-dithiophosphate!

2.6-di-tert-butyl-p-crcsol

(4-methyl-2-pentyl) - [(3,5-di-tert-butyl-4-hydroxy-

benzyl) propyl] -Zn-dithiophosphorus

Bis-cetyl-Zn-dithiophosphate 1

2,6-di-tert-butyl-p-cresol [

Cetyl - [(3,5-di-tert-butyl-4-hydroxy-benzyl) propyl] -

Zn-dithiophosphal

a strip of electrolytic copper immersed, which served as an oxidation catalyst. The change in the neutralization number, based on the weight in mg KOH per g oil. certainly.

The test was considered to have ended when the increase in the neutralization number was 0.25. Oxydationstests also were carried out at 150 ⁰ C in the same manner as those at 110 C. The concentration of the additives according to the invention was constant in each case. The phosphorus content was 10 " ⁴ g /%, corresponding to 0.7 mmol of dithiophosphate per kg of solution. The known comparison additives were selected from the zinc dithiophosphates obtained from aliphatic alcohols and mixtures thereof with 2,6-di-tert. butyl-p-cresol in equimolar concentrations, based on the additives according to the invention.

concentration
(mmol / kg solution)

Oxidation (number
of the hours
1 i0 ° C, the
Increase in
Neutralization number
required by 0.25
was)

Oxidation (number of hours at 150 ° C. Increase of the neutralization number by 0.25 were necessary)

310

810

1120

820

1350
1650

1260
1450

1250
1340

120
140

250
390

210

240

270
320

As shown in Table II given in Table 1 above

Results revealed, showed the invention

Zinc dithiophosphate has a high antioxidant additive tivitäi aut and that between the dialkyl zinc ditbiophosphates and the sterically hindered phenols existing synergism increases when this sterically hindered phenol part of the dithiophosphate molecule forms.

Concentration in %

Base oil
VE / 50 C

Niax. More specific

Load pressure at without the max.

Seizure load in kg without

Seizure in kg cm ^:

- 2.95

2. Determination of the anti-wear properties

When examining the anti-wear properties of an oil containing the additives of the invention compared to those of the same oil containing known additives, those in the Results given in Table II below were obtained.

With the letters A to i ^; marked additions were the following:

A = bis (3,5-di-tert-butyl-4-hydroxybenzyl) propyl zinc dithiophosphate (according to the invention Example 1);

B = (4-methyl-2-pentyl) - (3,5-di-tert-butyl-4-hydroxybenzyl) -propyl-zinc dithiophosphate (inventive example 2);

C = cetyl- (3,5-tert-butyl -4-hydroxytenzyl) -propyl zinc dithiophosphate (example 3 according to the invention);

D = di (isobutyl) zinc dithiophosphate (according to State of the art);

E = di (4-methyl-2-pentyl) zinc dithiophosphate (according to the prior art);

F = di (n - hexyl) zinc dithiophosphate (according to the prior art).

The anti-wear tests were carried out according to the instruction manual for Precision Shell four-bal! extreme pressure tester «. The tests were performed on a Shell four-ball wear tester performed with each test at a speed of 1200 rpm for 60 seconds took. The results obtained are summarized in Table II below.

A B C D

EF 0.4
0.4
0.4
0.4
0.4
0.4

2.95
2.95
2.95
2.95
2.95
2.95

55
115
120
110
UO
100
110

18 330 26 500

25 700

26 650 25 890

25 680

26 450

From the above Table II it can be seen that the additives according to the invention the unieruchen give oil essentially the same anti-wear properties as the known additives.

3. Investigation of the anti-rust properties

When investigating the anti-rust properties of oils containing the same additives as in the preceding Table II contained those summarized in Table III below Get results. These tests were performed using the ASTM D-665-54 method.

Table III concentration Base oil rust additive in % E. V./50'C education 0.03 2.95 is missing A. 0.03 2.95 is missing B. 0.03 2.95 is missing C. 0.03 2.95 weak D. 0.03 2.95 is missing E. 0.03 2.95 weak F.

From the above results it can be seen that the additives according to the invention the tested oils give better rust resistance than the known additives.

Claims (1)

Patent claims: 1. Zinc dietbiophosphate ester salts of the general formula R ¹ OSS OR ² \ ll II / P-S-Zn-S-P