DE1233524B - lubricant - Google Patents

Description

FEDERAL REPUBLKÄ GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

ClOm

CIOM 1 69 / OOB 20

German class:

Number: 1233 524

File number: S 72950IV c / 23 c

Filing date: March 13, 1961

Opened on: February 2, 1967

It is known that trimethylolethane esters of unbranched aliphatic monocarboxylic acids with three identical acyl radicals as high temperature lubricants, e.g. B. gzeugen for the operation of gas turbines at Flu to use. However, these esters have the disadvantage that they meet certain requirements, e.g. B. with regard to the flash point or the kinematic viscosity, are not sufficient.

These disadvantages are avoided by using ester oils from a reaction product of Tri methyloTäthan and unbranched aliphatic monocarboxylic acids with 4 to IOC atoms of the formula

R '

C = O

O CH ₂

il i

R "- C-Ο -H ₈ CC-CH ₃
CH ₂

lubricant

Applicant:

Shell International Research
Maatschappij NV, The Hague

Representative:

Dr. E. Jung, patent attorney,

Munich 23, Siegesstr. 26th

Named as inventor:
Benjamin Franklin Crouse jun.,
William Walter Rexnolds,
East Alton, JH. (V. St. A.)

Claimed priority:

V. St. v. America of March 14, 1960 (14 535)

C = O

R '

in which each R is an n-alkyl radical having 3 to 9 carbon atoms and at least one of the alkyl radicals is a number of carbon atoms different from those of the other alkyl groups than high temperature resistant Lubricants are used.

Examples of esters of the above formula are (2-butyryloxymethyl) - (2-caproyloxymethyl) -l-caproyloxypropane, (2 - butyryloxymethyl) - (2 - caprylyloxymethyl) -1 - capryloxypropane, 2,2 - di - (caproyloxymethyl) -l-butyryloxypropane, 2,2-di- (butyryloxymethyl) -1 - caproyloxypropane, 2,2 - di - (caproyloxymethyl) 1-capryloxypropane, (2-butyryloxymethyl) - (2-capryloxymethyl) -1-capryloxypropane and (2-caprylyloxymethyl) - (2-caproyloxymethyl) -l-capryloxypropane. Compounds in which the acyl radicals have an even number of carbon atoms are due to preferred because of their greater resistance to oxidation.

2

It can be seen that any two of the acyl radicals can be the same, but different from the third Are acyl radicals, or that all three acyl radicals can be different from one another.

These new esters and, in particular, mixtures of these esters are produced by known processes by esterifying trimethylolethane with a mixture of at least two unbranched aliphatic carboxylic acids with 4 to 10 carbon atoms in the molecule, the mixture containing at least 4 mol percent of each carboxylic acid.

A mixture of three or four carboxylic acids is preferably used for the esterification, since the the product then has the best lubricating properties owns.

Trimethylolethane is known to be produced by aldol condensation made of propionaldehyde with formaldehyde. The trimethylolethane used for the esterification should be free of bis (2,2-dimethylolpropyl ether and similar impurities because otherwise the esterification product will have an increased viscosity

709 501/358

and has other undesirable rheological properties and is less resistant to oxidation.

Although the individual esters from the esterification product easily z. B. by gas chromatography of each other can be separated, it has been found that it is precisely the mixture of esters Is lubricant with particularly desirable properties. It is therefore preferred when applying to use the unseparated reaction products as a lubricant. As a result of their proportionate Low viscosity combined with high temperature and oxidation resistance are the esters especially valuable where these properties are important.

When used, the esters can at high temperatures with metals, especially bearing metals, come into contact under conditions which in themselves favor severe corrosion. It has now been found that the corrosion z. B. the copper reduced to a minimum or can be prevented at all if one uses the acid mixture for the production of the ester at least 4 mole percent of capric acid or caprylic chloride is added, so that ester is obtained which is about this amount of Contains caprylic residues. Since the incorporation of large amounts of caprylic residues into the esters increases their viscosity, For some uses, a maximum level of about 6 mole percent n-capric acid is desirable.

Ester mixtures in which 4 to 6 mole percent of the The total number of acyl groups being caprylic shows an unexpected superiority in terms of cleanliness and lack of corrosiveness.

Also ester mixtures in which about 15 mole percent of the total number of acyl residues are n-butyryl residues, for example 45 mole percent n-caproyl radicals and about 40 mole percent n-cyprylyl residues have excellent properties.

ίο Under the conditions of the esterification reaction, a complete esterification of the trimethylolethane does not always occur

A low hydroxyl content in the esters is not harmful, although as the hydroxyl content increases, the corrosion of the copper by the triesters also increases. On the other hand, the hydroxyl groups increase the dispersing effect of the triesters and reduce the deposition of decomposition products of the lubricant, such as sludge on magnesium, steel, silver and aluminum. These conflicting effects are such that the optimum hydroxyl content for the esters should be about 0.3 moles per liter; a higher hydroxyl content is undesirable.

The lubricants can contain other known additives, e.g. B. oxidation or corrosion inhibitors contain.
The example illustrates the invention.

example

In Table I below are the properties and composition of compositions according to the invention Esters A to F are given.

Table I.

Ester OH value
Moles per liter Medium
Number of C Butyric acid
Mole percent Acids in the ester
Caproic acid
Mole percent Caprylic acid
Mole percent Capric acid
Mole percent A. 0.26 6.0 10 80 ! 0 - B. 0.24
0.19 6.5
6.5 15th
15th 45
45 40
40 - C. 0.28 7.0 10 31 59 D. 0.38 7.0 25th 25th 25th 25th 0.18 7.0 25th 25th 25th 25th E. 0.22 6.5 19.05 41.0 35.2 4.75 F. 0.18 6.5 16.6 45.9 33.0 4.50

In Table II, the kinematic viscosities and flash points of the triesters A to F according to the invention are compared with those of trimethylolethane esters in which all acyl radicals have the same number of carbon atoms. In the latter group, three classes are represented, namely n-acyl groups, branched acyl groups and mixtures of n-acyl groups and branched acyl groups.
It can be seen from the values that the flash points of the esters according to the invention are in general comparable with those of the other group, the kinematic viscosities at those indicated

Temperatures, however, are visibly lower, making the triesters according to the invention the known Esters are superior.

Table II

formula

Trimethylol ethane ester

n-capryl

Branched caprylyl

Branched caprylyl

n-caproyl and branched

Caproyl mixed

n-caprylyl and branched

Caprylyl mixed

(A)
(B)
(C)
(D)
(E)
(F)

Kinematic

Viscosity in centistokes 38 ⁰ CI 99 ° C

24.5
27.1
46.5

12.2

19.1

11.42
12.89
14.57
15.27
13.46
13.18

5.12 4.72 6.42

2.91

3.92

2.87 3.13 3.40 3.54 3.22 3.17

Claims (1)

Claim: Flash point 279 249 266 218 252 238 246 235 238 Use of a reaction product of trimethylolethane and unbranched aliphatic Monocarboxylic acids with 4 to IOC atoms of R '
ι O I.
C = O O
Il CH ₂ CH ₃ Il
R "—C- -0 —H ₄ CC- CH ₂
I. I.
O C = O R '" in which each R is an n-alkyl radical having 3 to 9 carbon atoms and at least one of the alkyl radicals has a number of carbon atoms that is different from that of the other alkyl radicals, as a high temperature lubricant. Considered publications:
Industrial and Engineering Chemistry, 1953, 1766 to 1775. 709 507/358 1.67 © Bundesdruckerei Berlin