Note: Descriptions are shown in the official language in which they were submitted.
2~ ~4 ~3~
USE OF ADDUCTS OF O,O-DIALKYLDITHIOPHOSPHORIC ACIDS
Use of adducts of O,O-dialkyldithiophosphoric acids with
unsaturated monohydric alcohols or ethoxylates and/or
proproxylates of the same as lubricant additives.
5The invention relates to the use of adducts of
O,O-dialkyldithiophosphoric acids of the general formula
(RlO)(R20)P(S)-SH (I)
where Rl and R2 are identical or different and are a
straight-chain or branched alkyl group having from 4 to
18 carbon atoms,
with unsaturated compounds selected from the group
consisting of
a) unsaturated, straight-chain or branched
monohydric alcohols having from 10 to 24 carbon
15atoms and an iodine number in the range from 45
to 180, and
b) addition products of ethylene oxide and/or
propylene oxide with unsaturated, straight-chain
or branched, monohydric alcohols having from 10
20to 24 carbon atoms, having iodine numbers in the
range from 30 to 160,
as anti-wear additives (AW additives) for lubricants.
A typical example of hitherto customary AW
additives are zinc salts of alkyldithiophosphoric acids
(zinc alkyldithiophosphates). Although these additives
have satisfactory properties in the relevant tests, e.g.
in accordance with DIN 51350 (weld load; wear diameter),
and are accordingly widely used in lubricants, they do at
the same time have the disadvantage that they are not
stable to hydrolysis and have an unpleasant odor;
furthermore their metal content is undesired for reasons
of environmental protection.
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US-A 2 528 732 describes the uæe of adducts of O,O-
dialkyldithiophosphoric acids with oleyl alcohol as
stabilizers for mineral oils; however no reference is
made to lubricant properties of these adducts. The same
applies to analogous adducts with terpenes as described
in US-A 2 665 295 and US-A 2 689 258.
Furthermore, US-A 3 574 795 describes adducts of O,O-
dialkyldithiophosphoric acids with conjugated dienes and
their use as lubricant additives. However, the achievable
AW and EP (extreme pressure) effects change greatly even
if adducts with butadiene are compared with those with
chloroprene, so that no predictions are possible herefrom
for the behavior of adducts with unsaturated alcohols.
Furthermore, the previously known adducts are lacking a
free OH group which is very advantageously noticeable in
the adducts to be used according to the invention.
Furthermore, GB-A 700 530 describes adducts of dialkyl-
dithiophosphoric acids with succinic acid and the use of
the metal salts derived from the adducts as lubricant
additives which are, however, then no longer metal-free.
Although metal-free analogous adducts with maleic and
fumaric esters are known from US-A 3 359 203, these
adducts have esterified carboxylic acid functions which
can be destroyed by hydrolysis and, in addition, give
downstream products having unpleasant smells.
There is therefore a need for lubricant additives which
have equally good properties in the appropriate tests and
are odor-free and metal-free and are furthermore stable
to hydrolysis and have an improved thermal stability.
These requirements are met by the adducts of the inven-
tion to be used according to the invention.
Typical examples of the radicals R1 and R2 in the O,O-
dialkyldithiophosphoric acids of the general formula I
are butyl, pentyl, hexyl, methylpentyl, 2-ethylhexyl,
octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl,
2~3~
heYA~ecyl and octadecyl, with isobutyl, isoamyl and 2-
ethylhexyl being particularly advantageous. The compounds
of the $ormula I are commercially available or can be
prepared by conventional methods.
Typical examples of unsaturated, straight-chain or
br~nche~ monohydric alcohols to be used according to the
invention are olefinically unsaturated fatty alcohols
having from 10 to 24 carbon atoms and an iodine number in
the range from 45 to 180, which are commercial products
and which are obtainable from animal and/or plant fats
and oils or else by a synthetic route, e.g. lauroleyl,
myristoleyl, palmitoleyl, oleyl, gadoleinyl, erucyl,
linoyl, and linoleyl alcohols, including industrial mix-
tures of these fatty alcohols; particular preference is
given to industrial oleyl alcohol mixtures having a high
content of oleyl alcohol.
Addition products of ethylene oxide and/or propylene
oxide with unsaturated, straight-chain or br~nche~
monohydric alcohols, in particular olefinically unsa-
turated fatty alcohols having from 10 to 24 carbon atomsas in the above examples,-having iodine numbers in the
range from 30 to 160, can also be used according to the
lnvention .
Preferred adducts to be used according to the invention
are those of 0,0-dialkyldithiophosphoric acids in which
the radicals R1 and R2 are a straight-chain or branched
alkyl group having from 4 to 12, in particular from 4 to
8, carbon atoms.
Adducts to be preferably used can furthermore also be
obtained using addition products of ethylene oxide and/or
propylene oxide with unsaturated fatty alcohols having
from 16 to 22 carbon atoms; typical examples of such
fatty alcohols have already been mentioned above.
The adducts to be used according to the invention have an
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OH group originating from the monohydric alcohols or
alkoxylates thereof which has a surprisingly favorable
effect on the AW properties. Although these adducts have
a lower sulfur and phosphorus content than comparable
adducts obtained using olefins without an OH group, in
tests they show essentially the same AW properties.
The adducts of the invention can be used as wear-reducing
additives in water-miscible and water-immiscible
lubricants containing mineral oils or free of mineral
oils. Typical examples of such lubricants, which include
metal forming fluids, are the following:
motor oil, gearbox oil, diesel motor oil, turbine oil,
greases, hydraulic oils;
for non-cutting metal forming: drawing oils, stamping
oils, rolling oils;
for cutting metal forming: cutting oils, ho~;ng oils,
gr; n~; ng oils, reaming oils, deep-well drilling oils.
Adducts having relatively short alkyl groups, in parti-
cular those having from 4 to 6 carbon atoms such as butyl
or isobutyl and pentyl or isoamyl and also hexyl are here
particularly suitable as additives for water-containing
lubricants. Adducts having longer alkyl groups, e.g.
having 8 or more than 8 carbon atoms, are particularly
suitable as additives for water-free lubricants.
The invention further relates to adducts of O,O-dialkyl-
dithiophosphoric acids of the above general formula I, in
where R1 and R2 are each straight-chain or branched alkyl
groups having from 4 to 6 carbon atoms, with unsaturated
compounds as defined above.
The adducts of the invention can be prepared in a manner
known per se by addition of O,O-dialkyldithiophosphoric
acids to monohydric alcohols having olefinic double bonds
X~.t39~
-- 5
or to ethylene oxide and/or propylene oxide adducts of
the same, generally at elevated temperatures, preferably
from 110 to 150C, in particular from 125 to 140C. At
these reaction temperatures the use of catalysts i8
generally not necessary.
The reaction times required are in the order of a few
hours. If the reaction times at a certain reaction
temperature become too long, the temperatures can be
increased to a certain extent, as long as no decom
position pheno~en~ occur in the reaction mixture. Shorter
reaction times are also achieved by using the dialkyl-
dithiophosphoric acids of the formula I in a small
excess, e.g. up to 10 %, based on unsaturated compound8
used. The excess mercapto groups then contained in the
reaction mixture are advantageously neutralized after the
reaction is complete with bases, in particular amines, to
a pH in the range from 7 to 8; amines particularly
suitable for this purpose are mono-, di- or, if steri-
cally possible, tri-(C4-C18)- alkylamines having straight-
chain, branched or cyclic alkyl groups; furthermore alsoalkanolamines such as ethanolamine, diethanolamine or
triethanolamine, but these- only if the compounds to be
used according to the invention are intended for water-
miscible lubricants. Furthermore, the treatment with the
abovementioned amines is also advisable as deodorisation
for adducts prepared from equimolar amounts of monoal-
cohols and dialkyldithiophosphoric acids.
The invention is illustrated below by means of examples
of preferred embodiments; the Comparative Examples 1, 2
and 3 are not according to the invention. Comparative
Example 3 shows, by use of diisopropyldithiophosphoric
acid, a good WSD value which results from this product
decomposing rapidly owing to its low thermal stability
and thus the high proportion of S and P being reacted.
Even the use of relatively long-chain alcohols as in
Examples 3 and 4 shows that, owing to the free OH groups
of the oleyl alcohols used, the polar properties ensure
Xl;3~
-- 6
a greater affinity for the metal surface, which leads to
the same WSD values although the S and P available is
~ignificantly lower.
Comparative Example 1
Commercial zinc 2-ethylhexyldithiophosphate cont~;n;ng
9.5 % of zinc, 8 % of phosphorus and 16 % of sulfur.
Comparative Example 2
2-ethylhexylamine salt of 2-ethylhexyldithiophosphoric
acid cont~;n;ng 16 % of mineral oil. Sulfur content:
about 11 %, phosphorus content: about 5.5 %.
Comparative Example 3
Reaction product of O,O-diisopropyldithiophosphoric acid
with ethyl acrylate as described in DE-A 29 21 620; S
content: about 20 % by weight, P content: about 9.9 % by
weight.
Example 1
354 g (1 mol) of O,O-bis(2-ethylhexyl)dithiopho~phoric
acid were heated with 267 g (1 mol) of OcenolR 90/95
(industrial C18 fatty alcohol; IN 90-95; from Henkel)
under nitrogen at 130C for 8 hours while stirring. The
unreacted SH groups were neutralized with 30 g (0.23 mol)
of 2-ethylhexylamine to pH 8.
This gave a clear, low-viscosity product having an acid
number of 16.
Sulfur content: about 10.4 %, phosphorus content: about
5 %.
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Example 2
490 g (1 mol) of an adduct of oleyl alcohol with 5 mol of
EO (IN 42-50) were heated with 354 g (1 mol) of O,O-
bis(2-ethylhexyl)dithiophosphoric acid under nitrogen for
12 hours at from 125 to 130C while stirring.
This gave an intermediate-viscosity, clear product having
an acid number of 27.
Sulfur content: about 7.6 %, phosphorus content: about
3.7 %.
Example 3
242 g (1 mol) of O,O-diisobutyldithiophosphoric acid were
heated with 270 g (1 mol) of OcenolR 110/130 (IN 110-130;
from Henkel) under nitrogen at 120C for 9 hours while
stirring. The remaining SH groups were neutralized with
20 g (0.15 mol) of 2-ethylhexylamine to pH 8.
This gave a clear, intermediate-viscosity product having
an acid number of 15.
Sulfur content: about 12.5 %, phosphorus content: about
6.1 %.
Example 4
334 g (1 mol) of O,O-bis(2-ethylhexyl)dithiophosphoric
acid were heated with 270 g (1 mol) of Ocenol 110/130 (IN
110-130; from Henkel) under nitrogen at 120C for 8 hours
while stirring. The remaining SH groups were neutralized
with 25 g (0.19 mol) of 2-ethylhexylamine to pH 8.
Thi~ gave a clear, intermediate-viscosity product having
an acid number of 16.
Sulfur content: 10.3 %, phosphorus content: 5.0 %.
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The properties of the abovementioned adducts or compara-
tive products as lubricant additives were determined in
accordance with DIN 51350 (Tentative Method IP 239/69) in
a Shell four-ball apparatus. In detail, the following
were measured:
1. WL = weld load. This is the load at which the
four balls of the apparatus weld together
within 60 seconds.
2. WSD = wear scar diameter in mm. This is the
10mean wear diameter at a load of 800 N for
one hour.
The base oil used was an undoped mixed basic spindle oil
(Shell Gadus 22/40).
The load of 800 N was selected because no wear diameters
15could be determined at 150 or 300 N as prescribed by DIN.
Results of testing in the four-ball apparatus:
Lubricant Additive - WL WSD
Type Conc. in N mm
% by weight
Comparative Example 1 1 1800 2.3
Comparative Example 2 1 1800 2.3
Comparative Example 3 1 1800 0.9
Example 1 1 1800 2.3
Example 2 1 1800 2.3
Example 3 1 1800 0.9
~xample 4 1 1800 0.9
As is shown by the above table, the adducts of
the invention have the same lubricant properties as the
comparative products. However, in contrast to these, they
are stable to hydrolysis and metal-free.
