Note: Descriptions are shown in the official language in which they were submitted.
-" ~o70665
Synthetic esters, the so-called ester oils, have
beeA increasingly used in recent years as high-grade lubricat-
ing oils. Thus, diesters of dicarboxylic acids with monovalent
alcohols, such as dioctyl sebacate or dinonyl adipate, or
esters of polyols with monocarboxylic acids, such as trimethylol
propane tripelargonate, have been proposed as lubricants for
,~ :
aircraft turbines. In recent times, so-called complex esters
have also been developed for lubricating problems of this type.
In addition to polyhydric alcohols, such as trimethylolpropane
or neopentylglycol, these complex esters contain, as esterifi-
cation components, monocarboxylic acids having 6 to 10 carbon
atoms, and dicarboxylic acids, such as sebacic acid or azelaic
acid. The suitability of the synthetic esters as lubricants
results from the fact that they have a more favorable viscosity/
temperature behavior than conventional lubricants based on
mineral oils, and that upon adjusting to com arable viscosities,
the pour points are distinctly lower. However, for many
ranges of application, for example, for the new multigrade
transmission oil class 80 W-90 (see U.S. Military Specifica-
tion Mil-L-2105 C), which requires highly viscous transmission
oils having viscoxity values of at least 14 cSt at 210F and
a maximum of 150,000 cP at -15F, the known synthetic esters
are unsuitable owing to their limited viscosity properties. -
On the oth~r hand, however, lubricating oils based
on mineral oils, and which have adequate viscosity properties
can only be manufactured by adding polymers, such as a styrene/
butadiene copolymer (German Auslegeschrift No. 1,811,516).
When adding copolymers to increase the viscosity of transmis-
sion oils, one disadvantage is the shearing sensitivity of the
polymers. As a result of shearing, i.e., by irreversible
~ .
1070665
fracture of the polymers, considerable reductions in the
viscosity of the corresponding oils occur.
An ob~ect of the present inven-tion is the develop-
ment of a synthet.ic ester oil which, in addition to having a
low pour point, has a high viscosity and a satisfactory
viscosity/temperature behavior (high viscosity index).
Another object of the present inven,ion is the
development of a high viscosity neutral complex polyester
lubricant produced by esterifying a mixture of
(a) a branched alkanepolyol having 2 to 4 prir.. ary hydroxyls
and 4 to 10 carbon atoms,
(b) polyacids selected from the group consisting of dimeric
fatty acids and trimeric fatty acids produced by the
dimerization of unsaturated fatty acids having 16 to 18
carbon atoms, and
(c) alkanoic acids having 6 to 16 carbon atoms,
in such proportions that the acid numb~r of said polyester is
,;
0.3 or below, the hydroxyl number of said polyester is 0.5 or
below, and the proportion of said hydroxyl groups being ester-
ified by said alkanoic acid is from 50~ to 90~.
These and other objects of the invention will
become more apparent as the description thereof proceeds.
The present invention relates to novel, highly
viscous neutral complex esters of polyols wlth polymeric fatty
acids and aliphatic monocarboxylic acids, and their use in
; ~ lubricating oils.
More particularly, we have now discovered that the
requirements of a high viscosity lubricant with a low pour
point have been met, to an extent not hitherto attained, by
novel, neutral complex esters derived from:
:; ` 1070665
(a) polyvalene, branched, aliphatic alcohols having 2 to 4
primary hydroxy groups and 4 to 10 carbon atoms,
(b) dimeric and/or trimeric fatty acids produced by polymerization
of unsaturated fatty acids having 16 to 18 carbon atoms, and
(c) saturated 4traight chain or branched chain, aliphatic mono-
carboxylic acids having 6 to 16 carbon atoms,
the proportion of the hydroxy groups esterified by monocarboxylic
acits being 50% to 90%.
Our invention is, therefore, a high viscosity neutral
complex polyester lubricant produced by esterifying a mixture of
~ (a) a branched alkanepolyol having 2 to 4 primary hydroxyls and
.: 4 to lO carbon atoms, (b) polyacids produced by the dimerization
and trimerization of unsaturated fatty acids having 16 to 18 carbon .
atoms, wherein said polyacids are a mixture containing at least
75% of dimeric fatty acids, and (c) alkanoic acids having 6 to 16
carbon atom~ selected from the group consisting of (1) mixtures
of saturated fatty acids having 6 to 12 carbon atoms, and (2)
alkanoic acids having 12 to 16 carbon atoms and having a branched
chain in the a-position to the carboxyl group, in such proportions
that the acid number of said polyester is 0.3 or below, the hydroxyl
number of said polyester is 0.5 or below, and the proportion of
said hydroxyl groups being esterified by said alkanoic acid i8
from 50% to 90%.
The alcoholic component forming the basis of the
highly viscous, neutral complex esters in accordance with the
present invention can be any branched, aliphatlc polyol having 2
to 4 primary hydroxy groups and 4 to 10 carbon atoms, more
particularly a branched alkanepolyol having 2 to 4 primary hydroxyls
and 4 to 10 carbon atoms, such as neopentyl glycol, trimethyl-
olethane, trimethylolpropane or pentaerythritol. The trihydric :
alcohol trimethlolpropane is particularly important.
The polycarboxylic acid component is a mixture of
3- :
~, :
, ' : . .: ' ' ''
,
--` 1070665
polyacids selected from the group consisting of dimeric fatty
acids and trimerlc fatty acids produced by the dimerlzation of
unsaturated fatty acids having 16 to 18 carbon atoms. The mixtures
of dimeric and trimeric fatty acids produced by dimerization of
olefinically-unsaturated fatty acids having 16 to 18 carbon atoms
are preferred as the polymeric fatty acids, and those wherein the
mixtures have a content of 75% by weight, and in excess thereof, -
of dimeric fatty acids are preferred. Such mixtures of polymeric
fatty acids are obtained, for example, by thermal polymerization
of olefinically-unsaturated fatty acids, such as oleic acid,
~ linoleic acid or linolenic acid or fatty acid mixtures having a
; content of olefinically-unsaturated fatty acids, such as the fatty
acids obtained from soybean oil or tall oil, at temperatures of
approximately 200C to 300C in the presence of small quantities
of water and a mineral catalyst such as montmorillonite.
~ .
~ 4-
,;~,; ~
~ ' ~
1070665
The monocarboxylic acid component of the neutral
complex esters in accordance with the present invention may
comprise a wide variety of saturated, straight chain or branched
chain, aliphatic monocarboxylic acids or alkanoic acids
having 6 to 16 carbon atoms. By way of example, fatty acids,
such as capronic acid, caprylic acid, capric acid, lauric
- acid, myristic acid or palmitic acid and mixtures thereof,
are suitable. Preference is given to mixtures of saturated
fatty acids having 6 to 12 carbon atoms, which, for example,
are produced as pre-run fatty acids during the distillation
of coconut fatty acids.
Branched chain monocarboxylic acids which have
proved to be particularly advantaveous are the alkanoic acids,
havi~g 12 to 16 carbon atoms, branched in the ~-position
to the carboxyl group. Carboxylic acids of this type can be
produced by, for example, Guerbetizi~g of medium chain length, -
unbranched, saturated alcohols and subsequent oxidation of the
alcohols which are obtained. These acids are branched in the
second position and have a corresponding total number of
carbon atoms. An isopalmitic acid manufactured in this manner
by oxidation of 2-hexyldecanol was preferred as the monocar-
boxylic acid component in the complex esters in accordance
with the present invention.
The complex esters, in accordance with the present
invention, of branched alkanepolyols having 2 to 4 primary
hydroxy groups, polymeric, substantially dimeric, fatty acids
and saturated, straight chain or branched chain alkanoic acids
can be produced in accordance with known esterification pro-
cesses by heating the reactants (to 200C in a nitrogen
atmosphere) in the presence of an esterification catalyst such
'.
.. . . . ..
1070665
as powdered tin, p-toluene sulfonic acid or others, while
removing the water formed. Alternatively, esterification
can be effected in two stages, the alcoholic component being
reacted with dimeric fatty acids in the first step and being
- further esterified with the monocarboxylic acid after partial
reaction has been completed. Preferably a slight excess of
the alkanoic acid is employed. For the purpose of purifying
the product of esterification, the latter may be treated with
; an additive of l~to 5% by weight of activated bleaching clay.
Any free monocarboxylic acid which is still present can be
removed by distillation, so that complex esters are produced
whose acid numbers lie below 0.3 and whose hydroxyl numbers
æe below 0.5
Owing to their excellent properties, namely, their
high viscosity, their low pour point and their favorable
viscosity/temperature behavior, the neutral complex esters
in accordance with the present invention are eminently suitably
for use as lubricants, particularly for transmission fluid
and lubricants for two-stroke piston engines.
The complex esters in accordance with the present
invention may constitute the sole oil base in the finished
lubricant, or they may be mixed as a mixture component with
other products which are already known for this purpose. When
used as mixing components in lubricant and transmission oils,
any optional quantity ratios may be mixed which are deter-
mined exclusively by the required properties such as viscosity
pour point, and viscosity/temperature behavior. Ho~ever, the
content of complex esters will not usually be below 10%, and
preferably not below 30%, by weight in the finished product.
Various additives such as oxidation and corrosion inhibitors,
-- 6 --
-~ 1070665
dispersing agents, high pressure additives, anti-foaming
agents, metal deactivators and other additives suitable for
use in lubricant formulations based on synthetic esters, can
be added in conventional effective quantities.
The following examples are intended to further
illustrate the present invention, but wlthout limiting the
invention thereof.
EXA~LE 1
Production of the Neutral Complex ~sters
268 gm (2 mols) of trimethylolpropane, 565 gm (approx-
imately 1 mol) of dimeric fatty acid (a mixture of approxlmately -
95~ by weight of dimerize.d fatty acids, approximately 4% by
weight of trimerized fatty acids, and approximately 1~ by
weight of non-polymerized unsaturated fatty acids, the start-
ing unsaturated fatty acid being a mixture of olefinically
unsaturated fatty acids having 16 to 18 carbon atoms), and
632 gm (approximately 4 mols) of C6 to C12 saturated fatty
acids (a mixture of approximately 5~ by weight of C6 fatty
acids, approximately 45~ ~y weight of C8 fatty acids, approxi-
mately 45% by weight of C10 fatty acids, and approximately
5% by weight of C12 fatty acids as obtained from the distilla-
tion of coconut fatty acid), were heated to 200C in an auto-
clave provided with a water separator under passage of nitro-
gen, the nitrogen acting as a carrier gas to flush out the
water ofreaction. A mixture of powdered tin 1.5 gm and p-toluene
sulfonic acid 1.5 gm was used as an esterification catalyst.
~owards the end of the reaction,
further esterification was carried out at the same temperature,
but under reduced pressure (approximately 70 torr). After
cooling to 120C, 1.5 gm (approximately 1~ by weight) of
.' ~ .
: -- 1070665
.
activated bleaching clay were added and the mixture was again :
; heated to 200C and the surplus monocarboxylic acid was dis-
tilled off in vacuo. The acid number of the product A of
esterification (the proportion esterified with monocarboxylic
. acid was 67%) was 0.28. The product had a viscosity of 6~8
. cSt at 37.8C = (100F), and 57 cSt at 99C = (210F). The
viscosity index was 164 and the pour point was -38C.
The complex esters given in the following Table I
were produced in conformity with the above method.
~ - 1070665
. . __
., :
~ .:
~:r x u~
. ~ ~ ~ ~ ~ ~ ~ U)S
,, ~ ~ o o o o o o .~
~i . . _ ._ ~ ~ 3 '~ ~ :
~ ~_ o ~ _~ X ~ o ~ g
:~. ~ 1 o Ul1~1 ~ N ~1 ~ (~
: ~ O O O l I
_
... ..... _ .. __ __ .. ~ ~ ~ ~
;',~, . U ~ ~ I ~ O ~` O . ~1 ~ . -,-
' . ~ U~ ~ ~ IJ~ ~ 1/~ 1~ O
.~ ~ n H ~1 ~1 ~1 ~1 ~1 ~1 ~ / X
. . .... .. _ , ~ O rl ~O
,., .~ o IJ~ D C~ _l ~r t` ~ ol a~
:~ ~1 ~ cn ~ _ I ~ Il~
. ~ U~ ~ X
8 u~ ~ o
.~ ~ ~ ~ t~ O _, ~D .~
;~.. ' ~ ~ ~ _l ~1 00 D X ~q~l
~ ~, a~ ~ ~ u~ O
~ ~ ~-~ ~ ~ ~ ~ O
:: a ~ d~dP dP dP dP dP _, ~ u
.`' O ~ ~1 3 ~` ~ O 1` O u~ t~ <L)
~:', P; O S~ ~ I~ X CO ~D U~ I~
.. ', ~ P~ P~ O
~ ~s ~ e~ u ~ ~ -
H ~ Pl 1~ E1 h X ~ O o
1 E- U * .~ U~ ~0
... 1~ ~1 1~1 14 ~1 ~4 Q~ o ~ _
: ;~~ X _~ N e ~ ~1 ~I r~
m ~ x , ~ ~1 ~ _~
.i ~ o ~ ~ ~ C~ = .,~ ,~ ~ ~ o
,,¢ !~ 5~ l ~ o-~l l 3 3
2i S~ ~ ~ u~ U ~D .~
.. , E`~ O ~ U . ~ C.) H ~ C~ O (D .~ ~ ~I S X
,~~,. u o ~ ~ ~ CJ O O ~ $
:: ~ O O ~ ~ ~ ~ ~ ~ X X 3 U~ O~rl
~; ~ ~ ~ ~_~ ~ ~
~ .... ___ ... _._ . ~ ~ Q ~ ~ ~D ~
:' z ~ ~c
:. ~I) ~a ~ ~ ~ ~ ~ ~ N ,1
N- ~1 ~0 : ~ E3 - ~1 ~0 : ~ ~ X U~ ;
S-H¢ h S-l ~1 ~ O S ~-1 ~1)
~"' ~ ~ ~ u~ ~ ~ In ~ u~ u~
a O O .~ O O .~ O O ~ o ~ ~ o.. O ~d
.1 S~ h O O ~ ~
~' . l l l ~ 0~
.i _I_ ~ ~-1 0 ~1 1
,,, ~ 0 ~ ~ >1 ~ ~ ~ 0 4-1 14 Q
'.~ ~ X ~ ~ ~ R~
o a~ o ~ o o ~u o ~ ~
~1 ~ ~ ~ S~~ t~ ~rl Cq
~, _ ~1 ~ rl Q~O ~ ~ h
.. E~ O E~ O Z tJ~ ~ ~1
:' .
b t~ .
s~ ~ m c~
.. ~ * * .~,
~c
X ~ ~ ~ ~ u~
- .
.
~070665
.:
EXA~IPLE 8
:: USE
: Ageing tests at high temperatures were carried out
with a lubricating oil manufactured on the basis of the com-
plex esters in accordance with the present invention, and with
a commercially available lubricating oil. In addition, the
compatibility of those oils with various seal materials also
was tested. A commercially available single grade oil of the
class SAE 80 and a multi-grade oil, in accordance with the
present invention of the specification SAE 80 W-90 were used
- in the tests. The composition of the oil in accordance
with the present invention was as follows:
93.5~ by weight of Product D of Example 4 (complex ester
of 1 mol of trimethylolpropane, 0.3 mol of dimeric
- fatty acid [75%] and 2.4 mol of C6-C12 pre-run
' fatty acid),
6.5~ by weight of a commercially available transmi~sion
,- oil,additive (ANGLAMOL 99 Or Lubrizol?.
The characteristic data of the oil in acc~dance
with the present invention given in Table II show that the
.' additive used did not contain any agent for lowering the
pour point and any V.I. improver.
' -- 1 0
__,.. _ . . _ , ..... .. .
. . . .. . .. . . . . . . . .
1~75)665
T A B L E I I
CHARACTERISTIC DATA OF THE
LUBRICATING OILS TESTED
.
,.
CharacteristicIn Accordance Commercially
ValueWith InventionAvailable
.
~in. viscosity
at 37.8C 147 cSt115.4 cSt
7i Kin. viscosity
at 98.9C 18 cSt 11.5 cSt
~yn. viscosity
at -26.1C 25,000 cPs o 1 i d
Viscosity index 146 94
Pour point -41C -l9CC
Acid number 0.4 2.8
. .
: , .
a) Aging Tests
The lubricating oils to be tested were heated to
; 160C and 200C, respectively, for eight hours in a glass
flask, a quantity of air being conducted through the flask dur-
ing this period of time at a rate of 10 liters per hour. The
changes in the viscosities and acid numbers were determined
from the samples aged at 200C.
In AccordanceCommercially
with InventionAvailable
Change in viscosity
at 99C (210F)+ 33.2 ~ 52.7
in percent
Increase in acid
number 1.3 3.4
The lubricant in accordance with the present inven-
tion exhibited a substantially smaller degree of aging than the
commercially available product.
- 11 -
... .
::~ 10706~;5
..
The bearing capacities of the products aged at
160C were determined on a frictional wear balance according
to Reichert. The wear was determined under a load of 1500
kp/mm2 during friction of steel on steel (length of slide
path 100 mm).
In AccordanceCommercially
With Invention Available
Bearing capacity of
~ the aged sample1,250 750
,,. 10 (kg/cm2)
'.'
b) Swelling Behavior of Seal Materials
,
`~ In accordance with the regulations laid down by
DIN 53,521, various seal materials were immersed for 70 hours
in the lubricating oils which were to be tested and which had
been heated to 100C. The increase in weight of the seal
materials was subsequently determined.
Increase in Weight After
Swelling in Percent
In Accordance Commercially
Seal Material With Invention Available
Rubber ~NBR 61679) 11.7 15.5
Silicone 10.7 13.2
The lubricating oils, in accordance with the present
invention based on complex esters also gave better results in
this test and, with the seal materials tested, lead to less
swelling than is the case with known commercially available
oils.
- 12 -
,. .. . : ............. . . : , . .. .
. .
..
1~70665
The preceding specific embodiments are illustrative
of the practice of the invention. It is to be understood,
however, that other expedients known to those skilled in the
~` art, or disclosed herein, may be employed without departing
.. from the spirit of the invention or the scope of the appended
claims.
.~ " " ' .
- 13 -
. ' ", " '~' . .
