U.S. patent application number 14/203654 was filed with the patent office on 2014-09-18 for stabilized fluids for industrial applications.
This patent application is currently assigned to E I DU PONT DE NEMOURS AND COMPANY. The applicant listed for this patent is E I DU PONT DE NEMOURS AND COMPANY. Invention is credited to Raja Hari Poladi, HARI BABU SUNKARA.
Application Number | 20140259884 14/203654 |
Document ID | / |
Family ID | 50478588 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140259884 |
Kind Code |
A1 |
SUNKARA; HARI BABU ; et
al. |
September 18, 2014 |
STABILIZED FLUIDS FOR INDUSTRIAL APPLICATIONS
Abstract
The present invention is directed toward compositions suitable
for use as dielectric fluids, lubricant fluids and biodiesel
fluids. Compositions described herein are obtained from a
saturated, unsaturated or combinations of both monol, diol, triol
or polyol acyl ester based fluid and/or a non-ester based fluid and
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol and/or the
carboxylic acid salt of
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol. These
compositions demonstrate improved oxidative stability and/or
hydrolytic stability at higher use temperatures.
Inventors: |
SUNKARA; HARI BABU;
(Hockessin, DE) ; Poladi; Raja Hari; (Bear,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
E I DU PONT DE NEMOURS AND COMPANY |
Wilmington |
DE |
US |
|
|
Assignee: |
E I DU PONT DE NEMOURS AND
COMPANY
Wilmington
DE
|
Family ID: |
50478588 |
Appl. No.: |
14/203654 |
Filed: |
March 11, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61792363 |
Mar 15, 2013 |
|
|
|
Current U.S.
Class: |
44/306 ; 44/307;
44/388 |
Current CPC
Class: |
C10M 2207/2835 20130101;
C10L 1/188 20130101; C10L 1/2225 20130101; C08K 5/17 20130101; C10L
1/1881 20130101; C10L 1/14 20130101; C10L 2200/0476 20130101; C10M
2207/401 20130101; C10N 2030/66 20200501; Y02E 50/13 20130101; C10L
1/1824 20130101; C10M 2203/1006 20130101; C10M 127/04 20130101;
H01B 3/20 20130101; C10L 2230/081 20130101; C10L 1/026 20130101;
C10M 129/94 20130101; C10M 141/06 20130101; Y02E 50/10 20130101;
C08K 5/18 20130101; C10M 133/08 20130101; C10L 10/00 20130101; C10M
2215/042 20130101; C10M 2207/125 20130101; C10N 2030/10 20130101;
C10M 2207/026 20130101; C10M 169/04 20130101; C10L 1/2235 20130101;
C10M 2207/026 20130101; C10M 2207/289 20130101 |
Class at
Publication: |
44/306 ; 44/307;
44/388 |
International
Class: |
C10L 1/223 20060101
C10L001/223 |
Claims
1. A stabilized biodiesel fluid composition comprising: (a) a
methyl ester based fluid selected from the group consisting of
vegetable oil, algae oil, animal fat, tall oil and combinations
thereof; (b) optionally, a petrodiesel fluid; and (c) at least one
component selected from the group consisting of: (i)
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP; and
wherein the composition is characterized in that the stabilized
biodiesel fluid composition has an oxidative stability index (OSI)
of greater than about 10 hours at 110.degree. C. as measured by
AOCS 12b-92.
2. The stabilized biodiesel fluid composition of claim 1 wherein
the vegetable oil is selected from the group consisting of soybean
oil, rapeseed oil, sunflower oil, safflower oil, castor oil, palm
oil, palm kernel oil, coconut oil, camelina oil, olive oil,
cottonseed oil, grapeseed oil and combinations thereof.
3. The stabilized biodiesel fluid composition of claim 2 wherein
the vegetable oil comprises at least about 75 wt % of a high oleic
acid triglyceride composition.
4. The stabilized biodiesel fluid composition of claim 1, wherein
the ester based fluid comprises free fatty acids up to about 1 wt
%.
5. The stabilized biodiesel fluid composition of claim 1, wherein
the TAP is 2,4,6-tris(dimethylaminomethyl) phenol (TDAMP).
6. The stabilized biodiesel fluid composition of claim 1, wherein
the mono C.sub.12-C.sub.30 carboxylic fatty acid is selected from
the group consisting of oleic acid, stearic acid, palmitic acid,
myristic acid, lauric acid and tall oil.
7. The stabilized biodiesel fluid composition of claim 1, wherein
the salt is formed from oleic acid and
2,4,6-tris(dimethylaminomethyl) phenol (TDAMP).
8. The stabilized biodiesel fluid composition of claim 1, wherein
the stabilized biodiesel fluid composition has an oxidative
stability index (OSI) of greater than about 20 hours at 110.degree.
C. as measured by AOCS 12b-92.
9. A method for stabilizing a biodiesel fluid composition
comprising the steps: mixing together at or above ambient
temperature: (a) a methyl ester based fluid selected from the group
consisting of vegetable oil, algae oil, animal fat, tall oil and
combinations thereof; (b) optionally, a petrodiesel fluid; and (c)
at least one component selected from the group consisting of: (i)
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt mixture comprising at least one mono C.sub.12-C.sub.30
carboxylic fatty acid and a TAP, the salt mixture having a molar
ratio of up to 3 moles of mono C.sub.12-C.sub.30 carboxylic fatty
acid per mole of TAP.
Description
[0001] This application claims benefit of priority from U.S.
Provisional Application No. 61/792,363 which is herein incorporated
by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to compositions suitable for use as
dielectric fluids, lubricant fluids and biodiesel fluids.
BACKGROUND
[0003] High performance fluids for industrial applications can
include ester based fluids or non-ester based fluids or
combinations of ester and non-ester based fluids.
[0004] Ester based fluids, both natural and synthetic, have long
been used globally in a wide range of industrial applications as
base oils that include dielectric fluids, lubricant fluids,
biodiesel fluids, etc. Synthetic esters are obtained from an
alcohol, having one, two, three or more hydroxyl groups, wherein
the alcohol is esterified with a carboxylic acid or acid mixture.
Natural esters are triglycerides of vegetable oil, algae oil or
animal fats. Triglycerides are considered the esterification
product of glycerol, a triol, with three molecules of fatty acids.
Vegetable oils are biodegradable, nontoxic and renewably sourced,
unlike conventional mineral oils. They have low volatility, high
flash and fire points and good boundary lubrication properties.
However, the major drawbacks of vegetable oils are their poor
oxidative stability, poor hydrolytic stability and unfavorable
rheological fluid properties at low temperatures which severely
limit their use in industrial applications mentioned below.
[0005] Dielectric fluids are used in the electrical industry for
cooling electrical equipment such as transformers, power cables,
breakers and capacitors. Typically, these dielectric fluids are
used in combination with solid insulation such as in liquid-filled
transformers. Examples of dielectric fluids include mineral oil,
high molecular weight hydrocarbons (HMWH), silicone fluid, and
synthetic hydrocarbon oils (polyalpha-olefins). Such fluids must be
electrically insulating, resistant to degradation, and be able to
act as a heat transfer medium so that the high amount of heat
generated in an electrical apparatus can be dissipated to the
surrounding environment and thereby increase the life of the solid
insulation.
[0006] Lubricant fluids are used as hydraulic fluids, metal working
fluids, 2-cycle engine oil, process oils, chain bar oils, and
greases. A lubricant fluid is typically formulated by combining a
lubricant base stock, or a mixture of lubricant base stocks, with
additives and other optional formulation aids. Esters of monols,
diols, triols and polyols are frequently used.
[0007] Biodiesel fluids are used in primarily three markets, mass
transit, marine industry and in farming. Biodiesel fluids are made
from vegetable and animal oils. Biodiesel fluids offers a number of
advantages over petrodiesel fuels such as enhanced biodegradation,
increased flash point, reduced toxicity, lower emissions and
increased lubricity. When biodiesel fluids are blended with diesel
fuels, the blend has better properties. Since the biodiesel fluid
has the same fatty acid profile as the parent oil or fat, its
stability behavior is similar to that of its parent oil and faces
similar technical issues such as its susceptibility to oxidation
upon exposure to oxygen in ambient air and hydrolysis upon exposure
to moisture.
[0008] As mentioned above non-ester based fluids such as mineral
oil, high molecular weight hydrocarbons (HMWH), silicone fluid, and
synthetic hydrocarbon oils (polyalpha-olefins) can be used as
dielectric fluids. However, these fluids are not as environmentally
friendly materials as ester fluids.
[0009] Additives are often added to enhance the performance of base
fluids.
[0010] There is a need for an additive to improve the fluid
stability of dielectric fluids, lubricant fluids and biodiesel
fluids by improving the oxidative stability and hydrolytic
stability of the fluids, preferably at elevated use
temperatures.
SUMMARY
[0011] The present invention is directed toward a stabilized
aminophenolic composition comprising: (a) a
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(b) at least one component selected from the group consisting of:
(i) an ester based fluid comprising esters of mono-, di-, tri- or
polyhydroxyl alcohols; and (ii) at least one mono C.sub.12-C.sub.30
carboxylic fatty acid in a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP such that a
salt is formed from the mono C.sub.12-C.sub.30 carboxylic fatty
acid and the TAP; and wherein the stabilized aminophenolic
composition is characterized in that the stabilized aminophenolic
composition has improved stability relative to the TAP alone and
the improved stability being demonstrated by at least one of the
following performance metrics wherein: (aa) an extrapolated onset
of thermal decomposition of the TAP in the stabilized aminophenolic
composition occurs at a higher temperature than the extrapolated
onset of thermal decomposition of the substantially pure TAP as
measured by thermogravimetric analysis (TGA) ASTM E2402-11; and
(bb) the stabilized aminophenolic composition has an oxidative
stability index (OSI) of greater than about 20 hours at 130.degree.
C. as measured by AOCS 12b-92.
[0012] In another embodiment, the present invention is directed
toward a stabilized dielectric fluid composition comprising: (a) at
least one component selected from the group consisting of: (i) an
ester based fluid comprising saturated and/or unsaturated esters of
mono-, di-, tri- or polyhydroxyl alcohols; and (ii) a non-ester
based fluid selected from the group consisting of mineral oil,
silicones, poly(alpha olefins) and combinations thereof; and (b) at
least one component selected from the group consisting of: (i) a
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and a TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP; and
characterized in that the stabilized dielectric fluid composition
has an oxidative stability index (OSI) of greater than about 20
hours at 130.degree. C. as measured by AOCS 12b-92.
[0013] In another embodiment, the present invention is directed
toward a stabilized lubricant fluid composition comprising: (a) at
least one component selected from the group consisting of: (i) an
ester based fluid comprising saturated and/or unsaturated esters of
mono-, di-, tri- or polyhydroxyl alcohols; and (ii) a non-ester
based fluid selected from the group consisting of mineral oil,
silicones, poly(alpha olefins) and combinations thereof; (b) at
least one component selected from the group consisting of: (i)
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP; and (c) at
least one additive selected from the group consisting of
antioxidant, antiwear, antisieze and pour point depressant; and
wherein the stabilized lubricant fluid composition has an oxidative
stability index (OSI) of greater than about 20 hours at 130.degree.
C. as measured by AOCS 12b-92.
[0014] In still another embodiment, the present invention is
directed toward a stabilized biodiesel fluid composition
comprising: (a) a methyl ester based fluid selected from the group
consisting of vegetable oil, algae oil, animal fat, tall oil and
combinations thereof; (b) optionally, a petrodiesel fluid; and (c)
at least one component selected from the group consisting of: (i)
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP; and
wherein the composition is characterized in that the stabilized
biodiesel fluid composition has an oxidative stability index (OSI)
of greater than about 10 hours at 110.degree. C. as measured by
AOCS 12b-92.
BRIEF DESCRIPTION OF THE FIGURES
[0015] FIG. 1a is a percent weight loss graph of the thermal
gravimetric analysis (TGA) of TDAMP as a function of
temperature.
[0016] FIG. 1b is a percent weight loss graph of the TGA of TDAMP
as function of time at a constant temperature.
[0017] FIG. 2 is a graph of the TGA of 2-ethylhexanoic acid salt of
TDAMP as a function of temperature.
[0018] FIG. 3 is a graph of the TGA of lauric acid salt of TDAMP as
a function of temperature.
[0019] FIG. 4 is a graph of the TGA of oleic acid salt of TDAMP as
a function of temperature.
[0020] FIG. 5 is a graph of the TGA of oleic acid salt of TDAMP as
a function of time at a constant temperature.
[0021] FIG. 6 is a graph of oxidative stability of high oleic
soybean oil with various antioxidants at 130.degree. C.
DETAILED DESCRIPTION
Definitions
[0022] DAMP is dimethylaminomethyl phenol.
[0023] DBDAMP is 2,6-di-t-butyl-4-dimethylaminomethyl phenol.
[0024] BDAMP is 2,4-bis(dimethylaminomethyl) phenol.
[0025] TDAMP is 2,4,6-tris(dimethylaminomethyl) phenol.
[0026] TDAMP-TEH is 2-ethylhexanoic acid salt of TDAMP.
[0027] TAP is 2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl)
phenol.
[0028] ADPA is alkylated diphenylamine.
[0029] BHT is butylated hydroxytoluene.
[0030] BHA is butylated hydroxyanisole.
[0031] TBHQ is t-butylhydroquinone.
[0032] HMBBHC is
1,6-hexamethylenebis(3,5-t-butyl-4-hydroxyhydrocinnamate).
[0033] TTCC is trimethylolpropane tricaprylic-caprate.
[0034] SME is soybean methyl ester.
[0035] HOS oil is high oleic soybean oil.
[0036] HOME is high oleic soybean methyl ester.
[0037] The stabilized compositions of the present invention
comprise an ester based fluid selected from vegetable (plant) oil,
algae, animal fat and tall oil fatty acid esters and
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl)phenol, and these
compositions are useful in various industrial applications that
include but not limited to dielectric fluids, lubricant fluids and
fuel fluids. These compositions further comprise other synthetic
saturated esters and/or non-ester based oils that include but not
limited to mineral oil, silicones, polyalphaolefins, and diesel
fluids.
[0038] 2,4,6-tris(dimethylaminomethyl)phenol (TDAMP) is used widely
as a delayed-action gelation catalyst for polyurethane rigid foam,
and as a curing agent and as a tertiary amine activator for epoxy
resins. TDAMP is available commercially as Ancamine K54 or DMP-30.
Both DMP-30 and Ancamine K54 have 2,4,6-tris(dimethylamino)phenol
as the main component and 2,6-bis(dimethylaminomethyl)phenol as the
minor component.
[0039] Vegetable oils and animal fats have different structures and
are more polar than mineral oils and therefore have different
properties. The majority of vegetable oils consist primarily of
triacylglycerides, also known as triglycerides. The fatty acids in
the vegetable or plant oils can be saturated, unsaturated,
conjugated or isolated and the unsaturation can be mono-unsaturated
or poly-unsaturated. Different fatty acids have different levels of
unsaturation and the degree of unsaturation can be measured by
iodine value. Tall oil fatty acids refined from crude tall oil, a
by-product of the pulp industry, could be used as a feedstock to
make tall oil fatty acid ester compositions of the present
invention. The tall oil fatty acids are predominantly consist of
oleic and linoleic free fatty acids and these fatty acids can be
converted into esters by reacting with monol, diols, triols and
polyols.
[0040] The saturated, unsaturated or combination of both monol,
diol, triol or polyol acyl ester based fluid is selected from the
group consisting of a vegetable oil based fluid, algae oil, animal
fat, tall oil and combinations thereof. The ester based fluid
comprises free fatty acids up to about 1 wt %. An example of an
animal fat is tallow oil. The vegetable oil based fluid is selected
from the group consisting of soybean oil, rapeseed oil, sunflower
oil, safflower oil, castor oil, palm oil, palm kernel oil, coconut
oil, camelina oil, olive oil, cottonseed oil, grapeseed oil and
combinations thereof. In one embodiment, the vegetable oil based
fluid comprises at least about 75 wt % of a high oleic acid
triglyceride composition comprising fatty acid components of at
least about 75 wt % oleic acid. In another embodiment, the
vegetable oil based fluid comprises a reaction product obtained
from the transesterification of vegetable oil with alcohol.
[0041] Due to the presence of glycerol moiety, unsaturation groups
and residual free fatty acids, the vegetable oils have lower
thermo-oxidation stability than mineral oils. The presences of
ester groups and residual free fatty acids in the vegetable oils
make these oils susceptible to hydrolysis leading to the formation
of carboxylic acids and alcohols. In many of the industrial
applications, these oils can contact with metals such as iron and
copper at elevated temperatures, and these metals can accelerate
undesirable oxidation, hydrolysis and corrosion reactions in
vegetable oils. The vegetable oils upon oxidation can result in
increased acidity, corrosion, viscosity and volatility, and hence
limit the useful life of vegetable oil based fluids.
[0042] Use of additives to enhance the stability of the vegetable
oils is more cost effective than chemically modifying the oils. The
effectiveness of additives is affected by several factors including
the base oil composition, environmental conditions and the presence
of other additives. As a result of structural differences, the
additives that general work for mineral oils do not work very well
for vegetable oils.
[0043] The thermo-oxidative stability of vegetable oils can be
improved with phenolic antioxidants at much higher loadings than
are used in mineral oils. However, the phenolic antioxidants being
acidic in nature could accelerate the hydrolysis of esters when
these oils are exposed to moisture at elevated temperature and thus
make these oils less attractive in high temperature industrial
applications. The known efficient diphenylamine antioxidants such
Irganox.RTM. L-57 and Naugard.RTM. 445 when tested performed poorly
in vegetable oils, in fact, functioned as pro-oxidants, at
oxidation test temperatures of 110-130.degree. C. However, the same
antioxidants excelled in synthetic esters at the same temperature
range. The major difference between the synthetic esters and
vegetable oils is (poly) unsaturation. This observed pro-oxidant
effect of diphenylamines is consistent with the reported data. It
is interesting to note that the temperature effect of diphenylamine
antioxidants in vegetable oils and their inefficiency at lower
temperatures (below 175.degree. C.) because the diphenylamines are
expected to follow the basic radical scavenging mechanism as
hindered phenolic antioxidants. Because of thermo-oxidative and
hydrolysis instabilities, the temperature limit for vegetable oils
is well below 100.degree. C. and, therefore, these oils are limited
to only low temperature industrial applications.
[0044] Vegetable oils are thermally stable at high temperatures,
but less stable thermo-oxidatively. Any additive that enhances
thermo-oxidative stability of vegetable oils must be thermally
stable so that the fluids could be used in broad range of
temperatures. We have examined the thermal stability of the TDAMP
for suitability of its use an additive to vegetable oils.
[0045] The weight loss of neat TDAMP under inert atmosphere as a
function of both temperature (heating rate at 5.degree. C./min) and
time was investigated (FIGS. 1a and 1b) by thermogravimetric
analysis (TGA). The extrapolated onset decomposition temperature of
TDAMP was 152.5.degree. C. at which the weight loss begins (FIG.
1a) and this temperature agrees with the reported decomposition
temperature of 156.degree. C. in the prior art. The slight
difference in the decomposition temperature is may be due to
different heating rates. The first derivative peak temperature was
about 185.degree. C. The peak of the first derivative, also known
as inflection point, indicates the point of greatest rate of change
on the weight loss curve. At isothermal temperature of 130.degree.
C., the TDAMP decomposed by more than 97% in 1.5 hours (FIG. 1 b).
Therefore, it is anticipated that this material could not survive
in accelerated oxidative stability index tests conducted for
vegetable oils at 130.degree. C. Surprisingly, when we tested the
thermo-oxidative stability of vegetable oils at 130.degree. C., the
induction period for high oleic soybean oil composition containing
0.2 wt % TDAMP was about 30 hours and the induction period for the
high oleic soybean oil composition containing TDAMP along with
other phenolic antioxidants was even much higher (about 100 hours)
suggesting that the vegetable oils stabilize the TDAMP at these
temperatures, and the stabilized TDAMP improves the oxidative
stability of the vegetable oils. This is a rather surprising result
because usually additives are added to enhance the performance of a
base fluid, and in this case, the base fluids are enhancing the
thermal performance of the TDAMP additive and in turn their
thermo-oxidative stability was improved resulting in stabilized
compositions.
[0046] We have also prepared salts by reacting TDAMP with
carboxylic acids including renewable sourced carboxylic acids. The
selected carboxylic acids are: a branched C8 based (2-ethylhexanoic
acid), a linear saturated C12 based (lauric acid) and a
monounsaturated C18 based (oleic acid). Since the TDAMP has three
tertiary amine groups, three moles of one or more carboxylic acid
are needed for each mole of TDAMP to completely neutralize the
base. If basicity is desired, less than 3 moles of one or more
carboxylic acids can be added to one mole of TDAMP. The benefits
associated with the use of salts are many folds that include higher
thermal stability, greater solubility in oils, safer and less
hazardous. The thermal stability of the carboxylic acid salts of
TDAMP (completely neutralized) and their antioxidant efficiency
were tested. The thermal stability of 2-ethylhexanoic acid salt of
TDAMP (commercially available from Air Products) was tested. The
weight loss of 2-ethylhexanoic acid salt as a function of
temperature is shown in FIG. 2. A weight loss of 94.5% occurred at
200.degree. C. with a 4.6% residue. The first derivative peaks
indicate that the salt dissociates into corresponding amine and
acid at elevated temperature, and the 2-ethylhexanoic acid
volatilizes even before TDAMP decomposes. The lauric acid salt of
TDAMP was prepared by reacting TDAMP with lauric acid. The
renewably sourced lauric acid is a solid having melt (T.sub.m) and
recrystallization (T.sub.c) temperatures 44 and 39.degree. C.
respectively as measured from differential scanning calorimetry
(DSC), whereas, the carboxylic salt derived from TDAMP and lauric
acid is a liquid at room temperature with a single melt temperature
at -16.degree. C. and a single recrystallization temperature of
-24.degree. C. indicating a homogeneous composition of the salt.
The linear saturated lauric acid which is less volatile than the
branched 2-ethylhexanoic acid, a lower weight loss with higher
residue was observed with lauric acid salt compared to
2-ethylhexanoic acid salt as shown in FIG. 3. The first derivative
peak associated with TDAMP shifted to higher temperature by about
20.degree. C. indicating higher thermal stability of the lauric
acid salt. In contrast to lauric acid salt, the oleic acid salt of
TDAMP had no sharp melt and crystallization temperatures as evident
from DSC (not shown) and therefore this salt has superior low
temperature fluid properties. Unlike the other two acids, there was
only one single first derivative peak observed for the oleic acid
salt of TDAMP and this salt appears to be even more thermally
stable than lauric acid salt as shown in FIG. 4. As shown in FIG.
5, the weight loss of this compound at isothermal temperature of
130.degree. C. was about 9% in 1.5 hours and less than about 15% in
4 hours indicating much higher stability of TDAMP-oleic acid salt
compared to TDAMP (FIG. 1b).
[0047] The antioxidant efficiency of these three carboxylic acid
salts was tested by adding the salts to vegetable oils in
accelerated Oxidation Stability Index (OSI) test at 130.degree. C.
Surprisingly, all of the three carboxylic salts showed similar
efficiencies compared to TDAMP at equivalent moles despite the
amine groups being neutralized completely. Even more surprisingly,
the oleic acid salt, in spite of having unsaturation, showed good
antioxidant efficiency.
[0048] The present invention is directed toward a stable
composition suitable for use as a dielectric fluid, lubricant fluid
or fuel fluid. The present invention is directed toward a
stabilized aminophenolic composition comprising: (a) a
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(b) at least one component selected from the group consisting of:
(i) an ester based fluid comprising esters of mono-, di-, tri- or
polyhydroxyl alcohols; and (ii) at least one mono C.sub.12-C.sub.30
carboxylic fatty acid in a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP such that a
salt is formed from the mono C.sub.12-C.sub.30 carboxylic fatty
acid and the TAP; and wherein the stabilized aminophenolic
composition is characterized in that the stabilized aminophenolic
composition has improved stability relative to the TAP alone and
the improved stability being demonstrated by at least one of the
following performance metrics wherein: (aa) an extrapolated onset
of thermal decomposition of the TAP in the stabilized aminophenolic
composition occurs at a higher temperature than the extrapolated
onset of thermal decomposition of the substantially pure TAP as
measured by thermogravimetric analysis (TGA) ASTM E2402-11; and
(bb) the stabilized aminophenolic composition has an oxidative
stability index (OSI) of greater than about 20 hours at 130.degree.
C. as measured by AOCS 12b-92.
[0049] Also, the present invention is directed toward a method for
stabilizing an aminophenolic composition comprising mixing together
at or above ambient temperature: (a) a
2,4,6-tris(di-C1-C6-alkylaminomethyl) phenol (TAP); and (b) at
least one component selected from the group consisting of: (i) an
ester based fluid comprising esters of mono-, di-, tri- or
polyhydroxyl alcohols; and (ii) at least one mono C.sub.12-C.sub.30
carboxylic fatty acid in a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP such that a
salt is formed from the mono C.sub.12-C.sub.30 carboxylic fatty
acid and TAP; and whereby a stabilized aminophenolic composition of
claim 1 is obtained.
[0050] Preferably, the fluid comprising the saturated, unsaturated
or combinations of both monol, diol, triol or polyol acyl ester
based fluid and/or the non-ester based fluid comprises from about
50 to about 99.995 wt % and more preferably from about 90 to about
99.995 wt % based on the weight of the composition. Preferably, the
additive comprises from about 0.05 to about 3 wt %, more preferably
from about 0.05 to about 2.5 wt % and most preferably from about
0.5 to about 2 wt % based on the weight of the composition. The
carboxylic acid can react with one, two or all three reactive amine
sites on the 2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl)
phenol.
[0051] In a preferred embodiment, the
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol is
2,4,6-tris(dimethylaminomethyl) phenol (TDAMP). The TDAMP is a
tertiary amine having both phenolic and amine groups. TDAMP has
multifunctional properties and by virtue of its multifunctionality
it could enhance the performance of the fluids, in particular
saturated/unsaturated ester fluids, by inhibiting oxidation,
hydrolysis and corrosion. Besides, it also reacts with residual
free fatty acids present in the natural or synthetic esters and
also can react with acids that are generated during storage or
aging and which makes the fluids more stable. It also interacts
with acidic phenolic antioxidants and thereby reduces the impact of
these acidic additives on ester hydrolysis.
[0052] It is surprising to see the ineffectiveness of a well-known
alkylated diphenhylamine antioxidant in vegetable oils including
high oleic oils. It is unexpected to see the excellent antioxidant
behavior of TDAMP and relatively poor efficiency of hindered and
unhindered monodimethylaminophenols in vegetable oils. The
stabilization efficiency of TDAMP in vegetable oils is superior to
the well-known TBHQ antioxidant for vegetable oils. The
effectiveness of TDAMP is more pronounced for high oleic soybean
oils, saturated synthetic esters and blends of vegetable oils with
mineral oils.
[0053] Moreover, the synergistic effect of TDAMP in combination
with other phenolic antioxidant is also somewhat surprising. In
addition to adding antioxidants, the stabilized aminophenolic
composition may further comprise at least one additive consisting
of pour point depressant or colorant.
[0054] Though the carboxylic acid reacts with TDAMP and form salts,
the retention of antioxidant behavior of carboxylic salts of TDAMP
is unexpected. The additional benefits of TDAMP carboxylic acid
salts would include low volatility, low corrosivity, high
solubility, high temperature stability and low toxicity. Since the
decomposition temperature of TDAMP is 152.degree. C., the
carboxylic acid salts of TDAMP could be used where high temperature
performance is required.
[0055] The 2,4,6-tri(dimethylaminomethyl)phenol tricarboxylic acid
salts could be useful as bio-based lubricating additive to
lubricant base stock fluids and sulfur free fuels/diesel.
[0056] The use of vegetable oils as a lubricating fluid is limited
due to its oxidative and hydrolytic instability. The addition of
TDAMP or carboxylic acid salts of TDAMP to high oleic soybean oils
could increase the use of these oils as lubricants.
[0057] Although the hydrolytic stability of the vegetable oils can
be maximized by keeping the surroundings dry and minimizing the
amount of free fatty acids, for some applications it is a challenge
to minimize hydrolysis. For example, in transformer applications
wherein the solid cellulose insulation paper in vegetable oil
releases water and acids upon degradation and this water can
hydrolyze the vegetable oils generating more acids and can impact
the electrical performance of the transformers.
[0058] Though any saturated/unsaturated or branched/linear
carboxylic acid can be used to react with TDAMP, the preferred
carboxylic acid of the carboxylic acid salt of
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol is oleic
acid, stearic acid, palmitic acid, myristic acid, lauric acid or
tall oil. The amount of TDAMP or the carboxylic acid salt of TDAMP
to be added to a base fluid depends on the end use application. The
preferred amount for fuel application is in the range of 50 to 500
ppm, 200 to 10000 ppm for dielectric fluid use and about 2-3% for
lubricant use.
[0059] The oxidative stability of the fluids can be measured via
the oxidative stability index (OSI). Using test method AOCS 12b-92,
the composition of the present invention preferably has an OSI of
greater than about 20 hours at 130.degree. C. and more preferably
has an OSI of greater than about 100 hours at 130.degree. C. The
thermal stability of the stabilized aminophenolic composition is
characterized by the extrapolated onset of thermal decomposition of
the TAP in the stabilized aminophenolic composition occurring at a
temperature greater than 153.degree. C. as measured by TGA ASTM
E2402-11.
[0060] TDAMP can be added to other antioxidants to provide a
surprisingly synergistic effect of improved oxidative stability
over TDAMP and other antioxidants separately. The other
antioxidants are from about 0.01 to about 3 wt % of one or more
antioxidants selected from the group consisting of butylated
hydroxytoluene (BHT), butylated hydroxyanisole (BHA),
t-butylhyroquinone (TBHQ), dimethylaminomethyl phenol (DAMP),
2,6-di-t-butyl-4-dimethylaminomethyl phenol (DBDAMP),
2,4-bis(dimethylaminomethyl) phenol (BDAMP),
1,6-hexamethylenebis(3,5-t-butyl-4-hydroxyhydrocinnamate) (HMBBHC)
and combinations thereof.
[0061] The synergistic activity for oils that contain a mixture of
additives can be calculated using the following formula reported in
the literature: (ref: Rhet de Guzman, Haiying Tang, Steven Salley,
K. Y. Simon Ng, H., J. Amer. Oil Chem. Soc. 86, 459-467
(2009)).
Synergism , % = ( IP mix - IP 0 ) - [ ( P 1 - IP 0 ) + ( P 2 - IP 0
) ] [ ( P 1 - IP 0 ) + ( P 2 - IP 0 ) ] .times. 100 %
##EQU00001##
[0062] Biodiesel, a fuel derived from vegetable oils, animal fats
or used frying oils, largely consists of the mono-alkyl esters of
the fatty acids comprising these feedstocks. Transesterifying an
oil or fat with a mono-hydric alcohol usually methanol, leads to
the corresponding mono-alkyl esters. One of the major technical
issues facing biodiesel is its susceptibility to oxidation upon
exposure to oxygen in ambient air. The nature and amount of the
fatty acid chains found in biodiesel determine its oxidative
stability. Oxidative stability affects fuel quality.
[0063] The biodiesel standard EN 14214 calls for determining
oxidative stability at 110.degree. C. with a minimum induction time
of 6 h by the OSI method. This standard also specifies a maximum
iodine value of 120 g iodine/100 g and maximum acid value 0.50 mg
KOH/g.
[0064] As can be seen in the following examples, the oxidative
stability time for HOME without any antioxidants exceeds the
standard specification limits set for biodiesel on oxidative
stability whereas SME without antioxidant fails to meet standard
specifications. However, the addition of TDAMP to both SME and HOME
increased the induction times dramatically. In addition, TDAMP also
neutralizes the free fatty acids present in the biodiesel and
improves the hydrolytic stability as well.
[0065] Depending on the application, additional additives can be
added to the compositions of the present invention. Examples of
additive types include, but not limited to, are pour point
depressants, metal passivators, anti-foaming agents, electrostatic
agents, and lube enhancing additives.
[0066] TDAMP has a higher use temperature in vegetable oils. FIG.
1a shows the percent weight loss graph of the TGA for TDAMP as
function of temperature. The graph shows the decomposition
temperature of 152.degree. C. Also, the end use temperature of
TDAMP is unexpected extended to higher temperatures when mixed with
high performance fluids. This provides a method of using the
composition of the present invention as high performance fluid for
industrial applications at a use temperature from about 100.degree.
C. to about 200.degree. C., preferably from about 110.degree. C. to
about 180.degree. C., and most preferably from about 120.degree. C.
to about 160.degree. C. as a dielectric fluid, a lubricant fluid or
a fuel fluid.
[0067] A stable composition comprising a C.sub.12-C.sub.22
carboxylic acid salt of
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol. Preferably
the C.sub.12-C.sub.22 carboxylic acid is oleic acid, stearic acid
or lauric acid and the
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol is
2,4,6-tris(dimethylaminomethyl) phenol (TDAMP). The carboxylic acid
can react with one, two or all three reactive amine sites on the
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol. A single or
mixture of carboxylic acids can be added to TDAMP to form the
corresponding salt.
[0068] In another embodiment, the present invention is directed
toward a stabilized dielectric fluid composition comprising: (a) at
least one component selected from the group consisting of: (i) an
ester based fluid comprising saturated and/or unsaturated esters of
mono-, di-, tri- or polyhydroxyl alcohols; and (ii) a non-ester
based fluid selected from the group consisting of mineral oil,
silicones, poly(alpha olefins) and combinations thereof; and (b) at
least one component selected from the group consisting of: (i) a
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and a TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP; and
characterized in that the stabilized dielectric fluid composition
has an oxidative stability index (OSI) of greater than about 20
hours at 130.degree. C. as measured by AOCS 12b-92.
[0069] The antioxidant of the stabilized dielectric fluid
composition is selected from the group consisting of: butylated
hydroxytoluene (BHT), butylated hydroxyanisole (BHA),
t-butylhyroquinone (TBHQ), dimethylaminomethyl phenol (DAMP),
2,6-di-t-butyl-4-dimethylaminomethyl phenol (DBDAMP),
2,4-bis(dimethylaminomethyl) phenol (BDAMP), and
1,6-hexamethylenebis(3,5-t-butyl-4-hydroxyhydrocinnamate)
(HMBBHC).
[0070] Also, the present invention is directed toward a method for
stabilizing a dielectric fluid composition comprising: mixing
together at or above room temperature: (a) at least one component
selected from the group consisting of: (i) an ester based fluid
which comprises saturated and/or unsaturated esters of mono-, di-,
tri- or polyhydroxyl alcohols; and (ii) a non-ester based fluid
selected from the group consisting of mineral oil, silicones,
poly(alpha olefins) and combinations thereof; and (b) at least one
stabilizing additive selected from the group consisting of: (i)
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP.
[0071] In another embodiment, the present invention is directed
toward a stabilized lubricant fluid composition comprising: (a) at
least one component selected from the group consisting of: (i) an
ester based fluid comprising saturated and/or unsaturated esters of
mono-, di-, tri- or polyhydroxyl alcohols; and (ii) a non-ester
based fluid selected from the group consisting of mineral oil,
silicones, poly(alpha olefins) and combinations thereof; (b) at
least one component selected from the group consisting of: (i)
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP; and (c) at
least one additive selected from the group consisting of
antioxidant, antiwear, antisieze and pour point depressant; and
wherein the stabilized lubricant fluid composition has an oxidative
stability index (OSI) of greater than about 20 hours at 130.degree.
C. as measured by AOCS 12b-92.
[0072] The ester based fluid is a blend of: (a) at least one ester
based fluids selected from the group consisting of a vegetable oil,
algae oil, animal fat and tall oil fatty acid ester having
kinematic viscosity less than about 50 cSt at 40.degree. C. as
measured by ASTM D792-13; and (b) at least one ester based fluid
selected from the group consisting of castor oil, hydrogenated
castor oil and epoxidized triglyceride having kinematic viscosity
greater than about 200 cSt at 40.degree. C. as measured by ASTM
D792-13; characterized in that the kinematic viscosity of the
stabilized lubricant fluid composition is in the range of from
about 40 cSt to less than about 200 cSt at 40.degree. C. as
measured by ASTM D792-13.
[0073] Also, the present invention is directed toward a method for
stabilizing a lubricant fluid composition comprising the steps:
mixing together at or above ambient temperature: (a) at least one
component selected from the group consisting of: (i) an ester based
fluid which comprises saturated and/or unsaturated esters of mono-,
di-, tri- or polyhydroxyl alcohols; and (ii) a non-ester based
fluid selected from the group consisting of mineral oil, silicones,
poly(alpha olefins) and combinations thereof; and (b) at least one
stabilizing additive selected from the group consisting of: (i) a
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP.
[0074] In another embodiment, the present invention is directed
toward an article or a machine having moving parts wherein the
moving parts have surfaces in frictional contact with each other
and/or with other adjoining surfaces, and wherein a stabilized
lubricant fluid composition coats at least one of the surfaces. In
another embodiment, the present invention is directed toward a
process for operating this article comprising the step: operating
the article at a temperature of greater than about 60.degree.
C.
[0075] In still another embodiment, the present invention is
directed toward a stabilized biodiesel fluid composition
comprising: (a) a methyl ester based fluid selected from the group
consisting of vegetable oil, algae oil, animal fat, tall oil and
combinations thereof; (b) optionally, a petrodiesel fluid; and (c)
at least one component selected from the group consisting of: (i)
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt of a at least one mono C.sub.12-C.sub.30 carboxylic
fatty acid and TAP having a molar ratio of up to 3 moles of mono
C.sub.12-C.sub.30 carboxylic fatty acid per mole of TAP; and
wherein the composition is characterized in that the stabilized
biodiesel fluid composition has an oxidative stability index (OSI)
of greater than about 10 hours at 110.degree. C. as measured by
AOCS 12b-92.
[0076] Also, the present invention is directed toward a method for
stabilizing a biodiesel fluid composition comprising the steps:
mixing together at or above ambient temperature: (a) a methyl ester
based fluid selected from the group consisting of vegetable oil,
algae oil, animal fat, tall oil and combinations thereof; (b)
optionally, a petrodiesel fluid; and (c) at least one component
selected from the group consisting of: (i)
2,4,6-tris(di-C.sub.1-C.sub.6-alkylaminomethyl) phenol (TAP); and
(ii) a salt mixture comprising at least one mono C.sub.12-C.sub.30
carboxylic fatty acid and a TAP, the salt mixture having a molar
ratio of up to 3 moles of mono C.sub.12-C.sub.30 carboxylic fatty
acid per mole of TAP.
EXAMPLES
Materials
[0077] All commercial materials were used as received unless
otherwise indicated.
[0078] Refined, bleached, and deodorized high oleic soybean oil
(RBD HOS oil, referred to herein as "HOS oil") containing
triglycerides of the following fatty acids: palmitic acid (6.5 wt
%), stearic acid (4.15 wt %), oleic acid (73.9 wt %), linoleic acid
(8.77 wt %), and linolenic acid (2.94 wt %) was obtained according
to U.S. Pat. No. 5,981,781. The oil was carefully dried by rotary
evaporator at 90.degree. C. for 4 hours with application of <100
mTorr vacuum.
[0079] Commodity soybean oil was obtained from Homestead Farms, Des
Moines, Iowa.
[0080] DAMP, dimethylaminomethyl phenol, was obtained from
Aldrich.
[0081] DBDAMP, 2,6-di-t-butyl-4-dimethylaminomethyl phenol, was
obtained from Aldrich.
[0082] TDAMP, 2,4,6-tris(dimethylaminomethyl) phenol, was obtained
from Aldrich.
[0083] TDAMP-TEH, 2-ethylhexanoic acid salt of TDAMP, was obtained
as Ancamine.RTM. k 61B from Air Products.
[0084] ADPA, alkylated diphenylamine, was obtained as Irganox.RTM.
L 57 from BASF.
[0085] BHT, butylated hydroxytoluene, was obtained from
Aldrich.
[0086] TBHQ, t-butylhyroquinone, was obtained from Aldrich.
[0087] HMBBHC,
1,6-hexamethylenebis(3,5-t-butyl-4-hydroxyhydrocinnamate), was
obtained as Irganox.RTM. 259 from BASF.
[0088] Lauric acid (>98%) and oleic acid (90%) were obtained
from Aldrich.
[0089] TTCC, trimethylolpropane tricaprylic-caprate, was obtained
as Hatcol 2938 from Chemtura.
[0090] Mineral oil was obtained as Luminol from Petro-Canada.
[0091] Kraft paper (7 mil) was obtained from Weidmann Electrical
Technology Inc. (St. Johnsbury, Vt.) and cut into 2.5.times.12.7 cm
pieces.
Example Preparation
[0092] Examples were prepared by using a vegetable oil based fluid
alone or by blending a vegetable oil based fluid with one or more
antioxidants.
Thermal Stability of TDAMP
[0093] The percent weight loss of TDAMP as a function of
temperature (FIG. 1a) and as a function of time (FIG. 1 b) at an
isothermal temperature of 130.degree. C. was studied by using a
thermogravemetric analysis (TGA) under nitrogen atmosphere. For the
purposes of this invention, TGA weight loss was determined
according to ASTM D 3850-94, using a heating rate of 10.degree.
C./min, in air purge stream, with an appropriate flow rate of 0.8
mL/second.
[0094] The TGA was also measured using ASTM E2402-11.
Oxidative Stability of the Fluids
[0095] The Oxidation Stability Index (OSI) or also known as the Oil
Stability Index determines the length of time before the start of
rapid acceleration of oxidation and indicates the resistance to
oxidation of the oil.
[0096] Oxidative stability of the fluids was tested according to
the American Oil Chemists Society (AOCS) test method AOCS 12b-92
using the Oxidative Stability Instrument (Omnion, Inc, Rockland,
Mass.) at either 110 or 130.degree. C. Samples were run in
duplicate and the average OSI induction period (IP) values for each
fluid are reported.
[0097] Oxidative stability of the fluids was also tested according
to the American Society for Testing and Materials (ASTM) test
method ASTM D2440 method at Doble Lab. In this test method, the oil
is oxidized at a bath temperature of 110.degree. C. in the presence
of a copper catalyst coil and bubbling oxygen for 72 h and 164 h,
respectively.
Kinetic Viscosity
[0098] The Kinetic Viscosity was measured using ASTM D792-13 and
was reported in cSt.
Example 1 and Comparative Examples A-C
[0099] The oxidative stability of high oleic soybean (HOS) oils
with and without added antioxidants at a temperature of 110.degree.
C. was evaluated by OSI according to AOCS 12b-92. Examples were
prepared using HOS oil without an antioxidant, Comparative Example
A, blended separately with antioxidants, BHT, TBHQ and TDAMP,
Comparative Examples B and C and Example 1, respectively. The OSI
data are shown in Table 1.
TABLE-US-00001 TABLE 1 Oxidative Stability of HOS Oil at
110.degree. C. Amount OSI at 110.degree. C. Example Antioxidant wt
% .mu.mole/g (hours) A None 24.6 B BHT 0.1 4.54 35.9 0.2 9.08 38.2
C TBHQ 0.1 6.02 65.2 0.2 12.04 81.4 1 TDAMP 0.1 3.66 93.7 0.2 7.55
143.8
[0100] Example 1 using added TDAMP demonstrates superior oxidative
stability of HOS oil when compared to the absence of an antioxidant
and well-known antioxidants.
Example 2 and Comparative Examples D-G
[0101] The oxidative stability of HOS oils with and without added
antioxidants at a temperature of 130.degree. C. was evaluated by
OSI according to AOCS 12b-92. Examples were prepared using HOS oil
without an antioxidant, Comparative Example D, blended with
antioxidant ADPA, Comparative Example E, blended separately with
aminophenol antioxidants, DAMP, DBDAMP and TDAMP, Comparative
Examples F and G and Example 2, respectively. The OSI data are
shown in Table 2 and FIG. 6.
TABLE-US-00002 TABLE 2 Oxidative Stability of HOS Oil at
130.degree. C. Amount OSI at 130.degree. C. Example Antioxidant wt
% .mu.mole/g (hours) D None 3.1 E ADPA 0.2 3.14 1.7 F DAMP 0.2
13.24 6.0 G DBDAMP 0.2 7.60 9.4 2 TDAMP 0.2 7.54 29.9
[0102] Example 2 and FIG. 6 using added TDAMP demonstrate superior
oxidative stability of HOS oil when compared to the absence of an
antioxidant and other aminophenols and alkylated diphenylamine.
ADPA was found to be an ineffective (negative effect) antioxidant
for HOS oil at this temperature.
Examples 3 and 4 and Comparative Examples H and I
[0103] The oxidative stability of commodity soybean oil was
evaluated by combining TDAMP with another phenolic antioxidant
HMBBHC (Irganox.RTM. 259) at a temperature of 130.degree. C. was
evaluated by OSI according to AOCS 12b-92. Examples were prepared
using soybean oil without an antioxidant, Comparative Example H,
blended with antioxidants, HMBBHC and TDAMP separately, Comparative
Example I and Example 3 and blended with HMBBHC and TDAMP together,
Example 4. The OSI data are shown in Table 3.
TABLE-US-00003 TABLE 3 Synergistic Effects on Oxidative Stability
of Soybean Oil HMBBHC TDAMP OSI at 130.degree. C. Synergism Example
(wt %) (wt %) (hours) (%) H 0 0 1.0 27.0 I 0.9 0 3.0 3 0 0.2 6.95 4
0.9 0.2 11.1
[0104] Table 3 shows the positive synergistic effect of the
oxidative stability of soybean oil in the presence of TDAMP in
combination with HMBBHC over the oxidative stability of either
antioxidant alone.
Examples 5 and 6 and Comparative Examples J and K
[0105] The oxidative stability of HOS oil was evaluated by
combining TDAMP with the phenolic antioxidant HMBBHC at a
temperature of 130.degree. C. was evaluated by OSI according to
AOCS 12b-92. Examples were prepared using HOS oil blended without
an antioxidant, Comparative Example J, blended with antioxidants,
HMBBHC and TDAMP separately, Comparative Example K and Example 5
and blended with HMBBHC and TDAMP together, Example 6. The OSI data
are shown in Table 4.
TABLE-US-00004 TABLE 4 Synergistic Effects on Oxidative Stability
of HOS Oil HMBBHC TDAMP OSI at 130.degree. C. Synergism Example (wt
%) (wt %) (hours) (%) J 0 0 3.1 27.8 K 0.9 0 19.9 5 0 0.2 29.8 6
0.9 0.2 58.7
[0106] Table 4 shows the synergistic effect of the oxidative
stability of HOS oil in the presence of TDAMP in combination with
HMBBHC over the oxidative stability of either antioxidant
alone.
Examples 7 and 8 and Comparative Examples L and M
[0107] The oxidative stability of HOS oil was evaluated by
combining TDAMP with a mixture of antioxidants HMBBHC and TBHQ at a
temperature of 130.degree. C. was evaluated by OSI according to
AOCS 12b-92. Examples were prepared using HOS oil without an
antioxidant, Comparative Example L, blended with antioxidants,
HMBBHC and TBHQ, Comparative Example M, blended with TDAMP, Example
7 and blended with HMBBHC, TBHQ and TDAMP together, Example 8. The
OSI data are shown in Table 5.
TABLE-US-00005 TABLE 5 Synergistic Effects on Oxidative Stability
of HOS Oil HMBBHC TBHQ TDAMP OSI at 130.degree. C. Synergism
Example (wt %) (wt %) (wt %) (hours) (%) L 0 0 0 3.1 38.7 M 0.9 0.3
0 42.1 7 0 0 0.2 29.9 8 0.9 0.3 0.2 94.7
[0108] Table 5 shows the synergistic effect of the oxidative
stability of HOS oil in the presence of TDAMP in combination with
HMBBHC and TBHQ over the oxidative stability of antioxidant
combinations without TDAMP.
Comparative Examples N-Q
[0109] The oxidative stability of HOS oil was evaluated by
combining similar aminophenol additives to TDAMP with HMBBHC and
TBHQ at a temperature of 130.degree. C. was evaluated by OSI
according to AOCS 12b-92. Examples were prepared using HOS oil
blended with antioxidants, HMBBHC and TBHQ combined, Comparative
Example N, blended with HMBBHC and TBHQ combined with DAMP, DBDAMP
and ADPA separately, Comparative Examples O-Q. The OSI data are
shown in Table 6.
TABLE-US-00006 TABLE 6 Synergistic Effects on Oxidative Stability
of HOS Oil HMBBHC TBHQ Antioxidant OSI at 130.degree. C. Example
(wt %) (wt %) (wt %) (hours) N 0.9 0.3 0 42.1 O 0.9 0.3 DAMP 41.3
0.2 P 0.9 0.3 DBDAMP 39.8 0.2 Q 0.9 0.3 ADPA 40.7 0.2
[0110] None of the Comparative Examples of Table 6 show synergistic
effect on oxidative stability. Only TDAMP has been shown to produce
a synergistic effect on oxidative stability in the presence of
other antioxidants.
Example 9 and Comparative Examples R and S
[0111] The oxidative stability of HOS oil was evaluated by
combining TDAMP with other antioxidants TBHQ and HMBBHC at a
temperature of 110.degree. C. was evaluated by OSI according to
ASTM D2440. Examples were prepared using HOS oil blended without an
antioxidant, Comparative Example R, blended with antioxidants,
HMBBHC and TBHQ, Comparative Example S and blended with HMBBHC,
TBHQ and TDAMP together, Example 9. The OSI data are shown in Table
7.
TABLE-US-00007 TABLE 7 Synergistic Effects on Oxidative Stability
of HOS Oil OSI at 110.degree. C. OSI at 110.degree. C. After 72 h
After 164 h Neut. Neut. Exam- % No. mg % No. mg ple Antioxidants
Sludge KOH/g Sludge KOH/g R none 7.5 19.2 Polymerized S 0.3% TBHQ
0.05 0.34 13.5 20.1 0.9% HMBBHC 9 0.3% TBHQ 0.14 0.30 0.26 0.44
0.9% HMBBHC 0.2% TDAMP
[0112] Table 7 shows the synergistic effect of the oxidative
stability of HOS oil in the presence of TDAMP in combination with
TBHQ and HMBBHC over the oxidative stability of antioxidant
combinations without TDAMP.
Hydrolytic Stability of the Vegetable Oils
[0113] The hydrolytic stability of the commodity soybean oil and
high oleic soybean oil in the presence of antioxidants was tested
by adding 2000 ppm of water to the oils. The glass containers were
dried at 550.degree. C. for 24 hours, cooled to room temperature,
loaded with the oils separately, and then sealed in a nitrogen
atmosphere. Each tube was filled with about 84 cm.sup.3 fluid and
the head space was about 30-39 cm.sup.3. The test tubes containing
the oils were placed into an oven maintained at 130.degree. C. for
a period of 1 to 2 weeks.
Examples 10-12 and Comparative Examples T-V
[0114] Examples were prepared using soybean oil without an
antioxidant, Comparative Example T and blended with TDAMP without
additional antioxidants, Example 10. Additional examples were
prepared using HOS oil without an antioxidant, Comparative Example
U, blended with antioxidants, HMBBHC and TBHQ, Comparative Example
V, blended with TDAMP without additional antioxidants, Example 11
and blended with HMBBHC, TBHQ and TDAMP together, Example 12. The
fatty acid content in the oils was determined using proton NMR and
the percent oil hydrolysis was reported in Table 8.
TABLE-US-00008 TABLE 8 Hydrolytic Stability of Soybean Oils % Oil
Hydrolysis Example Oil Antioxidants 1 week 2 weeks T Soybean none
0.69 1.07 10 Soybean 0.2% TDAMP 0.58 0.89 U HOS none 0.55 0.96 V
HOS 0.3% TBHQ + 1.84 3.98 0.9% HMBBHC 11 HOS 0.2% TDAMP 0.32 0.79
12 HOS 0.3% TBHQ + 1.11 0.95 0.9% HMBBHC + 0.2% TDAMP
[0115] Both soybean and HOS oils undergo hydrolysis with time in
the presence of moisture at elevated temperatures. The phenolic
antioxidants increase the rate of hydrolysis of the oils which is
undesirable. When TDAMP was added by itself or along with phenolic
antioxidants, the hydrolytic stability of the oils was
improved.
Aging Stability
[0116] Aging studies were performed by immersing solid insulation
Kraft paper with the fluids at 110.degree. C., for 2 weeks (336
hours), 6 weeks (1008 hours) and 12 weeks (2016 hours). The paper
samples, the glass test tubes were carefully dried prior to the
tests. The glass containers were dried at 550.degree. C. for 24
hours, cooled to room temperature, loaded with the paper and the
fluid, and then sealed in a nitrogen atmosphere. Each tube was
filled with about 84 cm.sup.3 fluid, the average paper weight was
1.7 g, and the head space was about 30-39 cm.sup.3. The test tubes
containing the paper samples and oil were placed into an oven
maintained at 110.degree. C. After the desired aging time, the
tests tubes were removed from the oven and cooled to room
temperature. The solid insulation was removed from the oil and the
fatty acid content in the oils was analyzed by NMR spectroscopy and
the percentage of HOS oil hydrolysis was reported.
Example 13 and Comparative Examples W and X
[0117] Examples were prepared using HOS oil blended without an
antioxidant, Comparative Example W, with TBHQ and HMBBHC,
Comparative Example X, and with TBHQ, HMBBHC and TDAMP, Example 13.
The fatty acid content in the oils was determined using proton NMR
and the percent HOS oil hydrolysis was reported in Table 9.
TABLE-US-00009 TABLE 9 Aging Stability of HOS Oil % HOS Oil
Hydrolysis Example Antioxidants 2 weeks 6 weeks 12 weeks W none
0.20 0.23 0.98 X 0.3% TBHQ 0.39 0.77 1.34 0.9% HMBBHC 13 0.3% TBHQ
0.31 0.63 0.71 0.9% HMBBHC 0.2% TDAMP
[0118] Though the phenolic antioxidants of Comparative Example X
enhance the oxidative stability of the natural esters, they
decrease the hydrolytic stability. The hydrolytic stability of the
HOS oil is better when TDAMP was added to other phenolic
antioxidants of Example 13.
Carboxylic Acid Salts of TDAMP
[0119] Carboxylic acid salts of TDAMP were prepared and evaluated
their thermal stabilities using TGA. FIGS. 2-4 correspond to the
percent weight loss of 2-ethylhexanoic acid salt, lauric acid salt
and oleic acid salt of TDAMP as a function of temperature
respectively. FIG. 5 corresponds to the percent weight loss of
oleic acid salt of TDAMP as a function of time at constant
temperature of 130.degree. C. The Table 10 below compares the
percent residual weight left (total weight loss) of TDAMP and its
oleic acid salt at constant temperature of 130.degree. C. under
nitrogen atmosphere and at given time.
TABLE-US-00010 TABLE 10 Weight Loss of TDAMP Time Residual weight
TDAMP 1.5 h 2.4% TDAMP/Oleic acid salt 4.0 h 85.8%
[0120] The above salts were added separately to HOS oil and the
oxidative stability of the HOS oil at 130.degree. C. was evaluated
by OSI according to AOCS 12b-92 and reported in Table 11.
Examples 14 and 15
[0121] Examples 14 and 15 were prepared using HOS oil blended
separately with TDAMP and TDAMP-TEH, respectively. The oxidative
stability was measured and the OSI data are shown in Table 11.
Example 16
[0122] The oleic acid salt of TDAMP was prepared by mixing 3.78
mmoles of TDAMP and 10.46 mmoles of oleic acid in a 25 mL reactor
at 75.degree. C. for 1 h and then the reaction mixture was cooled
to room temperature while stirring was continued for 24 h. Then the
salt was blended with HOS oil. The oxidative stability was measured
and the OSI data are shown in Table 11.
Examples 17
[0123] The lauric acid salts of TDAMP were prepared by mixing 3.78
mmoles of TDAMP and separately 11.25, 7.6 and 3.78 mmoles of lauric
acid in a 25 mL reactor at 75.degree. C. for 1 h and then the
reaction mixture was cooled to room temperature while stirring was
continued for 24 h. Then the salt was blended with HOS oil to
produce Examples 17-19, respectively. The oxidative stability was
measured and the OSI data are shown in Table 11.
TABLE-US-00011 TABLE 11 Oxidative Stability of HOS Oil with
Carboxylic Acid Salts of TDAMP Amount OSI at 130.degree. C. Example
Antioxidant (wt %) .mu.mole/g (hours) 14 TDAMP 0.2 7.5 29.9 15
TDAMP-2- 0.51 7.5 28.4 ethylhexanoic acid 16 TDAMP-oleic acid 0.83
7.5 26.4 17 TDAMP-lauric acid 0.65 7.5 30.2
[0124] The oxidative stability of each carboxylic acid salt of
aminophenol in HOS oil inhibited oxidation of HOS oil as well as
TDAMP alone.
Oxidative Stability of Other Fluids and Blends
Examples 20 and 21 and Comparative Examples Y and Z
[0125] The oxidative stability of a synthetic saturated polyol
ester, trimethylolpropan tricaprylate-caprate (TTCC) was evaluated,
Comparative Example Y, and in the presence of 250 ppm of TDAMP,
Example 20. Two blends were prepared by mixing 80% commodity
soybean oil, 20% mineral oil and 0.3% BHT. One blend was measured
for oxidative stability, Comparative Example Z, and to the other
blend 0.2% TDAMP was added, Example 21, and measured for oxidative
stability at 130.degree. C. was evaluated by OSI according to AOCS
12b-92. The OSI data are shown in Table 12.
TABLE-US-00012 TABLE 12 Oxidative Stability TDAMP OSI at
130.degree. C. Example Fluid (wt %) (hours) Y TTCC 0 14.1 20 TTCC
0.025 123 Z 80/20 0.0 3.4 Soybean/mineral oil 21 80/20 0.2 15.4
Soybean/mineral oil
[0126] Table 12 shows the strong oxidation inhibition effect of
TDAMP on other fluids and blends as well.
Stability of Biodiesel
Example 22 and Comparative Example AA
[0127] Soybean methyl ester (SME) was prepared by mixing 920 g
commodity soybean oil and 200 g methanol into a 2 L four neck glass
round bottom flask fitted with mechanical stirrer and the reactor
was flushed with dry nitrogen gas and 11.7 g sodium hydroxide
solution (50 wt %) was added. The reaction temperature was raised
to 60.degree. C. while stirring in a nitrogen flow and the reaction
was continued for 4 h. After reaction, the obtained product was
transferred into separating funnel and allowed to separate. The
glycerol part was discarded and the top methyl ester was dried
using rotary evaporator to remove any unreacted methanol. The
obtained product was mixed with water and the aqueous layer was
removed after separation. The later step was repeated twice. The
product was again dried using a rotary evaporator at 80.degree. C.
for 1 h at about 400 mTorr. The obtained SME product, Comparative
Example AA, was characterized using proton NMR. Example 22 was
prepared by mixing 100 g of SME obtained in Example 20 with 0.2 g
of TDAMP and the product was thoroughly homogenized for 12 h. The
oxidation stability index was measured at 110.degree. C. by OSI
according to AOCS 12b-92 and reported in Table 13.
Example 23 and Comparative Example BB
[0128] High oleic soybean methyl ester (HOME) was prepared as
described in Comparative Example AA by replacing reactant commodity
soybean oil with high oleic soybean oil. The obtained HOME product
was characterized using proton NMR. Example 23 was prepared by
mixing 100 g of SME obtained in Example 20 with 0.2 g of TDAMP and
the product was thoroughly homogenized for 12 h. The oxidation
stability index was measured by OSI according to AOCS 12b-92 and
reported in Table 13.
TABLE-US-00013 TABLE 13 Oxidative Stability of SME & HOME at
110.degree. C. Iodine Value TDAMP OSI at 110.degree. C. Example
Biodiesel (g iodine/100 g) (wt %) (hours) AA SME 130 0 1.4 22 SME
0.2 12.2 BB HOME 86 0 10.8 23 HOME 0.2 >43
[0129] Table 13 indicates that the presence of TDAMP, Examples 22
and 23, improve the OSI over the fluids without TDAMP, Comparative
Examples AA and BB.
Stability of Lube Oils
Examples 24-28 and Comparative Examples CC-DD
[0130] Table 14 demonstrates that high performance lube base oils
can be formulated by blending a low viscosity and high viscosity
index (VI) fluid, high oleic soybean oil, with a high viscosity and
low viscosity index fluid, castor oil, with 1 wt % TDAMP-oleic acid
salt.
TABLE-US-00014 TABLE 14 Stability of Lube Oils TDAMP- HOS/ Oleic
OSI at Exam- Castor acid salt Kinematic viscosity, 130.degree. C.,
ple (wt %) (wt %) cSt 40.degree. C./100.degree. C. VI (h) CC 100/0
0 35.3 7.2 4.5 DD 0/100 0 256 19.33 85 14.0 24 97/3 1 41.0 8.57 194
34.4 25 86/14 1 46.6 8.96 176 32.5 26 70/30 1 60.4 10.08 154 38.7
27 45/55 1 95.6 12.20 120 35.0 28 20/80 1 160.8 15.44 97 34.5
Improved Stability of Insulation Paper in Stable Dielectric
Fluid
Examples 29-30 and Comparative Examples EE-FF
[0131] A blend fluid composition was prepared by mixing commodity
soybean oil (78.08%), mineral oil (19.52%, Luminol.RTM.), a mixture
of antioxidants (0.3% BHT, 0.9% Irganox.RTM. 259, and 0.2% TDAMP),
and a pour point depressant (1.0%, Viscoplex.RTM. 10-310). The
stability of the thermally upgraded Kraft (TUK) insulation paper in
this fluid blend was evaluated and compared with a commercial
vegetable oil based dielectric fluid (FR3.TM.) in an accelerated
aging testing conducted at 180.degree. C. over a period of time.
The thermal aging sample cells were set-up according to the IEEE
standard 057.100.2011 using TUK paper insulation. The headspace for
each sample was purged with nitrogen. Four sample cells were used
for each dielectric fluid since one cell was required for each test
period of 7, 14, 49 and 70 days. When the sample aging time was
reached for each cell, the contents of the cell (insulation and
fluid) were tested. The tensile strength of the insulation paper
was measured and the % tensile strength retention was calculated
and was reported in Table 15. The aged fluid properties are
reported in Table 16.
[0132] The higher percent tensile strength retention of insulation
paper in the blend fluid compared to the paper in the commercial
fluid suggesting the insulation paper is more stable in the blend
fluid than in the commercial oil. This higher stability of the
insulation paper in blend fluid may be due to higher stability of
the blend fluid (less change in viscosity and less acid
generation), and better heat transfer efficiency due to lower
viscosity (Table 16).
TABLE-US-00015 TABLE 15 Tensile Strength Retention of TUK
Insulation Paper in Fluids at 180.degree. C. Tensile strength
retention (%) Dielectric of Insulation Paper Example Fluid 336 h
672 h 1008 h 1176 h 1680 h EE Commercial 40.8 26.6 23.2 -- 20.3
vegetable oil based 29 Blend fluid 65.5 34.4 -- 33.7 25.7
composition
TABLE-US-00016 TABLE 16 Properties of Aged Fluids Viscosity
Neutralization Exam- Dielectric Aged Time @ 40.degree. C. Number
ple Fluid (h) (cSt) (mg/KOH) FF Commercial 0 32.5 0.03 vegetable
oil 336 34.4 2.41 based 672 35.2 8.73 1008 36.5 12.23 1680 38.1
19.35 30 Blend fluid 0 27.3 0.03 composition 336 27.5 1.35 672 27.0
2.75 1008 29.9 6.11 1680 28.1 5.67
* * * * *