Note: Descriptions are shown in the official language in which they were submitted.
~L~147~3
This invention relate~ to oven cleaniny compositions.
More particularly, th~s invention relates to oven cleaning com-
positions having a low caustic concentration and yet a cleaning
capa~ility equal to conventional, high caustic oven cleaners.
Ovens are subjected to heat and are liable to soiling
~y ~aked on organic deposits. The soiling matter deposited
consists of a complex organic mixture of natural fats and other
deposits from the cooking of food. ~hen heated at normal oven
temperatures, this soiling matter is converted into an infusible
polymeric mass in which part of the organic màterial may also be
charred. Detergents, scouring powders and similar cleaming
products, although highly efficient for removing normal greasy
soiling matter, are not usually adequate for removing baked-on
soil of the type found in ovens.
The removal of this type of soil is there~ore a con-
siderable problem, requiring powerful chemical or physical
`actiOn~ Among the most e~fective chemical compounds known for
this purpose are the caustic alkalis such as sodium or potassium ;;-~
h~vdroxide. They may be applied directly by brush or sponge, or
2~ more conveniently by means of an aerosol spray. Products of
t~s type, although efficient in their action, suffer from a
nu~ er of major disadvantages. On~ disadvantage is that such ;i; ;
products when applled to soiled oven surfaces ~ust attack the ~ `
soiling matter from the outer surface, while the most severe
charring and polymerization is generàlly present in the interior
of the soil layer, adjacent to the oven wall. This makes
cnleaning more difficult~ Secondly, because of the nature of
the caustic alkalis and of conventional oven cleaaing compo~
sitionæ having a hi~ concentration of caustic alkali, it has
been necessar~ ta emplo~ considerable safety meaaures in their
u~e~ T~u~, the advantage of providing an efficient oven cleaner ~;~
with a low level of caustic alkali is apparent. ~;
- 3 ~
._. ~ `
l0~7sa~
~lkalis less alkaline than caustic soda are not very
effect~ve ~n.,hydrolyzing baked-on deposits in a short time of
application, and consequently are not efficient oven cleaners,
In the prior art, various compositions for use in
hard surface or oven cleaning, have been disclosed w~ich utilize
caustic alkali as the predominant cleaning ingredient. U.S.
Patent No. 3,7lS,324 discloses a sto~e-cleaning composit1on com-
prising from 10-40~ sodium hydroxide, in addition to other
ingred~i`ents~.~ncludIn~.tr~*.thano~lamine. U.S. Patent Nos. 2,992,99
and 2,097,737 discl~se metal cleaning compositions comprising at ::~
least 10% and 6%, respect.vely o~ an alkali metal hydroxide, in
addition to other ingredients including alkanolamines. These
patents do not disclose the l-ow caustic compositions of the :~
present invention.
A number of oven cleaning compositions have been dis- ~ :~
closed in the prior art whi~h utilize as~little~as 1~ of a ~;
caustic alkali; however, these compositions comprise additional
ingredients for cleaning which are not contemplated in the ; ;-
compositions of the present invention. For example, U.S. Pa~nt .
No. 3,644,210 discloses an oven cleaner comprising fr~m 1-20% .
. of alkali metal hydroxide, an ethoxylated alkanolamide, and
numerous other ingredients which can be substituted in toto ~or . ~.
the alkali metal hydroxide. U.S. Patent No. 3j625,859 discloses
a composition comprising an alkali metal or ammonium salt of a
.
styrene-maleic anhydride~; copolymer in addition to the caustic.
U.S. Patent-l~3,03l,408 discloses a composition comprising addi-
tionally an alcoholic solvent, flow retarder, and amphoteric
deter~ent, U.S, Patent 3,591-,416 discloses an oven cleaning -`
composit~.~on compr;sing 9.9% sodium nitrate and.l~ sodium
~ drox~de, -.
"' ' .~'.
~04~9~3
South ~frican Patent No. 68/6992 to S.C. Johnson and
Son, Inc, entitled CLEANING COMPOSITI~N ~described in Chemical
Abstracts, Volume 71, 103474 C (1969)~ discloses an oven clean-
ing composition containing no alkali metal hydroxide and con-
sisting essentially oE primary, secondary, or tertiary amines
and includes builders such as carbonates, silicates or
; phosphates as the predominant source of alkalinity.
None of these prior art patents disclose oven clean-
ing compositions contemplated in the present invention, which .
comprise a low concentration of alkali metal hydroxide and an
alkanolamine. Oven cleaning compositlons are known which
comprise a concentration of alkali metal hydroxide, an
alkanolamine, and an alkylene glycol aryl ether. However, as
described in U.S. Patent NoO 3,663,447, these latter two .
ingredients are combined for use as an "accelerator composition" - :
to increase the effectiveness of the alkali metal hydroxide.
..The patent expressly states the alkanolamine when used without
tfie ether has substantially no accelerating effect on the
alkali metal hydroxide.
Thus, the oven cleaning compositions disclosed in ;:
.the prior art or known in the oven cleaning art do not . :
recognize or anticipate the use of alkanolamines in combination
with a low concentration of an alkali metal hydroxide to pro~
vide an oven cleaning composition equally effective as conven-
tional oven cleaning compositions with hlgh concentrations of
caustic alkali.
According to the present invention, oven cleaning
compositions are provided which comprise by weight from about
0.5% to about 4.0% of an alkali metal hydroxide; rom about :
1.0~ to about 20.0% of an alkanolamine selected from the group ..
consisting of: monoethanolamine, aminoethylethanolamine,
monoisopropanolamine, N,N-diethylethanolamine, N-methylethanol~
5-
.. . . . . ..
: ~ . . . . ~ -: . . - - : .
~L~479~3
amine, d~glycolamine, diisopropanolamine, -triisopropanolamine,
isopropanolam~ne, dimethylethanolam~ne, N,N-diisopropylethanol-
amine, diethanolamine, N-methyldiethanolamine and N ethyl-
diethanolamine; and up to about 98.5% water.
Some of the advantages provided by the oven cleaning
compositions of the present invention are the reduction of
caustic alkali and the increase in cleaning.
-- The oven cleaning compositions contemplated in this
invention may contain various additional ingredients which aid
in~-providing nan effective oven cleaner, such as for example,
bentonite, coconut oil fatty acid, lauryl alcohol, and propellant.
Bentonite is useful as a thic~ener and helps in preventing run
off of the oven cleaning composition from the $urface to be
cleaned. Since an oven has both vertical and horizontal sur- ~ ~
faces, the thickener concentration may be varied so as to pro- ~ -
vide an efficient medium for the composition so that all oven
~urfaces are ef~ectively cleaned. Other thickeners which may
~e utilized are polyoxyethylene compounds, carboxymethylcellulose~
ox titanium dioxide. Various soaps and detergents such as
coconut oil fatty acid or aluminum stearate, may be utilized
in the present invention to increase solubility of the ingre~
dients. Other solubilizers include lauryl alcohol~l methyl-
cellulose, or l,l,l-trichloroethylene. Some of the propellants
suitable in the compositions of the present invention are
.
propane, pentane, butane, or the halogenated hydrocarbona.
It is not intended to limit the present invention to any of
these specificall~ identifled additives because various other
oven cleaning additives ma~ also be used.
In determining the effectivaness of the oven cleaning
compositions of the pre$ent invention, the following procedures
have been utilized.
10~903
First~ an oven stain composition which would likely
occur ~n househo;ld ovens was prepared as shown in Table I below:
~'
~ABLE I -'
~ngredient Weight of Ingredient ~ '~
Peanut odl 45 g. ~,
Corn oil 25 g.
Cherry p~e mix 25 g. "-
~round beef 25 g.
Ground pork 25 g.
Sodium chloride 1 g.
Sodium glutamate 1 g. ~i, !',;, ,
;j Water 25 g. '`'~
The ingredients shown in Table I were mixed in a pan and coo~ed
in an oven at 400F for two hours. The cooked material was ,,~ ,
filtered through glass wool, storèd in a glass bottle, and ', ' '
,
before testing the bottle was shaken.
Effectiveness ofi an oven cleaning composition is
~elated to the type and nature of the stain to be removed. , ; ,
2a Thus, applicatlon and curing of the stain composition to a test ,,','~
surface is important. Approxiamately 0.28 to 0.30 grams of ,~
the above stain composition was placed on a 4-1/2" x 4-1/2" ';
,,- ,
porcelain test panel. The stain composition was spread as '
, '
uniformly as possible over the test panel surface with a flat
spatu~a. Stain material was added or removed from the test ~ ' '
panel until 0.25 grams of stain material remained. ~ ~
. -': .
The stained panels were oven cured in the following
manner and as-will be discussed~belo~, curing was performed in
vax~ous per~ods of t~me and at Yarious temperatures in order ~ ~-
to ~roduce sta~n~ o~ ~ar~ing,difficult~ of removal. Six `~
sta~ned panels were placed in a baking pan. Another baking pan ;
. ',
, :
~,7 ~
:: , :. : - , .:, -: , .. .. . .. .
~47903
was used as a cover. The pan and cover were shut tight with
hand-tightened screws and wingnuts. Since it was found that
any air currents affect the uniformity of the cured stain, the
pan and`cover were sealed with aluminum foil. Three sets
of pans and covers (each containing six porcelain test panels)
were placed on the three shelves (one set on each shelf) of
a "slue M" Model OV-490-A-2 constant temperature oven -~and
cured at a specified temperature for a specified time. The
oven was accurate to approximately ~ 2F. The oven was ~
equilibrated to the required temperature; the ov~n door was ;-;
opened and the pans placed in the oven as quic~ly as possible. ~ ~a
The tim~g was begun with the closing of the oven door. This
meant that at the start of the cure, the oven temperature was
Belo~ the thermostat setting. After the required length of
t~me, the pans were removed from the oven and allowed to cooi
to room temperature. The stained panels were then removed
from the pans. De~pite all precautions/ the aured stain would
usually;no,b be completely uniform. Some stained panels would
~ave areas in which there would be little stain and other areas
with more stain. Those panels with extreme variations of stain
density were eliminated~
I'est of the oven cleaning compositions of the
~resent invention were performed with formulations con~aining
the following ingredients listed in Table II:
1~47g03
T`~BLE II ~
Ingredient Weight Percent of Ingredient ~ -
Bentonite 2.5
Sodium hydroxide *
Monoethanolamine *
Coconut oil fatty acid 1.0
50/S0 Isobutane/n-butane 1.5 ;
Water (deionized) to 100% total
* The weight percent of this ingredient has been varied to ~-
determinP the effective range of proportions of this lngredient ~ -
in the oven cleaning compositions.
The oven cleaning compositions were prepared in 300 ;~
gram batches as follows: The approximate ~weight of aqueous
bentonite concentrate (to yield a final bentonite concentration
of 2,5%~ was weighed linto a 500 ml. Erlenmeyer flask into which ~ ~-
had been placed a two-inch teflon coated magnetic stirrer bar. ;
Additional water (as required~was added. Then the sodium
hydroxide was added, and the dispersion was s~irred unt~
uniform. The monoethanolamine was added and the dispersion
was stirred briefly. Then the coconut oil fatty acid was added
and the dispersion was again stirred until uniform. Two
.
hundred grams of the composition was weighed into an aerosol ~ `
can. The can was crimped and pressurized with 3 grams~o~ a
propellant mixture. The compositions either were prepared,
pre~surized and immed1ately used, or prepared and stored over-
night at around 85F in a crimped, unpressurized aerosol ¢an
and pressurized be~ore use.
Each o~en cleaning composition was tested on the
4-1/2" x 4~1'/2" porcelain stained panels. Preliminar~ tests - `~
were perfo~med in which the compositions were not aerosolized,
~ut were applled to the stained panels with a paint brush. ~`~
~ 9 -
' . ''' '. ' ' ~ . , ' ' , ~
1~)47~03
The cleaning was found -to be inferior to aerosol application.
All further tests used aerosol application. Since the housewife
would not be concerned with the quantlty (i.e. weigh-t) of stain
remaining in her oven after cleaning but rather with the area
of the oven in which,stain remained after cleaning, "percent
cleaning" was defined as the percent of the area of the 4-1/2"
x 4-1/2" stained panel which, after cleaning, was free of stain.
The percent cleaning of each stained panel was estimated by eye.
The same person estimated the percent cleaning of all stain
10 panels to eliminate the varying bias from person to person. ~-
A factor which was considered was the accuracy in
estimating the percent cleaning of each stained panel. Table
III below indicated the estimated accuracy in determining the
average percent cleaning of the stain panels.
TABLE III -
% Cleaning Range of Accuracy
0-2 ~ 0.
2-10 + 1%
10-30 - 3% ;
2030-80 + 5%
80-90 + 1% ;
90-95 + 0 7%
95-100 + 0.5%
Where the range of accuracy in determining the percent cleaning
was very critical, such as with 0-2% and 95-100%, the number of
stain panels tested was increased in order to ascertain the
reliability of the original test. - ~-~
As stated previously, difficulty in removing a stain
is affected by the conditions used in curing the stain~ i.e.,
30 period of time of curing and temperature. In order to `~
- 10 - . ~ ~
'`'
, .: ~' :.:
16;)47903
illustrate the effectiveness of the oven cleaning compositions
of the presen-t invention, stains of varying degrees of diffi-
culty of removal were prepared, as shown below in Table IV.
These stained panels were treated with a 3% sodium hydroxide
solution for a six-hour period, lightly rubbed with a sponge, and
rinsed with cold water. In all examples that follow, the `; -;
percentages of sodium hydroxide listed are the percentages -
added to the compositions. Since a constant quantity (1%) of -~
coconut oil fatty acid is added to each composition, 0.15% of ~
10 the s~iUm hydroxide is neutr~l~zed ~ thé fat~y ac~ There- ~ -
fore, the percentage of active sodium hydroxide in all compo-
sitions listed is 0.15% less than the number shown (i.e., a
3% sodium hydroxide test solution contains 2.85% free sodium
hydroxide). In all oven cleaning tests described below, only ~;~
the variable alkali metal hydroxide or alkanolamine is stated.
It should be noted that the rem~n~io~th~ ~ve~cL~an~n~
composition has been kept constant as described in Table II.
TABLE IV
Effect of Curing Conditions on Simulated Oven Stains
Test Composition: 3% NaOH
Experiment No. 1 2 3 4 5
Curing Time; Hrs. 1.0 1.25 1.25 2.0 1.5 ~`
Curing Temperature
O ' 425 450 460 450 475
Reaction Time: Hrs. 6 6 6 6 6
Stain Removal % 99.6 94.8 89.0 70.0 ~50-60
These results demonstrate that a stained panel, cured
for one hour at 425F, is easily cleaned by treatment for six
hours at room temperature with a 3% sodium hydro~ide solution.
Increasing the curing temperature to 450F, and the curing ~ ~
time to 1.25 hours, decreases the cleaning to 94.8%. The .~ -
effect of curing time is shown in experiments where the
-- 11 --
-
03
curing temperature is maintained at ~50F, but time is increas-
ed to two hours. In this situation, the ~ removal is reduced
to 70.0~. In con-tras-t, -the effec~ of increasiny the curing
temperature 10F, while maintaining the time at 1.25 hours is
shown in Experiment 4. In this case, the percent cleaning
is reduced from 94.8% to 89.0~. Experiment 5 shows the effect
of increasing the curing temperature an additional 15F to
475F, while increasing curing time to 1-1/2 hours. In this
experiment, the percent soil removal is reduced to approxi-
mately 55%. Based on these results, an arbitrary value for -~
degree of difficulty was assigned to each of these stains.
These degrees of difficulty are listed in the following Table
V. Degree of difficulty is defined by the following equation:
Degree of Difficulty = 10000
% Stain Removal of 3% NaOh (6 hours)
TABLE V
Degrees of Difficulty of Standard 5tains
- Used in Experimental Program
Experiment No. 1 2 3 4 5
Curing Time: Hrs. 1.0 1.25 1.25 2.0 1.5
Curing Temperatùre: ~F 425 450 460 450 475
Degree of Difficulty 100 105 112.5 143 167
These stains of varying degrees of difficulty of
removal have been prepared to illustrate the effectiveness of
the novel oven cleaning compositions of the present invention -
.
and have been utilized in the follo~ing experiments. It
should be noted that the 112.5 degree of difficulty stain
would most fre~uently be encountered in a household oven. -
The 100 stain is easier to remove and the 143 stain is more
difficult to remove than those normally encountered, but the
combination of these standard stains provides a simple means ~ ~-
- 12 -
1~47903
for measuring the performance oE -the oven cleaning compositions
of the present invention. '~
In order to measure the performance of these composi- ~ -
tions accurately, the range of stains was utilized so that per-
formance would not be dependent upon the stain to be removed.
In this regard, composition testing on the 167 stain was discon- ;
tinued due to difficulty in obtaining accurate and reproducible
results.
The following experiments illustrate the unexpected ;~
effectiveness of oven cleaning compositions comprising a low
concentration of alkali metal hydroxide and an alkanolamine in
aqueous solution.
Table VI illustrates the reduction in cleaning when
the caustic concentration is reduced from the 3% used to deter-
mine the standard stain, to 2%. ~ ,
TAsLE VI
Effect of NaOH Concentration Reduction on
Stain Removal of Standard Stains ~
Experlment No. 1 2 3 4 5 6 7 8 `
Standard Stain 100 100 105 105 112.5 112.5 143 1~3 ~
Caustic Concen- 3 2 3 2 3 2 3 2 `
tration; % Wt.
Stain Removal;% 99.6 98.1 94.8 79.0 89.0 79.0 70.0 23.0
: .
Table VII illustrates the unexpected advantages of the
oven cleaning compositions of the present inventlon. Referring
to the values for 2% and 3% caustic alone given in Table VI, it -
can be shown that addition of a small amount of alkanolamine
increases the cleaning capabiltiy of these compositions to a
level equal to or greater than that of the higher caustic
compositions. ~ ,
- 13 -
-
~04~90~
TABLE VII
...._
Effect oE Addition of 5% Monoethanolamine to
Composition of 2% Sodium Hydroxide on
_ Removal of Standard Stains
Experiment No. 1 2 3 4
Standard Stain 100 105 112.5 143
Stain Removal; % 99.7 96.6 96.2 88.0
It is evident that for each standard stain, the oven
cleaning compositions having 2% caustic are not only more effi-
cient because of the addition of 5% of an alkanolamine, butunexpectedly, these compositions are also more efficient than
the 3% caustic compositions.
In order to emphasize th~s unexpected efficiency in
the oven cleaning compositions of this invention, Tables VIII ;
and IX are presented. ~ ~
TABLE VI I I ~ :
Effect of Addition of Small Amounts of
Monoethanolamine to Composition of
~ Sodium Hydroxide on Stain Removal
__ of 100 Standard Stain
Experiment No. 1 2 3 4 5 6
Sodium Hydroxide; ;~
% Wt. .5 .5 1 1 2 2
....~ .
Monoethanolamine; ~;-; `~
% Wt. 0 1 0 1 0 5
Stain Removal; % 5.6 81.0 82.0 89.9 98.1 99.7
TABLE IX
Effect of Addition of Small Amounts of
Monoethanolamine to Composition of
30Sodium Hydroxide on Stain Removal
of 105 Standard Stain
Experiment No. 1 2 3 4 5 6 7 ~;
~; . ,
Sodium Hydroxide; ~
% Wt. 2 2 2 2.2~ 2.25 2.35 2.35 ~ -
Monoethanolamine;
% Wt. 0 .25 5 0 .25 0 1
Stain Removal; % 79.0 69.0 96.6 80.0 99.0 87.0 95.6
~ '
- 14 -
~:
1~479~3 ~ :
As evident from Tables VIII and IX, addition oE a small
amount of an alkanolamine contributes greatly t~ the cleaning
capability of the oven cleaning compositions of the present
invention. This is surprising in two respects. For example, :
as shown in Table VIII, Experiments 1 and 2, and Iable IX,
Experiments 4 through 7, the addition of a small àmount of an ~:.
alkanolamine to low concentrations of an alkali metal hydroxide :~.
provides a significant increase in stain removal. Also, even
though compositions having caustic alone clean very well on ~
standard stains 100 and 105, which are easier to clean, the ~ `,
addition of a relatively small amount of alkanolamine improves~
the effect on stain removal.
Stained panels cured at 460F for 1-1/4 hours (112.5 -~
~ ~,
degree of difficulty staln) were subjected for six hours to
oven cleaning compositions of~the present inventlon comprising
varying concentrations of caustic and alkanolamine. These tests ~ ~.
were conducted to determine if alkanolamines had a significant
effect on cleaning capabil~ty of low caustic oven cleaning i~
compositions comprising from 0.5 to 4.0% alkali metal hydroxide.
TABLE X ~
Effect on S~ain Removal in Using
Compositions of Varying NaOH and
Monoethanolamine Concèntrations
Experiment No. 1 2 3 4 5 6
Caustic Concen- :~
tration; % Wt. 0.5 0.5 1.0 1.0 1.0 1.0 .-
Monoethanolamine
Concentration:~
% Wt. 15 20 0 5 9 10
Stain Removal; % 42.0 90.0 4.0 58.0 85.0 92.8 ~ :
.
- 15 - : ~
~L~479~)3
Table X (Cont'd.) ~ `
Experiment No. 7 8 9 10 11 12
Caustic Concèn-
tration: % Wt. 1.0 1.5 1.5 2.0 2.0 2.0
Monoethanolamine
Concentration:
% Wt. 20 0 5 0 1 2
Stain Removal; % 96.1 46.0 76.0 79.0 78.0 97.0
Experiment No. 13 14 15 16 17 18 ~ -
10 Caustic Concen-
tration; % Wt. 2.0 2.6 2.6 3.0 3.0 3.5
Monoethanolamine
Concentration;
% Wt. 5 0 1 0 1 0
Stain Removal; % 96.2 88.0 93.9 89.0 95.9 98.4 ~ `
Experiment No. 19 20 21 22 23 24
Caustic Concen-
tration: % Wt. 3.5 4.0 4.0 4.0 4.0 4.0
Monoethanolamine
Concentration;
% Wt. 5 0 0 2 5 10
Stain Removal; % 99.8 97.1 98.9 99.5 99.5 99.7 ~-;
The results of these experiments demonstrate the inter~
action of alkanolamine and alkali metal hydroxide. For example,
even with as low as 1% caustic, the percent of stain removal
.
achieved by the addition of 10% of monoethanolamine is greater ~;
than the percent of stain removal with 3% caustic along (see
Experiments 6 and 16). Also it is significant that those ov~n
cleaning compositions comprising an alkanolamine in addition to
alkali metal hydroxide exhlbit superior staln removal compared
to those compositions comprising alkali metal hydroxide alone,
for eve~ caustic concentration from 0.5 to 4.0%.
It is not intended that the invention be limited by
any particular theory as to why addition of an alkanolamine to
a low caustic composition provides an oven cleaner as
-, '':` ~ ''
- 16 -
. .... . . .
7g~3
~ffective as compositions having high caustic, however, the
following discussion may be pertinent. Caus-tic alkali attacks
an oven s-tain from the surface and gradually dissolves it with-
out penetrating -through the stain. On the other hand, an
alkanolamine, in the presence of caustic, reacts quite differently
than a caustic alkali. The alkanolamine penetrates through the
stain, probably attacking the bond between the stain and the `
surface so as to lift the stain from the oven surface. While
caustic alone is effective at high concentrations to remove
a common household stain in an adequate perlod of time, the
unique combination of an alkanolamine plus a low concentration
of caustic is superior in stain removal since this latter oven
cleaning composition can penetrate through the stain to lift
the stain off the oven surface and allow some caustic to
,
attack the stain from its under surface. This results in a
synergistic cooperation between the caustic alkali and alka-
nolamine so that a high concentration of caustic alkali is
not required. In order to show that various other alkanolamines
are as effective as the monoethanolamine described above, oven
cleaning compositions comprising other alkanolamines, listed
below in Tables ~I and XII, and 1.5% sodium hydroxide or 2.0
sodium hydroxide were tested on the 112.5 stain. For all
experiments, the names of the alkanolamines tested will be
abbreviated as follows:
~lonoethanolamine MEA
Triethanolamine TEA
,
MonoisopropanQlamine MIPA
N-methylethanolamine N-MEA
Aminoethylethanolamine AEEA . :~
Diglycolamine DiGA
Diisopropanolamine DiIPA :
Triisopropanolamine TriIPA
- 17 -
1~479~3
Mixed isopropanolamine ~made by the
Union Carbide Company conSisting
of a mixture of 10 to 15 weight %
mono-, 40 to 50 weight ~ di-, and
40 to 50 weight % tri-isopropanol-
amine) IPA -~
N,N-diethylethanolamine DiEEA
N,N-dimethylethanolamine DiMEA :
N,N-diisopropylethanolamine DiIPEA
Diethanolamine DiEA
N-methyldiethanolamine MDiEA ;~
N-ethyldiethanolamine EDiEA
,, " ,~
TABLE XI
Effect of Addition of Other Alkanolamines
To A Composition of 2.0% Sodium Hydroxide
on Removal of 112 5 Stain
Test No. 1 2 3 4 5
Alkanolamine -- AEEA MIPA N-MEA DiGA
Alkanolamine;
% Wt. __ 8.52 6.15 6.15 8~6 ` ~
Stain Removal;% 79.0 96.78 84.89 90.89 94.22 ; ,-
Test NO. 6 7 8 9 10 ,`~ `
AlkanolamineDiIPA TriIPA IPA DiMEA DiEEA ~ `
: . ,
Alkanolamine; `,~ `
% Wt. ` 10.8 15.66 12.41 7.3 9.64
Stain Removal; % 89.22 93.67 90.22 76.9 96.9 '
Test NO. 11 12 13 `~`
Al]canolamine MDiEA EDiEA DiPEA
Alkanolamine;
% Wt.9. 75 10. gl 10~.90
Stain Removal; % 59.0 94.0 98.8
TABLE XII
Effect of Addition of Other Alkanolamines
To Composition of 1.5% Sodium Hydroxide
on Removal of 112.5 Stain `
Test No. 1 2 3 4 S - -
Alkanolamine -- AEEA MIPA N-MEA DiGA - ~
-~ .
. -.
18- `;
'
16)4~3
Table XII Con-t'd.
Alkanolamine; % Wt. -- 8.52 6.15 6.15 8.6
Stain Removal; % 47.22 88.0 41.0 71.0 62.0
Test No. 6 7 8 9 10
Alkanolamine DiIPA TriIPA IPA DiMEA DiEEA
Alkanolamine; % Wt. 10.8 15.66 12.41 7.3 9.64
Stain Removal; % 84.0 85.0 89.0 54.5 79.0
Test No. 11 12 13
Alkanolamine MDiEA EDiEA DiPEA
Alkanolamine; % Wt. 9.75 10.91 10.9
Stain Removal; % 32.0 50.0 95.11
It is apparent from Table XI that at the 2% sodium
hydroxide level all alkanolamines tested, except for N,N-
dimethylethanolamine and N-methyldiethanolamine effect a
significant improvement over caustic alone in their cleaning :
capabiltiy. In fact, these oven cleaning compositions com- ; ~
prising 2% sodium hydroxide and the other alkanolamines in ~ `
molar concentrations equal to that of 5% monoethanolamine ;
clean equal to or better than the 3% caustic composition, ~;
.
as shown in Table IV, Experiment 3. B~ decreasing the
caustic concentration to 1.5% as shown in Table XII, the
cleaning capabiltiy of compositions comprising 1.5% caustic .
alone is reduced to 47.22%. This means that at this lower
caustic concentra.tion, the alkanolamines must be more
efficient so as to yield a satisfactory level of oven stain .
removal. For example, in T.àble XI, monoisopropanolamine
provides good stain removal as compared with the composition
comprising 2% caustic alone, but the composition comprising ..
1.5% caustic and monoisopropanolamine does not increase :;~ .
the percent of stain .removal over that of 1.5% caustic alone. ~
When stains of a greater degree of difficulty are ~ .
utilized for testing of these oven cleaning compositions
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such as the 143 s-tain, the contribution of the addition of
an alkanolamine becomes even more signiflcant. As shown in
Table XIII below, oven cleaning compositions comprising
various concentrations of sodium hydroxide and of monoethanol- -
amine were tested on the 143 stain.
TABLE XIII
Effect of Compositions of Sodium
Hydroxide and Monoethanolamine ~ -
on Removal of 143 Stain
10Experiment No. 1 2 3 4 5
Sodium Hydroxide;
~ Wt. 1 2 2 2 3
Monoethanolamine;
~ Wt. ~ 5 10 --
Stain Removal; ~ 2.8 23.0 88.0 83.0 70.0
';"",,~ . ' "
Experiment No. 6 7 8 9 10 11 i~ -
Sodium H~droxide;
% Wt. 3.5 3.7 3.7 3.7 4.0 4.0 ~;~
Monoethanolamine- .,
% Wt. -- -- 1 5 -- 5 ;~ ~-
20Stain Removal; % 80.0 78.0 84.3 96.0 97.1 99.3 ~
-:., ,, ~ .:
It is evident from Table XIII that even when testing this more
difficult stain, stain removal is significantly increased by
the addition of a small amoun* of an monoethanolamine (compare `~;
Experiments #2 to #3, and #7 to ~9). This is also the case
for the other alkanolamines previously tested as shown in the ~;
following Table XIV. In this set of experiments, compositions
comprising 3.7~ sodium hydroxide and the other alkanolamines
were applled to the 143 stain.
TABLE XIV
,:
Effect of Addition of Alkanolamines and
3.7~ 5Odium H~droxide on Rémoval o 143 Stain -~
~,
Test No. 1 2 3 4 5 6
Alkanolamine -- AEEA MIPA N-MEA DiGA DiIPA
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Table XIV Cont'd.
Alkanolamine; % Wt. -- 8.52 6.15 6.15 8.60 10.8
Stain Removal; ~ 78.0 98.9 97.1 98.0 82.0 95.4
Test No. 7 8 9 10
Alkanolamine TriIPA IPA DiMEA DiEEA
Alkanolamine; ~ 15.66 12.41 7.3 9.64
Stain Removal; ~ 89.4 97.1 96.7 94.7
Test No. 11 12 13
Alkanolamine MDiEA EDiEA DIPEA ~ ~
Alkanolamine; ~ 9.75 10.91 10.9 :-
Stain Removal; % 90.7 90.9 99.3
In comparing the oven cleaning composition comprising 3.7% -
caustic alone., which removed 78% of the 143 stain, with the
oven cleaning compositions comprising 3.7% caustic and an ~ .
alkanolamine, there is a significant improvement in cleaning ~.
with compositions comprising the alkali metal hydroxide~
.
alkanolamine combination. The weight percentages of the .
alkanolamines listed in Ta.bles XI, XII, and XIV are such that ~;
the alkanolamines are equimolar.
Effect of Addition of MEA to
Composition of 2.09% Lithium Hydroxide
On Removal of 112.5 Stain :~
Experiment No. 1 2 - .
Monoethanolamine, ~ -- 5 ;~
Stain Rè~oval; % 83.0 98.4
Since oven cleaning compositions comprising a caustic
alkali and triethanolamine have been disclosed in the prior art,
.
experiments were conducted on the various standard stains with
various concentrations of both sodium hydroxide and tri- : .
ethanolamine to determine the effectiveness of this particular
alkanolamine in oven cleaning compositions having low caustic.
'
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TABLE XVI
Evalua-tion of Compositions having TEA to Compositions
having MEA in % Stain Removal
Experiment No. 1 2 3 4 5 6
Standard Stain 112.5 112.5 112.5 112.5 112.5 112.5
Sodium Hydroxide;
% Wt. 0.5 0.5 0.5 1.5 1.5 1.5
Alkanolamine MEA MEA TEA -- MEA TEA
Alkanolamine; % Wt. 15 20 15 -- 5 12.21 - ;
Stain Removal; % 42.0 90.0 41.7 46.0 76.0 16.0 -~
Experiment No. 7 8 9 10 11 12
Standard Stain 112.5 112.5 112.5 112.5 112.5 112.5 '`~
Sodium Hydroxide;
~ Wt. 2 ~2 2 3 3 3
Alkanolamine -- MEA TEA ~- MEA TEA ;
. ~ . .- :
Alkanolamine; % Wt. -- 5 12.21 -- 1 12.21
Stain Re~oval; % 79.0 92.1 72.3 89.0 95.9 86.0
Experiment No. 13 14 15 16 17 18
Standard Stain 112.5 112.5 112.5 143 143 143
Sodium Uydroxide;
% Wt. 3.5 3.5 3-5 3-7 3-7 3-7 ,~
Alkanolamine -- MEA TEA -- MEA TEA
- .
Alkanolamine; % Wt. -- 5 12.21 -- 5 12.21
Stain Removal; % 98.4 99.8 93.1 78.0 96.0 95.0
Experiment No. 19 20 21
Standard Stain 143 143 143
Sodium Hydroxide;
% Wt 4 4 4
Alkanolamine -- MEA TEA ~ ,
,. ~
Alkanolamine; % Wt. -- 5 12.21
Stain Removal; ~ 97.1 99.5 92.8
''
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It is evident from Table XVI that triethanolamine
does not increase the cleaning capabiltiy of compositions com
prising from 0.5 to 4.0% ~austic. Further, triethanolamine has
a deleterious effect on the composi-tions tested in Experiment
6, 9, 12, 15 and 21 because these compositions exhibit less
stain removal than those compositions having caustic alone.
Some oven cleaning compositions have been prepared
utilizing the ingredients of the present invention as follows:
TABLE XVII
% by % by % by % by
Ingredients Wt. (A) Wt. (B) Wt. (C) Wt. (D)
Water (DI) 81.0076.14 75.63 83.40
Bentonite 2.43 2.43 2.41 2.50 ~ -
50% Aqueous NaOH 3.93 3.97 3.85 4.00
Monoethanolamine 4.86 9.72 9.65 5.00 ~-
Lauryl Alcohol0.87 0.87 0.87 0.90
Coconut oil fatty acid 0.970.97 0.96 1.00
Perfume 0.19 0.19 0.19 0.20
Propellant 5.75 5.75 6.44 3.00 ` ;~
Examples A and B in Table XVII are preferred embodiments of
this invention.
In a preferred range of ingredients the oven cleaning
compositions of the present invention comprise, by weight, from
about 1.5% to about 3.7% of an alkali metal hydroxide; from
about 3% to 15% of an alkanolamine selected from the group
consisting of: monoethanolamine, monoisopropanolamine,
N-methylethanolamine, aminoethylethanolamine, diglycolamine,
diisopropanolamine, triisopropanolamine, mixed isopropanolamine,
N,N-diethylethanolamine, N,N-diisopropylethanolamine, diethanol- ;~
amine, and N-ethyldiethanolamine~ and up to about 95.5% of
water. ~`~
-~:
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Another preferred embodiment of the oven cleaning
compositions of the present invention comprises, by weight, ;~
about 2.0% of sodium hydroxide; about 5.0% of monoethanolamine;
about 2~5% bentonite; about 1.0% of a coconut oil fatty acid;
about 1.5% of an isobutane-n-butane propellant and up to about ;
88.0% water.
Another preferred embodiment of the oven cleaning ~ ~
compositions of the present invention comprises, by weight, ~ -
about 2.0% of sodium hydroxide; about 10.0% of monoethanolamine; -~ ;
about 2.5% bentonite; àbout 1.0% of a coconut fatty acid; ~ ~
.:. .
about 1.5% of an isobutane-n-butane propellant and up to about ;
83.0% water.
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