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Description  |
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BACKGROUND OF THE INVENTION
Many industrial process cleaning compositions have been based upon
fluorinated and fluorinated/chlorinated solvents. As ecological concerns
have risen in importance, the search for replacements for such cleaners
has attained increased importance. Several requirements exist for
replacement cleaners including: cleaning efficacy, non-corrosiveness to
metal parts, ease of use, and safety. Safety concerns raise several
different requirements, including nontoxicity and high flashpoint. To
date, no replacement cleaner has attained these properties.
Terpene hydrocarbons have been used for some time in general purpose
cleaners, and in some specific formulations for specific industrial
cleaning purposes, such as cleaning printed circuit boards or removal of
graffiti. Those prior cleaners have relatively low flashpoints, typically
well below their boiling point. Thus, basic problems associated with
providing an effective and safe industrial cleaner have not been
considered or solved using terpene hydrocarbon based cleaning
compositions.
SUMMARY OF THE INVENTION
The present invention relates to an aqueous based micellar solution in the
form of a microemulsion which is an effective all-purpose solvent and
degreaser and which has a flashpoint in excess of its boiling point,
typically greater than 212 degrees Fahrenheit.
A further aspect of the invention is a terpene hydrocarbon based cleaning
composition which is admixed with an organic solvent, or which may be
admixed with an organic solvent. An additional aspect of the invention
involves the use of a terpene alcohol as a degreasing agent without
requiring the solvents of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an improved cleaning composition which
provides sufficient cleaning efficacy to be useful in many industrial
applications which presently rely on fluorinated or
chlorinated/fluorinated solvents; and which has a flashpoint in excess of
200 degrees Fahrenheit. These improved cleaning compositions comprise:
5 to 35 weight percent terpene alcohol which has no significant amount of
alpha pinene and beta pinene; and from 1 to 35 weight percent of a
surfactant or combination of surfactants.
The surfactant or combination of surfactants can comprise up to 35 weight
percent of the composition in total, and may be the combination of two or
more different types of surfactants. A typical combination may comprise:
1.0 to 35 weight percent nonionic surfactant;
1.0 to 35 weight percent cationic, anionic or zwitterionic surfactant
wherein both surfactant components do not include surfactants unreacted
with ethylene oxide components. It is important that any surfactant used
in the present invention not have free ethoxide components which are quite
volatile and defeat the objective of obtaining a cleaning composition
which is not combustible.
The compositions may also comprise from 0.1 to 25 weight percent terpene
hydrocarbon which has been specially prepared so that no significant
amount of alpha pinene or beta pinene are present in the terpene
hydrocarbon component.
The compositions of the invention also include non-aqueous systems
employing one or more organic solvents admixed with the terpene
hydrocarbon.
The aqueous compositions are further characterized by being clear micellar
solutions which are stable to phase changes and dilutions. Repeated
freeze/thaw cycle experiments establish that the present cleaners do not
break into two phase mixtures as many d-limonene based systems
demonstrate. For instance, many terpene hydrocarbon/surfactant systems are
emulsion systems which will become cloudy upon dilution with regular
water. In some limonene and surfactant based systems dilution causes the
cleaning solution to gel. In automated cleaning processes this can be a
serious disadvantage as it may cause cleaning apparatus to fail, or the
gels formed may not be removed from the article being cleaned.
The cleaning compositions of the present invention may be in the form of
microemulsions. Microemulsions are two phase mixtures comprising an oil
phase and a water phase. Regular emulsions appear cloudy or opaque because
the size of the droplets of oil is larger than quarter wavelengths of
white light, and thus scatter light rather than allowing it to pass
through the mixture unscattered. Microemulsions have oil droplets less
than about 10 microns in size and thus do not scatter light. They appear
clear. Furthermore, microemulsions tend to be much more stable than
regular emulsions. True microemulsions are easier to form from their
constituent components than regular emulsions. Typically, emulsions
require special equipment in order to be formed, such as ultrasonic mixers
or emulsifiers which produce tremendous shear forces. The compositions of
the present invention require only standard, non-shear mixing apparatus to
be produced.
For purposes of this application the term terpene hydrocarbon shall be
understood to include all compounds of the general structure:
##STR1##
which are monocyclic terpenes, and acyclic terpenes. The terpene
hydrocarbons used in the present invention are derived from a number of
natural sources. Typically, the terpene hydrocarbon is a blend of
naturally occurring terpene compounds. These compounds include the class
of mono- or sesquiterpenes and mixtures thereof and can be acyclic or
monocyclic in structure. Acyclic terpene hydrocarbons useful in the
present invention include 2-methyl-6-methylene-2, 7-octadiene and 2,
6-dimethyl-2, 4, 6-octadiene. Monocyclic terpene hydrocarbons include
terpinene, terpinolene and limonene classes and dipentene. While the
examples provided here employ naturally occurring mixtures of these
compounds, it is understood that pure samples of these compounds could be
employed as well. When refined samples of naturally occurring terpene
hydrocarbons are employed care must be taken to insure that no significant
amount of alpha or beta pinene are present, or that any alpha or beta
pinene are removed by means of distillation or filtering.
Specifically excluded from the term "terpene hydrocarbon" are bicyclic
terpenes which include alpha and beta pinene, and terpene alcohols.
The term "terpene alcohol" is understood for purposes of the present
invention to encompass compounds of the formulae:
##STR2##
which are monocyclic, bicyclic and acyclic alcohols, respectively. Terpene
alcohols are structurally similar to terpene hydrocarbons except that the
structures also include some hydroxy functionality. They can be primary,
secondary, or tertiary alcohol derivatives of monocyclic, bicyclic or
acyclic terpenes as well as the above. Such tertiary alcohols include
terpineol which is usually sold commercially as a mixture of alpha, beta,
and gamma isomers. Linalool is also a commercially available tertiary
terpene alcohol. Secondary alcohols include borneol, and primary terpene
alcohols include geraniol. Terpene alcohols are generally available
through commercial sources, however, one must take care in practicing this
invention to insure that no significant amount of alpha pinene or beta
pinene are present in the terpene alcohol source, or that care is taken to
remove such pinenes.
As used herein, the term "no significant amount" of alpha pinene and beta
pinene means a terpene hydrocarbon in which the quantity of alpha pinene
or beta pinene present is insufficient to cause the flashpoint of the
terpene hydrocarbon to be significantly below its boiling point. I
estimate that the alpha pinene and beta pinene volume percentage in the
raw alcohol should be less than about 0.5%, because otherwise a sudden and
significant decrease in the flashpoint will be experienced.
Examples of nonionic surfactants which are employed include propylene oxide
or ethylene oxide condensation products of higher aliphatic alcohols,
alkyl phenols, carboxylic acids, amides, amines and sulphonamides. These
well-known surfactants include the sorbitan esters of fatty acids having
10 to 22 carbon atoms; polyoxyethylene sorbitan esters of C10 to C22 fatty
acids having up to 95 percent propylene oxide; polyoxyethylene sorbitol
esters of C10 to C22 fatty acids, polyoxyethylene derivatives of fatty
phenols having 6 to 20 carbon atoms and up to 95 percent propylene oxide;
fatty amino and amido betaines having 10 to 22 carbon atoms;
polyoxyethylene condensates of C10 to C22 fatty acids or fatty alcohols
having up to 95 percent propylene oxide. Polyoxyethylene and
polyoxypropylene analogs of the above surfactants can be used in the
present invention as long as care is taken to insure that polyoxyethylene
polymers or polyoxypropylene polymers which have not been completely
reacted with the fatty acid portion of the surfactant. Most importantly,
volatile oligomeric fractions must be absent from the surfactants used in
the present invention. A convenient way this goal can be accomplished is
by using oxypropylene analogs of the above mentioned species of
surfactants where feasible.
Ionic surfactants employed include surfactants such as the alkylaryl
sulfonates of 6 to 20 carbons in the alkyl group; C10 to C22 fatty acid
soaps; C10 to C22 fatty sulfates; C10 to C22 alkyl sulfonates; alkali
metal salts of dialkyl sulfosuccinates; C10 to C22 fatty amine oxides;
fatty imidazolines of C6 to C20 carbon atoms; fatty amido sulfobetaines
having 10 to 22 carbon atoms; quaternary surfactants such as the fatty
ammonium compounds having 10 to 22 carbon atoms; C10 to C22 fatty
morpholine oxides; alkali metal salts of carboxylated ethoxylated C10 to
C22 alcohols having up to 95 percent propylene oxide; propylene oxide
condensates of C10 to C22 fatty acid monoesters of glycerins having up to
95 percent of propylene oxide; the mono- or diethanol amides of C10 to C22
fatty acids; and alkoxylated siloxane surfactants containing propylene
oxide units and/or propylene oxide units; and phosphate esters, etc.
As is well-known in the field of surfactants, the counter ion in the case
of anionic surfactants may be any of the alkali metals, ammonia, or
substituted ammonias such as trimethylamine or triethanol amine. Usually
ammonium, sodium and potassium are preferred. In the case of cationic
surfactants, the counter ion is usually a halide, sulfate, or
methosulfate, the chlorides being the most common industrially available
compounds. The foregoing compounds have been described with particular
reference to fatty derivatives. It is the fatty moiety usually forming the
lipophilic moiety. A common fatty group is an alkyl group of natural or
synthetic origin.
In most instances, the alkyl group may be replaced by the corresponding
ethylenically saturated group having one or more ethylene linkages such as
commonly occurs in nature. Common unsaturated groups are oleyl, linoleyl,
decenyl, hexadecenyl, dodecenyl, etc. In appropriate cases, as known in
the art, the alkyl group may be cyclic, i.e., cycloalkyls, or may be
straight or branched chain. Other suitable surfactants include sorbitol
monolaurate-propylene oxide condensates; sorbitol monomyristate-propylene
oxide condensates; sorbitol monostearate-propylene oxide condensates;
dodecylphenol-propylene oxide condensates; myristylphenol-propylene oxide
condensates; octylphenyl-propylene oxide condensates;
nonylphenyl-propylene oxide condensates; stearylphenol-propylene oxide
condensates; lauryl alcohol-propylene oxide condensates; stearyl
alcohol-propylene oxide condensates; secondary alcohol-propylene oxide
condensates such as C14-C15 secondary alcohols condensed with propylene
oxide; decyl amino betaine; coco amido sulfobetaine; oleyl amido betaine;
coco imidazoline; coco sulfoimidazoline; cetyl imidazoline;
1-hydroxyethyl-2-heptadecenyl imidazoline; 1-hydroxyethyl-2-mixed
heptadecenyl heptadecadienyl imidazoline; n-coco morpholine oxide; decyl
dimethyl amine oxide; coco amido dimethyl amine oxide; sorbitan
tristearate condensed with propylene oxide; sorbitan trioleate condensed
with propylene oxide; sorbitan trioleate; sodium or potassium dodecyl
sulfate; sodium or potassium stearyl sulfate; sodium or potassium dodecyl
benzene sulfonate; sodium or potassium stearyl sulfonate; triethanol amine
salt of dodecyl sulfate; trimethyl dodecyl ammonium chloride; trimethyl
stearyl ammonium methosulfate; sodium laurate; sodium or potassium
myristate; and sodium or potassium stearate.
Optionally, the cleaning compositions of the present invention may also
include a suitable solvent for specific cleaning purposes. Such solvents
include n-methyl pyrrolidone, dipropylene glycol and ethylene glycol
monobutyl ether.
All of the chemical components used in the present invention are
commercially available.
EXAMPLES
The following examples illustrate certain aspects of the present invention.
They are not intended to exemplify the full scope of the invention. In
certain aspects they enable certain aspects of the invention.
Example 1
The following ingredients in the following proportions were combined and
mixed:
______________________________________
Ingredient Volume Wt. %
______________________________________
H.sub.2 O 175 35.0
monoethanolamine 7.5 1.5
dodecylbenzene 13.0 2.6
sulfonic acid
nonylphenoxy 38.5 7.7
polyethoxy ethanol
dipropylene glycol
38.5 7.7
sodium xylene 11.5 2.3
sulfonate
e.d.t.a. 4.0 0.8
terpeniol 62.0 12.4
assorted terpene 35.0 7.0
alcohols
n-methyl pyrrolidone
115 23.0
100.0%
______________________________________
The combination was clear and stable. When tested it exhibited a flashpoint
in excess of 212 degrees Fahrenheit. In fact, it exhibited no flashpoint
below the boiling point of the composition.
Example 2
A mixture of the following components:
______________________________________
Ingredient Volume Wt. %
______________________________________
H.sub.2 O 545 54.2
monoethanolamine 20 2.0
dodecylbenzene 35.0 3.5
sulfonic acid
nonylphenoxy 100 10.0
polyethoxy ethanol
terpeniol 93.0 9.3
assorted terpene 52.5 6.0
alcohols
n-methyl pyrrolidone
150 15.0
______________________________________
The components formed a clear microemulsion with mixing. The composition
had a flashpoint in excess of 212 degrees Fahrenheit.
Example 3
______________________________________
Ingredient Volume Wt. %
______________________________________
terpeniol 200 33.33
n-methyl pyrrolidone
200 33.33
dipropylene glycol
200 33.33
______________________________________
This clear mixture was clear, stable and had a flashpoint in excess of 212
degrees Fahrenheit.
Example 4
Another sample was made with the following composition:
______________________________________
Ingredient Volume (ml)
Wt. %
______________________________________
H.sub.2 O 470 47.0
dodecyl benzene sulfonic
35.5 3.5
acid
ethylene glycol monobutyl
100 10.0
ether (EB)
Rexol 25/10 100 10.0
sodium xylene sulfonate
30 3.0
e.d.t.a. 10 1.0
terpeniol 250 25.0
1 N NaOH 4.5 0.5
100.0%
______________________________________
The solution was adjusted to a pH between about 6 and 8. This solution was
clear and stable. The solution did not flash below its boiling point.
Examples 5-7
Clear stable microemulsions of the following formulations were made, all of
which displayed flashpoints in excess of 212 degrees Fahrenheit.
Example 5
______________________________________
Ingredient Volume (ml)
Wt. %
______________________________________
H.sub.2 O 415 41.5
monoethanolamine 15 1.5
dodecylbenzene sulfonic
26 2.6
acid
nonylphenoxy polyethoxy
77 7.7
ethanol
dipropylene glycol
77 7.7
sodium xylene sulfonate
30 3.0
ethylene diamine 10 1.0
tetraacetic acid
terpeniol 250 25.0
n-methyl pyrrolidone
100 10.0
______________________________________
Example 6
______________________________________
Ingredient Volume (ml)
Wt. %
______________________________________
H.sub.2 O 545 54.5
monoethanolamine 15 1.5
dodecylbenzene sulfonic
26 2.6
acid
sodium metasilicate
10 1.0
nonylphenoxy polyethoxy
77 7.7
ethanol
dipropylene glycol
77 7.7
sodium xylene sulfonate
30 3.0
ethylene diamine 10 1.0
tetraacetic acid
terpeniol 150 15.0
n-methyl pyrrolidone
50 5.0
______________________________________
Example 7
______________________________________
Ingredient Volume (ml)
Wt. %
______________________________________
H.sub.2 O 495 49.5
monoethanolamine 15 1.5
dodecylbenzene sulfonic
26 2.6
acid
sodium metasilicate
10 1.0
nonylphenoxy polyethoxy
77 7.7
ethanol
______________________________________
______________________________________
Ingredient Volume (ml)
Wt. %
______________________________________
dipropylene glycol
77 7.7
sodium xylene sulfonate
30 3.0
ethylene diamine 10 1.0
tetraacetic acid
terpeniol 200 20.0
n-methyl pyrrolidone
50 5.0
______________________________________
The preceding Examples 1-7 were directed principally to aqueous based
cleaning compositions. These compositions are environmentally improved
over prior cleaning compositions because the terpene hydrocarbons are
naturally occurring materials which are biodegradable. Particularly
applications, however, may not be practical for use with an aqueous system
and I have therefore developed a composition utilizing water miscible
organic solvents in admixture with the terpene hydrocarbon.
I prefer that the organic solvents be water miscible in order to facilitate
the cleaning of spills, and to minimize the possible contamination to
ground water supplies in the event of a spill or leakage. Furthermore,
because the solvents and the terpene hydrocarbon are water miscible, then
the cleaning composition may be produced so as to be mixed with water by
the user.
A preferred terpene hydrocarbon is produced by Technical Ltd. of Anacortes,
Washington. The terpene alcohol had a product name of Terpene Alcohols
95%, and had the following analysis by gas liquid chromatography:
______________________________________
Alpha fenchone 2.1%
Terpinen-4-OL 1.0%
Cis-beta-terpineol
1.9%
Isoborneol 0.6%
Trans-beta terpineol
1.4%
Alpha terpineol 91.4%
Total terpene alcohols
98.8%
______________________________________
I have found that commercially available terpene alcohols actually are a
mixture of various alcohols. The alcohol types and percentages may also be
related to the starting composition from which the alcohol is produced.
Many terpene alcohols are produced from wood waste and I have found, for
example, that the terpene hydrocarbon produced from trees originating in
Brazil have a lower concentration of the alpha and/or beta pinenes than
those originating in Florida.
Formulation of the composition as set out in Example 1 with the
above-identified Tecnal Ltd. material resulted in a cleaning composition
with a flashpoint above the boiling point of 220.degree. F. The flashpoint
test was based upon the closed cup method recommended by the Department of
Transportation at 49 Code of Federal Regulations, Chapter I,
.sctn.173.115(d)(i)(A). Formulation into an organic composition as set
forth below in Example 8 resulted in a composition with a flashpoint of
207.degree. F. and a Kb value in excess of 500.
I have found that terpene alcohols containing 95% to 100% terpene alcohol,
when substantially free of the alpha and beta pinenes or other impurities
adversely affecting the flashpoint, can be formulated to produce a terpene
based solvent as a microemulsion or an organic solvent blend having
flashpoints in excess of 200.degree. F. and with very low trace odor. The
odor of prior terpene compositions was quite distinctive, required
ventilation, and adversely impacted use of those formulations. The
disclosed formulations exhibit little or none of the trace odor. In
addition, because the flashpoint of the disclosed compositions exceed
200.degree. F. then they may be safely transported and landfilled.
The purified terpene alcohols may be blended in any proportion with other
solvents, diluents, and thinners to produce a non-aqueous solvent blend
which has a flashpoint in excess of 200.degree. F. and a faint low or
trace terpene odor. Solvent blends may be developed with specific
properties based upon specific applications. Suitable organic solvents
include mineral based oil, tridecyl alcohol, ethylene glycol, propylene
glycol, diethylene glycol, dipropylene glycol, triethylene glycol,
tripopylene glycol, glycerine, monoethanolamine, monoisopropanolamine,
diethanolamine, triethanolamine, di-tri-isopropanolamine, dibasic ester,
glycol ether acetate DE, glycol ether acetate DB, isophorone, glycol
ethers and n-methyl pyrrolidone.
Example 8
______________________________________
Ingredient Volume %
______________________________________
N-methyl pyrrolidone
33.3%
Dipropylene glycol
33.3%
Terpene alcohol 33.3%
______________________________________
The composition of Example 8 had a flashpoint in excess of 207.degree. F.,
and exhibited little of the distinctive terpene odor. The composition of
Example 8 utilized the Tecnal Ltd. alcohol as the terpene alcohol.
Example 9
______________________________________
Ingredient Volume %
______________________________________
n-methyl pyrrolidone
33.3%
Dipropylene glycol
33.3%
Glidcol 95 (terpene
33.3%
hydrocarbon)
______________________________________
Glidcol 95 is a commercially available terpene alcohol sold by Glidco
Chemical. Glibcol 95 contains alpha terpinene, among other terpene
hydrocarbons and terpene alcohols, and exhibits a flashpoint of between
180.degree. F. and 195.degree. F. depending upon the volatile impurities
present. The flashpoint of Glidcol 95 may be increased to over 212.degree.
F. by increasing the temperature of the product to 200.degree. F. for
approximately five (5) minutes, sufficient time for the volatile
impurities, including the alpha and beta pinenes, to be driven off.
Example 9 was allowed to sit for more than six (6) months, and even then
exhibited a flashpoint in excess of 212.degree. F.
Commercially available terpene alcohols may contain a significant amount of
terpene hydrocarbon impurities. The impurities include not only the alpha
and beta pinenes, but also limonene, dipentene, terpinene, terpinolene,
menthere, myrcene, sabinene, oneimene, thellandrene and mixtures thereof.
The compositions of the invention require that the terpene hydrocarbon
have no significant amount of these impurities, so that the flashpoint is
high and there is little or no trace odor.
In the event a solvent formulation is used, such as Example 8, then I
prefer that the solvents likewise have a relatively high flashpoint.
According to the Condensed Chemical Dictionary, 1956 Edition, Reinhold
Publishing Company, n-methyl pyrrolidone has a flashpoint of 204.degree.
F. and dipropylene glycol has a flashpoint of 280.degree. F.
Those skilled in the art will recognize that the terpene alcohols may
themselves be used to remove grease and other contaminants from various
materials, such as steel. The terpene alcohol, without solvents and
surfactants, may be contained within a tank into which the material to be
cleaned is placed. Heating of the terpene alcohol may not be needed,
depending upon the application, although because of the high flashpoint,
heating may be useful. Should the terpene alcohol bath become too
concentrated with dissolved grease, then the bath may be disposed of or
the grease separated from the alcohol by various | | |
