U.S. patent application number 09/911962 was filed with the patent office on 2002-01-10 for environmentally preferred fluids and fluid blends.
Invention is credited to Knudsen, George Andrew, Larson, Thomas Marshall, Schlosberg, Richard Henry, Yezrielev, Albert Ilya.
Application Number | 20020002933 09/911962 |
Document ID | / |
Family ID | 27374760 |
Filed Date | 2002-01-10 |
United States Patent
Application |
20020002933 |
Kind Code |
A1 |
Yezrielev, Albert Ilya ; et
al. |
January 10, 2002 |
Environmentally preferred fluids and fluid blends
Abstract
The invention concerns fluids that have a low reactivity with
respect to ozone formation, blends thereof, and the replacement of
conventional industrial solvents with said fluid or fluid blends in
order to reduce troposheric ozone formation.
Inventors: |
Yezrielev, Albert Ilya;
(Houston, TX) ; Schlosberg, Richard Henry;
(Bridgewater, NJ) ; Knudsen, George Andrew;
(Scotch Plains, NJ) ; Larson, Thomas Marshall;
(Houston, TX) |
Correspondence
Address: |
ExxonMobil Chemical Company
P.O. Box 2149
Baytown
TX
77522
US
|
Family ID: |
27374760 |
Appl. No.: |
09/911962 |
Filed: |
July 23, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09911962 |
Jul 23, 2001 |
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09288055 |
Apr 7, 1999 |
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6280519 |
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60084347 |
May 5, 1998 |
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60087150 |
May 29, 1998 |
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Current U.S.
Class: |
106/311 |
Current CPC
Class: |
C05G 5/30 20200201; C09D
7/20 20180101; C23G 5/032 20130101; C09D 11/033 20130101 |
Class at
Publication: |
106/311 |
International
Class: |
C08K 003/00 |
Claims
We claim:
1. In a non-combustion process utilizing a process fluid comprising
a first fluid wherein at least some of said first fluid evaporates
into the atmosphere, the improvement comprising replacing at least
a portion of said first fluid with a second fluid selected from
dimethyl carbonate, methyl pivalate, or a mixture thereof, thereby
decreasing ozone formation from atmospheric photochemical
reactions.
2. The process according to claim 1, wherein said process fluid
acts as a solvent, carrier, diluent, surface tension modifier, or
any combination thereof, in said process.
3. The process according to claim 1, wherein said process fluid
does not contain a halocarbon.
4. The process according to claim 1, wherein said decreasing ozone
formation is based on a calculation using an OFP scale.
5. The process according to claim 1, wherein said decreasing ozone
formation is based on a calculation using the relative MIR scale,
using an ROG=3.93.
6. The process according to claim 1, wherein said process is a
stationary industrial process.
7. The process according to claim 1, wherein said replacing results
in at least one of the following improvements: i) an OFP at least
10% less than the OFP of the process fluid prior to said replacing;
ii) the flash point or a weighted average flash point of the
process fluid increasing to above -6.1.degree. C.; iii) an increase
in toxicity level of the process fluid to at least 2000 mg/kg; iv)
a measureable decrease in the formation of particulates having a
diameter less than 2.5 microns produced by said process; v) a
change in the evaporative rate of the process fluid into the range
of 0.1 to 12 relative to normal butyl acetate; vi) a decrease in
the decomposition of the process fluid based on reactions with acid
catalysts present in said fluid.
8. The process according to claim 7, further comprising at least
two of said improvements i)-vi).
9. The process according to claim 7, further comprising at least
three of said attributes i)-vi).
10. The process according to claim 1, wherein said replacing
results in a blend of fluids, and wherein said blend has a flash
point or a weight average flash point of at least greater than
15.degree. C.
11. The process according to claim 10, wherein said blend has a
flash point or a weight average flash point of at least greater
than 60.degree. C.
12. The process according to claim 4, wherein said replacing
results in a reduction in the OFP of the process fluid by at least
10%.
13. The process according to claim 12, wherein said reduction is at
least 25%.
14. The process according to claim 12, wherein said reduction is at
least 50%.
15. The process according to claim 1, wherein said process is a
coating process comprising coating a substrate with a composition
comprising at least one fluid which is intended to evaporate.
16. The process according to claim 15, providing a painted
substrate.
17. The process according to claim 1, wherein said first fluid
replaced is selected from toluene, xylenes, methanol, ethanol,
n-butanol, n-pentanol, isopropyl alcohol, diacetone alcohol,
sec-butanol, ethyl acetate, propyl acetate, butyl acetate, isobutyl
isobutyrate, isoamyl isobutyrate, propylene glycol methyl ether
acetate, methyl ethyl ketone, methyl isobutyl ketone,
C.sub.5-C.sub.10 linear ketones, cyclic ketones, halocarbons,
methyl t-butyl ether; and mineral spirits.
18. The process according to claim 1, the improvement comprising
replacing at least some of said first fluid with dimethyl
carbonate.
19. The process according to claim 1, the improvement comprising
replacing at least some of said first fluid with methyl
pivalate.
20. The process according to claim 1, wherein said first fluid
replaced has an evaporative rate ranging from that of MEK to that
of n-butyl acetate, and after said replacing the process fluid has
an evaporative rate ranging from that of MEK to that of n-butyl
acetate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority of U.S.
Provisional Application Ser. No. 60/084,347, filed May 5, 1998, and
60/087,150, filed May 29,1998.
FIELD OF THE INVENTION
[0002] This invention relates to the selection and use of
environmentally preferred fluids and fluid blends which exhibit low
or reduced reactivity with respect to ozone formation. These
environmentally preferred fluids and fluid blends are useful in a
number of applications, particularly as industrial solvents, and
allow formulators an effective means to improve the environmental
preference of their formulations or products.
BACKGROUND OF THE INVENTION
[0003] Fluid applications are broad, varied, and complex, and each
application has its own set of characteristics and requirements.
Proper fluid selection and fluid blend development have a large
impact on the success of the operation in which the fluid is used.
For instance, in a typical industrial coatings operation, a blend
of several fluids is used in order to get an appropriate
evaporation profile. Such a blend must also provide the appropriate
solvency properties, including formulation stability, viscosity,
flow/leveling, and the like. The fluid blend choice also affects
the properties of the dry film, such as gloss, adhesion, and the
like. Moreover, these and other properties may further vary
according to the application method (e.g., spray-on), whether the
substrate is original equipment (OEM), refinished, etc., and the
nature of the substrate coated.
[0004] Other operations involving the use of fluids and fluid
blends include cleaning, printing, delivery of agricultural
insecticides and pesticides, extraction processes, use in
adhesives, sealants, cosmetics, and drilling muds, and countless
others. The term "fluid" encompasses the traditional notion of a
solvent, but the latter term no longer adequately describes the
possible function of a fluid or blend in the countless possible
operations. As used herein the term "fluid" includes material that
may function as one or more of a carrier, a diluent, a surface
tension modifier, dispersant, and the like, as well as a material
functioning as a solvent, in the traditional sense of a liquid
which solvates a substance (e.g., a solute).
[0005] The term "industrial solvent" applies to a class of liquid
organic compounds used on a large scale to perform one or more of
the numerous functions of a fluid in a variety of industries.
Relatively few of the large number of known organic compounds that
could be used as fluids find use as industrial solvents. Fluids
that are used in large quantities have heretofore been selected
because they can be produced economically and have attractive
safety and use characteristics in manufacturing, consumer and
commercial environments. Examples of important industrial solvents
are toluene, the xylenes, and mineral spirits, n-butyl acetate,
methyl ethyl ketone (MEK), methyl isobutyl ketone (MIK), and
butanol.
[0006] In addition to the problems with fluid and fluid blend
selection mentioned at the outset, there is also the problem that,
in most applications, at least some of the fluid evaporates and can
escape into the environment. In some applications, such as in
certain coating operations, it is intended that the fluid
evaporate. This evaporative property causes environmental problems.
Although many industrial coating operations, such as in original
equipment manufacturing (OEM) and auto refinishing, utilize control
equipment to capture >95% solvent emissions, nevertheless at
least some inevitably enters the atmosphere.
[0007] The United States Environmental Protection Agency (EPA) has
developed National Ambient Air Quality Standards (NAAQS) for six
pollutants: ozone, nitrogen oxides (NO.sub.x), lead, carbon
monoxide, sulfur dioxide and particulates. Of all the NAAQS
standards, ozone non-attainment has the greatest impact on solvent
operations.
[0008] Solvents typically are volatile organic compounds (VOC),
which are involved in complex photochemical atmospheric reactions,
along with oxygen and nitrogen oxides (NO.sub.x) in the atmosphere
under the influence of sunlight, to produce ozone. Ozone formation
is a problem in the troposphere (low atmospheric or
"ground-based"), particularly in an urban environment, since it
leads to the phenomenon of smog. Since VOC emissions are a source
of ozone formation, industrial operations and plants using solvents
are heavily regulated to attain ozone compliance. As different
regulations have been adopted, the various approaches to
controlling pollution have evolved. Certain early regulations
controlled solvent composition, while later regulations primarily
concerned overall VOC reduction. A more recent regulation has
combined VOC reduction with composition constraints. While the
traditional source of emission reduction is large stationary
industrial facilities, the EPA and other governmental entities have
turned increasingly to consumer and commercial products for
reduction in their solvent usage as an additional means to lower
VOC emission and therefore ozone formation.
[0009] The EPA has developed a list of compounds with negligible
photochemical reactivity, such as methane, ethane, acetone, and
various halogenated compounds. The agency has determined that these
compounds do not contribute appreciably to ozone formation, and
granted them VOC exempt status. Numerous government and trade
publications discuss VOC's, and information is readily available on
the internet. See, for instance,
http://www.paintcoatings.net/VOCW97.html.
[0010] Various measurements of reactivity with respect to ozone
formation are known. For instance, reactivity can be measured in
environmental smog chambers, or they may be calculated using
computer airshed models. See, for instance, Dr. William P. L.
Carter, "Uncertainties and Research Needs in Quantifying VOC
Reactivity for Stationary Source Emission Controls", presented at
the California Air Resources Board (CARB) Consumer Products
Reactivity Subgroup Meeting, Sacramento, Calif. (Oct. 17,
1995).
[0011] There has also been developed a "K.sup.OH scale", which
provides a relative scale of the reactivity of VOC with the OH
radicals involved in the complex reactions that produce ozone. See,
for instance, Picquet et al., Int. J. Chem. Kinet. 30, 839-847
(1998); Bilde et al., J. Phys. Chem. A 101, 3514-3525 (1997).
[0012] Numerous other reactivity scales are known and new
reactivity scales are constantly being developed. Since this is a
rapidly changing area of research, the most up-to-date information
is often obtained via the internet. One example is Airsite, the
Atmospheric Chemistry International Research Site for Information
and Technology Exchange, sponsored by the University of North
Carolina and the University of Leeds, at
http://airsite.unc.edu.
[0013] Another way to measure the reactivity of a chemical in ozone
formation is by using a technique developed by Dr. Carter (supra)
at the Center for Environmental Research and Technology (CERT),
University of California at Riverside. The CERT technique measures
"incremental reactivities", the incremental amount of ozone that is
produced when the chemical is added to an already polluted
atmosphere.
[0014] Two experiments are conducted to measure the incremental
reactivity. A base case experiment measures the ozone produced in
an environmental smog chamber under atmospheric conditions designed
to represent a polluted atmosphere. The second experiment called
"the test case" adds the chemical to the "polluted" smog chamber to
determine how much more ozone is produced by the newly added
chemical. The results of these tests under certain conditions of
VOC and nitrogen oxide ratios are then used in mechanistic models
to determine the Maximum Incremental Reactivities (MIR), which is a
measure of ozone formation by the compound.
[0015] The State of California has adopted a reactivity program for
alternative fuels based on this technique and the EPA has exempted
several compounds due to studies conducted by CERT. See, for
instance, Federal Register 31,633 (Jun. 16, 1995) (acetone); 59
Federal Register 50,693 (Oct. 5, 1994) (methyl siloxanes), Federal
Register 17,331 (Apr. 9, 1998) (methyl acetate). CARB and EPA have
adopted a weight average MIR for regulatory purposes, wherein the
weight average MIR of a solvent blend is calculated by summing the
product of the weight percent of each solvent and its respective
MIR value.
[0016] A list of compounds and their MIR values is available in the
Preliminary Report to California Air Resources Board, Contract No.
95-308, William P. L. Carter, Aug. 6, 1998. A table of known MIR
values may be found on the internet at
http://helium.ucr.edu/.about.carter/index- .html. CERT obtains
other incremental reactivities by varying the ratios of VOC and
nitrogen oxides. A detailed explanation of the methods employed and
the determination of incremental reactivities and MIR scale may be
found in the literature. See, for instance, International Journal
of Chemical Kinetics, 28, 497-530 (1996); Atmospheric Environment,
29, 2513-2527 (1995), and 29, 2499-2511 (1995); and Journal of the
Air and Waste Management Association, 44, 881-899 (1994); Environ.
Sci. Technol. 23, 864 (1989). Moreover, various computer programs
to assist in calculating MIR values are available, such as the
SAPRC97 model, at
http://helium.ucr.edu/.about.carter/saprc97.htm.
[0017] Any of these aforementioned scales could be used for
regulatory purposes, however the MIR scale has been found to
correlate best to peak ozone formation in certain urban areas
having high pollution, such as the Los Angeles basin. MIR values
can be reported as the absolute MIR determined by the CERT method
or as a relative MIR. One common relative MIR scale uses the
Reactive Organic Gas (ROG) in the base case as a benchmark. The
Absolute Reactivity ROG is 3.93 g O.sub.3 per gram ROG. This value
is then the divisor for the absolute MIR of other VOCs, so each MIR
is cited relative to ROG. All MIR values cited herein are relative
to ROG=3.93.
[0018] Solvents currently viewed as essentially non-ozone producing
are those which have reactivity rates in the range of ethane.
Ethane has a measured reactivity based on the MIR method of 0.08.
In fact, the EPA has granted a VOC exemption to certain solvents
with reactivity values in this range including acetone (MIR=0.12)
and methyl acetate (MIR=0.03).
[0019] However, the number of known materials having reactivities
of 0.12 or less based on the MIR scale is relatively small.
Moreover, it is a discovery of the present inventors that many if
not most of the known fluids having acceptable reactivities with
respect to ozone formation have other unfavorable performance
characteristics, e.g., poor solvent properties, low flash point,
inappropriate evaporative or volatility characteristics,
unacceptable toxicity, unacceptable particulate matter formation,
thermal or chemical instability (e.g., reactive to species other
than NO.sub.x, and more particularly reactivity in solution), and
as such has limited, if any, applicability in industry. For
example, ethane, having an excellent MIR=0.08, is a gas under
ambient conditions and hence is a poor choice as an industrial
solvent. Methyl acetate has an excellent MIR=0.03 but a low flash
point of about -12.degree. C.; acetone has an acceptable MIR=0.12
but is extremely flammable. As a further example, tertiary butyl
acetate (t-butyl acetate) has an excellent MIR=0.04 but has limited
thermal stability and is unstable to acid catalysts which may be
present in an industrial operation.
[0020] Regarding particulate matter, the EPA has recently proposed
standards for particulate matter under 2.5 microns in diameter
("PM2.5"). See 61 Federal Register 65638-65713 (Dec. 13, 1996). The
proposal sets an annual limit, spatially averaged across designated
air quality monitors, of 15 .mu.g/m.sup.3, and a 24-hour standard
of 65 .mu.g/m.sup.3. Numerous discussions of this proposed standard
are available on the internet, such as at
http://www.cnie.org/nle/air.about.html, which cites numerous
references (such as Wolf, "The Scientific Basis for a Particulate
Matter Standard", Environmental Management (Oct. 26-31, 1996)). As
far as the present inventors are aware, the prior art has not
addressed ways of meeting these proposed requirements, much less in
meeting these requirements in conjunction with ozone reduction
requirements.
[0021] Moreover, the present inventors have also discovered that in
many applications, VOC exempt solvents cannot be used as a
one-for-one replacement for conventional solvents. Rather the
formulator must balance a number of performance factors to develop
an acceptable solvent or solvent blend for a particular
application. Some factors are more relevant than others for
specific applications. Nevertheless, many performance factors are
similar for a number of applications.
[0022] Numerous attempts have been made to utilize the concept of
"environmentally friendly" fluids in practical applications. For
instance, there are a number of cleaning and/or stripping
formulations available that are said to overcome certain prior art
environmental problems. Examples include a binary azeotrope of
octamethyltrisiloxane with n-propoxypropanol (U.S. Pat. No.
5,516,450), hexamethyldisiloxane and azeotropes and other mixtures
thereof (U.S. Pat. No. 5,773,403), a nonazeotropic mixture
including a halocarbon and an oxygenated organic solvent component
having at least 3 carbons, which may be, for instance,
dimethylcarbonate (U.S. Pat. No. 5,552,080), and a composition
comprising an amide and a dialkyl carbonate (U.S. Pat. No.
4,680,133).
[0023] In addition, there have been a number of patents and
literature references to materials intended to replace
chlorofluorocarbons (CFCs) as, for instance, blowing agents. These
efforts address stratospheric ozone depletion, which is the
opposite phenomenon addressed by the present invention. Examples
include the use of dimethoxymethane and cyclopentane (U.S. Pat.
Nos. 5,631,305; 5,665,788; and 5,723,509), cyclopentane (U.S. Pat.
No. 5,578,652) and polyglycols (U.S. Pat. No. 5,698,144). Still
further, a "non-ozone depleting" solvent comprising halogenated
compounds and an aliphatic or aromatic hydrocarbon compound having
6-20 carbon atoms is disclosed in U.S. Pat. No. 5,749,956.
Similarly, U.S. Pat. No. 5,004,480 describes a method for reducing
the levels of air pollution resulting from the combustion of diesel
fuel in engines comprising blending dimethyl carbonate (DMC) with
diesel fuel and combusting the blended fuel in engines. U.S. Pat.
No. 5,032,144 also discusses the addition of oxygenates, including
dimethyl pivalate (methyl 1,1,1-trimethyl acetate) to gasoline (as
octane boosters). The problems addressed by these patents do not
relate to the problem of industrial solvent evaporation.
[0024] WO 98/42774 discloses a solvent-resin compositions which "do
not contribute appreciably to the formation of ground based ozone".
Organic solvents are selected based upon having "reaction rates
with hydroxyl ion slower than ethane", and generally selected from
halogenated solvents such as chlorobromomethane, methyl chloride,
and the like. The only non-halogenated solvents that are suggested
are n-alkanes (C.sub.12-C.sub.18), methyl and t-butyl acetate,
acetone, dimethoxymethane, and mineral oils.
[0025] However, heretofore there has been no general solution to
the problem of ground-based ozone formation that also provides for
a fluid with appropriate performance attributes for an industrial
solvent.
SUMMARY OF THE INVENTION
[0026] The present invention is directed to environmentally
preferred fluids and fluid blends, their use as industrial
solvents, and to a method of reducing ozone formation in a process
wherein at least a portion of a fluid eventually evaporates.
[0027] The fluids and fluid blends of this invention have been
selected by the present inventors for their actual or potential low
reactivity in the complex photochemical atmospheric reaction with
molecular oxygen (O.sub.2) and nitrogen oxides (NO.sub.x) to create
ozone. Preferably the fluids selected are those having a reactivity
with respect to tropospheric ozone formation, hereinafter referred
to as "ozone formation potential" or OFP, similar to or less than
that of ethane. In a preferred embodiment, a blend of fluids
according to the present invention will have a weight average OFP
similar to or less than that of ethane. It is preferred that the
OFP be measured by the MIR scale.
[0028] It is preferred that the fluids and fluid blends also
provide at least one other desirable performance property such as
high flash point, low particulate formation, suitable evaporation
rates, suitable solvency, low toxicity, high thermal stability, and
chemical inertness with respect to non-ozone producing reactions,
particularly with respect to acids which may be present in coating
formulations.
[0029] In a particularly preferred embodiment, the fluids are used
in a blend with known industrial solvents or other fluids which
present an environmental problem with respect to OFP or lack one or
more of the aforementioned desirable performance properties, so
that the new fluid blends will have lower OFP than they would
without the substituted low ozone formation reactivity fluid or
have at least one of the aforementioned other desirable performance
properties.
[0030] The present invention is also directed to a method of
reducing ozone formation from atmospheric photochemical reactions
in an application wherein a fluid eventually evaporates, at least
partially, into the atmosphere, comprising replacing at least a
portion of a fluid having a relatively higher OFP with a fluid
having a relatively lower OFP. In the case where a blend results,
it is preferred that the weighted average OFP of the blend be
similar to or less than the OFP of acetone and more preferably
similar to or less than that of ethane.
[0031] A fluid or fluid blend according to the present invention
may be used in any process, e.g., any process using a fluid as a
carrier, diluent, dispersant, solvent, and the like, on any scale,
e.g., bench scale or laboratory scale, pilot plant scale, or
industrial scale. It is preferred that the process be a stationary
industrial process and it is preferred that the process is a
non-combustion process. The present invention offers its greatest
benefit from the standpoint of safety and health in large-scale
industrial or commercial processes, particularly industrial coating
processes or in formulations used in large quantities overall,
albeit on a small scale for each individual use, e.g., by a
consumer, such as in household paints, cosmetics, and the like. The
ordinary artisan can readily differentiate between what is an
industrial scale, pilot plant scale, and laboratory scale
processes.
[0032] Accordingly, it is an object of the present invention to
provide a method of selecting fluids and/or fluid blends for
applications which release fluids into the air and wherein there is
a need to inhibit ozone formation due to low atmospheric or
ground-based (tropospheric) photochemical reactivity, in order to
replace conventional solvents and/or solvent blends currently used
in various compositions or processes.
[0033] It is another object of the present invention to provide a
method of optimizing compositions comprising an evaporative fluid
by selecting a fluid and/or fluid blend providing low OFP as well
as at least one additional performance attribute selected from high
flash point, low particulate formation, suitable evaporation rates,
suitable solvency, low toxicity, high thermal and chemical
stability.
[0034] Still another object of the present invention includes the
selection of fluids and/or fluid blends providing low reactivity in
ozone formation having compatibility with wide a range of organic
compounds of different polarity and molecular weights to make the
fluids and/or fluid blends suitable for a wide range of
compositions.
[0035] It is yet another object of the present invention to provide
a method of reducing ozone formation caused by the release into the
troposphere of a fluid or fluid blend in a process utilizing the
fluid or fluid blend, comprising replacing at least a portion of
the fluid with another fluid having a lower OFP.
[0036] Yet still another object is to provide a method of reducing
ground-based ozone formation due to fluid evaporation without
resorting to expensive control equipment to capture all fluid
emission into the environment.
[0037] These and other objects, features, and advantages will
become apparent as reference is made below to a detailed
description, preferred embodiments, and specific examples of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] The fluids of this invention have been selected for their
low or reduced ozone formation potential (low or reduced OFP). The
OFP may be determined by any method providing a scale of
reactivities of fluids in the complex photochemical atmospheric
reaction to create ozone, such as the K.sup.OH scale, smog chamber
studies, and modeling studies. By "low OFP" is meant that the fluid
have an OFP similar to or less than that of acetone and more
preferably similar to or less than that of ethane. By "reduced OFP"
is meant that, in a process according to the present invention, a
first fluid is replaced, in whole or in part, by a second fluid,
the second fluid have an OFP lower than the first fluid. One of
ordinary skill in the art can determine ozone reactivity of a
material relative to another material, e.g., relative to acetone or
ethane.
[0039] The OFP is preferably determined by smog chamber studies,
modeling studies, or a combination thereof, but is more preferably
determined by "incremental reactivity", and still more preferably
by the MIR scale used herein, where the absolute MIR is divided by
the ROG value of 3.93, as discussed above.
[0040] The OFP of a fluid is preferably similar to or less than
that of acetone and more preferably similar to or less than that of
ethane, but the benefits of the present invention are realized if
ozone formation is reduced by replacing a first fluid with a second
fluid, in whole or in part, wherein the OFP of the second fluid is
reduced from that of the first fluid.
[0041] Since there is often some error associated with any
determination of OFP, by "similar to" is meant that the OFP be no
more than three times that determined for the reference compound
(i.e., acetone or ethane). For instance, the value of MIR acetone
is 0.12 and that for ethane is 0.08. Therefore, it is preferred
that the fluid according to the present invention have an
MIR<0.36 and more preferably .ltoreq.0.24, still more preferably
.ltoreq.0.16. In an even more preferred embodiment, the reactivity
in ozone formation is preferably equal to or less than that of
acetone and even more preferably equal to or less than that of
ethane, by whatever scale or method is used, but most preferably by
the MIR scale. Thus, in a more preferred embodiment, the fluid used
in a composition according to the present invention will have an
MIR less than or equal to 0.12, even more preferably less than or
equal to 0.08. Most preferably the fluid selected will have
MIR.ltoreq.0.06.
[0042] Specifically preferred fluids according to the present
invention include:
[0043] dialkyl carbonates, such as dimethyl carbonate (DMC), methyl
ethyl carbonate, methyl isopropyl carbonate, methyl sec-butyl
carbonate, methyl t-butyl carbonate, methyl neopentyl carbonate,
and diisopropyl carbonate;
[0044] alkyl acetates, such as neopentyl acetate, ethylene glycol
diacetate, 1,2-propylene glycol diacetate, 1,3-propylene glycol
diacetate, 1,2-butylene glycol diacetate, 1,3-butylene glycol
diacetate, 2,3-butylene glycol diacetate, neopentyl glycol
diacetate;
[0045] dioxolanes such as 2,2-dimethyl dioxolane, 2,2,4-trimethyl
dioxolane, 2,2,4,5-tetra methyl dioxolane;
[0046] pivalates such as methyl pivalate (methyl 1,1,1-trimethyl
acetate), isopropyl pivalate, t-butyl pivalate (TBP), neopentyl
pivalate (NPP), 1,2-propylene glycol bis-pivalate (PGBP), ethylene
glycol bis-pivalate, ethylene glycol monopivalate, 1,2-butylene
glycol mono-pivalate (1,2-BGMP), 2,3-butylene glycol monopivalate
(2,3-BGMP), 1,2-butylene glycol pivalate acetate (1,2-BGPA),
1,2-butylene glycol pivalate acetate (1,2-BGPA), 2,3-butylene
glycol pivalate acetate (2,3-BGPA), ethylene glycol pivalate
acetate, 1,2 propylene glycol monopivalate, neopentyl glycol mono
pivalate, and 1,2-propylene glycol pivalate acetate;
[0047] isobutyrate compounds such as methyl isobutyrate, isopropyl
isobutyrate, neopentyl isobutyrate, and neopentyl glycol mono
isobutyrate; and
[0048] 2,2,4,4-tetramethyl pentanonitrile (TMPN); isopropyl
neononanoate; pivalonitrile; methyl 2,2,4,4-tetramethyl pentanoate
(methyl neononanoate) and methyl-3,5,5-trimethyl hexanoate.
[0049] In the case of a blend, the weighted average OFP of the
fluids in a composition according to the present invention will
preferably be similar to or less than that of acetone and more
preferably similar to or less than that of ethane. When the OFP is
based on the MIR scale as used herein, the blend should thus have a
weight average MIR.ltoreq.0.36, more preferably .ltoreq.0.24, still
more preferably .ltoreq.0.16, yet still more preferably
.ltoreq.0.12, and most preferably .ltoreq.0.08.
[0050] In another preferred embodiment, wherein the blend results
from replacing part of a first fluid with a second fluid and
thereby reducing the weight average OFP, it is preferred that the
weight average OFP be reduced 10%, more preferably 25%, still more
preferably 50%, from the OFP calculated prior to the fluid
replacement.
[0051] In yet another preferred embodiment, the fluid or fluid
blends will provide at least one other desirable performance
property such as high flash point (or weighted average flash point
in the case of some blends), low particulate formation, suitable
evaporation rates, suitable solvency, low toxicity, high thermal
stability, and inertness with respect to non-ozone producing
reactions. Of course, it is more preferable that the fluid or
blends have two or more of these performance attributes, and so on,
so that the most preferred fluid or fluid blend has all of these
performance attributes.
[0052] In the case of a process of reducing ozone formation,
wherein a fluid according to the present invention replaces a
fluid, at least in part, having a higher OFP, described in more
detail below, it is preferred that this fluid replacement process,
in addition to reducing ozone formation (or decreasing OFP of the
process fluid), also results in an improvement in at least one and
preferably more of the aforementioned performance attributes. In
otherwords, the process results in decreased ozone formation as
well at least one of (i) increased flash point or weight average
flash point of the process fluid or blend; (ii) decreased
particulate formation caused by the process; (iii) provide a more
favorable evaporation profile of the fluid or blend; (iv) improved
solvency properties; (v) decreased toxicity; (vi) increased the
thermal stability; or (vii) provide a more inert fluid or fluid
blend.
[0053] The flash point of a fluid according to the present
invention is preferably at least -6.1.degree. C. or higher, more
preferably greater than +6.0.degree. C., even more preferably
greater than 15.degree. C., still more preferably greater than
25.degree. C., yet even more preferably greater than 37.8.degree.
C., and most preferably greater than 60.degree. C. One of ordinary
skill in the art can readily determine the flash point of a fluid
or blend (e.g., ASTM D92-78).
[0054] In the case of a blend, the flash point of the blend may be
the flash point of the more volatile component, in the instance
where the flash points of the individual components differ markedly
or where the more volatile component is the predominant component.
Or, the flash point of the blend may be some average of the flash
points of the individual components. As used herein, the term
"flash point" will refer to the flash point experimentally
determined for a single fluid or a blend, as applicable. In
addition, we also refer herein to the "weight average flash point"
of a blend; which means the calculated flash point by weight
average of the individual flash points (experimentally determined)
in a blend. Particularly advantageous blends according to the
present invention include blends of DMC and acetone, and of DMC and
methyl acetate, which provide a weight average flash point of
>-6.1.degree. C.
[0055] The fluid or blend thereof, according to the present
invention, should preferably not contribute measureably to
particulate formation of particulates having a size below 2.5
microns (diameter)--referred to as 2.5PM herein--in the atmosphere.
In a preferred embodiment of a process of reducing ozone formation,
the fluid selected to replace a previously-used solvent will be one
that also reduces particulate matter to .ltoreq.65 .mu.g/m.sup.3,
and more preferably .ltoreq.50 .mu.g/m.sup.3, when measured over a
24-hour period, preferably spatially averaged over all monitors in
a given geographic area.
[0056] The evaporation rate should be suitable for the intended
purpose. In many if not most applications, the fluid according to
the present invention will be used to replace, at least in part, a
fluid which is environmentally disadvantaged, meaning it has a
reactivity in ozone formation three times (3.times.) greater than
that of ethane and preferably greater than that of acetone, or an
MIR>0.24 or more preferably >0.36. The fluid selected
preferably will have a similar evaporation rate to the
disadvantaged fluid being replaced, particularly in the case where
a fluid blend is used and an acceptable evaporation profile is
desired. It is convenient for the fluid selected to have an
evaporation rate less than 14 times the evaporation rate of n-butyl
acetate, and more preferably .+-.50 percent of the rate of n-butyl
acetate. Evaporation rates may also be given relative to n-butyl
acetate at 1.0 (ASTM D3539-87). Ranges of evaporation rates
important for different applications are 5-3, 3-2, 2-1, 1.0-0.3,
0.3-0.1, and <0.1, relative to n-butyl acetate at 1.0. In a
preferred embodiment of the present invention wherein, in a method
of reducing ozone formation, a fluid according to the present
invention replaces, at least in part, another fluid not according
to the present invention, the fluid replaced has an evaporative
rate ranging from that of MEK (methyl ethyl ketone) to that of
n-butyl acetate.
[0057] The fluid or fluid blend according to the present invention
may act in the traditional manner of a solvent by dissolving
completely the intended solute or it may act to disperse the
solute, or it may act otherwise as a fluid defined above. It is
important that the solvency of the fluid be adequate for the
intended purpose. In addition to the required solvency, the
formulated product must be of a viscosity to enable facile
application. Thus, the fluid or fluid blend must have the
appropriate viscosities along with other performance attributes.
One of ordinary skill in the art, in possession of the present
disclosure, can determine appropriate solvent properties, including
viscosity.
[0058] Toxicity relates to the adverse effect that chemicals have
on living organisms. One way to measure the toxic effects of a
chemical is to measure the dose-effect relationship; the dose is
usually measured in mg of chemical per kg of body mass. This is
typically done experimentally by administering the chemical to mice
or rats at several doses in the lethal range and plotting the
logarithm of the dose versus the percentage of the population
killed by the chemical. The dose lethal to 50% of the test
population is called the median lethal dose (LD50) and is typically
used as a guide for the toxicity of a chemical. See, for instance,
Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition,
Vol. 24, pp. 456-490. Currently an LD50 of >500 mg/kg qualifies
as "not classified" for oral toxicity under OSHA rules. EU
(European Union) uses a cutoff of >2,000 mg/kg. It is preferred
that the fluid or fluid blend according to the present invention
have an oral rat LD50 of >500 mg/kg, more preferably >1000
mg/kg, still more preferably >2,000 mg/kg, even more preferably
>3,000 mg/kg, and most preferably >5,000 mg/kg. Likewise, the
fluid or blend should also cause no toxicity problems by dermal or
inhalation routes and should also not be an eye or skin irritant,
as measured by OSHA or European Union (EU) standards.
[0059] The fluid according to the present invention should be
thermally stable so that it does not break down. For instance, the
material should not break down into reactive species such as
peroxides. In a preferred embodiment, the fluid is more thermally
stable than t-butyl acetate, which decomposes at about
243-337.degree. C. (Cross, et al., Aust. J. Chem., 1967, Vol. 20,
177-181).
[0060] Inertness, as used herein, refers to the lack of a tendency
to undergo a reaction with other materials in the fluid, i.e., to a
solute or dispersed material. It may include, for example,
inertness towards acids or bases, but particularly to acid
catalysts, which are typically present in coating compositions.
[0061] The present invention also concerns a process of reducing
ozone formation comprising replacing at least a portion of a fluid
not having a low OFP, i.e., a fluid having an OFP greater than that
of acetone, preferably measure by the MIR scale, with a fluid
according to the present invention, i.e., a fluid having an OFP
similar to or less than acetone and more preferably similar to or
less than ethane, and more preferably wherein the OFP is based on
the MIR scale and having an MIR.ltoreq.0.36, more preferably
.ltoreq.24, more preferably .ltoreq.0.16, still more preferably
.ltoreq.0.12, and even more preferably .ltoreq.0.08. Still more
preferably the fluid according to the present invention has at
least one of the aforementioned desireable performance attributes,
yet even more preferably that the fluid have at least two, and so
on, so that the most preferable fluid has all the aforementioned
desireable performance attributes.
[0062] It is preferred that the fluid being replaced have an OFP
greater than that of acetone. In another embodiment, the
incremental reactivity, based on the MIR scale, of the fluid being
replaced is preferably >0.08, more preferably >0.12, still
more preferably >0.16, yet still more preferably >0.24, and
most preferably >0.36.
[0063] In another embodiment, it is critical that in a process of
reducing tropospheric ozone formation according to the present
invention that the fluid replaced have a greater OFP than the fluid
added, that is, the fluid according to the present invention. Of
course it is to be recognized that only a portion of the higher OFP
fluid need be replaced, thus obtaining a blend, in order to achieve
the ozone formation reduction, but the greater benefit of the
present invention is obtained if the fluid exchange of the higher
OFP fluid for the lower OFP fluid be such that the resultant
weighted average OFP of the blend, based on the MIR scale, is
.ltoreq.0.36, more preferably .ltoreq.0.24, still more preferably
.ltoreq.0.16, yet still more preferably .ltoreq.0.12, and even more
preferably .ltoreq.0.08.
[0064] However, in another embodiment of the present invention, the
fluid being replaced may have an acceptable MIR but be unacceptable
with respect to one or more of the aforementioned performance
attributes of flash point (possibly weight average flash point in
the case of some blends) or flammability, particulate formation,
evaporation rate, solvency, toxicity, thermal stability, or
inertness. Examples were previously given of a blend of DMC and
acetone and a blend of DMC and methyl acetate, wherein the
appropriate addition of DMC (or "replacement" of acetone or methyl
acetate, respectively) provided for an improvement in at least one
of these attributes.
[0065] Examples of fluids which are replaced by fluids according to
the present invention include aromatic and aliphatic hydrocarbon
fluids such as toluene, xylenes, straight chain alkanes, branched
alkanes (particularly C.sub.6-C.sub.9 alkanes), cycloaliphatic
hydrocarbons (particularly C.sub.6-C.sub.10); alcohols such as
methanol, ethanol, propanol, n-butyl alcohol, isopropyl alcohol,
diacetone alcohol, and sec-butanol; esters such as ethyl acetate,
propyl acetate, butyl acetate, isobutyl isobutyrate, isoamyl
isobutyrate, propylene glycol methyl ether acetate (PMAC); ketones
such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK),
and C.sub.5-C.sub.10 linear ketones, cyclic ketones; halocarbons,
particularly chlorinated and brominated hydrocarbons; ethers such
as diethyl ether and the like, cyclic ethers such as
tetrahydrofuran (THF), and methyl t-butyl ether (MTBE). Examples of
other common industrial solvents which may be replaced by fluids
according to the present invention are those listed in Kirk-Othmer
Encyclopedia of Chemical Technology, Fourth Edition, Vol. 22, p.
536-548.
[0066] Some particularly preferred replacements, i.e., a fluid
according to the present invention for a currently used industrial
solvent, include: in any application, but particularly coatings
applications, DMC or methyl pivalate for toluene, methyl ethyl
ketone (MEK) or t-butyl acetate; methyl isopropyl carbonate (MIPC)
for xylene, t-butyl acetate, n-butyl acetate, or methyl isobutyl
ketone (MIBK); and diisopropyl carbonate (DIPC) for methyl amyl
ketone (MAK), propylene glycol monomethyl ether acetate (PMAc), or
ethylene glycol monobutyl ether (EB); in any application, but
particularly consumer product applications DMC, MIPC, or DIPC for
hydrocarbons; in any application but particularly agricultural
applications, DIPC for aromatic fluids; in any application but
particularly cleaning applications, DIPC or methyl sec-butyl
carbonate (MSBC) for clorinated solvents; in any application, but
particularly inks, substitute DMC or methyl pivalate for MEK and
light acetates.
[0067] The fluids and blends according to the present invention may
be used in any process using a fluid, and particularly those
process wherein at least a portion of the fluid evaporates and even
more particularly wherein at least a portion evaporates into the
atmosphere. Preferred processes are those utilizing the fluid as
one or more of a carrier, diluent, dispersant, solvent, and the
like, include processes wherein the fluid functions as an inert
reaction medium in which other compounds react; as a heat-transfer
fluid removing heat of reaction; to improve workability of a
manufacturing process; as a viscosity reducer to thin coatings to
application viscosity; as an extraction fluid to separate one
material from another by selective dissolution; as a tackifier or
to improve adhesion to a substrate for better bonding; as a
dissolving medium to prepare solutions of polymers, resins, and
other substances; to suspend or disperse pigments and other
particulates; and the like.
[0068] It is preferred that the process be a stationary process and
also preferred that the process be a non-combustion process. It is
particularly beneficial if the fluid according to the present
invention be used to replace at least a portion of a traditional
industrial solvent in a process using a large amount of fluid,
e.g., a process using 800 lb/year, more preferably 1,000 lbs/year,
even more preferably 5 tons/year, still more preferably 50
tons/year, and most preferably one million lbs/year. In a preferred
embodiment, the process wherein the aforementioned fluid
replacement occurs is on the scale of at least pilot plant-scale or
greater.
[0069] It is also preferred that the process in which a fluid or
blend according to the present invention is used or in which at
least one fluid according to the present invention replaces, at
least partially, a fluid having a higher OFP, be a process in which
the fluid is intended to evaporate, such as in a coating process.
In such a process were the fluid is intended to evaporate, it is
preferred that at least 10% of the fluid or fluids evaporate, more
preferably 20% of the fluids, and so on, so that it is most
preferable if >99% of the fluid or fluids present in the coating
evaporate.
[0070] Furthermore, one of the greatest environmental benefits of
replacing a currently-used industrial solvent with a solvent
according to the present invention will be realized if performed in
a geographic area where monitoring for ozone and particulate matter
formation occurs, and more particularly in geographic areas defined
by a city and its contiguous area populated by at least 500,000
persons, and wherein the replacement of at least a portion of the
currently-used industrial solvent with a fluid according to the
present invention causes at least one of:
[0071] (i) a reduction in the ozone formation, as measured by
either monitoring devices or by a calculation of the reduction
using the OFP of the industrial solvent replaced and the fluid
added according to the present formation, preferably using the MIR
scale, and in a preferred embodiment wherein the reduction in OFP
is from above that of acetone to below that of acetone, more
preferably above that of acetone to below that of ethane; or
[0072] (ii) a reduction in particulate formation of particles
having a diameter less than 2.5 microns (2.5PM), preferably
measured as a 24 hour standard, more preferably wherein that
reduction is from greater than 65 .mu.g/m.sup.3 to less than that
amount in a 24 hour period, still more preferably from greater than
65 .mu.g/m.sup.3 to less than or equal to 50 .mu.g/m.sup.3 in a 24
hour period;
[0073] and more preferably both (i) and (ii).
[0074] In another embodiment, there is a method of selecting a
fluid for use in a process wherein at least a portion of the fluid
eventually evaporates into the atmosphere, comprising selecting as
the fluid a blend of:
[0075] (a) at least one fluid A having a low OFP, preferably
similar to or less than that of acetone and more preferably similar
to or less than that of ethane, and even more preferably where such
reactivity is based on the MIR scale, still more preferably wherein
the MIR is less than or equal to 0.36, more preferably less than or
equal to 0.24, yet still more preferably wherein the MIR is less
than or equal to 0.16, even yet still more preferably wherein the
MIR is less than or equal to 0.12 and still even more preferably
less than or equal to 0.08; and
[0076] (b) at least one fluid B characterized by having at least
one unsuitable attribute selected from: (i) high OFP, preferably
measured relative to acetone by any method but more preferably by
the MIR scale, e.g., having an MIR>0.12, more preferably
>0.16, even more preferably >0.24, and yet even more
preferably >0.36; (ii) high flash point or weight average flash
point, preferably less than or equal to 60.degree. C., more
preferably less than or equal to 37.8.degree. C., still more
preferably less than or equal to 25.degree. C., even more
preferably less than or equal to 15.degree. C., yet even more
preferably less than or equal to 6.0.degree. C., and most
preferably less than -6.1.degree. C.; (iii) formation of 2.5 PM
particulates (e.g., wherein said process, using fluid B, produces
2.5 PM greater than 65 micrograms per cubic meter or greater, as
measured in a 24-hour period); (iv) evaporation rate, particularly
those having an evaporative rate >.+-.50 percent with respect to
n-butyl acetate; (v) toxicity, preferably those having an oral rat
LD50 less than or equal to 5,000 mg/kg, more preferably less than
or equal to 3,000 mg/kg, still more preferably less than or equal
to 2,000 mg/kg, even more preferably less than or equal to 1,000
mg/kg, and most preferably less than or equal to 500 mg/kg; (vi)
thermal stability, preferably having a thermal stability equal to
or less than (more unstable) than t-butyl acetate; and (vii)
inertness in the fluid or fluid blend, particularly with repect to
any acids or bases present in the fluid or blend.
[0077] Preferred examples of fluid A include:
[0078] dialkyl carbonates, such as dimethyl carbonate (DMC), methyl
ethyl carbonate, methyl isopropyl carbonate, methyl sec-butyl
carbonate, methyl t-butyl carbonate, methyl neopentyl carbonate,
and diisopropyl carbonate;
[0079] alkyl acetates, such as neopentyl acetate, ethylene glycol
diacetate, 1,2-propylene glycol diacetate, 1,3-propylene glycol
diacetate, 1,2-butylene glycol diacetate, 1,3-butylene glycol
diacetate, 2,3-butylene glycol diacetate, neopentyl glycol
diacetate;
[0080] dioxolanes such as 2,2-dimethyl dioxolane, 2,2,4-trimethyl
dioxolane, 2,2,4,5-tetra methyl dioxolane;
[0081] pivalates (trimethyl acetates) such as methyl pivalate,
isopropyl pivalate, t-butyl pivalate (TBP), neopentyl pivalate
(NPP), 1,2-propylene glycol bis-pivalate (PGBP), ethylene glycol
bis-pivalate, ethylene glycol monopivalate, 1,2-butylene glycol
mono-pivalate (1,2-BGMP), 2,3-butylene glycol monopivalate
(2,3-BGMP), 1,2-butylene glycol pivalate acetate (1,2-BGPA),
1,2-butylene glycol pivalate acetate (1,2-BGPA), 2,3-butylene
glycol pivalate acetate (2,3-BGPA), ethylene glycol pivalate
acetate, 1,2 propylene glycol monopivalate, neopentyl glycol mono
pivalate, and 1,2-propylene glycol pivalate acetate;
[0082] isobutyrate compounds such as methyl isobutyrate, isopropyl
isobutyrate, neopentyl isobutyrate, and neopentyl glycol mono
isobutyrate; and
[0083] 2,2,4,4-tetramethyl pentanonitrile (TMPN); isopropyl
neononanoate; pivalonitrile; methyl 2,2,4,4-tetramethyl pentanoate
(methyl neononanoate); and methyl-3,5,5-trimethyl hexanoate.
[0084] Preferred examples of fluid B include aromatic and aliphatic
hydrocarbon fluids such as toluene and xylenes; alcohols such as
methanol, isopropyl alcohol, n-butyl alcohol, n-propyl alcohol,
diacetone alcohol, and sec-butanol; esters such as ethyl acetate,
propyl acetate, methyl isobutyrate, butyl acetate, isobutyl
isobutyrate, isoamyl isobutyrate, propylene glycol methyl ether
acetate; ketones such as methyl ethyl ketone (MEK),
C.sub.5-C.sub.10 linear ketones, cyclic ketones; halocarbons,
particularly chlorinated and brominated hydrocarbons; cyclic ethers
such as THF, and non-cyclic ethers such as methyl tert-butyl ether
(MTBE).
[0085] The present invention also concerns mixtures or blends of at
least one fluid according to the present invention and fluids which
are known to have acceptable low OFP, e.g., acetone (MIR=0.12),
methyl acetate (MIR=0.03), tert-butyl acetate (MIR=0.04), tertiary
butanol (MIR=0.10), dimethyl succinate (MIR=0.05), dimethyl
glutarate (MIR=0.10), and propylene carbonate (MIR=0.11). Such
blends can have some important advantages, for example, blends of
DMC and acetone, or DMC and methyl acetate, as previously
mentioned. These blends are also considered to be part of the
present invention. In combination with fluids having an MIR higher
than 0.12, the fluids still can provide significant reduction in
ozone formation for blended fluid compositions with other important
properties for the particular application. Therefore, fluid
compositions with low or reduced OFP comprising solvents selected
from the list above are important goals of the present invention,
even if their weighted OFP is above 0.12 in the MIR scale.
[0086] The fluids listed above are recommended to be used in
solvent compositions intended for release into air and are required
to provide low reactivity in ozone formation. The solvents selected
according to the present invention can be used in blends with each
other as well as in blends with other solvents (e.g., solvents B,
above), different from the solvents of present invention. When all
solvents included in the blend have MIR reactivity 0.12 or less,
the solvent blends also will have low atmospheric photochemical
reactivity with MIR of about 0.12 and less.
[0087] The present inventors have found that many solvent blends
can have an OFP in the range of ethane or acetone, even thought one
component may exceed that range, and therefore in terms of
reactivity toward ozone formation behave as exempt solvents. The
range of reactivities in exempt solvents allows a selection of
fluids with extremely low reactivity, with MIR number in range of
.ltoreq.0.08 and more suitably .ltoreq.0.06. These fluids can be
blended not only with fluids with reactivity based on MIR of
.about.0.12 or less but, with appropriately selected fluids with
MIR numbers >0.12 and at certain ratios still form fluid
compositions with weighted reactivity about 0.12 or less. These
blends can significantly expand the range of properties of solvent
compositions and provide formulators with necessary flexibility for
different applications. The selection of fluids with MIRs >0.12
can be relatively wide, however, to achieve significant reduction
in weighted reactivity to .about.0.12 or less, it is recommended to
choose solvent with MIR<0.4, suitably<0.3, and more
suitably<0.25.
[0088] The conception of blends demonstrating MIR of about 0.12 or
less can be applied to other solvents with known extremely low
reactivities. For example, methyl acetate has MIR 0.03 but flash
point .about.-12.degree. C. Thus, methyl acetate can be blended
with butyl acetate (MIR=0.24 and flash point 27.degree. C.) in
weight ratio of 57:43 forming a blend with MIR=0.12, providing
reactivity similar to exempt solvents. This blend would have better
weight average flash point and lower evaporation rate, making it
useful for many applications which methyl acetate could not satisfy
due to very low flash point. Butyl acetate which is not an exempt
solvent, would become part of a mixture which by its weighted
reactivity would behave similar to exempt solvent and, therefore,
constitute preferred solvent composition.
[0089] This special case of blends comprising at least one solvent
with MIR reactivity<0.12 and at least one solvent with MIR
>0.12 which have their weighted reactivity about 0.12 or less is
one very important part of the present invention. Among known
solvents with extremely low MIR, suitable components for the
preferred blended solvents are methyl acetate (MIR=0.03), t-butyl
acetate (MIR=0.04), dimethyl succinate (MIR=0.05) and methyl
siloxanes including cyclomethylsiloxanes. Blends of these solvents
with other solvents with MIR>0.12 resulting in weighted MIR of
about 0.12 or less for the blend are preferred solvents according
to the present invention.
[0090] However, some of most interesting blends are the blends of
at least one solvent with MIR reactivity<0.12, with at least one
with MIR reactivity >0.12, which can be generated with the
solvents from the list of the present invention.
[0091] The present invention offers fluids and fluid blends for use
in a variety of industrial applications such as paints and other
coatings, adhesives, sealants, agricultural chemicals, cleaning
solution, consumer products such as cosmetics, pharmaceuticals,
drilling muds, extraction, reaction diluents, inks, metalworking
fluids, etc.
[0092] Among the most preferred fluids according to the present
invention are dimethyl carbonate and methyl pivalate. Methyl
pivalate (MP) demonstrates outstanding thermal and chemical
resistance in acid and alkaline media, while its isomer t-butyl
acetate, which has recently been proposed by EPA to become an
exempt VOC, has limited thermal stability and is sensitive to
acids, which is a problem for many acid catalyzed compositions, as
used in a majority of coating formulations. Heretofore unrecognized
as a low OFP fluid, the present inventors have determined that MP
has an MIR, calculated using the SAPRC97 model discussed in the
introduction, of 0.06.
[0093] Likewise, dimethyl carbonate (DMC) is highly preferable and
can be blended with another organic solvent, even one having an MIR
greater than 0.12 to form a solvent system that would still have a
MIR of less than 0.12. DMC blended with another organic solvent
would also exhibit other desirable environmental properties because
DMC has a relatively high flash point and low toxicity. Again,
heretofore unrecognized as a low OFP fluid, the MIR of DMC is
calculated to be 0.02, using the SAPRC97 model.
[0094] The most preferred use of the fluids according to the
present invention is with any process wherein the reduction of
ozone formation is desired, and more particularly in consumer
products, and coatings such as auto refinishing, architectural and
industrial coatings, and even more preferably in protective
coatings, such as paints.
[0095] Paints and coatings comprise the largest single category of
traditional solvent consumption, accounting for nearly half the
solvents used. Fluids serve multiple functions in paints and
coatings, including solubility, wetting, viscosity reduction,
adhesion promotion, and gloss enhancement. Fluids dissolve the
resins, dyes and pigments used in the coating formulations. Also,
prior to application, it is common practice to add solvent thinner
to attain the desired viscosity for the particular application.
Solvents begin to evaporate as soon as the coating materials are
applied. As the solvent evaporates, film formation occurs and a
continuous, compact film develops. Single solvents are sometimes
used in coatings formulations, but most formulations are blends of
several solvents. In many coatings applications, the solvent system
includes a slow-evaporating active solvent that remains in the film
for an extended period to enhance the film's gloss and smoothness.
Because of evaporation and the large amounts of solvents used in
coatings, there is a significant amount of VOC emissions into the
atmosphere.
[0096] Resins which may be incorporated into compositions
comprising fluids according to the present invention include
acrylic, alkyd, polyester, epoxy, silicone, cellulosic and
derivatives thereof (e.g., nitrocellulosic and cellulosic esters),
PVC, and isocyanate-based resins. Numerous pigments and dyes may
also be incorporated into compositions according to the present
invention, and it is within the skill of the ordinary artisan to
determine proper selection of the resin and pigment and/or dye,
depending on the end use of the coating.
[0097] One of the cleaning applications is cold solvent cleaning
which is used to degrease metal parts and other objects in many
operations. Mineral spirits have been popular in cold cleaning, but
are being supplanted by higher flash point hydrocarbon solvents due
to emissions and flammability concerns. Efforts to eliminate
organic solvents entirely from cleaning compositions have not been
successful because aqueous cleaners do not have the performance
properties that make organaic solvent based cleaners so desirable.
This invention allows formulators the option to seek the use of
solvents with very low reactivity as environmentally preferred
products meeting environmental concerns and customer performance
concerns.
[0098] A cleaning solution application which uses evaporation to
clean is called vapor degreasing. In vapor degreasing, the solvents
vaporize and the cold part is suspended in the vapor stream. The
solvent condenses on the part, and the liquid dissolves and flushes
dirt, grease, and other contaminants off the surface. The part
remains in the vapor until it is heated to the vapor temperature.
Drying is almost immediate when the part is removed and solvent
residues are not a problem. The most common solvent used in vapor
degreasing operations has been 1,1,1-trichloroethane. However,
since 1,1,1-trichloroethane is being phased out due to ozone
depletion in the stratosphere, alternatives are needed. Moreover,
chlorine-based solvents have toxicity concerns. Thus, some of the
low reactivity, high flash point solvents in this invention can be
used in place of 1,1,1-trichloroethane and other halogenated
solvents.
[0099] An application that is similar to coatings is printing inks.
In printing inks, the resin is dissolved in the solvent to produce
the ink. Most printing operations use fast evaporating solvents for
best production speeds, but the currently used solvents are highly
reactive. Some of the previously described fast evaporation, high
flash point, low reactivity in ozone formation fluids according to
the present invention are suitable for printing inks.
[0100] An application that is suitable to the low toxicity, high
flash point and low reactivity in ozone formation fluids according
to the present invention is agricultural products. Pesticides are
frequently applied as emulsifiable concentrates. The active
insecticide or herbicide is dissolved in a hydrocarbon solvent
which also contains an emulsifier. Hydrocarbon solvent selection is
critical for this application. It can seriously impact the
efficiency of the formulation. The solvent should have adequate
solvency for the pesticide, promote good dispersion when diluted
with water, have low toxicity and a flash point high enough to
minimize flammability hazards.
[0101] Extraction processes, used for separating one substance from
another, are commonly employed in the pharmaceutical and food
processing industries. Oilseed extraction is a widely used
extraction process. Extraction-grade hexane is a common solvent
used to extract oil from soybeans, cottonseed, corn, peanuts, and
other oil seeds to produce edible oils and meal used for animal
feed supplements. Low toxicity, high flash point, low MIR fluids
and fluid blends of the present invention can be useful in such
industries.
[0102] In addition to the above-mentioned applications, other
applications that can use high flash point, low toxicity, low
reactivity in ozone formation fluids are adhesives, sealants,
cosmetics, drilling muds, reaction diluents, metal working fluids,
and consumer products, such as pharmaceuticals or cosmetics.
[0103] The invention is further described in the following
examples, which are intended to be illustrative and not limiting.
One of skill in the art will recognize that numerous variations are
possible within the scope of the appendaged claims.
EXAMPLE 1
[0104] A representative solvent/resin system was chosen to evaluate
the sensitivity of a system to solvent changes and evaporation rate
differences. Sequential changes to the solvent system were made,
and the impact on resin solubility and evaporation rate profile was
determined.
[0105] The initial system consisted of 30 wt % Acryloid B-66 resin
(an acrylic resin available from Rohm & Haas) in a fluid
mixture comprised of 40 wt % MEK (methyl ethyl ketone), 40 wt %
MIBK (methyl isobutyl ketone), and 20 wt % Exxate.RTM. 600 (a
C.sub.6 alkyl acetate available from Exxon Chemical Company). DMC
was substituted in increments for MIBK, while keeping the rest of
the system constant. For example, a solvent blend of 40 wt % MEK,
35 wt % MIBK, 5 wt % DMC and 20 wt % Exxate.RTM. 600 was evaluated,
and so on until the final solvent blend consisted of 40 wt % MEK, 0
wt % MIBK, 40 wt % DMC and 20 wt % Exxate.RTM. 600. This same
procedure was repeated substituting DMC for MEK, methyl pivalate
for MIBK, and methyl pivalate for MEK, while keeping the rest of
the solvent system the same. Ultimately, a solvent blend in which
both the MEK and MIBK were replaced by DMC (i.e., 80 wt % DMC and
20 wt % Exxate.RTM. 600) and in which both MEK and MIBK were
replaced by methyl pivalate (i.e., 80 wt % methyl pivalate and 20
wt % Exxate.RTM. 600) was considered. Evaporation profiles were
compared for each solvent blend.
[0106] The time required to evaporate 10, 50, and 90 wt % of the
fluid was calculated for the series of solvent blends using
CO-ACT.sup.SM computer program, which is Exxon Chemical Company's
proprietary computer program for estimating solubility parameters
for solvents and resins and modeling evaporative profiles of
solvent-resin formulations (see, for instance, Dante et al., Modem
Paint and Coatings, September, 1989). The results are shown below
in Table 1.
1TABLE 1 Evaporation Wt % (minutes) MIR in fluid (w/20 wt % Exxate
.RTM. 600) 10% 50% 90% Reduction 40 MEK/40 MIBK 0.7 4.9 46
(comparative) 40 MEK/0 MIBK/40 DMC 0.5 3.8 48 70% 0 MEK/40 MIBK/40
DMC 1.0 6.9 50 19% 0 MEK/0 MIBK/80 DMC 0.8 5.4 55 89% 40 MEK/0
MIBK/40 MP 0.5 3.5 44 68% 0 MEK.backslash.40 MIBK/40 MP 0.9 6.3 48
17%
[0107] The reduction in MIR is calculated using the known values of
0.34 for MEK, 1.19 for MIBK, and the values we have had determined
of 0.02 for DMC and 0.06 for methyl pivalate (MP).
[0108] These results show that there is very little difference in
the evaporation profiles between a known resin/solvent system and a
resin/solvent system using the fluids according to the present
invention. Moreover, the above results show the advantage of the
process according to the present invention of reducing ozone
formation by replacing at least a portion of a fluid not having a
low ozone formation potential (MIR.gtoreq.0.12) with a solvent
exhibiting a low reactivity in ozone formation.
Comparative Example 1
[0109] The above experiment was repeated using fluids known to have
low reactivity in ozone formation, methyl acetate (MeOAc, MIR=0.03)
and t-butyl acetate (t-BuOAc, MIR=0.05). The results are shown
below.
2TABLE 2 Evaporation Wt % (minutes) MIR in fluid (w/20 wt % Exxate
.RTM. 600) 10% 50% 90% Reduction 40 MEK/40 MIBK 0.7 4.9 46
(comparative) 40 MEK/0 MIBK/40 MeOAc 0.2 1.6 44 69% 0 MEK/40
MIBK/40 MeOAc 0.2 2.9 47 19% 40 MEK/0 MIBK/40 t-BuOAc 0.5 3.5 44
68% 0 MEK/40 MIBK/40 t-BuOAc 0.9 6.2 48 17%
[0110] The results do show a marked effect in the evaporation
profile when MeOAc is substituted for MEK or MIBK, and thus this
known low OFP fluid would not be a good substitute for
currently-used coating fluids. While t-BuOAc shows a similar
profile to DMC and MP, as discussed above t-BuOAc is thermally
unstable, and is not inert with respect to acids, as shown
below.
EXAMPLE 2
[0111] Acrylic solvent systems were prepared to test the stability
of methyl pivalate (MP) to acid catalysts, which are commonly
present in coating compositions. The formulations contained 28 wt %
methyl pivalate from Exxon Chemical Company, 28.8 wt % pentyl
acetate, 20 wt % n-butyl acetate, 16 wt % n-butyl alcohol, 5.2 wt %
isopropyl alcohol, and 2 wt % toluene as an internal standard. The
latter materials were purchased from Aldrich Chemical Co.
[0112] Para toluene sulfonic acid (pTSA), blocked (complexed) and
unblocked (pTSA* and pTSA, respectively, in Table 3 below) was
added to the above formulation (again, pTSA was purchased from
Aldrich Chemical Co.), in the amount of 0.5 wt %. The solutions
were sealed and placed in a vacuum oven at 50.degree. C. under a
nitrogen atmosphere, and samples were withdrawn at intervals for
testing. The decomposition of methyl pivalate to pivalic acid and
methanol was monitored over time by analysing for total acid number
(TAN) using a Mettler DL212 titrator and gas chromatographic
analysis using an HP 5890 gas chromatograph. The results are shown
below in Table 3 (all percentages are by weight).
Comparative Example 2
[0113] Formulations identical to those in Example 2, above, were
prepared, except using tert-butyl acetate (TBA) instead of methyl
pivalate. The decomposition of methyl pivalate to acetic acid and
isobutylene was monitored over time by analysing for TAN as in
Example 2. The results are shown below in Table 3.
3TABLE 3 Formulation time % acetic acid % pivalic acid TBA, 0.5%
pTSA 1 wk/2 wk 1.2/2.0 MP, 0.5% pTSA 1 wk/2 wk ND/ND TBA, 0.5%
pTSA* 1 wk/2 wk 0.32/0.37 MP, 0.5% pTSA* 1 wk/2 wk ND/ND ND = not
detectable; pTSA* contains methanol, propanol and pyridine
[0114] The above results clearly show that methyl pivalate is more
stable to acid catalysts than is t-butyl acetate. Thus, a coating
formulation containing methyl pivalate as a fluid would be expected
to be more storage stable than one containing t-butyl acetate.
Storage stability is an important attribute in a coating
composition, e.g., a paint.
EXAMPLE 3
[0115] A cold-cleaning solvent comprising about 10-60 wt %
fluorocarbon, about 1-30 wt % of a chlorinated solvent, and about
10-40 wt % of an oxygenated organic solvent is disclosed in U.S.
Pat. No. 5,552,080. The oxygenated organic solvent is preferably
n-butanol or isopropanol, but may be also selected from numerous
other oxygenated organic fluids, including DMC.
[0116] The present inventors have surprisingly discovered that
fluids according to the present invention may be used in the
aforementioned cleaning composition to reduce tropospheric ozone
formation, which is the opposite phenomenon from ozone depletion.
This is completely unexpected.
[0117] Moreover, contrary to the disclosure by the inventors of the
above-mentioned patent, DMC is superior to any of the solvents
listed, in terms of reduced ozone formation. That is, replacing
n-butanol (MIR=0.90) entirely with DMC (MIR=0.02) results in a huge
decrease in the overall weighted average of the blend. Likewise,
the present invention also contemplate a blend of, for instance,
50/50 n-butanol/DMC or 50/50 n-butanol/MP, along with the
halocarbons, as a cold cleaning solvent useful in reducing
ground-based ozone formation. This is a second unexpected result
provided by the present invention. Similar results can be expected
using methyl pivalate and the other fluids according to the present
invention, without a loss of cleaning efficacy.
EXAMPLE 4
[0118] Extraction-grade hexane, having a known MIR=0.43, is blended
with DMC (MIR=0.02) in a 24 wt %/76 wt % hexane/DMC mixture having
a weight average MIR equal to that of acetone (MIR=0.12). The blend
is used in an oilseed extraction process, greatly decrease ozone
formation without significant loss of extraction efficiency.
EXAMPLE 5
[0119] The delivery of seed coatings including insecticides and
other pesticides, and agents attenuating the growth of plants
(e.g., hormones) is extremely valuable to the agricultural
industry. In addition to traditional coating techniques, the OSIT
method (Organic Solvent Infusion Technique) has been studied and
may be useful in the germination of hard coated seeds. In this
method, the seed is soaked in the solvent for a fixed amount of
time. The solvents are generally highly volatile solvents such as
xylene, acetone, methylene chloride (MeCl.sub.2). This technique
has also been studied in the context of translocation experiments
for the production of transgenic crops.
[0120] The substitution of DMC and MP for MEK results in a similar
evaporation profile, while greatly reducing the MIR of the fluid
used, in the case of xylene (p-xylene has the lowest MIR of the
xylenes, at MIR=1.12) and acetone (MIR=0.12), and having a reduced
toxicity in the case of MeCl.sub.2 (MIR unknown).
[0121] The invention has now been described in detail, and it is to
be understood that the ordinary artisan in possession of the
present disclosure could practice the invention, within the spirit
and scope of the appended claims, other than as specifically set
forth. Hence, it will be appreciated that many variations of the
following preferred embodiments can be practiced:
[0122] a first preferred embodiment, which is a composition,
optionally suitable for a coatings application, comprising at least
one fluid, preferably an organic fluid, more preferably a liquid
organic fluid, still more preferably a liquid organic fluid which
is an oxygenated hydrocarbon, said fluid having a low OFP,
preferably similar to or lower than that of acetone and more
preferably less than that of ethane, wherein the low reactivity is
preferably measured by the. MIR scale;
[0123] even more preferably also having at least one or more of the
following attributes: satisfying at least one of the flash point
criterion set forth herein or otherwise having a low flammability,
low formation of particulates having a diameter of 2.5 microns or
less, as described in more detail above, suitable evaporation rates
and solvency that will be useful in a wide range of industrial
applications, such as by dispersing, solvating, acting as a
carrier, diluent, and the like, low toxicity such that LD50
satisfies the criteria as otherwise described herein, high thermal
stability, and inertness to reaction in solution, particularly to
acid or base catalyzed reactions;
[0124] and still more preferably wherein the composition comprises,
includes, consists or consists essentially of a fluid selected
from:
[0125] dialkyl carbonates, such as dimethyl carbonate (DMC), methyl
ethyl carbonate, methyl isopropyl carbonate, methyl sec-butyl
carbonate, methyl t-butyl carbonate, methyl neopentyl carbonate,
and diisopropyl carbonate;
[0126] alkyl acetates, such as neopentyl acetate, ethylene glycol
diacetate, 1,2-propylene glycol diacetate, 1,3-propylene glycol
diacetate, 1,2-butylene glycol diacetate, 1,3-butylene glycol
diacetate, 2,3-butylene glycol diacetate, neopentyl glycol
diacetate;
[0127] dioxolanes such as 2,2-dimethyl dioxolane, 2,2,4-trimethyl
dioxolane, 2,2,4,5-tetra methyl dioxolane;
[0128] pivalates such as methyl pivalate, isopropyl pivalate,
t-butyl pivalate (TBP), neopentyl pivalate (NPP), 1,2-propylene
glycol bis-pivalate (PGBP), ethylene glycol bis-pivalate, ethylene
glycol monopivalate, 1,2-butylene glycol mono-pivalate (1,2-BGMP),
2,3-butylene glycol monopivalate (2,3-BGMP), 1,2-butylene glycol
pivalate acetate (1,2-BGPA), 1,2-butylene glycol pivalate acetate
(1,2-BGPA), 2,3-butylene glycol pivalate acetate (2,3-BGPA),
ethylene glycol pivalate acetate, 1,2 propylene glycol
monopivalate, neopentyl glycol mono pivalate, and 1,2-propylene
glycol pivalate acetate;
[0129] isobutyrate compounds such as methyl isobutyrate, isopropyl
isobutyrate, neopentyl isobutyrate, and neopentyl glycol mono
isobutyrate; and
[0130] 2,2,4,4-tetramethyl pentanonitrile (TMPN); isopropyl
neononanoate; pivalonitrile; methyl 2,2,4,4-tetramethyl pentanoate
(methyl neononanoate); and methyl-3,5,5-trimethyl hexanoate;
[0131] preferably wherein the composition is used in a stationary,
non-combustion process, on an industrial scale, said composition
also including a second fluid, wherein the second fluid has a high
OFP, preferably an OFP greater than than of acetone, and more
preferably an OFP as measure on the MIR scale of >0.24; and even
more perferably wherein the composition further includes at least
one resin and yet still more preferably wherein the composition
further comprises a pgiment or dye;
[0132] and also a composition suitable for coating a substrate,
comprising one of the aforementioned fluids having a low OFP in the
first embodiment above, preferably dimethyl carbonate, methyl
pivalate, t-butyl pivalate, or a mixture thereof, and at least one
solute, wherein said solute is preferably selected from the group
consisting of resins, pigments, dyes, and mixtures thereof; and
optionally also wherein the composition does not contain a
halocarbon, more preferably wherein the composition contains less
than 1000 ppm of any chlorocarbon or bromocarbon; and also
optionally wherein the composition is not used in a combustion
process, and also optionally wherein the fluid has at least one of
the following attributes:
[0133] i) an MIR equal to or less than that of acetone or more
preferably equal to or less than that of ethane;
[0134] ii) a flash point of at least -6.1.degree. C., or the even
more preferable flash points set forth herein above, wherein the
flash point may be a weight average flash point in the case of a
blend;
[0135] iii) a toxicity level wherein oral rat LD50 is at least 500
mg/kg, or the even more preferable toxicity levels set forth
above;
[0136] iv) a low formation of particulates less than 2.5 microns,
where "low formation" is defined as less than 65 micrograms per
cubic meter measured over a 24 hour period or more preferably less
than 50 micrograms per cubic meter, measure over the same
period;
[0137] v) an evaporative rate of 0.1 to 14 relative to normal butyl
acetate or more preferably .+-.50 percent of that of n-butyl
acetate;
[0138] and even more particularly wherein DMC or methyl pivalate or
the mixture thereof is present in an amount sufficient to bring the
weight average MIR of a composition to below 0.36 and more
preferably below 0.24, and still more preferably below 0.16, yet
still more preferably below 0.12, still even more preferably below
0.08, and most preferably below 0.06, and in another embodiment
wherein the amount of DMC or methyl pivalate is at least 10 percent
by volume, more preferably in the amount of more than 25 percent by
volume, still more preferably in the amount of at least 50 percent
by volume of the organic liquid in the composition, and most
preferably wherein the fluid is a paint mixture containing a dye,
pigment, or mixture thereof.
[0139] Or, more particularly, this preferred embodiment relates to
a non-combustion process utilizing a process fluid comprising a
first fluid wherein at least some of said first fluid evaporates
into the atmosphere, the improvement comprising replacing at least
a portion said first fluid with a second fluid selected from
dimethyl carbonate, methyl pivalate, or a mixture thereof, thereby
decreasing ozone formation from atmospheric photochemical
reactions; and also more preferable embodiments including: where
said process fluid acts as a solvent, carrier, diluent, surface
tension modifier, or any combination thereof, in said process;
where said process fluid does not contain a halocarbon; where said
decreasing ozone formation is based on a calculation using an OFP
scale; where said decreasing ozone formation is based on a
calculation using the relative MIR scale, using an ROG=3.93; where
said process is a stationary industrial process; where said
replacing results in at least one of the following
improvements:
[0140] i) an OFP at least 10% less than the OFP of the process
fluid prior to said replacing;
[0141] ii) the flash point or a weighted average flash point of the
process fluid increasing to above -6.1.degree. C.;
[0142] iii) an increase in toxicity level of the process fluid to
at least 2000 mg/kg;
[0143] iv) a measureable decrease in the formation of particulates
having a diameter less than 2.5 microns produced by said
process;
[0144] v) a change in the evaporative rate of the process fluid
into the range of 0.1 to 12 relative to normal butyl acetate;
[0145] vi) a decrease in the decomposition of the process fluid
based on reactions with acid catalysts present in said fluid; or
where at least two and more preferably three, or even more
preferably four, or still more preferably five and most preferably
six of these properties are improved; where said replacing results
in a blend of fluids, and wherein said blend has a flash point or a
weight average flash point of at least greater than 15.degree. C.;
or where said blend has a flash point or a weight average flash
point of at least greater than 60.degree. C.; or where said
replacing results in a reduction in the OFP of the process fluid by
at least 10%; or where said reduction is at least 25%; or where
said reduction is at least 50%; or where said process is a coating
process comprising coating a substrate with a composition
comprising at least one fluid which is intended to evaporate; and
where said process provides a painted surface; where said first
fluid is selected from at least one of toluene, xylenes, methanol,
ethanol, n-butanol, n-pentanol, isopropyl alcohol, diacetone
alcohol, sec-butanol, ethyl acetate, propyl acetate, butyl acetate,
isobutyl isobutyrate, isoamyl isobutyrate, propylene glycol methyl
ether acetate, methyl ethyl ketone, methyl isobutyl ketone,
C.sub.5-C.sub.10 linear ketones, cyclic ketones, halocarbons,
methyl t-butyl ether; mineral spirits; and especially where the
second fluid is DMC, MP, or a mixture thereof; and finally where
said first fluid replaced has an evaporative rate ranging from that
of MEK to that of n-butyl acetate, and after said replacing the
process fluid has an evaporative rate ranging from that of MEK to
that of n-butyl acetate.
[0146] A second preferred embodiment is a method of selecting a
fluid system used in an industrial process or for a composition
manufactured by an industrial process, comprising selecting at
least one fluid having a low OFP as set forth above in the first
preferred embodiment, either specifically, e.g., as in DMC, or
generally, e.g., with reference to ozone formation, MIR, and the
like, preferably having an MIR.ltoreq.0.24, preferably
.ltoreq.0.16, more preferably .ltoreq.0.12, still more preferably
.ltoreq.0.08, and most preferably .ltoreq.0.06;
[0147] and also a second fluid, not having a low OFP, preferably
having an MIR>0.24, or in an embodiment selected from hydrcarbon
fluids such as toluene and xylenes; alcohols such as methanol,
isopropyl alcohol, diacetone alcohol, and sec-butanol;esters such
as ethyl acetate, propyl acetate, methyl isobutyrate, butyl
acetate, isobutyl isobutyrate, isoamyl isobutyrate, propylene
glycol methyl ether acetate; ketones such as methyl ethyl ketone
(MEK), linear ketones, preferably C.sub.5-C.sub.10 linear ketone,
cyclic ketones; halocarbons, particularly chlorinated hydrocarbons;
and methyl t-butyl ether (MTBE);
[0148] and wherein the selection is made so that the weight average
OFP, based on any OFP scale but preferably based on the MIR scale,
is equal to or less than that of acetone and even more preferably
equal to or less than that of ethane, and when measured by the MIR
scale is less than or equal to the preferred MIR of the blends set
forth above (e.g., weight average MIR.ltoreq.0.24, etc), and even
more preferably wherein the blend has at least one of the
aforementioned performance attributes, and/or especially wherein at
least one of the following criterion renders the blend superior, in
that criterion, to such a composition without a fluid according to
the present invention: e.g.; blend flash point or weighted average
flash point, solvency, formation of 2.5PM, evaporation rate,
toxicity, thermal stability, and inertness.
[0149] Finally, but not in the least, there is the third preferred
embodiment of an improved industrial process which uses a fluid,
the improvement comprising decreasing the contribution of said
process to ground-based ozone formation by substituting for at
least a portion of the fluid used a fluid according to the present
invention, and preferably selected from any one or more of the low
OFP fluids set forth in the first embodiment above, and even more
preferred wherein the final fluid used in the process is a blend as
set forth in the second preferred embodiment, and particularly
wherein the process is one set forth herein and even more
preferably wherein the process is a coating process, an extraction
process, a drilling process, or the process is one used to produce
a consumer product, such as a pharmaceutical or cosmetic, and
preferably wherein the decrease in contribution of said process to
ground-based ozone formation is such that the MIR of the process
fluid, whether it be a single fluid or blend, decreases from
>0.24 to less than or equal to 0.24, more preferably from
>0.24 to less than or equal to 0.16, even more preferaably from
>0.24 to less than or equal to 0.12, and so on as set forth
above. In this embodiment, it is preferred that at least one of the
previously recited performance properties be absent in the initial
fluid and present in the final fluid.
* * * * *
References