Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
1998-12-14
2001-04-17
Diamond, Alan (Department: 1753)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C252S301500, C252S301500, C252S301500, C252S301500, C252S301500, C252S301500, C252S391000, C252S391000, C252S391000, C252S391000, C510S285000, C510S289000, C510S290000, C510S291000, C510S279000, C510S280000, C510S405000, C510S418000, C510S397000, C424S043000, C424S045000, C424S046000, C008S142000, C071S064080, C106S311000
Reexamination Certificate
active
06218353
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to liquid carbon dioxide compositions that contain solid particles. Such compositions may be used, among other things, for spraying or dispensing the solid particles, with the liquid carbon dioxide serving as a propellant. Aerosol containers may be pressurized with systems as described and used to dispense the solid particles, with the carbon dioxide serving as a propellant.
BACKGROUND OF THE INVENTION
Numerous different aerosol formulations are known, and there are numerous applications for the spraying or dispensing of an ingredient with a propellant. Because there are environmental concerns associated with many common propellants, there is a continued need to develop alternative propellant systems.
Carbon dioxide has been used as an aerosol propellant for many years (see, e.g., U.S. Pat. No. 2,524,590 to Boe), but was, in general, replaced by the current generation of propellants.
U.S. Pat. No. 5,169,433 to Lindsay et al. describes methods of preparing mixtures of active ingredients and excipients using liquid carbon dioxide, but requires the suspended material to be substantially soluble in the carbon dioxide.
U.S. Pat. No. 5,301,664 and U.S. Pat. No. 4,970,093, both to Sievers, concern methods of generating aerosols with a carbon dioxide propellant, but the carbon dioxide is used in a supercritical state. Supercritical carbon dioxide requires high-pressure containment.
U.S. Pat. No. 4,161,458 concerns the formulation of water-based aerosols using carbon dioxide as a propellant.
U.S. Pat. No. 4,139,607 to Simons describes the use of mixed propellant systems in which fluorinated dimethyl ethers are employed in liquid form and carbon dioxide is employed in gaseous form.
Means for delivering particulate matter (i.e., solid particles) with a liquid carbon dioxide propellant have neither been suggested nor described.
SUMMARY OF THE INVENTION
Without wishing to be bound to any particular theory of the instant invention, we have found a method for dry-cleaning articles such as fabrics and clothing in carbon dioxide, which method comprises contacting an article to be cleaned with a liquid dry cleaning composition for a time sufficient to clean the fabric. The liquid dry-cleaning composition comprises a mixture of carbon dioxide, water, a surfactant, and an organic co-solvent. When used to clean particulate matter from a substrate, the process forms a liquid composition comprising a mixture of carbon dioxide, water, a surfactant, an organic co-solvent, and the suspended particulate matter (i.e., solid particles). Such liquid compositions (with water being optional) may advantageously be used for a variety of purposes in addition to dry cleaning, such as dispensing the particulate matter from the carbon dioxide liquid, as explained below.
Preferably, the liquid composition is at ambient temperature, of about 0° C. to 30° C. The surfactant is soluble in the co-solvent. The surfactant may or may not be soluble in the CO
2
. Hence, in one embodiment, the surfactant may contain a CO
2
-philic group. However, in the preferred embodiment, the surfactant does not contain a CO
2
-philic group. Hence, an advantage of the present invention is that, by proper use of the co-solvent, conventional surfactants may be employed in a liquid carbon dioxide systems. Further, where the particulate is difficult to suspend in the solution, use of a co-solvent with a surfactant that does contain a CO
2
-philic group may advantageously be employed to better suspend the particulate.
DETAILED DESCRIPTION OF THE INVENTION
The present invention may be employed with any solid particulate material to be suspended. Such solid particles may be formed of organic or inorganic compounds, including polymeric and non-polymeric compounds. The particles may be mixtures of compounds. The particles may be small particles (i.e., about 0.01, 0.1 or 1 to 5 or 10 microns in diameter) or larger particles (i.e., about 5 or 10 microns up to 50, 100 or 500 microns in diameter or more). The particles may be porous or non-porous. Any solid particle material which it may be desired to suspend in the carbon dioxide liquid may be employed, including but not limited to: coatings, abrasive particles, reflective particles, pigments, nanoparticles, carbon particles, opacifiers, talc, deodorants, agricultural chemicals, insecticides, pesticides, herbicides, mycoherbicides, fungicides, fertilizers, drugs, stickers, adjuvants, etc.; soot, lamp-black, silicon oxide, cadmium sulfide, titanium dioxide.
While the present invention is described primarily with respect to the use of solid particles, it may be applied to liquid particles as well.
Liquid compositions useful for carrying out the present invention typically comprise:
(a) from 0.0 or 0.02, 0.05 or 0.1 to 5 or 10 percent by weight (more preferably from 0.0 or 0.1 to 4 percent by weight) water;
(b) carbon dioxide (to balance; typically at least 30 percent by weight);
(c) surfactant (preferably from 0.001, 0.01, 0.05, 0.1 or 0.5 percent by weight to 5, 10, 20 or 40 percent by weight total, which may be comprised of one or more different surfactants);
(d) from 0.1 to 50 percent by weight (more preferably 1, 2 or 4 percent by weight to 30 percent by weight) of an organic co-solvent;
(e) from 0.01, 0.05 or 0.1 to 10, 20, 30 or 50 percent by weight of solid particulate (solid particles).
Percentages herein are expressed as percentages by weight unless otherwise indicated.
The water in the system is not critical, and typically may be carried into the system by the other constituents (i.e., where the carbon dioxide or cosolvent absorbs water, where the solid particles are hygroscopic, etc.). Thus the system may be aqueous or nonaqueous (it being understood that “nonaqueous” systems may still contain small or nominal amounts of water).
The composition is typically provided in liquid form at ambient, or room, temperature, which will generally be between zero and 50° Centigrade. The surfactant and/or the organic co-solvent are included in an amount effective to inhibit aggregation or agglomeration of the solid particles. It is not necessary to completely prevent aggregation or agglomeration of the solid particles; for example, primary particles can agglomerate to some extent as long as the agglomeration is not unduly deleterious to the desired characteristics of the aerosol, or the invention can operate to facilitate redispersion of agglomerated particles upon aerosolization, spraying, or agitation. The composition is preferably held at a pressure that maintains it in liquid form within the specified or desired temperature range.
The organic co-solvent is, in general, a hydrocarbon co-solvent. Typically the co-solvent is an alkane co-solvent, with C
10
to C
20
linear, branched, and cyclic alkanes, and mixtures thereof (preferably saturated) currently preferred. The organic co-solvent preferably has a flash point above 140° F., and more preferably has a flash point above 170° F. The organic co-solvent may be a mixture of compounds, such as mixtures of alkanes as given above, or mixtures of one or more alkanes. Additional compounds such as one or more alcohols (e.g., from 0 or 0.1 to 5% of a C1 to C15 alcohol (including diols, triols, etc.)) different from the organic co-solvent may be included with the organic co-solvent.
Examples of suitable co-solvents include, but are not limited to, aliphatic and aromatic hydrocarbons, and esters and ethers thereof, particularly mono and di-esters and ethers (e.g., EXXON ISOPAR L, ISOPAR M, ISOPAR V, EXXON EXXSOL, EXXON DF 2000, CONDEA VISTA LPA-170N, CONDEA VISTA LPA-210, cyclohexanone, and dimethyl succinate), alkyl and dialkyl carbonates (e.g., dimethyl carbonate, dibutyl carbonate, di-t-butyl dicarbonate, ethylene carbonate, and propylene carbonate), alkylene and polyalkylene glycols, and ethers and esters thereof (e.g., ethylene glycol-n-butyl ether, diethylene glycol-n-butyl ethers, propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and dipropylene glycol m
Cauble, Jr. David F.
McClain James B.
Romack Timothy J.
Diamond Alan
MiCell Technologies, Inc.
Myers Bigel & Sibley & Sajovec
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