Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-05-27
2001-03-13
Gupta, Yogendra (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S286000, C510S289000, C510S290000, C510S338000, C510S342000, C510S407000, C510S432000, C510S466000, C008S142000
Reexamination Certificate
active
06200943
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to carbon dioxide-based cleaning formulations that contain surfactants and methods of using the same. The compositions and methods are particularly suitable for the cleaning of garments and fabrics.
BACKGROUND OF THE INVENTION
Commercial dry cleaning systems currently employ potentially toxic and environmentally harmful halocarbon solvents, such as perchloroethylene. Carbon dioxide has been proposed as an alternative to such systems in U.S. Pat. No. 4,012,194 to Maffei. A problem with carbon dioxide is, however, its lower solvent power relative to ordinary solvents.
PCT Application WO 97/16264 by The University of North Carolina at Chapel Hill describes dry cleaning systems that employ liquid or supercritical carbon dioxide in combination with a surfactant that contains a “CO
2
-philic” group. The term “CO
2
-philic” was first coined in conjunction with such surfactants by J. DeSimone and colleagues. See, e.g., J. DeSimone et al.,
Science
265, 356-359 (Jul. 15, 1994).
PCT Application WO96/27704 (Sep. 12, 1996) by Unilever, describes dry cleaning systems using densified carbon dioxide and special surfactant adjuncts. The term “densified carbon dioxide” means “carbon dioxide in a gas form which is placed under pressures exceeding about 700 psi at about 20° C.” (pg. 5, lines 1-3). The surfactants employed have a supercritical fluid CO
2
-philic moiety connected to a supercritical fluid CO
2
-phobic moiety (pg 3, lines 30-32). In the method and apparatus described, a vertical rotating drum 5 (FIG. 1) containing soiled fabrics, surfactants, modifier, enzyme, peracid and mixtures thereof is charged with densified CO
2
fluid at a pressure ranging between 700 and 10,000 psi. The CO
2
is then heated to its supercritical range of about 20° C. to about 60° C. by a heat exchanger 4 (pg. 36 line 26 to pg. 37 line 8) and the cleaning cycle initiated. Other densified molecules that have supercritical properties, ranging from methane and ethane through n-heptane to sulfur hexafluoride and nitrous oxide, are noted that may also be employed in the described process, alone or in mixture with CO
2
(pg. 6 lines 25-35). See also U.S. Pat. No. 5,683,473 to Jureller et al; U.S. Pat. No. 5,683,977 to Jureller et al.; U.S. Pat. No. 5,676,705 to Jureller et al.
U.S. Pat. No. 5,377,705 to Smith et al. describes a precision cleaning system in which a work piece is cleaned with a mixture of CO
2
and a co-solvent. Smith provides an entirely non-aqueous system, stating: “The system is also designed to replace aqueous or semi-aqueous based cleaning processes to eliminate the problems of moisture damage to parts and water disposal” (col. 4 line 68 to col. 5 line 3). Co-solvents that are listed include acetone and ISOPAR™ M (col. 8, lines 19-24). Use in dry cleaning is neither suggested nor disclosed. Indeed, since some water must be present in dry-cleaning, such use is contrary to this system.
In view of the foregoing, there is a continuing need for effective carbon dioxide-based dry cleaning systems.
SUMMARY OF THE INVENTION
A method for dry-cleaning garments or fabrics in carbon dioxide comprises contacting a garment or fabric article to be cleaned with a liquid dry cleaning composition for a time sufficient to clean the article, said liquid dry-cleaning composition comprising a mixture of carbon dioxide, water, a first surfactant, and a second surfactant, and then separating the article from the liquid dry cleaning composition. the first surfactant comprises a CO
2
-philic group covalently joined to a hydrophilic group; and the second surfactant comprising a CO
2
-philic group covalently joined to a lipophilic group. Preferably at least one, and most preferably both, CO
2
-philic groups are siloxane containing groups such as polydimethylsiloxane.
In a CO
2
based cleaning environment, the combination of a CO
2
-philic/hydrophilic surfactant and a CO
2
-philic/lipophilic surfactant provides distinct advantages over either independently. This is in contrast to situations employing an aqueous (hydrophilic) or oil (lipophilic) solvent system since in either of the latter two instances, there is a favorable interaction between the hydrophilic or lipophilic characteristics of the soil to be removed and entrained in the solvent system employed. Since CO
2
is neither hydrophilic nor lipophilic, this is not the case in a CO
2
-based solvent system, thus a surfactant combination that encompasses both the CO
2
-philic/hydrophilic and CO
2
-philic/lipophilic components is advantageous. Note that this also extends to a single surfactant molecule that combines all three components (CO
2
-philic, lipophilic, and hydrophilic groups).
DETAILED DESCRIPTION OF THE INVENTION
The term “clean” as used herein refers to any removal of soil, dirt, grime, or other unwanted material, whether partial or complete. The invention may be used to clean nonpolar stains (i.e., those which are at least partially made by nonpolar organic compounds such as oily soils, sebum and the like), polar stains (i.e., hydrophilic stains such as grape juice, coffee and tea stains), compound hydrophobic stains (i.e., stains from materials such as lipstick and candle wax), and particulare soils (i.e., soils containing insoluble solid components such as silicates, carbon black, etc.).
Articles that can be cleaned by the method of the present invention are, in general, garments and fabrics (including woven and non-woven) formed from materials such as cotton, wool, silk, leather, rayon, polyester, acetate, fiberglass, furs, etc., formed into items such as clothing, work gloves, rags, leather goods (e.g., handbags and brief cases), etc.
The invention can be employed with any carbon-dioxide dry cleaning system, such as described in U.S. Pat. No. 5,683,473 to Jureller et al; U.S. Pat. No. 5,683,977 to Jureller et al.; U.S. Pat. No. 5,676,705 to Jureller et al; and U.S. Pat. No. 4,012,194 to Maffei, the disclosures of which applicants specifically intend to be incorporated herein by reference. Of course, all such systems must be modified to incorporate the combination of surfactants described herein.
In one particular embodiment, Liquid dry-cleaning compositions useful for carrying out the present invention typically comprise:
(a) from 0.1 to 10 percent (more preferably from 0.1 to 4 percent) water;
(b) carbon dioxide (to balance; typically at least 30 percent);
(c) first surfactant (preferably from 0.1 or 0.5 percent to 5 or 10 percent); and
(d) second surfactant (preferably from 0.1 or 0.5 percent to 5 or 10 percent); and
(e) from zero or 0.1 to 50 percent (and in one embodiment from 4 to 30 percent) of an organic co-solvent. Percentages herein are expressed as percentages by weight unless otherwise indicated.
In another particular embodiment, a liquid dry-cleaning compositions useful for carrying out the present invention comprises:
(a) from 0.1 to 10 percent (more preferably from 0.1 to 4 percent) water;
(b) carbon dioxide (to balance; typically at least 30 percent);
(c) surfactant (preferably from 0.1 or 0.5 percent to 5 or 10 percent) where the surfactant contains a CO
2
-philic group or segment, a lipophilic group or segment, and a hydrophilic group or segment covalently joined to one another, directly or indirectly (i.e., joined through the other segment), in a single molecule; and
(d) from zero or 0.1 to 50 percent (and in one embodiment from 4 to 30 percent) of an organic co-solvent.
The compositions are provided in liquid form at ambient, or room, temperature, which will generally be between zero and 50° Centigrade. The composition is held at a pressure that maintains it in liquid form within the specified temperature range. The cleaning step is preferably carried out with the composition at ambient temperature.
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 po
DeYoung James P.
Romack Timothy J.
Boyer Charles
Gupta Yogendra
MiCell Technologies, Inc.
Myer Bigel Sibley & Sajovec
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