Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-03-02
2001-11-06
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S405000, C510S407000, C510S500000
Reexamination Certificate
active
06313079
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed to a surfactant comprising a heterocyclic group. More particularly, the invention is directed to a surfactant comprising a heterocyclic group that results in superior cleaning properties in a dry cleaning system.
BACKGROUND OF THE INVENTION
In many cleaning applications, it is desirable to remove contaminants (e.g., stains) from substrates, like metal, ceramic, polymeric, composite, glass and textile comprising substrates. Particularly, it is highly desirable to remove contaminants from clothing whereby such contaminants include dirt, salts, food stains, oils, greases and the like.
Typically, dry-cleaning systems use organic solvents, like chloro fluorocarbons, perchloroethylene and branched hydrocarbons to remove contaminants from substrates. In response to environmental concerns, other dry-cleaning systems have been developed that use inorganic solvents, such as densified carbon dioxide, to remove contaminants from substrates. The systems that use carbon dioxide to remove contaminants from substrates generally employ a surfactant and a polar co-solvent so that a reverse micelle may be formed to trap the contaminant targeted for removal.
In view of the environmental concerns associated with dry cleaning in, for example, halogenated hydrocarbons, many cleaning establishments have expressed their interests in cleaning with continuous phase solvents that comprise densified gases such as densified carbon dioxide as well as a biodegradable functionalized hydrocarbon or a silicon comprising surfactant. Unfortunately, however, cleaning with such solvents is not made easy because only very few surfactants are compatible with such continuous phases.
It is of increasing interest to develop surfactants that enhance cleaning in a system that uses a densified gas, functionalized biodegradable hydrocarbon and/or a silicon comprising solvent. This invention, therefore, is directed to a surfactant comprising a heterocyclic group that unexpectedly results in superior cleaning properties in a dry cleaning system that utilizes a densified gas, a functionalized biodegradable hydrocarbon and/or silicon comprising solvent.
BACKGROUND MATERIAL
Efforts have been disclosed for dry cleaning with carbon dioxide. In U.S. Pat. No. 5,676,705, a superior dry cleaning method which employs densified carbon dioxide is described.
Other efforts have been disclosed for dry cleaning with carbon dioxide. In U.S. Pat. No. 5,683,473, a superior method for dry cleaning fabrics with a surfactant having a polysiloxane, branched polyalkylene oxide or halocarbon group is described.
Still further, U.S. Pat. No. 5,683,977 discloses a superior dry cleaning system with carbon dioxide and a surfactant adjunct.
Finally, in U.S. Pat. No. 5,866,005, a cleaning process using carbon dioxide as a solvent along with molecularly engineered surfactants is described.
SUMMARY OF THE INVENTION
In a first embodiment, the present invention is directed to a dry cleaning system comprising a surfactant having the formula:
A−Z
wherein A is a portion of the surfactant that is soluble in carbon dioxide and Z is a portion of the surfactant that is not soluble in carbon dioxide and Z comprises a heterocyclic group, with the provisos that:
(i) when Z is pyrrolidone, nitrogen is not substituted with a hydrocarbon having less than five carbon atoms;
(ii) when Z is a polymeric vinyl pyrrolidone, the dry cleaning system is a system for removing soil from fabrics;
(iii) when A is a polysiloxane, Z is not a beta carboxylic acid substituted pyrrolidone having the polysiloxane joined to nitrogen with a bridging radical; and
(iv) when A is not a hydrocarbon, Z is not a carbohydrate.
In a second embodiment, the present invention is directed to a method for dry cleaning using the dry cleaning system of the first embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
There generally is no limitation with respect to the surfactant used in this invention as long as the surfactant will enhance cleaning in a system which utilizes a continuous phase solvent comprising a densified gas, biodegradable functionalized hydrocarbon or a silicon comprising solvent, and the surfactant meets the criteria set forth in the above-described provisos (i)-(iv).
Often, the surfactants which may be used in this invention are selected from the group consisting of
wherein each R and T are independently a hydrogen, C
5
to C
18
hydrocarbon, polysiloxane, CO
2
soluble polyalkylene oxide or halocarbon, with the proviso that at least T or one R group is not hydrogen, L is C(R
2
) or y-(T)
t
, x is an integer from about 1 to about 6, each y is independently N, P, S, B or O and t is 0 or 1 with the proviso that t is 0 when y is oxygen, or sulfur.
In a preferred embodiment the hydrocarbon is a C
6
to C
12
hydrocarbon, the polysiloxane is polydimethysiloxane with or without polypropylene oxide substituents and having a weight average molecular weight of about 200 to about 200,000, the polyalkylene oxide is polypropylene oxide having a weight average molecular weight of about 100 to about 100,000, and the halocarbon is a C
2
to C
8
fluoroalkylene or fluoroalkenylene, x is an integer from about 2 to about 4 and the heteroatom is N. The preferred polysiloxanes and halocarbons are derived from those described in U.S. Pat. Nos. 5,676,705, 5,683,473 and 5,683,977, the disclosures of which are incorporated herein by reference. The preferred polysiloxanes are often bridged to the heterocyclic group with a C
1
to C
20
hydrocarbon bridging radical, and preferably, a C
3
hydrocarbon bridging radical.
In a most preferred embodiment, structure I represents the surfactant comprising a heterocyclic group and each R is hydrogen, y is N, T is a C
8
or C
12
hydrocarbon, L is C(R
2
), x is 2 and t is 1. When T is a C
8
hydrocarbon, such a surfactant is sold under the name Surfadone LP-100 and when T is a C
12
hydrocarbon, such a surfactant is sold under the name Surfadone LP-300, both of which are made commercially available by International Specialty Products. Still another most preferred embodiment results when at least one R is a C
5
to C
18
group, L is oxygen, y is oxygen and x is 2.
The surfactant comprising the heterocyclic group which may be used in this invention can be prepared via numerous well known processes which include the condensation of butyrolactone with methylamine. Such reactions are disclosed in The Kirk-Othmer Encyclopedia of Chemical Technology, Volume 20, 4th Edition, pages 697-720 (1996), the disclosure of which is incorporated herein by reference.
Other surfactants comprising heterocyclic groups which may be used in this invention (as defined by the formulas above) include those made and described in Introduction to Organic chemistry, Second Edition, Streitwieser, Jr. et al., Chapter 32 (1981), the disclosure of which is incorporated herein by reference.
Still other surfactants that may be used in this invention (as defined by the formulas above) include those prepared by a conventional hydrosilation reaction wherein at least one reactant comprises a heterocyclic group.
If desired, the surfactants which can be employed in this invention may be purchased from suppliers such as BASF, Arco and, again, International Specialty Products.
There generally is no limitation with respect to the continuous phase solvent (i.e., fluid) which may be employed with the surfactants comprising a heterocyclic group of this invention other than that the solvent is a densified gas (e.g., fluid which is a gas at standard temperature and pressure), a biodegradable hydrocarbon or a silicon comprising solvent, and capable of being a continuous phase in a dry cleaning application. Illustrative examples of the types of solvents which may be employed in this invention include a C
2
-C
4
substituted or unsubstituted alkane, carbon dioxide, silicone oil, and an azeotropic solvent.
Regarding the solvent which is a densified gas, such a solvent may be, within the dry cleaning composition or process, a gas, liquid or supercritical fluid de
Boyer Charles
Gupta Yogendra N.
Squillante, Jr. Edward A.
Unilever Home & Personal Care USA division of Conopco
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