Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-06-05
2001-02-20
Del Cotto, Gregory R. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S170000, C510S174000, C510S211000, C510S245000, C510S255000, C510S505000, C134S038000
Reexamination Certificate
active
06191087
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a solvent that is biodegradable and generally benign to human health, and more particularly to a mixture of a lactate ester and an ester of fatty acid derived from an edible oil; the mixture provides effective solvency for a broad range of tasks. This blended solvent is shown to provide effective performance for paint removal, de-inking, degreasing, and as a general surface cleaning agent that provides for a non-toxic, cost effective alternative to commonly used toxic solvents.
2. Background Art
A solvent is a substance that is generally capable of dissolving another substance, or solute, to form a uniformly dispersed mixture (solution) at the molecular or ionic level. Solvents are either polar (high dielectric constant) or non-polar (low dielectric constant). Water, the most common solvent, is strongly polar having a dielectric constant of 81. Hydrocarbon solvents are non-polar and are comprised of two groups, aliphatics such as alkanes and alcohols, and aromatics, which generally have a higher solvency power than aliphatics. Other organic solvent groups are esters, ethers, ketones, amines, nitrated hydrocarbons and halogenated hydrocarbons.
The chief uses of organic solvents include dissolution of coatings (paints, varnishes, and laquers), industrial and household cleaners, printing inks, and extractive processes. Because many solvents are flammable and toxic to health, there is a need to develop safer solvents for commercial use without sacrificing critical performance.
For decades industrial and household cleaning products have been utilized to provide certain tasks such as paint removers, ink removers, degreasers, etc. Solvents are also used to clean, maintain, and prepare wood, metal, masonry, natural and synthetic fabrics, plastic components, electronic components. Although providing the needs of these many and mission-critical tasks, most solvents generally, are toxic, thus posing a threat to health and to the environment. These environmental and health threats include ozone depleting air pollutants and water pollution that threaten aquatic organisms and drinking water supplies. Many of these solvents are carcinogenic and hazardous to health in general.
Although government, industry and the community at large are all relatively well informed to the dangers of toxic solvents, the dangers associated with the use of such solvents have not dramatically diminished their use. Safer handling, disposal, recycling, recovery and other responsible methods of dealing with toxic substances are improving. However, the availability of safer alternative solvents is still not wide spread, especially in second and third world countries, which is due, primarily, to the high cost of the solvent alternatives and because the majority of the environmentally safer solvent alternatives do not provide satisfactory performance.
In order for an “environmentally friendly” solvent alternative to gain wide spread acceptance, a solvent should meet several criteria. First, it should provide effective performance. Second, it should be economically viable and affordable. Third, it should be widely available and, of course, it should be non-toxic to the environment generally and humans specifically.
Several alternative solvents have been introduced by industry for decades, but in general do not meet the criteria stated above. Further, many of these solvents are not completely biodegradable, just less toxic.
A solvent described hereinafter provides high solvency performance while overcoming the toxicity issues associated with most other organic solvents. In addition, a contemplated solvent is biodegradable.
BRIEF SUMMARY OF THE INVENTION
The present invention contemplates an environmentally friendly solvent. This solvent is biodegradable in normal sewerage treatment plants, and has a low volatile content so that it can be used indoors with minimal ventilation.
A contemplated solvent composition comprises:
(A) about 10 to about 60 weight percent C
1
-C
4
ester of a C
16
-C
20
fatty acid having a melting point of −10° C. or less;
(B) about 20 to about 75 weight percent of a C
1
-C
4
ester of lactic acid;
(C) zero to about 20 (preferably zero to about 5) weight percent of a surfactant;
(D) zero to about 20 (preferably zero to about 10) weight percent of a thickener; and
(E) zero to about 50 (preferably zero to about 35 or more preferably zero to about 20) weight percent organic solvent.
The composition is a homogeneous liquid or gel at zero degrees C and has a closed cup flash point in excess of 60° C., and preferably in excess of 60° C.
In one preferred embodiment, the composition comprises:
(A) about 30 to about 60 weight percent of a C
1
-C
4
ester of a C
16
-C
20
fatty acid having a melting point of −10° C. or less;
(B) about 30 to about 60 weight percent of a C
1
-C
4
ester of lactic acid;
(C) zero to about 5 weight percent of a surfactant;
(D) zero to about 10 weight percent of a thickener; and
(E) zero to about 35 weight percent organic solvent.
Preferably, in the above embodiment, the weight percent of the lactic acid ester is equal to the weight percent of the fatty acid ester, plus or minus about 5 weight percent.
In another preferred embodiment, the composition comprises:
(A) about 20 to about 40 weight percent of a C
1
-C
4
ester of a C
16
-C
20
fatty acid having a melting point of −10° C. or less;
(B) about 20 to about 40 weight percent of a C
1
-C
4
ester of lactic acid;
(C) zero to about 20 (preferably zero to about 5) weight percent of a surfactant;
(D) zero to about 20 (preferably zero to about 10) weight percent of a thickener; and
(E) zero to about 35 (preferably zero to about 20) weight percent organic solvent.
In each of the embodiments of the invention, the particularly preferred C
1
-C
4
ester of a C
16
-C
20
fatty acid is an ester of a mixture of oleic and linoleic acids. The methyl ester is preferred, and the fatty acid mixture is preferably that of soybean oil so that methyl soyate is particularly preferred. The particularly preferred C
1
-C
4
ester of lactic acid is the ethyl ester so that ethyl lactate is also particularly preferred.
The present invention has several benefits and advantages.
One benefit of the invention is that a contemplated composition is much safer than a halogenated organic solvent.
A related advantage is that a contemplated composition can be used in occupied areas. The characteristic odor from traditional solvents makes them unsafe to use indoors.
A benefit of a composition according to the present invention is that it has a closed cup flash point greater than about 60° C.
An additional advantage of the present invention is that the cleaning solvent is miscible with water, and thus can be removed with water rinsing, including high pressure water. This rinsing factor can offer some industrial advantages that do not exist with traditional cleaning solvents.
Yet another benefit of a preferred embodiment of the present invention is that it is biodegradable, non-toxic and is derived from two major crops, corn and soybeans.
Another benefit of a paint-stripping embodiment of the invention is that paint strippers containing a contemplated composition can be scraped off, collected and reused. This can not be done with methylene chloride-based paint strippers, due to the significant product that is lost to evaporation.
A further benefit of a paint-stripping embodiment of the invention is that although a contemplated paint stripper composition took a longer period of time to loosen paint than a conventional paint stripper based on methylene chloride, paint stayed wet and workable for a much longer duration.
This offers many advantages in commercial applications.
A further advantage of an ink- and paint-removing embodiment of the invention in the cleaning of air dry inks and paints is that a contemplated composition cleaned tougher grade inks and often cleaned dried inks and paints, whereas soy methyl ester alone showed no effectiveness.
Still another advantage of an ink-removing embodiment
Bergemann Eugene P.
Henneberry Mark
Opre James E.
Del Cotto Gregory R.
Vertec Biosolvents, LLC
Welsh & Katz Ltd.
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