Patent Grant
7833959
Many industrial processing cleaning compositions have been based on acetone, xylene and other ketone, alcohol, ester, aromatic hydrocarbon, aliphatic hydrocarbon, and ether solvents. As ecological concerns have risen in importance, the search for replacements for such cleaners has attained increased importance. Several requirements exist for replacement cleaners and/or solvents. One of the requirements is a concern for ozone depletion by volatile organic compounds. A solvent used historically is acetone. In 1990 2,330 million pounds were used in the United States and 110 million pounds were exported.
The greatest danger regarding acetone is that is poses a serious fire hazard. Although acetone is an excellent solvent and is relatively non-toxic, it is extremely flammable. It has a flash point of −18° C. (0° F.). If handled improperly, acetone may pose a dangerous fire risk. Under the United States Environmental Protection Agency's (U.S. EPA) Clean Air Act, acetone is an exempt volatile organic compound (VOC). Thus, basic problems associated with providing an effective, VOC exempt, and safe solvent has not been considered or solved using terpene alcohols to eliminate the fire hazard.
The present invention relates to a method to increase flash points of solvents, which are typically below 140° F., to over 140° F.
A further aspect of the invention is an acetone based cleaning composition which is admixed with a terpene alcohol, or which may be admixed with other organic solvents. An additional aspect of the invention involves the admix of solvents with acetone, a terpene alcohol, and other organic solvents to bring the blended formulation in compliance with Federal and state VOC (Volatile Organic Compound) regulations and DOT (Department of Transportation) flash point regulations.
The present invention relates to increasing the flash points of aliphatic hydrocarbon, aromatic hydrocarbon, alcohol, ethers, esters and ketone solvents. Solvents which provides a safer environment to be useful in many industrial applications and processes which presently rely on low flash point solvents, such as acetone, isopropyl alcohol, ethanol, toluene, xylene, hexane, kerosene, and heptane which have flash points lower than 140° F. A solvent of particular interest is acetone, which under the United States Environmental Protection Agency's 1990 Clean Air Act Amendment has exempted acetone as a VOC (Volatile Organic Compound). Acetone is extremely flammable with a flash point of −18° C. (0° F.).
These improved flash point compositions comprise:
1 to 25 wt percent terpene alcohol and from 1 to 99 wt percent of an organic solvent or combination of organic solvents.
The organic solvent or combination of solvents can comprise up to 99 weight percent of the composition in total, and may be the combination of two or more different types of organic solvents. A typical combination may comprise;
1.0 to 99 weight percent organic solvent.
1.0 to 25 weight percent of terpene alcohol and specifically alpha terpineol.
The term “terpene alcohol” is understood for purposes of the present invention to encompass compounds of the formulae C10H18O which are monocyclic, bicyclic, and acyclic alcohols, respectively. Terpene alcohols are structurally similar to terpene hydrocarbons except the structure also includes some hydroxyl functionality. They can be primary, secondary, or tertiary alcohol derivatives of monocyclic, bicyclic, or acylic terpenes as well as above. Such tertiary alcohols include terpineol which is usually sold commercially as a mixture of alpha, beta, and gamma isomers. Linalool is also a commercially available tertiary terpene alcohol. Secondary alcohols include bomeol, and primary terpene alcohols include geraniol. Terpene alcohols are generally available through commercial sources.
Optionally, the solvent blended compositions of the present invention may also include a suitable solvent for a specific solvate purpose. Such solvent blends include individual solvents with a flashpoint greater than 140° F. Such solvents include the groups of ketones, alcohols, aromatic and aliphatic hydrocarbons, esters, ethers, and amines
Examples of organic solvents, which are employed, include 1) polyhydric alcohols, flash point 232° F. consisting of ethylene glycol, diethylene glycol, 1,3 butandiol flash point 249.8° F.; 2) aliphatic hydrocarbons consisting of 140 solvent, flash point 140° F., naphtha, flash point 143.6° F.; 3) aromatic hydrocarbons consisting of isopar L flash point 147.2° F.; 4) esters consisting of propylene carbonate flash point 269.6 F, dibasic ester flash point 212° F.; 5) ethers consisting of diethylene glycol monoethyl ether flash point 204.8° F., diethylene glycol dimethyl ether flash point 145.4° F., ethylene glycol dibutyl ether flash point 185° F.; and 6) amines consisting of methyl pyrrolidone flash point 269° F.
All of the chemical components used in the present invention are commercially available.
The following examples illustrate certain aspects of the present invention. They are not intended to exemplify the full scope of the invention. In certain aspects they enable certain aspects of the invention.
A method was used to determine the correct steiociometric mixture to maximize the highest point of flash. An example using xylene which has a normal flash point from between 76° F. to 82° F. With certain percentage mixes of alpha terpineol the flash point is raised and the physical characteristics of the solvent are not harmed. It was observed the addition of alpha terpineol increased the flash point to a maximum and then decreased the flash point as the alpha terpineol concentration surpassed the optimum amount.
Standard flash point xylene—(76° F.)
90.0% xylene 10.0% alpha terpineol—flash point 140° F. (60° C.)
88.5% xylene 11.5% alpha terpineol—flash point 144° F. (62.2° C.)
85.0% xylene 15.0% alpha terpineol—flash point 156° F. (68.9° C.)
82.5% xylene 17.5% alpha terpineol—flash point 145° F. (62.8° C.)
20.0% xylene 80.0% alpha terpineol—flash point 139° F. (59.4° C.)
The combination was clear and stable. The optimum blend contained 85% xylene and 15% alpha terpineol and increased amounts of alpha terpineol resulted in a decreased flash point.
The combination was clear and stable. When tested it exhibited a flash point of 145.4° F. (63.0° C.) using a Pensky-Martens Closed Cup Flash Point procedure.
The combination was clear and stable. When tested it exhibited a flash point of 141.6° F. (62.0° C.) using a Pensky-Martens Closed Cup Flash Point procedure.
The combination was clear and stable. When tested it exhibited a flash point of 143.6° F. (62.0° C.) using a Pensky-Martens Closed Cup Flash Point procedure.
The combination was clear and stable. When tested it exhibited a flash point of 141.8° F. (61.0° C.) using Pensky-Martens Closed Cup Flash Point procedure.
The combination was clear and stable. When tested it exhibited a flash point of 145.4° F. (63.0° C.) using Pensky-Martins Closed Cup Flash Point procedure.
The preceding examples 1-6 were directed principally to increase the flashpoint of organic solvents to over 140° F. These compositions are environmentally and significantly safer for handling and storage over the individual organic solvent.
The solvent system of this invention can be used as is, may be blended with other organic solvents to produce an environmentally and safer performance solvent system. Acetone has a flashpoint of 0° F. (−18.0° C.) by itself. In example 4 the acetone mixed at 82.0 wt percent with 18.9 wt percent of alpha terpineol, the resulting flashpoint is increased to 141.6° F. (62.0° C.). The acetone and alpha terpineol mixture can be mixed with other environmentally correct solvents with flash points over 140° F. resulting in a safer solvent designed for a specific application, such as, a paint stripper. The acetone portion of the preferred mixture is an exempt volatile organic compound and therefore provides a solvent system that meets Federal and state regulations.
The combination was clear and stable. When tested it exhibited a flash point of −4.2° C. using Pensky-Martens Closed Cup Flash Point Tester.
Another sample was made adding alpha terpineol to the formulation, as exhibited in Example 8.
The composition of example 8 had a flashpoint of 141.6° F. (62.0° C.) using Pensky-Martens Closed Cup Flashpoint Tester. By the addition of 10% alpha terpineol, the flash point of the mixture in Example 7 was increased by 64.2° C. The composition of example 8, contains 0% Volatile Organic Compound content based on USEPA regulations that a component or mixture having a vapor pressure less than 0.1 mm Hg at 20° C., exempts that mixture from the VOC content limit making the composition compliant with Federal and state VOC regulations. N-methyl pyrrolidone, dibasic ester, and alpha terpineol exhibit vapor pressures less than 0.1 mm Hg at 20° C. and acetone is VOC exempt under Federal regulations. The increased flash point complies with DOT flammability regulations.
Alpha terpineol is a commercially available terpene alcohol sold by Millennium Chemical. Alpha terpineol can contain alpha terpene, among other terpene hydrocarbons, and exhibits a flashpoint of between 180° F. and 200° F., depending upon the volatile impurities present.
In the event a solvent formulation is used, such as example 8, then I prefer that the solvents, other than the low flash point solvent blended with alpha terpineol, likewise have a relativity high flash point. According to the Condensed Chemical Dictionary 1956 edition, Reinhold Publishing Company, n-methyl pyrrolidone has a flash point of 204° F. and dibasic ester has a flash point of 212° F.
Those skilled in the art will recognize that the alpha terpineol/solvent blend may themselves be used to remove grease and other contaminants from various materials, such as steel, aluminum, and other substrates. The terpene alcohol blend with other solvents may be contained within a tank into which the material to be cleaned is placed. Heating of the terpene alcohol/solvent blend may not be needed, depending upon the application, although because of the high flash point, heating may be useful. Should the terpene alcohol/solvent blend become too concentrated with contaminates, then the bath may be disposed of or the contaminate separated from the alcohol/solvent blend by various means, including membrane filtration.
While this invention has been described as having a preferred design, it is understood that it is capable of further modifications, uses and/or adaptations of the invention, following the general principle of the invention and including such departures from the present disclosure has come within known or customary practice in the art to which the invention pertains, and as may be applied to the central features hereinbefore set forth, and fall within the scope of the invention of the limits of the appended claims.
Having described the invention, what is desired to be protected by Letters Patent is presented in the subsequent appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5425893 | Stevens | Jun 1995 | A |
| 7273839 | Koetzle | Sep 2007 | B2 |
