Cleaning solvent compositions exhibiting azeotrope-like behavior and their use

Abstract

An azeotropic cleaning solvent composition has from about 96 to about 98 weight percent 1,1,1,3,3,3-hexafluoro-2-methoxypropane (“HFMOP”) and from about 2 to about 4 weight percent acetone, for example, about 97 weight percent HFMOP and about 3 weight percent acetone. Another composition of the invention has a weight ratio of HFMOP to acetone of about 24 to about 99, for example, about 24 to 49. Conventional additives such as surfactants, lubricants and co-solvents may be present in an amount not to exceed about 10 weight percent of the composition. A method of the invention comprises contacting an article of manufacture with the solvent composition in order to clean the article of manufacture and then removing the solvent composition from the article of manufacture.

Claims

1. A solvent composition having azeotrope-like properties and comprising 1,1,1,3,3,3-hexafluoro-2-methoxypropane ether (“HFMOP”) and acetone, the HFMOP and the acetone being present in a weight ratio of about 24 to about 99 parts HFMOP to one part acetone.

2. The composition of claim 1 wherein the HFMOP and the acetone are present in a weight ratio of about 24 to about 49 parts HFMOP to one part acetone.

3. The composition of claim 1 or claim 2 further comprising one or more additives which do not adversely affect the azeotropic-like properties of the composition and, if present, are present in an amount not exceeding about 10 weight percent of the composition.

4. The composition of claim 3 wherein the additives, when present, are selected from the class consisting of one or more of surfactants, lubricants and co-solvents.

5. The composition of claim 3 wherein the surfactants, when present, are selected from the class consisting of one or more of alkylphosphate amine salts, ethoxylated alcohols, and quaternary ammonium salts; the lubricants, when present, are selected from one or more of mineral oil, alkyl benzenes, polyol esters, perfluoropolyethers, fluorosilicones, polytetrafluoroethylene, and polytrifluorochloroethylenes; and the co-solvents, when present, are selected from the class consisting of one or more of methanol, ethanol, n-propanol, isopropanol, benzyl alcohol, esters, ethers, ether alcohols, pentane, cyclopentane, hexane, cyclohexane, heptane and octane.

6. The composition of claim 3 wherein the HFMOP and acetone are present in a weight ratio of from about 27.6 to about 39.0 parts HFMOP to one part acetone.

7. A solvent composition having azeotrope-like properties and comprising from about 96 to about 99 weight percent 1,1,1,3,3,3-hexafluoro-2-methoxypropane ether (“HFMOP”) and from about 1 to about 4 weight percent acetone.

8. The composition of claim 7 comprising from about 96 to about 98 weight percent 1,1,1,3,3,3-hexafluoro-2-methoxypropane ether (“HFMOP”) and from about 2 to about 4 weight percent acetone.

9. The composition of claim 7 wherein acetone comprises from about 2.5 to about 3.5 weight percent of the composition.

10. The composition of claim 7 wherein acetone comprises from about 2 to about 3 weight percent of the composition.

11. A method of cleaning an article of manufacture by contacting the article with a solvent composition having azeotrope-like properties and comprising 1,1,1,3,3,3-hexafluoro-2-methoxypropane ether (“HFMOP”) and acetone, the HFMOP and the acetone being present in a weight ratio of from about 24 to about 99 parts HFMOP to one part acetone, and the composition optionally further comprising, one or more additives which do not adversely affect the azeotrope-like properties of the composition and, if present, are present in an amount not exceeding about 10 weight percent of the composition, the additives, when present, being selected from the class consisting of one or more surfactants selected from one or more of alkylphosphate amine salts, ethoxylated alcohols, and quaternary ammonium salts; the lubricants, when present, being selected from one or more of mineral oil, alkyl benzenes, polyol esters, perfluoropolyethers, fluorosilicones, polytetrafluoroethylene, and polytrifluorochloroethylenes; and the co-solvents, when present, are selected from the class consisting of one or more of methanol, ethanol, n-propanol, isopropanol, benzyl alcohol, esters, ethers, ether alcohols, pentane, cyclopentane, hexane, cyclohexane, heptane and octane and removing the solvent composition from the article after the contacting of the article with the solvent composition.

12. The method of claim 11 wherein the HFMOP and the acetone are present in a weight ratio of from about 24 to about 49 parts HFMOP to one part acetone.

13. The method of claim 11 or claim 12 wherein the composition is vaporized and the article is contacted with the resulting vapor, and after such contacting the vapor is condensed to the liquid composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view in elevation of a bench top simulation of a standard 2-sump vapor degreaser comprising a “dual bulb” apparatus of the type used to develop the data illustrated in FIGS. 2-5;

(2) FIG. 2 is a graph plotting the change in composition of the HFMOP and acetone components of a cleaning solvent embodiment of the present invention over seven hours of operation measured in the boil sump of the apparatus of FIG. 1;

(3) FIG. 3 is a graph identical to that of FIG. 2 except that it shows the change in composition in the rinse sump of the dual bulb apparatus;

(4) FIG. 4 is a graph plotting the data of FIGS. 2 and 3 against the time of operation of the apparatus, but showing the change in quantity of the HFMOP component in the boil and rinse sumps; and

(5) FIG. 5 is a graph identical to that of FIG. 4 except that it plots the change in quantity of the acetone component.

DETAILED DESCRIPTION OF THE INVENTION AND SPECIFIC EMBODIMENTS THEREOF

(6) FIG. 1 schematically illustrates a conventional dual-bulb bench top laboratory glassware of the type utilized to simulate operation of a VDG unit and generate the data presented below. Laboratory glassware 10 comprises a boil bulb 12 having a neck 12a which protrudes into rinse bulb 14. Neck 12a has formed therein an aperture 12b which is disposed within rinse bulb 14. A condenser 16 is fitted to rinse bulb 14 at the outlet end thereof and comprises a cooling coil 18 disposed within condenser 16. A cold water inlet 18a is connected to a source of cooling water (not shown) and a cold water outlet 18b is connected to a water discharge (not shown). Boil bulb 12 is disposed upon a heating mantel 20.

(7) In use, a solvent composition to be tested is introduced into boil bulb 12 and heated to boil the solvent composition and generate a vapor which rises to rinse bulb 14 and then into condenser 16 as indicated by arrows V.sub.1. Vapor is condensed by contact with cooling coil 18 and flows into rinse bulb 14 as indicated by arrows C.sub.1. When the condensate collected in rinse bulb 14 reaches the level of aperture 12b, the overflow solvent flows back into boil bulb 12 as indicated by arrow C.sub.2.

(8) Standard Test Procedure. Trials were conducted in a bench top simulation of a standard 2-sump vapor degreaser using a “dual bulb” apparatus of the type illustrated in FIG. 1, having a sampling port (not shown in FIG. 1) on the boil flask. Samples from various locations and times are analyzed by gas chromatography using an Agilent Corporation DB-200 capillary column (trifluoropropyl methyl dimethyl siloxane stationary phase) and an FID detector. The following Examples report the results of trials conducted pursuant to this Standard Test Procedure.

Example 1

(9) Formulation of an embodiment (designated 17-90-1) of the present invention containing 97 wt percent HFMOP and 3 wt percent acetone is distilled in laboratory glassware of the type schematically illustrated in FIG. 1.

(10) TABLE-US-00002 Part A-Change in Boil Composition by Distillation in Laboratory Glassware Simulating a Vapor Degreaser Prototype 17-90-1 Vapor Degreaser Simulation Total Time wt % wt % Distilled (hours) HFMOP ACETONE 0 97.00 3.00 1 95.45 4.55 2 95.57 4.43 3 95.59 4.41 4 95.62 4.38 5 95.60 4.40 6 95.58 4.42 7 95.58 4.42
The change in HFMOP starting content is 97.00-95.58=1.42. This represents a reduction of HFMOP in the boil composition over the course of seven hours of distillation of 1.42/97.00=1.46 wt %.

(11) TABLE-US-00003 Part B-Change in Rinse Composition by Distillation in Laboratory Glassware Simulating a Vapor Degreaser Prototype 17-90-1 Vapor Degreaser Simulation Total Time wt % wt % Distilled (hours) HFMOP ACETONE 0 97.00 3.00 1 98.24 1.76 2 98.09 1.91 3 98.02 1.98 4 97.98 2.02 5 97.96 2.04 6 97.93 2.07 7 97.90 2.10
The change in HFMOP content in the rinse composition over the seven hours of distillation, calculated as for the boil composition, is an increase of 0.90/97.00=0.93 wt %.

(12) As the above data shows, Prototype 17-90-1 exhibits azeotropic properties. The boiling point of Prototype 17-90-1 was determined to be 51.3° C., which is 4.5° C. lower than the calculated boiling point. The distillation data indicate that the composition does shift initially from 3 wt % acetone to 2 wt % in the rinse and 4 wt % in the boiling areas of the system. The 7-hour distillation evaluation depicts the stability of the blend after the initial shift.

(13) Example 1 demonstrates that only a limited change in the initially present quantity of each component of the blend is sustained in the boil and rinse sumps after an evaporation and condensation period of seven hours in the apparatus of FIG. 1 as is shown in FIGS. 2 and 3. FIGS. 4 and 5 show the changes in composition in the boil and rinse sumps of the apparatus of FIG. 1 for, respectively, HFMOP and acetone.

(14) HFMOP in combination with acetone in the stated proportions has been found to provide an advantageous alternative to known compositions containing other hydrofluoroethers (“HFEs”) in combination with a high KB flammable solvent. A major benefit of using HFEs instead of hydrofluorocarbons (“HFCs”) in cleaning solvents is improved environmental characteristics. HFMOP has shown flammability suppression characteristics which allow it to be blended with flammable solvents having a high KB value, such as acetone, to provide non-flammable compositions. It is of course highly desirable to form non-flammable azeotropes with the HFE and flammable cleaning solvents.

(15) The following compositions were tested by a “pan test” for flammability. A metal pan was filled with 10 mL of solvent in a fume hood. A flame source was passed over the surface of the liquid and the flame was monitored for size and duration. Once the flame extinguished, the fumes were allowed to dissipate for 30 seconds. The flame source was then passed over the solvent surface again. This process was repeated until all of the solvent had evaporated. The testing was ceased if the flames did not self-extinguish within 10 seconds. A solvent which self-extinguished the flames in less than 5 seconds was deemed “non-flammable.” A solvent which did not extinguish the flames after 5 seconds was deemed “flammable.” This test method is a procedure employed to gauge flammability potential for solvent blends before testing via closed-cup or open-cup methods.

Example 2

(16) Each composition comprised the stated weight % of solvent, balance HFMOP.

(17) TABLE-US-00004 Part A-Comparative Examples Composition Flammability Results HFMOP and Ethanol 3 wt % ethanol flammable 5 wt % ethanol flammable HFMOP and Trans-dichloroethylene (″Trans″) 50 wt % trans non-flammable 80 wt % trans flammable 95 wt % trans flammable HFMOP and Isopropyl Alcohol (IPA″) 3 wt % IPA flammable HFMOP and Acetone (Example taken from Yuji et al. JPH 10130183A, noted above) 25 wt % acetone highly flammable

(18) TABLE-US-00005 Part B-Embodiments of the Present Invention Composition Flammability Results HFMOP and acetone   1 wt % acetone non-flammable   2 wt % acetone non-flammable 2.5 wt % acetone non-flammable 3 wt % acetone (Prototype 17-90-1) non-flammable   4 wt % acetone non-flammable

(19) The flammability tests of Example 2 demonstrate that blends of HFMOP or other HFEs with certain alcohols or trans-dichloroethylene as taught in the prior art are flammable. In contrast, Prototype 17-90-1, a blend of HFMOP with acetone (3 wt % acetone) is self-extinguishing. Further, flammability studies of Prototype 17-90-1 indicate that the blend does not become flammable over time. A low acetone content less than one percent is of course non-flammable but results in poor cleaning power.

(20) The present invention has been described in detail with respect to specific embodiments thereof but these specific embodiments are not intended to be construed as limitations on the scope of the invention.