Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
1999-07-20
2001-01-16
Hardee, John (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S407000, C510S408000, C510S412000, C510S365000, C134S010000, C134S012000, C134S040000
Reexamination Certificate
active
06174850
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns the field of fluorohydrocarbons and relates more particularly to novel compositions which can be used to clean or dry solid surfaces.
BACKGROUND OF THE INVENTION
1,1,2-Trichloro-1,2,2-trifluoroethane (known in the field by the name F113) has been widely used in the industry for cleaning and degreasing solid surfaces of very diverse nature (metal components, glass, plastic, composites), for which an absence—or at least the lowest possible residual content—of impurities, in particular of organic nature, is required. F113 was particularly suitable for this use on account of its non-corrosive nature with respect to the materials used. This product has been used in particular in the field of manufacturing printed circuits, to remove the residues of the substances used to improve the quality of the solders (known by the term soldering fluxes). This removal operation is known in the field as “defluxing”.
Mention may also be made of the applications of F113 to the degreasing of heavy metal components and to the cleaning of high-quality and high-precision mechanical components such as, for example, gyroscopes and military, aerospace or medical equipment. In its various applications, F113 is usually combined with other organic solvents (for example methanol), in order to improve its cleaning capacity. In this case, it is preferred to use azeotropic or quasi-azeotropic mixtures. For the purposes of the present invention, the term “quasi-azeotropic mixture” means a mixture of generally miscible chemical compounds which, under certain specific conditions of proportions, temperature and pressure, boils at a substantially constant temperature while at the same time retaining substantially the same composition. When it is heated to reflux, such a quasi-azeotropic mixture is in equilibrium with a vapour phase whose composition is substantially the same as that of the liquid phase. Such azeotropic or quasi-azeotropic behaviour is desirable to ensure satisfactory functioning of the machines in which the abovementioned cleaning operations are carried out, and in particular to ensure recycling by distillation of the cleaning fluid.
F113 is also used in fields, in particular in optics, for which it is necessary to have available water-free surfaces, i.e. surfaces on which water is only present at trace levels which are undetectable by the method of measurement (Karl Fisher method). With this aim, F113 is used in operations for cleaning (or dewetting) the said surfaces, in combination with hydrophobic surfactants.
However, the use of compositions based on F113 is now banned since F113 is among the chlorofluorocarbons (CFCs) suspected of attacking or degrading stratospheric ozone.
In these various applications, F113 can be replaced with 1,1-dichloro-1-fluoroethane (known by the name F141b), but the use of this substitute is already regulated since, although weak, its destructive effect on ozone is not nonexistent.
Patent application EP 0,512,885 describes a composition comprising from 93 to 99% by weight of 1,1,1,3,3-pentafluorobutane and from 1 to 7% of methanol, which can be used as a substitute for F113. 1,1,1,3,3-Pentafluorobutane, also known in the field by the name F365 mfc, has no destructive effect on ozone.
DESCRIPTION OF THE INVENTION
The aim of the invention is to propose other compositions which can be used as substitutes for F113 or F141b, and which have no destructive effect on ozone.
To contribute towards solving this problem, a subject of the present invention is thus azeotropic or quasi-azeotropic compositions comprising from 1 to 25% of 1,1,1,2,3,4,4,5,5,5-decafluoropentane, preferably from 5 to 20%, and from 75 to 99% of 1,1,1,3,3-pentafluorobutane, preferably from 80 to 95%. Unless otherwise indicated, the percentages used in the present text to indicate the content of the compositions according to the invention are percentages by weight. 1,1,1,2,3,4,4,5,5,5-Decafluoropentane is a compound (also known by the name 43-10 mee) which is totally free of any destructive effect on ozone.
In this field, there is an azeotrope whose boiling point is 36.5° C. at normal atmospheric pressure (1.013 bar).
The compositions according to the invention make it possible to obtain very good results for the cleaning and degreasing of solid surfaces, as well as in operations for drying and dewetting surfaces. Furthermore, these compositions have no flashpoint under the standard determination conditions (ASTM standard D 3828) and thus make it possible to work in total safety.
The compositions according to the invention can readily be prepared by simple mixing of the constituents. 43-10 mee is commercially available; 365 mfc can be prepared by at least one of the following methods:
Zh. Org. Khim. 1980, 1401-1408 and 1982, 946 and 1168; Zh. Org. Khim. 1988, 1558. J. Chem. Soc Perk. I, 1980, 2258; J Chem. Soc Perk. Trans, 2. 1983, 1713; J. Chem. Soc. C Perk. Trans, 2. 198, 1713: J. Chem. Soc. C 1969, 1739: Chem. Soc. 1949, 2860: Zh. Anal. Khim, 1981 36 (6), 1125; J. Fluorine Chem. 1979, 325; Izv. Akad. Nauk. SSSR. Ser Khim. 1980, 2117 (in Russian); Rosz. Chem. 1979 (48), 1697 and J.A.C.S. 67. 1195 (1945), 72, 3577 (1950) and 76, 2343 (1954).
According to a preferred variant, a ternary composition according to the invention comprises from 5 to 20% of 43-10 mee, from 75 to 90% of 365 mfc and from 1 to 10% of methanol. A ternary composition containing 10 to 15% of 43-10 mee, 80 to 85% of 365 mfc and 2 to 8% of methanol is more particularly preferred. In this field, there is an azeotrope whose boiling point is 33.2° C. at normal atmospheric pressure.
As with the known cleaning compositions based on F113 or F141b, the cleaning compositions based on 43-10 mee and 365 mfc according to the invention can, if so desired, be protected against the chemical attacks resulting from their contact with water (hydrolysis), with light metals (constituting the solid surfaces to be cleaned) and/or against the radical attacks liable to occur in the cleaning processes, by adding thereto a common stabilizer such as, for example, nitroalkanes (in particular nitromethane, nitroethane or nitropropane), acetals (dimethoxyethane) and ethers (1,4-dioxane or 1,3-dioxolane). The proportion of stabilizer can range from 0.01 to 5% relative to the total weight of the composition. It is preferred to use dimethoxymethane as stabilizer, the boiling point of which is close to that of the azeotropic compositions according to the invention; as a result, this stabilizer follows the evaporation and condensation cycle of the solvent entirely, which is particularly advantageous in cleaning applications.
The compositions according to the invention can be used in the same applications and can be employed according to the same methods as the previous compositions based on F113 or F141b. They are thus particularly suitable for use in cleaning and degreasing solid surfaces, preferably in defluxing printed circuits, as well as in operations for drying surfaces.
As regards the embodiments, mention may be made in particular of the use in devices adapted to the cleaning and/or drying of surfaces, as well as by aerosol.
These compositions can also be used as agents for expanding polyurethane foams, as agents for the dry-cleaning of textiles and as refrigeration fluids.
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Zh. Org. Khim. 1980, 1401-1408 and 1982,, pp. 946-950, “New Syntheses of Coumarins,”, Panetta, et al., and 1168.
Zh. Org. Khim. 1988, Vo. 53, pp. 1557-1560, “Regioselective Synthesis of 2- and 3-(Phenylthio)juglone Derivatives”, Laugraud, et al.
J.Chem.Soc. J.C.S. Perkin 1, 1980, pp. 2258-2266, “C-Nucleoside
Atofina
Hardee John
Smith , Gambrell & Russell, LLP
Webb Gregory E.
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