Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
2000-04-21
2001-08-28
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S408000
Reexamination Certificate
active
06281186
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of fluorinated hydrocarbons and has more particularly as subject-matter novel compositions which can be used for cleaning or drying solid surfaces.
BACKGROUND OF THE INVENTION
1,1,2-Trichloro-1,2,2-trifluoroethane (known in the trade under the name F113) has been widely used in industry for cleaning and degreasing highly-varied solid surfaces (metal components, glasses, plastics, composites) for which the absence or at least the lowest possible residual content of impurities, in particular of organic nature, is required. F113 was particularly well suited to this use because of its nonaggressive nature with regard to the materials used. This product was used in particular in the field of the manufacture of printed circuits , for removing the residues of the substances used to improve the quality of the soldered joints (denoted by the term solder flux). This removal operation is denoted in the trade by the term “defluxing”.
Mention may also be made of the applications of F113 in the degreasing of heavy metal components and in the cleaning of mechanical components of high quality and of great accuracy, such as, for example, gyroscopes and military, aerospace or medical equipment. In its various applications, F113 is generally used in combination with other organic solvents (for example methanol), in order to improve its cleaning power. It is then preferable to use azeotropic or near-azeotropic mixtures. The term “near-azeotropic mixture” is understood to mean, within the sense of the present invention, a mixture of generally miscible chemical compounds which, under certain specific conditions of proportions, temperature and pressure, boils at a substantially constant temperature while retaining substantially the same composition. When it is heated to reflux, such a near-azeotropic mixture is in equilibrium with a vapour phase, the composition of which is substantially the same as that of the liquid phase. Such azeotropic or near-azeotropic behaviour is desirable in ensuring satisfactory operation of the devices in which the abovementioned cleaning operations are carried out and in particular in ensuring the recycling by distillation of the cleaning fluid.
F113 is also used in fields, in particular in optics, where it is required to have available surfaces which are devoid of water, that is to say surfaces where water is only present in the form of traces undetectable by the measurement method (Karl Fischer method). F113 is, for this purpose, employed in drying (or dewetting) operations on the said surfaces, in combination with hydrophobic surface-active agents.
However, the use of compositions based on F113 is now forbidden as F113 is one of the chlorofluorocarbons (CFCs) suspected of attacking or damaging the stratospheric ozone.
In these various applications, F113 can be replaced by 1,1-dichloro-1-fluoroethane (known under the name F141b), but the use of this substitute is already controlled because, although low, it still has a destructive effect with regard to ozone.
Application EP 0,856,578 discloses a composition, comprising from 10 to 90% by weight of 1,1,1,2,3,4,4,5,5,5-decafluoropentane, from 10 to 90% of dichloromethane and from 0 to 10% of methanol, which can also be used as substitute for F113. 1,1,1,2,3,4,4,5,5,5-Decafluoropentane, known in the trade under the name 43-10mee, also has no destructive effect with regard to ozone.
DETAILED DESCRIPTION OF THE INVENTION
The aim of the invention is to provide other compositions capable of being used as substitute for F113 or F141b and which have no destructive effect with regard to ozone.
In order to contribute to the resolution of this problem, the subject-matter of the present invention is therefore azeotropic or near-azeotropic compositions comprising:
from 35 to 55% of 1,1,1,2,3,4,4,5,5,5-decafluoropentane, preferably from 40 to 50%,
from 20 to 40% of dichloromethane, preferably from 25 to 35%,
from 10 to 20% of cyclopentane, preferably from 15 to 20%, and
from 0.5 to 10% of methanol, preferably from 1 to 5%.
Except when otherwise indicated, the percentages used in the present text to indicate the content of the compositions according to the invention are percentages by weight.
In this range, there exists an azeotrope, the boiling temperature of which is 31.4° C. at standard atmospheric pressure (1.013 bar).
The compositions according to the invention make it possible to obtain very good results in the cleaning and degreasing of solid surfaces, as well as in drying and dewetting operations on surfaces.
The compositions according to the invention can be easily prepared by simple mixing of the constituents. 43-10mee is commercially available.
As in the known cleaning compositions based on F113 or F141b, the cleaning compositions based on 43-10mee, on dichloromethane, on cyclopentane and on methanol according to the invention can, if desired, be protected against chemical attacks resulting from their contact with water (hydrolysis) or with light metals (constituting the solid surfaces to be cleaned) and/or against radical attacks capable of taking place in cleaning processes by adding a conventional stabilizer thereto, such as, for example, nitroalkanes (in particular nitromethane, nitroethane or nitropropane), acetals (dimethoxymethane) or ethers (1,4-dioxane or 1,3-dioxolane). The proportion of stabilizer can range from 0.01 to 5% with respect to the total weight of the composition. It is preferable to use dimethoxymethane as stabilizer, the boiling point of dimethoxymethane being close to that of the azeotropic compositions according to the invention; for this reason, this stabilizer conforms perfectly to the cycle of evaporation and condensation of the solvent, which is particularly advantageous in cleaning applications.
The compositions according to the invention can be mixed with other solvents, such as alcohols, ketones, ethers, acetals, esters, hydrocarbons, chlorinated, brominated or iodinated solvents, sulphones or water, in the presence of (anionic, nonionic or cationic) surfactants which comprise fluorine or silicone, or not, in order to obtain specific properties, in particular in dry-cleaning.
The compositions according to the invention can be used in the same applications and be employed according to the same methods as the prior compositions based on F113 or F141b. They are therefore particularly suitable for use in the cleaning and degreasing of solid surfaces, preferably in the defluxing of printed circuits, as well as in drying operations on surfaces.
As regards the latter use, it is preferable to add a soluble hydrophobic surfactant to the composition, in order to further improve the removal of water from the surfaces to be treated, until 100% removal is achieved.
Among hydrophobic surfactants, the diamides of formula:
R—CO—NR—(CH
2
)
n
—NH—CO—R (I)
in which R is an alkyl radical comprising from 14 to 22 carbon atoms, preferably from 16 to 20 carbon atoms, and n is an integer between 1 and 5 inclusive, preferably equal to 3.
According to this preferred alternative form of the compositions according to the invention, the composition generally comprises from 92 to 99.5% of the quaternary azeotropic composition and from 0.05 to 8% of surfactant.
As regards the forms of use of the compositions according to the invention, mention may particularly be made of the use in devices suitable for the cleaning and/or drying of surfaces, as well as by aerosol.
As regards the aerosol use, the compositions according to the invention can be packaged with, as propellant, 134a (or 227e of formula CF
3
CHF—CF
3
) and their mixture with 152a and/or DME (dimethyl ether), in order to offer additional cleaning possibilities, in particular at room temperature. The compositions according to the invention, thus packaged, do not exhibit a flame length according to Standard 609F of the Fédération Européenne des Aérosols [European Aerosol Federation] (Brussels, Belgium)(Determination of the ignition distance of a spray or of a stream emitted from
Martin Jean-Jacques
Michaud Pascal
Atofina
Gupta Yogendra N.
Smith , Gambrell & Russell, LLP
Webb Gregory E.
LandOfFree
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