EP1046703B1 - Cleaning or drying compositions based on pentafluorobutane, methylene chloride, methanol and decafluoropentane - Google Patents

Description

The present invention relates to the field of fluorinated hydrocarbons and more particularly for the subject of new compositions which can be used for cleaning or drying solid surfaces.

1,1,2-Trichloro-1,2,2-trifluoroethane (known in the trade under the designation F113) has been widely used in industry for cleaning and degreasing very diverse solid surfaces (metal parts, glasses, plastics, composites), for which an absence - or at least a residual content as low as possible - in impurities, especially organic in nature, is required. The F 113 was suitable particularly well for this use because of its non-aggressive nature towards used materials. This product has been used in particular in the field of manufacturing printed circuits, to remove residues from substances used to improve the quality of welds (designated by the term weld flux). This operation elimination is designated in the art by the term "defluxing".

We can also mention the applications of F113 to degreasing parts heavy metal and cleaning of high quality and large mechanical parts precision such as, for example, gyroscopes and military, aerospace or medical. In its various applications, the F113 is most often associated with other organic solvents (eg methanol), to improve its cleaning capacity. It is therefore preferable to use azeotropic or quasi-azeotropic mixtures. We hear by quasi-azeotropic mixture within the meaning of the present invention a mixture of compounds generally miscible chemicals which under certain specific conditions of proportions, temperature and pressure, tip at substantially constant temperature while retaining substantially the same composition. When heated to reflux, such quasi-azeotropic mixture is in equilibrium with a vapor phase whose composition is substantially the same as that of the liquid phase. Such azeotropic behavior or almost azeotropic is desirable to ensure satisfactory operation of machines in which the abovementioned cleaning operations are carried out, and in particular for recycling the cleaning fluid by distillation.

The F113 is also used in the fields, in particular in optics, for which are required to have water-free surfaces, i.e. surfaces where water is only present in traces undetectable by the measurement method (method Karl Fisher). For this purpose, F113 is used in drying operations (or dewetting) of said surfaces, in combination with surfactants hydrophobic.

However, the use of compositions based on F113 is now prohibited since the F113 is one of the chlorofluorocarbons (CFCs) suspected of attacking or degrading ozone stratospheric.

In these various applications, F113 can be replaced by 1,1-dichloro-1-fluoroethane (known as F141b), but the use of this substitute is already regulated because, although weak, its destructive effect on ozone is not zero.

Application EP 0512885 describes a composition comprising from 93 to 99% by weight of 1,1,1,3,3-pentafluorobutane and from 1 to 7% of methanol, usable as substitute for F113. 1,1,1,3,3-pentafluorobutane, also known in the art as denomination of F365mfc, has no destructive effect with respect to ozone.

EP 0856578 describes a composition comprising from 10 to 90% in weight of 1,1,1,2,3,4,4,5,5,5,5-decafluoropentane, 10 to 90% of dichloromethane, and 0 10% methanol, also usable as a substitute for F113. 1,1,1,2,3,4,4,5,5,5-decafluoropentane known in the art under the name of 43-10mee is also devoid of destructive effect with respect to ozone.

The object of the invention is to propose other compositions capable of being used as a substitute for F113 or F141b, and devoid of any destructive effect on it of ozone.

• de 45 à 65 % de 1,1,1,3,3-pentafluorobutane, de préférence de 50 à 60 %,
• de 30 à 50 % de dichlorométhane, de préférence de 35 à 45 %
• de 1 à 10 % de méthanol, de préférence de 2 à 5 % et
• de 0,1 à 2 % de 1,1,1,2,3,4,4,5,5,5-décafluoropentane, de préférence de 0,2 à 1%.

To contribute to solving this problem, the present invention therefore relates to azeotropic or quasi-azeotropic compositions comprising:

• from 45 to 65% of 1,1,1,3,3-pentafluorobutane, preferably from 50 to 60%,
• 30 to 50% dichloromethane, preferably 35 to 45%
• from 1 to 10% of methanol, preferably from 2 to 5% and
• from 0.1 to 2% of 1,1,1,2,3,4,4,5,5,5-decafluoropentane, preferably from 0.2 to 1%.

Unless otherwise indicated, the percentages used in this text for indicate the content of the compositions according to the invention are percentages by weight.

In this area, there is an azeotrope with a boiling point of 31.9 ° C at normal atmospheric pressure (1.013 bar).

The compositions according to the invention make it possible to obtain very good results for cleaning and degreasing of solid surfaces, as well as in drying and dewetting of surfaces. In addition, these compositions do not have a point flash under standard determination conditions (ASTM D 3828) and allow therefore to work safely.

The compositions according to the invention can be easily prepared by simple mixing of the constituents. The 43-10 mee is commercially available; 365mfc 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. Fluorite Chem. 1979, 325; Izv, Akad. Nauk. SSSR. Ser Khim. 1980, 2117 (in Russian); Rosz. Chem. 1979 (48), 1697 and JACS 67. 1195 (1945), 72, 3577 (1950) and 76, 2343 (1954).

As in the known cleaning compositions based on F113 or F141b, cleaning compositions based on 365 mfc, dichloromethane, methanol and 43-10 mee, according to the invention, can, if desired, be protected against attack chemicals resulting from their contact with water (hydrolysis), with light metals (constituting the solid surfaces to be cleaned), and / or against radical attacks likely to occur in cleaning processes, adding a usual stabilizer such as, for example, nitroalkanes (especially nitromethane, nitroethane, nitropropane), acetals (dimethoxymethane) or ethers (1,4-dioxane, 1,3-dioxolane). The proportion of stabilizer can range from 0.01 to 5% relative to the total weight of the composition. As stabilizer, it is preferred to use dimethoxymethane, the point of which of boiling is close to that of the azeotropic compositions according to the invention; thereby, this stabilizer perfectly follows the evaporation and condensation cycle of the solvent, which is particularly interesting in cleaning applications.

It is possible to mix with the compositions according to the invention other solvents such as alcohols, ketones, ethers, acetals, esters, hydrocarbons, solvents chlorinated, brominated, iodinated, sulfones, or water, in the presence of surfactants (anionics, non-ionic or cationic) fluorinated, silicone or not, in order to obtain properties specific, especially in dry cleaning.

The compositions according to the invention can be used in the same applications and be implemented in the same manner as the compositions prior to F113 or F141b. They are therefore particularly suitable for use for cleaning and degreasing solid surfaces, preferably for defluxing of printed circuits, as well as for surface drying operations.

Regarding the latter use, it is preferred to add a surfactant hydrophobic soluble in the composition, in order to further improve the elimination of water from surfaces to be treated, until 100% elimination is achieved.

Among the hydrophobic surfactants, the diamides of formula: R-CO-NR- (CH ₂ ) n-NH-CO-R 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 inclusive between 1 and 5, preferably equal to 3.

According to this preferred variant of the compositions according to the invention, the composition generally comprises from 92 to 99.5% of the quaternary azeotropic composition, and 0.05 to 8% surfactant.

Regarding the methods of implementation of the compositions according to the invention, one can cite in particular the implementation in devices adapted to the cleaning and / or drying of surfaces, as well as by aerosol.

Concerning the use by aerosol, 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 (Dimethylether) to offer additional cleaning possibilities, especially at room temperature. The compositions according to the invention thus conditioned do not have a flame length, according to standard 609F of the European Aerosol Federation (Brussels, Belgium) (Determination of the ignition distance of a spray or a jet emitted at from an aerosol container).

These compositions can also be used as a blowing agent for polyurethane foams, as a dry cleaning agent for textiles, and as a fluid refrigerant.

The following example illustrates the invention without limiting it.

EXAMPLE 1 : a) Demonstration of an azeotrope 365mfc / dichloromethane / methanol / 43-10mee:

50 g of 43-10 are introduced into the distiller of a distillation column (30 trays) mee and 100 g of 365mfc, 50 g of methanol and 100 g of dichloromethane. The mixture is then heated at reflux for an hour to bring the system to balance.

When we observe a temperature plateau, we collect a fraction of about 20g. This fraction and the fraction of the bottom remaining in the boiler are analyzed. by gas chromatography.

Examination of the results recorded in the table below indicates the presence of an azeotropic composition.

b) Verification of the azeotropic composition:

In the boiler of a distillation column (30 trays), 200 g of a mixture comprising 56.2% of 365mfc, 39.8% of CH2Cl2, 3.5% of MeOH, and 0.5% of 43-10. The mixture is then heated at reflux for one hour to bring the system equilibrium.

A fraction of approximately 20 g is withdrawn, which is analyzed by chromatography in gas phase.

Examination of the results, recorded in the following table, indicates the presence of a quaternary azeotrope 365mfc / CH2Cl2 / CH3OH / 43-10mee, since the fraction collected has the same composition as the initial mixture. It is a positive azeotrope since its boiling point is lower than that of each of the pure products, i.e. 40 ° C for 365mfc, 40 ° C for CH2Cl2, 65 ° C for CH3OH, and 55 ° C for 43-10 mee.

The above azeotropic composition can be stabilized with 0.5% of dimethoxymethane.

EXAMPLE 2 : Cleaning of welding flux

The following test is carried out on five test circuits conforming to the IPC-B-25 standard. described in the IPC (Institute for Interconnecting and Packaging Electronic Circuits; Lincolnwood, IL, USA). These circuits are coated with flux rosin-based solder (product marketed by ALPHAMETAL under the name flow R8F) and annealed in an oven at 220 ° C for 30 seconds.

To eliminate the rosin thus annealed, these circuits are cleaned using the azeotropic composition of Example 1, in a small ultrasonic machine for 3 minutes by immersion in the liquid phase and 3 minutes in the vapor phase.

The cleaning is evaluated according to the standardized procedure IPC 2.3.26 (described also in the manual cited above) using a precision conductivity meter.

The value obtained, 1.9 µg / cm ² eq.NaCl, is lower than the ionic impurity threshold tolerated by the profession (2.5 µg / cm ² eq.NaCl).

EXAMPLE 3 Surface drying

250 ml of a drying composition comprising 99.8% of the composition described in Example 1, to which 0.2% of oleylamido dioleyl is added propylene amide (compound of formula (I), in which R is an alkyl radical comprising on average 18 carbon atoms, and n equals 3).

A 5x3 cm stainless steel grid is soaked in water for a few seconds.

The water retention capacity of this grid is measured by soaking the grid in absolute ethyl alcohol, then assay by the Karl Fisher method implemented with this alcoholic solution.

This grid is then immersed for 30 seconds in the composition of drying thus prepared, by stirring manually. We remove the grid from this composition, and the residual water is assayed using the Karl Fischer method, as described above.

The amount of water called the elimination rate (expressed as a percentage) residual after drying divided by the water retention capacity of the grid (corrected for the water content of the absolute ethyl alcohol used).

We measure a water removal rate of 100%.

Claims (5)

1. Azeotropic or quasi-azeotropic compositions comprising:

   from 45% to 65% and preferably from 50% to 60% of 1,1,1,3,3-pentafluorobutane,

   from 30% to 50% and preferably from 35% to 45% of dichloromethane,

   from 1% to 10% and preferably from 2% to 5% of methanol, and

   from 0.1% to 2% and preferably from 0.2% to 1% of 1,1,1,2,3,4,4,5,5,5-decafluoropentane.
2. Composition according to Claim 1, in the form of an azeotrope with a boiling point of 31.9°C at normal atmospheric pressure.
3. Compositions according to either of Claims 1 and 2, also comprising a stabilizer, preferably dimethoxymethane.
4. Compositions according to one of Claims 1 to 3, also comprising a soluble hydrophobic surfactant, preferably a diamide of formula: R-CO-NR-(CH₂)n-NH-CO-R in which R is an alkyl radical containing from 14 to 22 carbon atoms and preferably from 16 to 20 carbon atoms, and n is an integer between 1 and 5 inclusive, preferably equal to 3.
5. Use of the compositions according to one of Claims 1 to 6, for cleaning and degreasing solid surfaces, preferably for defluxing printed circuits, and also for operations for drying surfaces.