FR2731436A1 - USE OF HYDROFLUOROALCENES AS CLEANING AGENTS, AND COMPOSITIONS USEFUL THEREFOR - Google Patents

Abstract

To replace 1,1,2-trichloro-1,2,2-trifluoroethane (F 113) or 1,1-dichloro-1-fluoroethane (F141b) in their applications for cleaning solid surfaces, the invention proposes to 'use a hydrofluoroalkene of general formula: RF - (CH2 -CF2) n -CH = CF2 in which n is equal to 1 or 2 and RF represents a perfluoroalkyl radical. Hydrofluoroalkenes are not likely to degrade stratospheric ozone.

Description

USE OF HYDROFLUOROALCENES AS

  CLEANING AGENTS AND COMPOSITIONS

USES THEREFOR

  The present invention relates to the field of fluorinated hydrocarbons and more particularly to the use of hydrofluoroalkenes as agents of

cleaning of solid surfaces.

  Because of its physicochemical characteristics, especially its inin-

  flammability, its high wetting power, its low solvent power, and its low boiling point ol0, 1,1,2-trichloro-1,2,2-trifluoroethane (known in the art under

  the designation of F113) is still widely used in industry for the net-

  cleaning and degreasing of very diverse solid surfaces (metal, glass,

  plastics, or composites). In electronics, the F113 has notably found an application

  This is important in defluxing and cold-cleaning printed circuit boards.

  Other examples of applications of F113 include the degreasing of metal parts and the cleaning of high quality mechanical parts and

  such as, for example, gyroscopes and military, aerial and

  space or medical, as well as the cleaning of sensitive textiles and leathers.

  In these various applications where F113 will be replaced by 1,1-

  dichloro-1-fluoroethane (known under the designation F141b), these solvents are

  often associated with other organic solvents (eg methanol),

  especially in the form of azeotropic or near azeotropic mixtures which

  not mix and which, employed at reflux, have substantially the same composition in

  the vapor phase only in the liquid phase.

  Unfortunately, F113 is a complete chlorofluorocarbon

  halogenated drugs that are currently condemned, and F 141b is one of the

  hydrochlorofluorocarbons that are already regulated because they are suspected of attacking or degrading stratospheric ozone. We are therefore looking for products devoid of destructive effect vis-à-vis ozone and able to replace the F113

  and the F141b in their various applications.

  It has now been found that hydrofluoroalkenes of the general formula: RF- (CH2-CF2) n-CH = CF2 (1) in which n is 1 or 2 and RF is a perfluoroalkyl radical,

  linear or branched, containing from 1 to 3 carbon atoms, have

  physicochemical parameters similar to those of F113 and F141b, and

  the latter, are not likely to degrade stratospheric ozone.

  The subject of the invention is therefore the use of a hydrofluoroalkene of formula (I) as a substitute for F113 or F141b in their various applications. Also included in the present invention are cleaning compositions based on

a hydrofluoroalkene.

  The compounds of formula (I) are known products (see for example US Pat. ). They can be obtained industrially by processes known per se, for example by a multistage process consisting essentially of: the addition of 1,1-difluoroethylene to the corresponding perfluoroalkyl RFI iodide in the presence of a catalyst based on copper and ethanolamine, and

  the dehydroiodination of iodide RF- (CH 2 CF 2) n + 1-1 thus obtained in

alcoholic potash.

  Among the compounds of formula (I) according to the invention, it is more particularly preferred

  1,3,3,3,5,5,6,6,6-nonafluorohex-1-ene CF3CF2-CH2CF2-CH = CF2 which, as indicated in the following table, has characteristics close to those of F113 except regarding the potential for ozone depletion

(O.D.P. Ozone Depletion Potential).

  CHARACTERISTICS F113 C2F5-CH2-CF2-CH = CF2

  Boiling point 47.6 C 75 C Surface tension at 25 C (mN.m-1) 19 15.9 Density at 20 C 1.57 1.51 Flammability n / a none Flash point (C) none none Solvent power (IKB at 25 ° C) 31 10 Solubility of water (ppm) 110 50

O.D.P. 0.78 0

  The cleaning techniques using F113 or F141b, as well as the various compositions based on F 113 or F 141b implemented for these

  applications, are well known to those skilled in the art and are described in the literature.

  ture. Therefore, for the practice of the present invention, it is sufficient for one skilled in the art to replace F113 or F141b by the same amount in

  hydrofluoroalkene of formula (I), preferably 1,1,3,3,5,5, 6,6,6-

nonafluorohex-1-ene.

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  As in the case of F113 or F141b, hydrofluoroalkenes form

  mule (I) can be used alone, mixed with one another or mixed with other organic solvents which are liquid at room temperature, for example with alcohols, such as methanol, ethanol and isopropanol, and ketones such as acetone, esters such as methyl or ethyl acetate and ethyl formate,

  chlorinated or non-chlorinated hydrocarbons such as methylene chloride, 2-methylpentane

  tane, 2,3-dimethylbutane, n-hexane and hexene-1.

  Particularly interesting mixtures for net operations

  are the azeotropic or near-azeotropic compositions formed by 0o 1,1,3,3,5,5,6,6,6-nonafluorohex-1-ene with linear or branched alcohols containing from 1 to 8 carbon atoms. carbon such as methanol, ethanol, propanol, isopropanol, butanol, secondary butanol, isobutanol, pentanol, alcohol

amyl or isoamyl.

  As in the known cleaning compositions based on F113 or F141b, the hydrofluoroalkene-based cleaning compositions according to the invention

  can, if desired, be stabilized against hydrolysis and / or

  likely to occur in the cleaning process, by adding a

  conventional stabilizer such as, for example, a nitroalkane (nitromethane, nitroethane,

  tropropane ...) or an acetal, the proportion of stabilizer can range from 0.01 to 5%

  relative to the total weight of the composition.

  The following examples illustrate the invention without limiting it.

  EXAMPLE 1 Azeotrope C2FsCH2-CF2-CH = CF2 / Methanol a) Demonstration of the Azeotrope In the boiler of a distillation column (30 trays), 100 g

  of the compound C2F5-CH2-CF2-CH = CF2 and 100 g of methanol. The mixture is

  then put total reflux for an hour to bring the system to equilibrium. At the temperature step (55.5 C), a fraction of about 40 g is collected.

  analysis by gas chromatography.

  The examination of the results, recorded in the following table, indicates the

  sence of C2F5CH2-CF2-CH = CF2 / Methanol azeotrope.

Composition (% by weight)

C2F5, CH2-CF2-CH = CF2 CH3OH

  Initial mix 50 50 Fraction collected at 55.5 C 84.6 15.4 d -4- b) Verification of the azeotropic composition

  In the boiler of an adiabatic distillation column (30 trays),

  produced 200 g of a mixture comprising 84.5% by weight of C2F5CH2-CF2CH = CF2 and 15.5% by weight of methanol. The mixture is then refluxed for one hour to bring the system to equilibrium, then a fraction of about 50 g is withdrawn and analyzed by gas chromatography and that of the distillation foot. The results recorded in the following table

  show the presence of an azeotrope.

  Composition (weight) C2FsCH? -CF? -CH = CF2 CHIOH Initial mixture 84.5 15.5 Fraction collected 84.6 15.4 Distillation foot 84.5 15.5 Boiling temperature corrected for 1.013 bar: 55, 5 C

  This azeotrope, used for cleaning weld flux or degreasing

  wise mechanical parts, gives good results.

EXAMPLES 2 to 8

  The procedure is as in Example 1, but replacing the methanol with other alcohols. The following table shows the boiling temperature at the pressure

  normal (1.013 bar) and the composition of the azeotropes.

  Weight Composition of Azeotrope Eb Alcohol (%) Ex C2FsC H2-CF2-CH = CF2 Alcohol (C) 2 Ethanol 87.9 12.1 63.8 3 1-Propanol 84.7 15.3 70.3 4 Isopropanol 87 13 66.9 Isobutanol 96.2 3.8 73.9 6 Tertiobutanol 85.1 14.9 68.2 7 2-Butanol 94 6 72.5 8 2-Methyl-2-butanol 97 3 74.1 - EXAMPLE 9 Stabilized composition In an ultrasonic cleaning tank, 150 g of a mixture containing by weight 93% of C2F5CH2-CF2-CH = CF2, 6% of 2-butanol and 1% of nitromethane as stabilizer are introduced. . After refluxing the system for one hour, an aliquot of the vapor phase is taken. His analysis, by gas chromatography, shows the presence of nitromethane, which indicates that the

  mixture is stabilized in the vapor phase.

  I | Composition (% by weight) C2F5CH2'CF2-CH = CF2 2-Butanol CH3NO2 Initial mixing 93 6 1 Steam phase 93.15 6 0, 85 o EXAMPLE 10: Welding flux cleaning In a small single-tank laboratory machine equipped with An ultrasonic generator is charged with 125 ml of the azeotropic composition of Example 1, and then

  bring the liquid to the boil.

  Five standardized test circuits (model IPC-B-25), coated with rosin-based solder flux (R8F flux from ALPHAMETAL), annealed at 230 ° C for

  seconds and cooled, are immersed for 3 minutes in the boiling liquid.

  under ultrasound, then rinsed in the vapor phase for 3 minutes.

  After air drying, the quality of the cleaning is evaluated by determining the ionic residue content according to the standardized procedure IPC-TM 650 n 2.3.25 and 2.3.26 and according to the MIL-STD-2000 standard. The value obtained, 1.79 pg eq.NaCl / cm 2, is very

  below the threshold (2.5 μg eq NaCl / cm 2) tolerated in the field of electronics.

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Claims (8)

  1. Application of a hydrofluoroalkene of general formula: RF- (CH2-CF2) n -CH = CF2 (1) in which n is 1 or 2 and RF represents a perfluoroalkyl radical, linear or branched, containing from 1 to 3 carbon atoms, as agent of cleaning of solid surfaces.   The use according to claim 1, wherein the hydrofluoroalkene is   1,1,3,3,5,5,6,6,6-nonafluorohex-1-ene.   3. Composition for cleaning solid surfaces, characterized in that it consists of a mixture of a hydrofluoroalkene according to claim 1 or 2   with at least one organic solvent liquid at room temperature.   4. Composition according to claim 3 wherein the solvent is chosen   among alcohols, ketones, esters and chlorinated or non-chlorinated hydrocarbons.   5. Composition according to claim 4 consisting of 1,1,3,3,5,5,6,6,6-   nonafluorohex-1-ene and alcohol, linear or branched, containing from 1 to 8 carbon atoms.   6. Composition according to one of claims 3 to 5, further comprising at least one stabilizer.   The composition of claim 6, wherein the stabilizer is a nitroalkane or an acetal.   The composition of claim 6 or 7, wherein the proportion of   stabilizer is from 0.01 to 5% relative to the total weight of the composition.