EP0443911B1 - Use of (perfluoroalkyl)-ethylenes as cleaning or drying agents - Google Patents

Abstract

To replace 1,1,2-trichloro-1,2,2-trifluoroethane (F113) in its applications to the cleaning and drying of solid surfaces, the invention propose to employ a (perfluoroalkyl) ethylene of formula: RfCH=CH2 in which Rf denotes a linear or branched perfluoroalkyl radical containing from 3 to 6 carbon atoms. In contrast to F113, (perfluoroalkyl)ethylenes are not liable to degrade stratospheric ozone.

Description

The present invention relates to the field of fluorinated hydrocarbons and more particularly relates to the use of (perfluoroalkyl) -ethylenes as cleaning or drying agents for solid surfaces.

Due to its physicochemical characteristics, in particular its non-flammability, its high wetting power, its low solvent power and its low boiling point, 1,1,2-trichloro-1,2,2-trifluoroethane (known in the art under the designation F113) is currently widely used in industry for cleaning and degreasing a wide variety of solid surfaces (metal parts, glass, plastic or composites). In electronics, the F113 has notably found an important application in defluxing and cold cleaning of printed circuits. Other examples of applications of F113 include the degreasing of metal parts and the cleaning of high quality and high precision mechanical parts such as, for example, gyroscopes and military, aerospace or medical equipment. In its various applications, F113 is often combined with other organic solvents (for example methanol), in particular in the form of azeotropic or pseudo-azeotropic mixtures which do not demix and which, when used at reflux, have substantially the same composition in the vapor phase than in the liquid phase.

F113 is also used in industry for drying various solid substrates (metal parts, plastics, composites or glasses) after cleaning in an aqueous medium. In this application, intended to remove the water remaining on the surface of the cleaned substrates, F113 is often added with one or more surfactants (see in particular the patents FR 2 353 625, FR 2 527 625, EP 0 090 677 and 0 189 436 and the references cited in these patents).

Unfortunately, F113 is one of the completely halogenated chlorofluorocarbons that are currently suspected attack or degrade stratospheric ozone. We are therefore looking for products devoid of any destructive effect with respect to ozone and capable of replacing F113 in its various applications.

It has now been found that the (perfluoroalkyl) -ethylene of formula



R _F -CH = CH₂ (I)



in which R _F represents a perfluoroalkyl radical, linear or branched, containing from 3 to 6 carbon atoms, have physicochemical characteristics similar to those of F113 and, unlike the latter, are not likely to degrade stratospheric ozone.

In addition, these compounds are particularly stable to oxidation and do not damage plastics (polystyrene, ABS, ...) or elastomers such as ethylene-propylene copolymers.

The subject of the invention is therefore the use of a (perfluoroalkyl) -ethylene of formula (I) as a substitute for F113 in the various applications of the latter. Also part of the present invention, the cleaning or drying compositions based on a (perfluoroalkyl) -ethylene.

• l'addition d'éthylène sur l'iodure de perfluoroalkyle R_FI correspondant en présence d'un catalyseur à base de cuivre et d'éthanolamine, et
• la déhydroiodation du iodure R_F-CH₂CH₂I ainsi obtenu, en présence de potasse alcoolique.

The compounds of formula (I) can be obtained industrially by methods known per se, for example by a two-step process successively consisting of:

• the addition of ethylene to the corresponding perfluoroalkyl iodide R _F I in the presence of a catalyst based on copper and ethanolamine, and
• dehydroiodination of iodide R _F -CH₂CH₂I thus obtained, in the presence of alcoholic potassium hydroxide.

Among the compounds of formula (I) according to the invention, more particularly preferred is (n.perfluorobutyl) -ethylene C₄F₉-CH = CH₂ which, as indicated in the following table, has characteristics very close to those of F113, except with regard to the ozone depletion potential (ODP: ozone-depletion potential).

The cleaning or drying techniques using F113, as well as the various compositions based on F113 used for these applications, are well known to those skilled in the art and are described in the literature. Consequently, for the implementation of the present invention, it is sufficient for a person skilled in the art to replace F113 with substantially the same amount by volume of a (perfluoroalkyl) -ethylene of formula (I), preferably ( n.perfluorobutyl) -ethylene C₄F₉CH = CH₂.

As in the case of F113, the (perfluoroalkyl) -ethylene of formula (I) can be used alone or as a mixture with one another or with other organic solvents which are liquid at room temperature, for example with alcohols such as methanol, ethanol, and isopropanol, ketones like acetone, esters like methyl or ethyl acetate and ethyl formate, ethers like methyl tert-butyl ether and tetrahydrofuran, acetals like dimethoxy- 1.1 ethane and 1,3-dioxolane, chlorinated or non-chlorinated hydrocarbons such as methylene chloride, trichlorethylene and 1,1,1 trichloroethane, 2-methyl pentane, 2,3-dimethyl butane, n.hexane and hexene-1.

A particularly interesting mixture for cleaning operations is that which comprises by weight from 85 to 98% of the compound C₄F₉CH = CH₂ and from 2 to 15% of methanol. In this area, there is indeed an azeotrope whose boiling temperature is 46.3 ° C at normal atmospheric pressure (1.013 bar) and the mixture has a pseudo-azeotropic behavior, that is to say that the composition of the vapor and liquid phases is substantially the same, which is particularly advantageous for the intended applications. Preferably, the content of compound C₄F₉CH = CH₂ is chosen between 90 and 95% by weight and that of methanol between 5 and 10% by weight. Such a mixture also has the significant advantage of not having a flash point under the standard conditions of determination (standard ASTM-D 3828) and is therefore non-flammable. The azeotrope C₄F₉CH = CH₂ / methanol is a positive azeotrope since its boiling point (46.3 ° C) is lower than those of the two constituents (C₄F₉CH = CH₂: 59 ° C and methanol: 65 ° C).

• . C₄F₉CH = CH₂ (91 à 98 %) + isopropanol (9 à 2 %)
• . C₄F₉CH = CH₂ (41 à 51 %) + chlorure de méthylène (59 à 49 %)
• . C₄F₉CH = CH₂ (89 à 97 %) + trichloroéthylène (11 à 3 %)
• . C₄F₉CH = CH₂ (83 à 90 %) + 1,3-dioxolanne (17 à 10 %)
• . C₄F₉CH = CH₂ (84,8 à 97,8 %) + méthanol (15 à 2 %) + acétate de méthyle (0,2 à 2,2 %)
• . C₄F₉CH = CH₂ (90 à 98 %) + isopropanol (9 à 1 %) + 1,3-dioxolanne (1 à 7 %)
• . C₄F₉CH = CH₂ (90,95 à 97,95 %) + isopropanol (9 à 2 %) + diméthoxy-1,1 éthane (0,05 à 1 %)

   Comme dans les compositions de nettoyage connues à base de F113, les compositions de nettoyage à base de (perfluoroalkyl)-éthylène selon l'invention peuvent, si on le désire, être stabilisées contre l'hydrolyse et/ou les attaques radicalaires susceptibles de survenir dans les processus de nettoyage, en y ajoutant un stabilisant usuel tel que, par exemple, un nitroalcane (nitrométhane, nitroéthane, ...) un oxyde d'alkylène (propylène, butylène, isoamylène, ...) ou un mélange de ces composés, la proportion de stabilisant pouvant aller de 0,01 à 5 % par rapport au poids total de la composition.Other examples of binary or ternary mixtures, which are particularly interesting, are the following (% by weight):

• . C₄F₉CH = CH₂ (91 to 98%) + isopropanol (9 to 2%)
• . C₄F₉CH = CH₂ (41 to 51%) + methylene chloride (59 to 49%)
• . C₄F₉CH = CH₂ (89 to 97%) + trichlorethylene (11 to 3%)
• . C₄F₉CH = CH₂ (83 to 90%) + 1,3-dioxolane (17 to 10%)
• . C₄F₉CH = CH₂ (84.8 to 97.8%) + methanol (15 to 2%) + methyl acetate (0.2 to 2.2%)
• . C₄F₉CH = CH₂ (90 to 98%) + isopropanol (9 to 1%) + 1,3-dioxolane (1 to 7%)
• . C₄F₉CH = CH₂ (90.95 to 97.95%) + isopropanol (9 to 2%) + dimethoxy-1.1 ethane (0.05 to 1%)

As in the known cleaning compositions based on F113, the cleaning compositions based on (perfluoroalkyl) -ethylene according to the invention can, if desired, be stabilized against hydrolysis and / or free radical attacks likely to occur. in cleaning processes, by adding a usual stabilizer such as, for example, a nitroalkane (nitromethane, nitroethane, ...) an alkylene oxide (propylene, butylene, isoamylene, ...) or a mixture of these compounds, the proportion of stabilizer can range from 0.01 to 5% relative to the total weight of the composition.

The ability of the (perfluoroalkyl) -ethylenes according to the invention to remove the water remaining on the surface of substrates after their cleaning in an aqueous medium has been demonstrated, compared to F113, by a test consisting in determining the quantity of water remaining on a wet support after immersion in the drying solvent. The test is carried out as follows:
A grid of 100% polyamide fabric weighing 8.4 mg / cm² and dimensions 5 x 2 cm is immersed in water for 30 seconds, then allowed to drip without stirring and then immersed for 10 seconds in 50 ml of absolute alcohol. The alcohol water concentration is then determined by the Karl-Fisher method and this concentration serves as a control.

The same grid is again immersed in water for 30 seconds, then allowed to drip without stirring and then immersed for 5 minutes under ultrasound in 50 ml of F113 or (n.perfluorobutyl) -ethylene. The grid is then immersed for 10 seconds in 50 ml of absolute alcohol and the water concentration of the alcohol is then measured as above. The results thus obtained are collated in the following table:

These results indicate that (n.perfluorobutyl) -ethylene eliminates water in much the same way as F113.

The compositions according to the invention containing (perfluoroalkyl) -ethylenes intended for drying (elimination of water) from the solid substrates after cleaning in an aqueous medium may contain, in a proportion ranging from 0.01 to 5% by by weight (preferably from 0.1 to 3%), the same additives as the drying compositions based on F113. These well known additives are generally surface-active agents such as, for example, mono- or dialkylphosphates of amines, salts of the dioleate type of N-oleylpropylenediamine, diamides of the dioleyl-oleylamidopropyleneamide type, cationic compounds derived from l imidazoline, or compounds resulting from the reaction of a quaternary ammonium hydrochloride with an alkylphosphoric acid in the presence of a fluorinated amine or not.

The following examples illustrate the invention without limiting it.

a) Demonstration of the azeotrope

100 g of (n.perfluorobutyl) -ethylene and 100 g of methanol are introduced into the boiler of a distillation column (30 trays). The mixture is then put under total reflux for one hour to bring the system to equilibrium. At the temperature level (46.3 ° C), a fraction of about 50 g is collected which is analyzed by gas chromatography.

Examination of the results, recorded in the following table, indicates the presence of an azeotrope C₄F₉CH = CH₂ / methanol.

b) Verification of the azeotropic composition

200 g of a mixture comprising 92% by weight of C₄F₉CH = CH₂ and 8% by weight of methanol are introduced into the boiler of an adiabatic distillation column (30 trays). The mixture is then brought to reflux for one hour to bring the system to equilibrium, then a fraction of approximately 50 g and its analysis is carried out by gas chromatography as well as that of the distillation bottom. The results recorded in the following table show the presence of a positive azeotrope since its boiling point is lower than those of the two pure constituents: C₄F₉CH = CH₂ and methanol.

This azeotrope, used for cleaning solder flux or degreasing mechanical parts, gives good results.

150 g of a mixture containing by weight 91.9% of C₄F₉CH = CH₂, 8% of methanol, and 0.1% of nitromethane as stabilizer are introduced into an ultrasonic cleaning tank. After putting the system at reflux for one hour, an aliquat of the vapor phase is removed. Its analysis by gas chromatography shows the presence of nitromethane which indicates that the mixture is stabilized in the vapor phase.

If example 2 is repeated, replacing the nitromethane with propylene oxide, the following results are obtained:

Example 2 is repeated using 0.1% nitromethane and 0.1% propylene oxide. The following results are obtained:

200 g of the azeotropic composition C₄F₉CH = CH₂ / methanol are introduced into an Annemasse ultrasonic tank, then the mixture is brought to the boiling temperature.

Printed circuits coated with solder flux and annealed in an oven for 30 seconds at 220 ° C, are immersed for 3 minutes in the boiling liquid under ultrasound, then rinsed in the vapor phase for 3 minutes.

After air drying, there is a total absence of solder flux residue.

The procedure is as in Example 1, but replacing the methanol with other solvents. The following table shows the normal boiling point (at 1.013 bar) and the composition of the azeotropes.

In a distillation column (30 trays) we introduce 200 g of the azeotropic composition C₄F₉CH = CH₂ / methanol from Example 1 and 50 g of a third solvent. The mixture is then put under total reflux for one hour to bring the system to equilibrium, then an aliquat of the condensed phase is withdrawn at the temperature level and analyzed by gas chromatography.

The boiling temperatures observed for the ternary compositions are lower than those of the azeotrope C₄F₉CH = CH₂ / methanol, which indicates that we are in the presence of ternary azeotropes whose weight composition and normal boiling point (at 1.013 bar) are collated in the following table:

The composition and normal boiling point of three other ternary azeotropes are shown in the following table.

The procedure is as in Example 1, but by replacing C₄F₉CH = CH₂ by C₆F₁₃CH = CH₂ or by iso-C₃F₇CH = CH₂ and optionally by replacing methanol with ethanol or isopropanol.

The weight composition and the normal boiling point of the azeotropes are indicated in the following table:

Claims (18)

1. Application of a (perfluoroalkyl)ethylene of formula:
   
   
   
           R_FCH=CH₂   (I)
   
   
   
   in which R_F denotes a linear or branched perfluoroalkyl radical containing from 3 to 6 carbon atoms, as a cleaning or drying agent for solid surfaces.
2. Application according to Claim 1, in which the compound of formula (I) is (n-perfluorobutyl)ethylene C₄F₉CH=CH₂.
3. Composition for cleaning solid surfaces, characterized in that it consists of a mixture of a (perfluoroalkyl)ethylene according to Claim 1 or 2 with at least one organic solvent chosen from alcohols, ketones, esters, ethers, acetals and chlorinated or unchlorinated hydrocarbons.
4. Composition according to Claim 3, comprising from 85 to 98 % by weight of (n-perfluorobutyl)ethylene and from 2 to 15 % of methanol.
5. Composition according to Claim 4, containing from 90 to 95 % by weight of (n-perfluorobutyl)ethylene and from 5 to 10 % of methanol.
6. Composition according to Claim 4 in the form of an azeotrope boiling at 46.3°C at normal atmospheric pressure.
7. Composition according to Claim 3, comprising 91 to 98 % by weight of (n-perfluorobutyl)ethylene and 2 to 9 % of isopropanol.
8. Composition according to Claim 3, comprising 41 to 51 % by weight of (n-perfluorobutyl)ethylene and 49 to 59 % of methylene chloride.
9. Composition according to Claim 3, comprising 89 to 97 % by weight of (n-perfluorobutyl)ethylene and 3 to 11 % of trichloroethylene.
10. Composition according to Claim 3, comprising 83 to 90 % by weight of (n-perfluorobutyl)ethylene and 10 to 17 % of 1,3-dioxolane.
11. Composition according to Claim 3, comprising 84.8 to 97.8 % by weight of (n-perfluorobutyl)ethylene, 2 to 15 % of methanol and 0.2 to 2.2 % of methyl acetate.
12. Composition according to Claim 3, comprising 90 to 98 % by weight of (n-perfluorobutyl)ethylene, 1 to 9 % of isopropanol and 1 to 7 % of 1,3-dioxolane.
13. Composition according to Claim 3, comprising 90.95 to 97.95 % by weight of (n-perfluorobutyl)ethylene, 2 to 9 % of isopropanol and 0.05 to 1 % of 1,1-dimethoxy-ethane.
14. Composition according to one of Claims 3 to 13, additionally comprising at least one stabilizer.
15. Composition according to Claim 14, in which the stabilizer is a nitroalkane, an alkylene oxide or a mixture of such compounds.
16. Composition according to Claim 14 or 15, in which the proportion of stabilizer is from 0.01 to 5 % of the total weight of the composition.
17. Composition for drying solid surfaces, characterized in that it consists of a mixture of (perfluoroalkyl)ethylene according to Claim 1 or 2 with at least one surface-active agent.
18. Composition according to Claim 17, in which the content of surface-active agent is from 0.01 to 5 % by weight, preferably 0.1 to 3 %.