EP0378140B1 - Cleaning compositions - Google Patents

Abstract

The cleaning compositions are based on hydrochlorofluorocarbons, alkanols and esters from the group comprising methyl propionate, ethyl propionate and ethyl acetate. The compositions may optionally contain further additives and are outstandingly suitable for industrial cleaning processes or for steam degreasing, in particular, for example, for removing resin solder fluxes with a high activator content.

Description

The present invention relates to improved cleaning compositions based on chlorofluorocarbons, alkanols and esters from the group of ethyl propionate, methyl propionate and ethyl acetate.

It is generally known to use mixtures of chlorofluorocarbons (as main solvent) with a cosolvent in addition to pure chlorinated and / or fluorinated hydrocarbons for industrial cleaning processes or for steam degreasing. Such mixtures can be both non-azeotropic and azeotropic or azeotrope-like. Azeotrope-like is understood here to mean that mixtures boil substantially constantly over a larger concentration range (change in boiling temperature by no more than 5 ° C.) and therefore behave similarly to azeotropes for practical use.

Many efforts have been made to achieve cleaning compositions with the desired properties. For example, it is known from DE-OS 29 42 799 to use mixtures of trichlorotrifluoroethane with ethanol and methyl acetate to remove resin soldering fluxes.

The known mixtures, however, are still in need of improvement in their application properties. In particular, in connection with the technical developments in the field of fluxes, new requirements have arisen with regard to the removal of these newly developed fluxes. These requirements are not always or often only satisfactorily met by the known solvent mixtures. There is therefore a need for new solvent mixtures with new, special properties.

The object was therefore to provide new solvent mixtures which overcome the disadvantages of the prior art and which are particularly well suited to removing modern fluxes.

The object is achieved by the compositions according to the invention, the uses and methods according to the invention.

The invention relates to compositions which are 98.9 to 45% by weight of a chlorofluorocarbon having 1 to 3 carbon atoms, 1.0 to 50% by weight of an alkanol having 1 to 4 carbon atoms and Mark 0.1 to 5 wt .-% of an ester from the group ethyl propionate, methyl propionate or ethyl acetate. The chlorofluorocarbon component in the compositions according to the invention can also be a mixture of different chlorofluorocarbons with 1 to 3 carbon atoms. Likewise, the ester component in the compositions according to the invention can also be a mixture of the above-mentioned esters.

In a sub-variant of the invention, the compositions are characterized in that they contain 97.5 to 89.0% by weight of the chlorofluorocarbon, 2.0 to 8.0% by weight of the alkanol and 0.5 to 3.0% by weight. -% of the ester included.

Preferred chlorofluorocarbons are those which boil at normal pressure in the temperature range from + 20 ° C. to + 120 ° C. These are known as such and can be found, for example, in Kaltron ^R paperback, Kali-Chemie AG, 6th ed. 1978, pages 14 to 16. Appropriately are especially chlorofluorocarbons with 1 to 2 carbon atoms, which are selected from the group trichlorofluoromethane, tetrachlorodifluoroethane, trichlorotrifluoroethane, tetrachloromonofluoroethane, trichlorodifluoroethane, dichlorotrifluoroethane, dichlorodifluoroethane and dichloromonane. Compositions with trichlorofluoromethane, tetrachlorodifluoroethanes, trichlorotrifluoroethanes, dichlorotrifluoroethanes and dichloromonofluoroethanes are preferred.

Tetrachlorodifluoroethanes in the sense of the invention are the isomeric chlorofluorocarbons of the empirical formula CCl₄F₂. It is therefore the chlorofluorocarbon 1,1,2,2-tetrachloro-1,2-difluoroethane (R112) and the isomeric 1,1,1,2-tetrachloro-2,2-difluoroethane (R112a) or their mixtures .

Trichlorotrifluoroethanes in the sense of the invention are the isomeric chlorofluorocarbons of the empirical formula C₂Cl₃F₃. It is therefore the chlorofluorocarbon 1,1,2-trichloro-1,2,2-trifluoroethane (R113) and the isomeric 1,1,1-trichloro-2,2,2-trifluoroethane (R113a) or their mixtures .

Tetrachloromonofluoroethanes in the sense of the invention are the chlorofluorocarbons bearing a hydrogen atom of the empirical formula C₂HCl₄F. These are the two non-fully halogenated isomeric chlorofluorocarbons 1,1,2,2-tetrachloro-2-fluoroethane (R121) and 1,1,1,2-tetrachloro-2-fluoroethane (R121a) or their mixtures.

Trichlorodifluoroethanes in the sense of the invention are the chlorofluorocarbons carrying a hydrogen atom of the empirical formula C₂HCl₃F₂. These are the three non-fully halogenated isomeric chlorofluorocarbons 1,1,2-trichloro-2,2-difluoroethane (R122), 1,1,2-trichloro-1,2-difluoroethane (R122a) and 1.1.1 -Trichlor-2,2-difluoroethane (R122b) or their mixtures.

Dichlorotrifluoroethanes in the sense of the invention are the chlorofluorocarbons bearing a hydrogen atom of the empirical formula C₂HCl₂F₃. These are the three not fully halogenated isomeric chlorofluorocarbons 1,1-dichloro-2,2,2-trifluoroethane (R123), 1,2-dichloro-1,1,2-trifluoroethane (R123a) and 1,1-dichloro -1,2,2-trifluoroethane (R123b) or their mixtures.

Dichlorodifluoroethanes in the sense of the invention are the chlorofluorocarbons carrying a hydrogen atom of the empirical formula C₂H₂Cl₂F₂. It is therefore the four not fully halogenated isomeric chlorofluorocarbons 1,2-dichloro-1,2-difluoroethane (R132), 1,1-dichloro-2,2-difluoroethane (132a), 1,2-dichloro-1,1 -difluoroethane (R132b) and 1,1-dichloro-1,2-difluoroethane (R132c) or their mixtures.

Dichloromonofluoroethanes in the sense of the invention are the chlorofluorocarbons bearing a hydrogen atom of the empirical formula C₂H₃Cl₂F. These are the three not fully halogenated isomeric chlorofluorocarbons 1,2-dichloro-1-fluoroethane (R141), 1,1-dichloro-2-fluoroethane (R141a) and 1,1-dichloro-1-fluoroethane (R141b) and their mixtures.

Particularly preferred compositions contain trichlorofluoromethane (R11), 1,1,2,2-tetrachloro-1,2-difluoroethane (R112), 1,1,2-trichloro-1,2,2-trifluoroethane (R113), 1 as the chlorofluorocarbon , 1,2,2-tetrachloro-2-fluoroethane (R121), 1,1,2-trichloro-2,2-difluoroethane (R122), 1,1-dichloro-2,2,2-trifluoroethane (R123), 1,2-dichloro-1,2-difluoroethane (R132) and 1,1-dichloro-1-fluoroethane (R141b). For example, 1,1,2-trichloro-1,2,2-trifluoroethane (R113) has proven particularly favorable. But also compositions with 1,1-dichloro-1-fluoroethane (R141b), 1,1-dichloro-2,2,2-trifluoroethane (R123), 1,1,2,2-tetrachloro-1,2-difluoroethane (R112) or trichlorofluoromethane (R11) give very good results.

The alkanols with 1 to 4 carbon atoms used in the compositions according to the invention are selected from the group consisting of methanol, ethanol, i-propanol, n-propanol, n-butanol, sec. Butanol and tert. Butanol, preferably methanol, ethanol and i-propanol. Ethanol has proven to be particularly cheap. But methanol or isopropanol are also well suited.

In a very advantageous embodiment of the compositions according to the invention, they are characterized by an azeotrope-like behavior and a content of approximately 94.2% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane, 3.5% by weight Ethanol and 2.3% by weight of ethyl acetate.

The compositions according to the invention are clear solutions at room temperature, to which additives known per se can be added.

A group of additives known per se are stabilizers. This group includes those compounds which prevent an undesired reaction of constituents of the composition with one another or with other reactants, such as, for example, atmospheric oxygen, water, metal, etc. Known stabilizers are, for example, nitroalkanes, especially nitromethane, nitroethane, alkylene oxides, especially butylene oxide, or branched alkynols such as e.g. 2-methylbutin (3) ol (2). These stabilizers can be used alone or in combination with one another, amounts of 0.01 to 5% by weight, preferably 0.05 to 1% by weight, based on the mixture as a whole, being very suitable.

Another group of additives includes known compounds from the group of corrosion inhibitors, nonionic or ionic emulsifiers and dyes.

The above compositions have numerous uses in the cleaning and / or steam degreasing sector. In these methods known per se, the object to be cleaned is immersed in one or more stages in liquid and / or vaporous cleaning mixture or sprayed with liquid cleaning mixture. The cleaning effect can be increased in known processes by using elevated temperature and / or ultrasound and / or stirring. Also an improvement of the cleaning effect through mechanical action, e.g. Brushing, known.

For example, the electronics industry for soldering processes predominantly uses organic resin fluxes, the excess of which must be removed from printed circuit boards after the soldering process. This is done with organic solvents that are compatible with the printed circuit boards and the electronic parts, ie the solvent must not react with them. The resin fluxes to be removed are mixtures of polar and non-polar compounds and often also contain special activators. Fluorinated hydrocarbons alone, which are not polar, are not effective in removing the polar components of the resins. Mixtures known per se which, in addition to fluorinated hydrocarbons, contain an alcohol are likewise not able to completely remove, in particular, special fluxes containing high activators. However, the compositions of the present invention can remove both the polar and the non-polar components and are therefore broadly effective as a resin flux removal agent, particularly those with a high activator content. Compositions of R113 / ethanol / ethyl acetate are particularly suitable for this application, in particular in an azeotrope-like composition of 94.2% / 3.5% / 2.3%. However, other compositions of R113, for example also with the alcohols methanol or isopropanol and an ester from the group ethyl propionate, methyl propionate or ethyl acetate, show very good results, as well as compositions according to the invention with R141b, R123, R112 or R11.

Thus, bare and populated (in particular also SMD-tipped) printed circuit boards can be easily cleaned with the compositions according to the invention even when using fluxes with a high activator content, without the "white deposits" feared when using the usual cleaning agents.

The new compositions according to the invention are also desirable systems for coolants and lubricants because the compositions have a low surface tension, a low viscosity and for the most part a high density of about 1.4 to 1.6 g / cm³ at 20 ° C . The above physical properties are those that are desirable for lubricant applications. For example, the compositions of the invention are desirable when the mixture is used as a lubricant in metalworking machines, e.g. when drilling, milling, turning, tapping, punching or the like, where a residue-free surface is required. For these applications, lubricant additives known per se (such as described in DE-OS 33 42 852 or DE-OS 33 35 870) can also be added.

The low surface tension, the high wettability and density of the compositions according to the invention make them particularly suitable for cleaning capillary systems.

• zur Reinigung von Kleinteilen bzw. Schüttgut (vorzugsweise in geschlossenen Anlagen),
• zum Strippen von Lack,
• als spezielles Lösungs-, Extraktions- und/oder Umkristallisationsmittel in der chemischen und pharmazeutischen Industrie.

The compositions according to the invention can also be used, for example, as follows:

• for cleaning small parts or bulk goods (preferably in closed systems),
• for stripping paint,
• as a special solvent, extraction and / or recrystallization agent in the chemical and pharmaceutical industry.

As mentioned at the beginning, cleaning compositions are already known from DE-OS 29 42 799 which contain 1,1,2-trichloro-1,2,2-trifluoroethane as the chlorofluorocarbon, ethanol as the alkanol and methyl acetate as the ester, and those for removal of resin solder fluxes are used. However, the use of these methyl acetate-containing compositions does not always guarantee the very high degree of purity that is found in special fields of application, e.g. when cleaning components and printed circuit boards in the electronic industry. Their properties are therefore in some cases just as inadequate as the chlorofluorocarbon / alkanol compositions known in the prior art without an additive such as methyl acetate. It is therefore all the more surprising that the new mixtures according to the invention which contain chlorofluorocarbons, alkanols and, as an additive, the esters ethyl propionate, methyl propionate or ethyl acetate have superior cleaning properties and are very suitable for the applications mentioned. The mixtures according to the invention enable new solutions to problems in a wide range of applications. In particular, e.g. also mixtures of 1,1,2-trichloro-1,2,2-trifluoroethane (R113), ethanol and ethyl acetate (see Table 1, No. 15, boiling point approx. 44.3 ° C) or of 1.1, 2-trichloro-1,2,2-trifluoroethane (R113), ethanol and ethyl acetate / methyl propionate (see Table 1, No. 14, boiling point approx. 45.6 ° C) no flash points (open cup method).

The following examples are intended to explain the invention in greater detail, but without restricting its scope. Unless otherwise stated,% are always percent by weight.

Example 1: Cleaning printed circuit boards

In a commercial 2 or. 3-chamber cleaning system, cleaning tests were carried out with printed circuit boards that were contaminated with solder flux containing a high level of activator. The cleaning compositions, cleaning conditions and cleaning results are shown in Table 1.

In the cases marked "++" in the "Result" column, a very good cleaning effect was achieved in the cases marked "+" and no "white deposits" were formed. In the cases marked with "-", "white deposits" were formed.

It is clearly visible that the compositions according to the invention (experiments 1 to 8, 11, 12, 14, 15, 19, 21, 22, 24 to 26) correspond to the mixtures according to the prior art (experiments 9, 10, 13, 16 to 18, 20 and 23) are superior.

Example 2: Cleaning bulk goods

Bulk material (transistor caps) were cleaned to remove drawing oils in a 2-chamber system (3 minutes of ultrasound, 1 minute of steam degreasing) with an azeotrope-like mixture of 94.2% R113, 3.5% ethanol and 2.3% ethyl acetate . After treatment, the bulk goods were perfectly clean.

Claims (10)

1. Compositions, characterised by a content of 98.9 to 45% by weight of at least one fluorochlorohydrocarbon with 1 to 3 C atoms, 1.0 to 50% by weight of an alkanol with 1 to 4 C atoms and 0.1 to 5% by weight of an ester of the group ethyl propionate, methyl propionate or ethyl acetate, or a mixture of the afore-mentioned esters.
2. Compositions according to Claim 1, characterised in that they contain 97.5 to 89.0% by weight of the fluorochlorohydrocarbon, 2.0 to 8.0% by weight of the alkanol and 0.5 to 3% by weight of the ester.
3. Compositions according to Claim 1 or 2, characterised in that the fluorochlorohydrocarbon in itself has a boiling point in the range of 20°C to 120°C.
4. Compositions according to one of the preceding Claims, characterised in that a fluorochlorohydrocarbon with 1 to 2 C atoms is selected from the group trichlorofluoromethane, tetrachlorodifluoroethanes, trichlorotrifluoroethanes, tetrachloromonofluoroethanes, trichlorodifluoroethanes, dichlorotrifluoroethanes, dichlorodifluoroethanes and dichloromonofluoroethanes, preferably from the group trichlorofluoromethane, tetrachlorodifluoroethanes, trichlorotrifluoroethanes, dichlorotrifluoroethanes and dichloromonofluoroethanes.
5. Compositions according to one of the preceding Claims, characterised in that the fluorochlorohydrocarbon with 1 or 2 C atoms is selected from the group trichlorofluoromethane (R11), 1,1,2,2-tetrachloro-1,2-difluoroethane (R112), 1,1,2-trichloro-1,2,2-trifluoroethane (R113), 1,1,2,2-tetrachloro-2-fluoroethane (R121), 1,1,2-trichloro-2,2-difluoroethane (R122), 1,1-dichloro-2,2,2-trifluoroethane (R123), 1,2-dichloro-1,2-difluoroethane (R132) and 1,1-dichloro-1-fluoroethane (R141b).
6. Compositions according to one of the preceding Claims, characterised in that the alkanol is selected from the group methanol, ethanol, i-propanol, n-propanol, n-butanol, sec. butanol and tert. butanol, preferably methanol, ethanol and i-propanol.
7. Compositions according to one of the preceding Claims, characterised by an azeotrope-like composition of approximately 94.2% by weight 1,1,2-trichloro-1,2,2-trifluoroethane (R113), 3.5% by weight ethanol and 2.3% by weight ethyl acetate.
8. Compositions according to one of the preceding Claims, characterised by an additional content of stabiliser of 0.01 to 5% by weight, preferably 0.05 to 1% by weight, relative to the entire mixture, preferably from the group nitroalkane, alkylene oxide and/or alkinol.
9. Use of the compositions according to one of the preceding Claims in immersion and/or spray cleaning processes or in vapour de-greasing.
10. Process for cleaning surfaces, characterised in that the surfaces, preferably surfaces to be cleaned of printed circuit boards contaminated with soldering flux or residues of soldering flux, are treated with compositions according to one of Claims 1 to 8.