WO1997032963A1

WO1997032963A1 - Method of cleaning objects

Info

Publication number: WO1997032963A1
Application number: PCT/EP1997/001192
Authority: WO
Inventors: Oskar K. Wack; Martin Hanek; Karsten Lessmann
Original assignee: Dr. O.K. Wack Chemie Gmbh
Priority date: 1996-03-08
Filing date: 1997-03-10
Publication date: 1997-09-12
Also published as: EP1191095A3; EP1191095B1; EP0885287A1; DE59710188D1; EP1191095A2

Abstract

The invention concerns a method of cleaning objects, according to which vapours produced by heating a liquid which has cleaning activity are brought into contact with the objects to be cleaned. The method is characterized in that an azeotropic preparation in the form of a mixture of water and at least one further component having molecules with hydrophilic and lipophilic groups is used as the liquid having cleaning activity. The further component(s) and the water form an azeotrope during the phase transition from the liquid to the vapour phase.

Description

Process for cleaning objects

The present invention relates to a method for cleaning objects and materials made of metal, glass, ceramic, plastic (s) or composite materials thereof or textiles.

Cleaning methods in which a vapor produced by heating a cleaning-active liquid is brought into contact with the objects to be cleaned are used for cleaning a wide variety of objects, such as metallic objects, industrially manufactured objects, such as printed circuit boards, articles of clothing, etc., of undesired ones Impurities such as greases, lapping and polishing pastes, soldering pastes, adhesives, mixtures of inorganic (for example salt-like) and organic (for example consisting of fat residues) dirt etc. Typically, chlorinated hydrocarbons have been used until recently for such cleaning tasks. Because of their lack of environmental compatibility, in particular because of their ozone depletion potential, their carcinogenicity and their toxic effect, these have now been banned or at least can only be used under very strict conditions. An advantage of using chlorinated hydrocarbons was that they do not have a flash point at temperatures which usually occur. Because of the above disadvantages, they have been replaced by other hydrocarbons or solvents such as polypropylene glycol ether, alcohols, acetone, etc. These have a flash point in the range of normally occurring temperatures and are therefore at risk of ignition. They also have a disadvantage in that they scarcely remove pigment dirt or dirt with ionic salts, since these solvents only very poorly dissolve pigments or salts owing to their ionic character. The invention was based on the object of developing a generic cleaning method in such a way that it can be carried out in an environmentally compatible manner while achieving a good cleaning effect.

A further object of the invention was to provide a new cleaning method with which mixtures of inorganic and organic dirt can be removed efficiently at the same time. Another object of the invention was to provide a method for cleaning objects and materials made of metal, which works more gently than previously known methods.

The above-mentioned objects are achieved with a method having the features of patent claim 1. Advantageous developments of the method according to the invention can be found in claims 2 to 19.

Azeotropic preparations which can be used according to the invention as cleaning-active liquids initially have the advantage that their liquid phase dissolves pigment dirt and dirt well with ionic components, for example salts, because of the water content, if the azeotropic preparation used as cleaning-active liquid is in liquid state with the objects to be cleaned comes into contact. The lipophilic group-containing molecules of the at least one further component, which is preferably a liquid in itself under ambient conditions or at low treatment temperatures, ensure good fat-dissolving power of the azeotropic preparation.

When the azeotropic preparation used as a cleaning-active liquid is heated, both water and the other (n.) Go because of their azeotropic character (because of the definition of "azeotrope": see Römpps Chemie Lexikon, 9th edition (1989), page 323) ) Component (s) in a composition corresponding to the special azeotrope into the vapor phase. In the event of contact between the vapor of the azeotropic preparation and the objects to be cleaned, a reliable cleaning and "rinsing" of all contaminations of the objects to be cleaned removed by the cleaning process takes place. It is particularly advantageous that the steam is not flammable because of its high water content. Protective measures in this regard in a device used to carry out the method according to the invention are superfluous. The flash point of the vapor, if such exists at all, is above the temperatures normally occurring in such a cleaning process, but at least above the sieving temperature of the liquid and advantageously above about 200 ° C. A flash point above 200 ° C. is particularly advantageous because the protective measures to be taken when carrying out the cleaning process are less extensive than when using cleaning-active liquids with lower flash points. The azeotropic preparation, which is present in vapor form at least in part of the process according to the invention, can be condensed either on the objects to be cleaned or by lowering the temperature to the liquid phase, so that complex measures for protecting the atmosphere surrounding the device for carrying out the process, such as they are required in conventional processes, can largely be avoided.

An additional advantage of the method according to the invention is therefore that the azeotropic preparation used as the cleaning-active liquid is hardly used because of its extensive back condensation. A closed circuit can thus be created, in which the azeotropic preparation used as a cleaning-active liquid does not have to be filled in or only in negligibly small amounts. This is additionally supported by the fact that the azeotropic preparation used as cleaning-active liquid according to the invention can be free of surfactants, which settle on the filter surface when the cleaning-active liquid is filtered for dirt removal in conventional processes and require re-sharpening in the case of conventionally used solutions .

Surprisingly, the method according to the invention also reliably removes complex types of dirt, such as dried-up body fluids or other dirt that occurs in everyday use, dirt caused by rain or snow, etc., from the objects to be cleaned. The method according to the invention is not restricted to closed systems. For example, it can also be carried out in the form of an open steam jet cleaning.

When selecting the azeotropic preparations according to the invention used as cleaning-active liquid or the further component (s) contained therein with molecules with hydrophilic (eg -OH, -NH ₂ , -COC-, -C (= O) -C- , -C (= O) -O etc.) groups and lipophilic (eg CH ₂ chains or Q- to C, _2- alkyl- etc.) groups stand in addition to the good cleaning power the following criteria: The water content of the azeotrope of water and further component or further components must be so large that there is no flash point or the steam is not combustible. The liquid and the steam formed from it by heating must neither be toxic nor have ozone depletion potential, nor may they pose a water hazard if the preparation accidentally gets into the environment. Water-soluble, homogeneous azeotrope-forming components or water-insoluble, heterogeneous azeotrope-forming components are suitable.

In a preferred embodiment, the method according to the invention for cleaning objects comprises the steps of

an azeotropic preparation of water and at least one component with molecules with hydrophilic and lipophilic groups in a weight ratio (component ^) with hydrophilic and lipophilic groups): water from 0.05 to 99.95: 99.95 to 0, 05 forms; brings the objects to be cleaned into contact with the azeotropic preparation at least once and allows the liquid azeotropic preparation including the contaminants removed therefrom to run off from the objects to be cleaned; Residues of the azeotropic preparation on or in the objects to be cleaned removed by evaporation; and the vapor of the azeotropic preparation is condensed and the azeotropic preparation recovered by condensation is used for a renewed cleaning step. It corresponds to a particularly preferred embodiment of the method according to the invention to bring the objects to be cleaned into contact with a vapor of the azeotropic preparation at least once and to allow the vapor of the azeotropic preparation to condense on the objects to be cleaned during the duration of the contact. For example, the objects to be cleaned can first be brought into contact with the liquid azeotropic preparation once or several times, for example by immersion, spraying, sprinkling or comparable methods of applying a liquid which are known per se from the prior art. The objects to be cleaned can then be brought into contact with the azeotropic preparation in the form of their vapor once or even several times. The vapor of the azeotropic preparation regularly condenses on the objects to be cleaned and, when it expires, entrains residues removed from the objects to be cleaned. As an alternative to this, however, the process according to the invention can be carried out by bringing the objects to be cleaned into contact with a vapor of the azeotropic preparation at least once, but preferably several times. Here too, the steam condenses on the objects to be cleaned for the duration of the contact and thereby removes the impurities.

According to a particularly preferred embodiment of the method, an azeotropic preparation of water and at least one component with molecules with hydrophilic and lipophilic groups is used, in which the weight ratio (component (s) with hydrophilic and lipophilic groups): water in the range of 1, 0 to 35.0: 99.0 to 65.0, more preferably in the range 4.0 to 15.0: 96.0 to 85.0.

It corresponds to a further preferred embodiment of the method according to the invention that an azeotropic preparation in the form of a mixture of water and at least one further component with molecules with hydrophilic and lipophilic groups is used as the cleaning-active liquid, the further (n) Component (s) and the water in the phase transition liquid phase / vapor phase form an azeotrope and the azeotrope an azeotrope with a miscibility gap at a temperature between 0 ° C. and the temperature of the Phase transition is liquid phase / vapor phase at normal pressure. Surprisingly, it has been found that azeotropes with gaps in the mixture have particularly advantageous cleaning properties. An azeotrope with a mixture gap at a temperature in the range from 20 ° C. and 110 ° C. at normal pressure is particularly preferably used.

In the description and in the claims, the term “at normal pressure” is understood to mean an atmospheric pressure (about 1 atm; about 10 ⁵ Pa).

Without being bound at this point to a theoretical interpretation of the invention, it has been found that azeotropic preparations which can be used as cleaning-active liquid in the process according to the invention are clear at low temperatures of, for example, 20 to 25 ° C. In other words: the components are completely detached from one another. At any temperature, there are defined ratios of the composition of the components in the mixing phase. The phases present separately at elevated temperature can be converted into a milky-looking emulsion by suitable process steps, preferably for example by sonication with ultrasound, by intensive agitation during pumping or stirring, etc. This emulsion has discontinuous droplets of the organic component (s) in a continuous aqueous phase. The emulsion has excellent fat-dissolving power due to its content of organic components (with molecules with lipophilic groups), but due to the continuous water phase also dissolves water-soluble, eg ionic, impurities, for example salts. If the temperature of the azeotropic preparation is increased further, it passes into the vapor phase in which the components are present in the special composition typical of the respective azeotrope. When condensing, the azeotropic preparation again migrates through the miscibility gap; the vapor of the azeotropic preparation which condenses on the objects to be cleaned is therefore again in the form of the emulsion which has excellent loose properties for both fatty and ionic impurities. In view of the criteria mentioned above, some organic components which form homogeneous azeotropes with water are preferred for use as organic components in the azeotropic preparations which are used to carry out the process according to the present invention. However, as will be readily apparent to those skilled in the art, the invention is not limited to the preferred azeotrope forming compounds.

The preferred compounds can best be described by the following general formula

R ¹ - [X] _n - R ³ wherein

R ¹ and R ³ each independently represent H; straight-chain or branched saturated or unsaturated C _r to C ₁₈ alkyl groups in which one or more non-adjacent -CH ₂ groups can be replaced by -O-; saturated or unge¬ saturated cyclic C, - to C ₈ - alkyl groups in which one or more non benach¬ disclosed -CH ₂ groups may be replaced by -O-; Hydroxy; C _r to C ₈ alkoxy; Amino, in which one or both of the hydrogens) can be replaced by C 1 -C ₈ -alkyl groups; and

X stands for -O-; -C (= O) -; -C (= O) -O-; -NH-; -NR ¹ -; -N (-OH) -; straight-chain or branched - (C _r to C ₈ -) alkylene groups in which one or more non-adjacent -CH ₂ groups can be replaced by -O-; and n stands for integers of 1, 2, 3, etc.

In other words: The organic components of the azeotropic preparations which are used in the process according to the present invention can be selected from organic compounds which belong to the groups alcohols, glycols, amines, ethers, glycol ethers, esters, ketones and amino alcohols as well as N-heterocycles or organic acids. In a particularly preferred procedure, compounds of the general formula given above are used as organic component (s) of the azeotropic preparation or as further organic component (s) in which R ¹ and R ³ each independently of one another are saturated or unsaturated C _r to C ₁₂ -alkyl groups, even more preferred for saturated or unsaturated C _r to C ₈ -alkyl groups, in which one or more non-adjacent CH ₂ group (s) can be replaced by -O-, for hydroxy, for C, - to C ₈ alkoxy and for unsubstituted or substituted by alkyl groups amino groups; and / or X represents -O-; -C (= O) -; -C (= O) -O-; -NH-; -NR ¹ -; -N (-OH) -; -OCH (R ² ) -CH ₂ - (wherein R ^{2 is} H or methyl); and n represents 1 or 2.

Specific examples of the groups represented by R ¹ and R ³ are hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, i-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, furfuryl-2, tetrahydrofuryl-2, hydroxy, methoxy, ethoxy and propoxy. Specific examples of the groups represented by X are -O-; -C (= O) -; -C (= O) -O-; -NH-; -NR ¹ -; -N (-OH) -; Ethyleneoxy and propyleneoxy.

Even more preferred methods according to the invention use compounds of the general formula given above as organic component (s) of the azeotropic preparations or as further organic component (s) which are selected from the group

(C _r to C ₁₂ alkyl) - C (= O) -O - (C _r to C ₁₂ alkyl);

(C _r to C ₁₂ alkyl) - O - (C _r to C ₁₂ alkyl);

(C _r to C ₁₂ alkyl) - C (= O) - (C _r to C ₁₂ alkyl);

(C _r -C ₂ - alkyl) - [N - (H or C _r to C _I2 - alkyl) (H or C _r to C ₁₂ - alkyl)];

HO- (CH ₂ ) _{1? 2, «} . - [NH ₂ or NH (C _r to C ₁₂ alkyl) or N (C _r to C, ₂ alkyl) ₂ ];

H - [O - CH (H or CH ₃ ) - CH ₂ ] _{,, 2> etc} - OH; and

(H or C _r to C ₁₂ alkyl) - [O - CH (H or CH ₃ ) - CHJ,, _{2 etc} - [OH or O (C _r to C ₁₂ alkyl)].

Specific examples of organic components which, alone or in groups of several of the compounds mentioned, together in azeotropic preparations of the cleaning-active Liquid that can be used are selected from propylene glycol ether; Dipropylene glycol monomethyl ether; Dipropylene glycol mono-n-propyl ether; Tripropylene glycol monomethyl ether; 3-methoxy-3-methylbutanol; Furfuryl alcohol; Tetrahydrofurfuryl alcohol; 1-aminobutanol-2; Monoisopropanolamine; 2-amino-2-methylpropanol-1; 2-amino-2-methylpropanediol-1,3; 3- (aminomethyl) pyridine; Ethanolamine; Furfurylamine; Methyl lactate; Isopropyl lactate; Aminoacetaldehyde dimethyl acetal; 4-aminomorpholine; 1-methyl imidazole; 1,2-dimethylimide azole; 1-vinylimidazole; 1,4-diazabicyclo [2.2.2] octane (DABCO); 1,5-diazabicyclo [4.3.0] non-5-ene; and 1,8-diazabicyclo [5.4.0] undec-7-ene.

It corresponds to a further, likewise preferred embodiment that at least one cleaning booster which does not evaporate independently is added to the cleaning-active liquid for the process according to the invention. This should preferably distill with the azeotropic preparation. Such non-self-evaporating cleaning amplifiers are known to the person skilled in the art from the prior art and therefore do not require any further listing at this point.

It is also preferred according to the invention to add at least one corrosion protection additive to the cleaning-active liquid. This (s) should preferably distill with the azeotropic preparation. Corrosion protection additives of this type are particularly advantageous when objects made of non-ferrous metals or light metals are to be cleaned. For example, aluminum parts can be excellently cleaned with an azeotropic preparation comprising 1-methylimidazole. This acts as an inhibitor. The cleaning of parts made of copper can also be carried out advantageously with azeotropic preparations comprising 1-methylimidazole. This lightens the surface. Instead of the compound mentioned above, other corrosion protection additives and inhibitors can also be added, as are known to the person skilled in the art from the prior art.

Particularly preferred, since this leads to excellent cleaning results, are methods for cleaning objects according to the invention, in which the cleaning-active fluids are liquid uses an azeotropic preparation of water and an organic component. In this case, the organic component is preferably a compound which is selected from the group dipropylene glycol monomethyl ether; Dipropylene glycol mono-n-propyl ether; Tripropylene glycol monomethyl ether; 3-methoxy-3-methylbutanol; Furfuryl alcohol; Tetrahydrofurfuryl alcohol; l-aminobutanol-2; Furfurylamine; Methyl lactate and isopropyl lactate.

The compounds mentioned belong to the following groups of compounds of the general formula R ¹ - [X] _n - R ³

(A) glycol ether: organic component No. 1: dipropylene glycol monomethyl ether R ¹ = CH ₃ ; R ³ = OH; X = OCH ₂ -CH (CH ₃ ) -; n = 2; organic component no. 2: tripropylene glycol monomethyl ether R ¹ = CH ₃ ; R ³ = OH; X = OCH ₂ -CH (CH ₃ ) -; n = 3; Organic Component No. 3: 3-methoxy-3-methylbutanol R ¹ = CH ₃ ; X = OC (CH ₃ ) ₂ - (CH ₂ ) ₂ -; n = 1; organic component no. 4: dipropylene glycol n-propyl ether R ¹ = nC ₃ H ₇ ; R ³ = OH; X = OCH ₂ -CH (CH ₃ ) -; n = 2;

(B) alcohols: organic component No. 5: furfuryl alcohol R ¹ = furfuryl-2; X = O; R ³ = H; n = 1; Organic Component No. 5: tetrahydrofurfuryl alcohol R ¹ = tetrahydrofurfuryl-2; X = O; R ³ = H; n = 1;

(C) Amines: Organic Component No. 7: 1-aminobutanol-2 R ¹ = OH; X = sec-butyl; R ³ = NH ₂ ; n = 1; organic component no. 8: furfurylamine R ¹ = furfuryl-2; X = -NH-; R ³ = H; n = 1; Organic Component No. 11: 2-amino-2-methylpropanol-1 R ¹ = CH ₃ ; X = CH ₃ - C - CH ₂ OH; R ³ = -NH ₂ ; n = 1; Organic Component No. 12: 2-Amino-2-methylpropanediol-1,3 R ¹ = HIGH ₂ ; X = CH ₃ - C - CH ₂ OH; R ³ = -NH ₂ ; n = 1;

(D) Ester: Organic Component No. 9: methyl lactate

R ¹ = hydroxyethyl; X = C (= O) O-; R ³ = CH ₃ ; n = 1; Organic Component No. 10: isopropyl lactate

R ¹ = hydroxyethyl; X = C (= O) O-; R ³ = iC ₃ H ₇ ; n = 1;

In such azeotropic preparations to be used as cleaning-active liquid in the process according to the invention, water and an organic component are present in relative amounts of (100 - x)% by weight: x% by weight. In this, x is in the range from 0 <x <35, preferably in the range 3 x x <25, particularly preferably in the range

4 <x <15.

In a further preferred method, the mixing ratio of water and the further component (s) in the azeotropic preparation is essentially adjusted to the ratio which is present in the vapor which is produced from the liquid azeotropic preparation when heated.

According to a further, likewise preferred embodiment, the method according to the invention for cleaning objects comprises the step of using an azeotropic preparation of water and two organic components as the cleaning-active liquid. An azeotropic preparation of water, dipropylene glycol mono-n-propyl ether and another organic component is particularly preferably used as the cleaning-active liquid. Of course, in this embodiment, too, further components can be contained in the azeotropic preparation used as the cleaning-active liquid, for example at least one non-self-evaporating, particularly preferably with the azeotropic preparation of distilling cleaning boosters, as is known as such from the prior art and has already been mentioned above, and / or at least one (with particular preference distilling with the azeotropic preparation) corrosion protection additive or corrosion protection Inhibitor as it is also known as such or from the prior art and has already been mentioned above.

According to this preferred embodiment, a compound from the group l-aminobutanol-2; Monoisopropanolamine; 2-amino-2-methylpropanol-1; 2-amino-2-methyl propanediol-1,3; 3- (aminomethyl) pyridine; Ethanolamine; Aminoacetaldehyde dimethyl acetal; 4-aminomorpholine; 1-methylimide azole; 1,2-dimethylimidazole; 1-vinylimidazole; 1,4-diazabicyclo [2.2.2] octane (DABCO); 1,5-diazabicyclo [4.3.0] non-5-ene; and 1,8-diazabicyclo [5.4.0] undec-7-ene.

The organic compounds mentioned can be used alone or in combination with one another.

It is also particularly preferred to use a further organic component from the group consisting of acetic acid, hydroxyacetic acid, formic acid and butyric acid. The acids mentioned can also be used alone or in combination with one another or with other, for example the above-mentioned, organic components.

According to the preferred embodiment described above, the cleaning-active liquid used is an azeotropic preparation of water, a glycol ether (preferably dipropylene glycol mono-n-propyl ether) and a further organic component in relative amounts of 90% by weight: (10 - y )% By weight: y% by weight, in which y is in the range from 0 <y <5, particularly preferably in the range from 0 <y <2.

A device in which the method according to the invention can be carried out is shown schematically in the attached figure: A storage tank 2 with a separation chamber 4 and an overflow chamber 6 is connected via a feed pump 8 and a heating device 10 a cleaning device 12 connected. The interior of the cleaning device known per se in its construction, which can contain cleaning nozzles, a circumferential basket, etc., is connected in the example shown in the figure to a pressure compensation vessel 14, which, however, is not functionally essential.

A glue leads from the bottom of the cleaning device 12 to a filter device 16. The filter device 16 is connected to the top of the separating chamber 4 by gluing with a feed pump 18. Another line leads from the filter device 16 via a vacuum pump 20 through a condenser 22 and a cooler 24 back to the separation chamber 4.

Furthermore, a line leads from the overflow chamber 6 via a feed pump 26 through a heat exchanger 28 into a distillation device 30 and from there into the cleaning device 12 or back into the storage tank 2.

A feed line 32 leads into the storage tank 2 for charging the storage tank 2 with cleaning-active liquid. The storage tank 2 further contains a device (not shown) for removing sludge, which settles in the separation chamber 4.

A ventilation line 34 leads into the normally tightly closed cleaning device 12.

The structure of the individual components of the cleaning device 12 described and electrical control of the individual assemblies (not shown) are known per se and are therefore not described in detail.

The function of the device described is as follows: after loading the cleaning device 12 with the material to be cleaned, in an exemplary but not restrictive embodiment, liquid cleaning takes place first, in which the feed pump 8 is started and cleaning-active liquid which the heater 10 against can also be tempered, the cleaning device 12 is supplied. In the cleaning device 12 there is an immersion bath of the circulating items to be cleaned and / or the items to be cleaned are sprayed with liquid. The liquid is drawn off from the cleaning device 12 through the filter device 16 by means of the feed pump 18 and fed to the separating chamber 4. Predominantly inorganic dirt settles in the filter device 16 and is removed. In the separation chamber 4 mainly fatty dirt settles, which is also removed.

The liquid cleaning stage described by way of example is followed by rinsing under the same conditions with cleaning-active liquid from the tank 6.

This is followed by a steam cleaning stage or steam rinsing stage, in which the feed pump 26 is started, so that the cleaning-active liquid in the distillation device 30 is heated and converted into steam. As a result of the azeotropic character of the azeotropic preparation used as the cleaning-active liquid, this vapor has a predetermined content of water and the further component or components. The liquid azeotropic preparation is preferably already composed of its components in such a way that this also corresponds to the content of the corresponding components in the vapor phase. The steam comes into intensive contact with the material to be cleaned in the cleaning device 12, at least part of the steam condensing. The condensate is fed into the separation chamber by means of the feed pump 18 after flowing through the filter device 16.

If the steam from the distillation device 30 is returned to the storage tank 6 via the condenser 22 and the cooler 24, the liquid can thereby be processed.

Steam cleaning or steam flushing is advantageously followed by forced-air drying or vacuum drying. Vapor inside the cleaning device 12 is sucked off by means of the vacuum pump 20, whereby in the cleaning Vorrichmng 12 forming condensate flows through the filter device 16. The vapor mixed with the condensate is supplied to the storage tank 2 again as a liquid after flowing through the condenser 22 and the cooler 24.

After completion of the vacuum drying, the separation chamber 4 is ventilated via the ventilation line 34, and the cleaned material can be removed.

In an alternative embodiment, which likewise leads to advantageous results, the objects to be treated are sprayed in the cleaning device 12 with the azeotropic preparation used as the cleaning-active liquid. This is done in such a way that the objects to be cleaned are soaked in the liquid. The subsequent process steps are essentially the same as those described above.

The objects to be treated are in a significantly better state after treatment than after treatment in a conventional process, i.e. using conventional organic solvents for the cleaning steps under identical conditions. In particular, it was surprisingly found that not only all organic dirt, including lipophilic or oil-like or fat-like substances, is removed, but also all inorganic dirt, in particular inorganic salts from sweat, color pigments, etc. The treated articles have no unpleasant odor and show an excellent appearance.

As already stated above, azeotropic preparations with a miscibility gap show surprisingly good cleaning behavior which is clearly superior to conventional preparations.

If azeotropic preparations with a miscibility gap are used, in the case of treatment in the liquid phase, the objects to be cleaned are brought into contact with an azeotropic preparation which is in a state in which the components of the azeotropic preparation are separated or at least partially separate phases For example, the liquid azeotropic preparations present in the state of phase separation are treated with ultrasound or intensively pumped around or stirred, so that a milky emulsion of the azeotropic preparations is formed. This emulsion not only dissolves fat-like or oily components well, but also ionic or salt-like impurities.

In the case of treating the objects to be cleaned with the azeotropic preparation in the vapor phase, the azeotropic preparation - as described above - is heated and a steam is produced in which the components are present in the proportions which are characterized by the characteristic azeotrope. Properties are determined. The steam condenses at least partially on the objects to be cleaned, and the same milky emulsion is obtained as in the liquid phase. Excellent fat and salt dissolving power is also observed in this case.

When the temperature of the azeotropic preparation increases to the phase transition from liquid phase to vapor phase, the components pass into the vapor phase in the quantitative ratio corresponding to the azeotrope, and the azeotropic preparation can be prepared by distillation without any problems.

The last-mentioned embodiment of the method according to the invention is particularly advantageous for cleaning metal parts. For example, when using azeotropes with a mixing gap, lapping and polishing pastes can be excellently removed from metal parts. For this purpose, for example, an azeotropic preparation mixed with acidic additives is used as an active cleaning liquid. Cleaning takes place in the one-chamber system described above and can be carried out continuously or in a batch process.

It is also surprisingly easy to remove SMD adhesives (SMD = Survace Mount Devices) from electronic components, such as those used in the manufacture of SMD parts with double-sided assembly, so that the components do not come loose during the soldering process. The adhesive is usually applied using dispenser systems or templates. brings before the circuit boards are attached. Printed or dispensed PCBs or stencils can be cleaned. The azeotropic preparations used according to the invention can surprisingly achieve cleaning results which significantly exceed those with conventional solvents such as butyl acetate or isopropanol. In addition, protective measures (for example against explosions in the case of correspondingly endangered solvents) are superfluous.

In the same way, excess soldering pastes applied during soldering can be removed in a simple and environmentally friendly manner from misprinted plates and stencils using the method according to the invention using the azeotropic preparations mentioned. It is also possible to remove flux residues after soldering. The cleaning is carried out by spraying, spray rinsing and drying the objects to be cleaned, preferably in an immersion process using ultrasound (cleaning stage), rinsing with or without ultrasound (rinsing stage) and drying. The cleaning is preferably carried out at a temperature in the range from 40 to 60 ° C., but is not restricted to this temperature range. In particular when treating the objects to be cleaned in the cleaning stage with the steam from the azeotropic preparation, the temperature can be significantly higher, for example also above 100 ° C.

Azeotropic preparations according to Table I below are particularly preferably used for cleaning processes according to the invention. This table also gives the preferred ratios of organic components (O.K.): water, the boiling points of the respective azeotropic preparation and the temperatures at which objects to be cleaned can be treated as examples with the respective azeotropic preparation. Of course, the invention is not restricted to the specified ratios of the components and treatment temperatures.

If azeotropes with a mixture gap are used, three-component mixtures of water, dipropylene glycol mono-n-propyl ether and amine compounds or N-heterocyclic compounds or organic acids according to the Table II below used. An exemplary, but not restrictive, composition of the azeotropes is as follows: water (90% by weight), dipropylene glycol mono-n-propyl ether (10% by weight), y% by weight of those given in Table II Links.

Table I

Table II

Table II also shows the boiling point (° C.) of the azeotropic preparation formed from water, dipropylene glycol mono-n-propyl ether and the compounds indicated.

The invention is illustrated by the following examples, but without being restricted to these.

example 1

The drum of the cleaning device 12 described above was loaded with material to be cleaned. The material consisting of textiles was treated in the first step under liquid cleaning conditions with azeotropic preparations at elevated temperatures. The azeotropic preparations and the respective treatment temperatures are given in Table I above. The material was immersed in the warm azeotropic preparation while moving. The warm azeotropic preparation was carried out in a closed circuit from the drum of the cleaning device 12 via a filter device 16 and fed to the separation chamber 4. Mainly inorganic dirt (salts) settled in the filter device 16 and was removed. In the separation chamber 14 mainly fatty dirt settled, which was also removed.

The first treatment step was followed by a second treatment step, which was also carried out under liquid treatment conditions. Fresh azeotropic preparation (composition: see Table I; in each run the azeotropic preparation of the second treatment step had the same composition as that of the first step), the drum of the cleaning device 12 was fed at elevated temperature. The material was fed in a second closed circuit from the drum to the cleaning device 12 via a filter device 16 to the separation chamber 4. The separation of inorganic and organic substances was carried out in the same way as in the first treatment step. The second treatment step was followed by a third treatment step, in which the material to be treated was treated with the steam of the respective azeotropic preparation. This had the composition typical for the respective azeotrope (see Table I). After passing through the feed pump, the azeotropic preparation was transferred into a distillation device in the vapor phase. The steam was brought into intimate contact with the material to be treated in the drum of the cleaning device 12. At the time of contact with the material, part of the vapor was condensed. The liquid from the cleaning step after the condensation was removed from the drum and, after passing through the filter device 16, was passed to the separating chamber 4 for separating the organic substances, where organic contaminants were separated. The steam, which was not already condensed in the drum of the cleaning device 12, was withdrawn from the drum, condensed and (after filtration, if any) carried to the storage tank 2 for further use.

After removal of the vapor of azeotropic Zubereimng was evacuated the drum spielsweise on IO ^"2 bar, and the remaining vapor was removed in the same manner as above be¬ written. The warm material treated put the water and the organic component of the azeotropic Zubereimng released in vacuo so that it was dry after 10 minutes of vacuum treatment.

The material to be treated was in much better condition than material which had been treated in a conventional manner. Both inorganic and organic contaminants were completely removed. The material did not have an unpleasant smell and had an excellent appearance. It could be ironed or pressed with good results.

The third step (steam treatment) is not absolutely necessary after liquid cleaning; the same good results as described above were achieved even without the steam treatment. It is also possible according to the invention to perform the steps of treating the material to be cleaned with liquid azeotropic preparation by means of steps of treatment to be replaced entirely or partially with vaporous azeotropic preparation. With this procedure, equally good cleaning results were achieved.

Example 2

Misprinted printed circuit boards or stencils from SMD production were treated with a three-component mixture of water, dipropylene glycol mono-n-propyl ether or an amine compound or N-heterocyclic compound or organic acids, as can be seen from Table II is. The three-component mixtures which were used as cleaning-active liquids consisted of 90% by weight of water, (10-y)% by weight of dipropylene glycol mono-n-propylene ether and y% by weight of one of the compounds listed in Table II. The cleaning was done by spraying.

In order to remove SMD adhesive at the boiling temperatures given in Table II, the printed circuit boards or templates were treated with the liquid azeotropic preparations using ultrasound (however, ultrasound is not absolutely necessary to achieve good cleaning results). The azeotropic preparations were in the form of a milky emulsion that became almost clear when ultrasound was applied. The adhesive was removed completely without protective devices, for example for protection against explosions, having to be provided in the system.

The cleaning results were considerably better than when using conventional solvents such as butyl acetate or isopropanol. In addition, protection of the system against explosions must be provided for the latter for occupational safety reasons.

Claims

claims

1. A method for cleaning objects, in which a steam produced by heating a cleaning-active liquid is brought into contact with the objects to be cleaned, characterized in that an azeotropic preparation in the form of a mixture of water and at least one further-wide is used as the cleaning-active liquid Ren component with molecules with hydrophilic and lipophilic groups used, the further component (s) and the water during the phase transition liquid phase / vapor phase form an azeotrope.

2. The method according to claim 1, comprising the steps of preparing an azeotropic preparation of water and at least one component with molecules with hydrophilic and lipophilic groups in a weight ratio (component (s) with hydrophilic and lipophilic groups): water from 0.05 to 99.95: forms 99.95 to 0.05; brings the objects to be cleaned into contact with the azeotropic preparation at least once and allows liquid azeotropic preparations including contaminants removed therefrom to run off from the objects to be cleaned; Remains of the azeotropic preparation on or in the objects to be cleaned removed by evaporation; and the vapor of the azeotropic preparation condenses and the azeotropic preparation recovered by condensation is used for a renewed cleaning step.

3. The method according to claim 1 or claim 2, wherein the objects to be cleaned are brought into contact with a vapor of the azeotropic preparation at least once and the vapor of the azeotropic preparation is allowed to condense on the objects to be cleaned during the duration of the contact.

4. The method according to any one of claims 1 to 3, wherein an azeotropic preparation in the form of a mixture of water and at least one further component with molecules with hydrophilic and lipophilic groups is used as the cleaning-active liquid, the further component (s) ) and the water in the phase transition liquid phase / vapor phase form an azeotrope and the azeotrope an azeotrope with a miscibility gap at a temperature between 0 ° C. and the temperature of the phase transition liquid phase / vapor phase at normal pressure, preferably an azeotrope with a miscibility gap at one temperature in the range of 20 ° C and 110 ° C at normal pressure.

5. The method according to any one of claims 1 to 4, wherein in addition to water as a further component of the cleaning-active liquid, an organic component of the general formula

R ¹ - [X] "- R ³ is used, wherein

R ¹ and R ³ each independently represent H; straight-chain or branched saturated or unsaturated C _r to C, _g - alkyl groups in which one or more non-adjacent -CH ₂ groups can be replaced by -O-; saturated or unge¬ saturated cyclic C, - to C ₈ - alkyl groups in which one or more non benach¬ disclosed -CH ₂ groups may be replaced by -O-; Hydroxy; C _r to C ₈ alkoxy; Amino in which one or both of the hydrogen (s) can be replaced by C to C ₈ alkyl groups; and

6. The method according to any one of claims 1 to 5, wherein the mixing ratio of water and the further component (s) in the azeotropic preparation is essentially adjusted to the ratio that is present in the vapor that comes from the liquid azeotropic preparation occurs when heated.

7. The method according to any one of claims 1 to 6, wherein at least one non-self-evaporating cleaning booster and / or at least one corrosion protection additive is added to the cleaning-active liquid, preferably at least one non-self-evaporating cleaning booster and / or at least one anti-corrosion agent Additive that distills with the azeotropic preparation.

8. The method according to any one of claims 1 to 7, wherein an azeotropic preparation of water and an organic component is used as the cleaning-active liquid.

9. The method according to any one of claims 1 and 8, wherein an azeotropic preparation of water and an organic component in relative amounts of (100 - x) wt .-%: x wt .-% is used as cleaning-active liquid, where x in the range

0 <x <35, preferably in the range 3 <x <25, particularly preferably in the range 4 <x <15.

10. The method according to any one of claims 1 to 7, wherein an azeotropic preparation from water and two organic components is used as cleaning-active liquid, preferably an azeotropic preparation from water, dipropylene glycol mono-n-propyl ether and a further organic component.

11. The method according to any one of claims 1 and 10, wherein the cleaning-active liquid is an azeotropic preparation of water, a glycol ether, preferably dipropylene glycol mono-n-propyl ether, and a further organic component in relative amounts of 90% by weight. : (10-y) wt .-%: y wt .-% used, wherein y is in the range 0 <y <5, preferably in the range 0 <y <2.