EP0240763A1 - Cleaning process for soiled solid articles - Google Patents

Abstract

To clean primarily pigment and grease stains, the molded parts are treated with ultrasound in baths, which contain largely insoluble catchers for absorbing the detached dirt. This process can be combined with further washing and rinsing steps which take place without the action of ultrasound.

Description

The invention relates to improvements in the cleaning of solid materials or molded parts by treating them in a washing or cleaning bath with simultaneous exposure to ultrasound on the bath liquid and / or the material to be cleaned. The removal of in particular pigment and / or grease soiling from the surface of solid workpieces or molded parts in washing and cleaning baths with the simultaneous use of ultrasound to facilitate dirt removal is a secure part of the relevant process engineering today, with the entire area of only occasional cleaning processes - for example in the Cleaning historical coins - right up to the independent process step in the continuous large-scale production of, for example, motor vehicles. There is considerable literature on the laws, the systems and fields of application of ultrasonic cleaning technology, but recent publications include: R. Sievers "Systems and fields of application of ultrasonic cleaning technology" in metal, International Journal of Technology and Economics 35 ( 1981), 763 ff. And Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, Wiley-Interscience (1983), Vol. 23, 462 to 479, in particular 463 to 465.

The most important procedural elements are still the following conditions today: frequency range about 20 to 60 kHz, use of predominantly piezoceramic and magnetostrictive transducers, power densities in the sonicated volume in the range of about 5 to 15 W / l with individual significant deviations, mainly upwards as above all, use of aqueous, in particular aqueous, surfactant baths and / or organic solvents as washing liquid. Chlorinated or fluorinated hydrocarbons (CHC or CFC) are mainly used as organic solvents.

The relief of the cleaning effect is based essentially on the cavitation and the shock-like extreme pressure fluctuations triggered in the immediate vicinity of the soiled solid surface. It is known that cavitation in aqueous cleaning solutions is harder and more effective than in organic solvents. Because of the extremely different types of contamination, however, depending on the degree of contamination, either aqueous and / or organic washing baths are used, depending on the existing technical possibilities. Organic solvents are particularly suitable for degreasing, but often leave the degreased pigment-like residues on the surface to be cleaned as a dry, dusty coating. Aqueous, mainly alkaline and possibly surfactant-containing wash baths are less suitable for removing greasy soils, but rather for removing pigment-like soils or, at best, for removing easily emulsifiable greasy deposits or residues on the solid surface.

It applies to both the aqueous and the organic detergents or cleaning agents that the liquid phase accumulates rapidly with the washed-off dirt during use, so that a dirt concentration is reached quite soon, which again residues on the surfaces to be cleaned and thus only insufficient cleaning performance. In the continuous process in particular, it is therefore necessary to constantly replace the wash bath liquid phase with fresh bath liquid. In the plants known today, this can be done batchwise or continuously. Regeneration of the contaminated liquid phase is generally provided. This applies in particular to organic washing liquids which are generally purified by distillation and returned to the process. The regeneration of aqueous wash bath fluids often requires so much effort that the used bath fluid is discarded instead and replaced by freshly prepared aqueous bath fluid.

The teaching of the invention is based on the task of substantially improving the cleaning of shaped material parts and in particular the cleaning of the surface of such molded parts from pigment and / or grease stains in suitable washing and cleaning baths with the simultaneous action of ultrasound in several respects. For example, the invention intends to enable batch or continuous regeneration of the bath fluids even and precisely during the use of these baths, without the bath liquid having to be distilled. The advantages of the new development are intended to apply equally to organic bath liquids and to aqueous baths, the invention, in a particularly important embodiment, having the task of making it possible, partially or preferably completely, to dispense with organic wash baths precisely where they have been used up to now has been regarded as indispensable by CKW and / or PKW in particular. The object of the invention is also to clean effectively with aqueous bath liquids under comparatively mild working conditions, in particular pH and process temperature, even the most difficult cleaning tasks in the Neutral range and at moderately elevated temperatures in aqueous washing or cleaning baths should be possible using ultrasound. Finally, in a particular embodiment, the invention aims to enable the dirt to be separated from the bath liquid in such a way that, in essence, stationary baths can be used with batch-wise or continuous throughput of shaped materials to be cleaned without exhausting the cleaning capacity of the wash baths used. Further specific objects of the invention will become apparent from the description of the invention below.

According to a first embodiment, the invention relates to a method for cleaning the surface of solid, shaped materials or molded parts, in particular pigment and / or fat stains, by treating them in a washing and cleaning bath with at least temporary exposure to ultrasound, if desired in conjunction with further washing - And / or rinsing stages without the action of ultrasound, the characteristic of the method being that washing or cleaning baths are used for the ultrasound treatment, which are characterized by a content of catchers which are at least largely insoluble in the bath liquid for the absorption of at least part of the detached dirt award. It is preferred to work with insoluble dirt traps, which can be removed manually and / or mechanically from the cleaned molded material parts. In a particularly important embodiment of the invention, the insoluble dirt traps are used in such a way that they can also be removed manually and / or mechanically from the liquid phase of the washing or cleaning bath. The undissolved catchers which are present as solids are preferably designed such that they have a substantial retransmission under the cleaning conditions and in particular also under the action of ultrasound Prevent the dirt on the solid surfaces to be cleaned.

In a particularly preferred embodiment of the invention, in the cleaning stage using ultrasound, aqueous washing or cleaning baths are used which contain at least partially dissolved surfactant components. In the preferred embodiment of the invention, aqueous surfactant liquor, pigment and / or grease soiling to be removed and the dirt trap used, which is not dissolved in the washing liquor, are coordinated with one another in such a way that the entire pigment and / or grease soiling removed - or at least the main part thereof - Is taken up by the undissolved dirt trap and can be discharged from the cleaning step by separating this undissolved dirt trap phase from the washing bath liquid. This separation can take place batchwise or continuously. It can be carried out in this form during the operation of the bath or during a break in operation or on the liquid phase drawn off from the bath. Details can be seen from the following.

The essence of the teaching according to the invention lies in the following: The method according to the invention - with the aid of the cleaning forces triggered by ultrasound - removes the impurities from the surface of the goods to be cleaned, but does not leave it at this step. At the same time, in the process according to the invention, a catcher which is insoluble in the wash liquor is provided in solid form, on the surface of which the dirt is deposited at least in part. Accordingly, in the method according to the invention, the dirt is transferred from an emitting solid surface to an accommodating, separately arranged solid surface. The wash bath liquid now essentially only serves Cavitation formation and thus easier cleaning by the action of ultrasound and the transport of the detached dirt particles on the surface of the dirt trap, which is in a separate solid phase. The wash bath liquid itself is not used up. It regenerates itself to the extent that the dirt it absorbs is absorbed by the strainer.

Technical soiling, in particular pigment soiling and / or greasy soiling, is to be expected or eliminated. The catcher systems used according to the invention are tailored to this. They can consist of only one substance that is able to bind both pigment dirt and grease dirt, but in particular different catcher systems can also be used, which are more suitable for binding pigment dirt on the one hand and for grease dirt on the other hand. The corresponding capture solids can be used in a mixture with one another, but they can also be used separately in successive process stages. It is particularly important for the teaching of the invention that under these conditions of transferring dirt from one solid surface to another while at the same time regenerating the washing liquid, the use of aqueous systems becomes possible, regardless of whether it is the removal of pigment stains or grease stains. The method according to the invention makes use of the extensive knowledge for washing or cleaning with aqueous surfactant liquors both in the field of technical cleaning and in the field of textile washing. The catcher systems used according to the invention are in particular designed such that they contain the dirt traps immobilized at least on the surface of the undissolved catch systems. In particular, it is also possible to use the catcher systems used according to the invention in the washing or Use the cleaning bath immediately and especially under the influence of ultrasound, without this causing the dirt picked up by the catcher to be transferred back to the materials to be cleaned. The teaching according to the invention thus extends the application of a working principle in the field of cleaning, in particular technical cleaning, of solid, shaped materials under the action of ultrasound, which is described in a number of older applications by the applicant, preferably for washing textile materials under conventional washing conditions . Reference is made to the earlier applications DE 35 45 990.5 (D 7478/7495), DE 36 05 716.9 (D 7538) and DE 36 06 729.6 (D 7554). The use of this new working principle in the field of textile washing using ultrasound, in particular to facilitate the removal of pigment and / or grease stains, is described in the earlier patent application DE 36 10 386.1 (D 7583). The disclosure of all of these older patent applications mentioned is hereby expressly made the subject of the present disclosure.

For the method step of cleaning according to the invention, in particular technical cleaning under the influence of ultrasound on shaped objects, the invention provides as an essential element the use of so-called catchers for taking up at least part of the detached pigment and / or grease dirt. As such, these catchers are insoluble in the wash liquor and are present in such a form that they can be separated manually and / or mechanically from the cleaned material and, if desired, from the wash liquor used.

A first class of such capture substances, which is particularly important according to the invention, is insoluble and / or polyfunctional ones present or immobilized on correspondingly insoluble solid supports quaternary ammonium compounds (PQAV), which are used in particular in the form of their insoluble or immobilized PQAV / surfactant complexes and in detail in the older applications and here again in particular in applications DE 36 06 729.6 (D 7554) and DE 36 10 386.1 ( D 7583) are described.

The earlier application DE 35 45 990.5 (D 7478/7495) relates to the use of polyfunctional quaternary ammonium compounds (PQAV) which are insoluble in aqueous surfactant washing or cleaning solutions, even under the temperature loads of the washing process, and / or on aqueous ones Solutions corresponding to insoluble solids are not washable, immobilized, as a particle-dirt-collecting cleaning booster in aqueous surfactant washing or cleaning solutions, which can be manually and / or mechanically separated from the goods to be cleaned after washing or cleaning. At least a considerable proportion of the dirt, in particular pigment dirt, that is solubilized in textile washing is absorbed by the PQAV present in the solid phase and thus ultimately transferred from the textile material that was originally soiled and to be cleaned to the dirt collector.

The teaching of the earlier application DE 36 05 716.9 (D 7538) changes the use of those PQAVs which are insoluble in aqueous washing and cleaning solutions and / or are immobilized on solids which are correspondingly insoluble in these aqueous solutions to the effect that the new auxiliaries containing PQAV are present for the at least partial regeneration of dirt-laden cleaning liquors, in particular for their subsequent reuse. According to the teaching of this property right, it is possible in particular to use aqueous-alkaline cleaners, if desired containing surfactants supply liquors, in particular washing solutions from textile washing, are subjected to regeneration in such a way that the soiled cleaning liquor is treated with the insoluble or immobilized PQAV either already during the textile washing and / or thereafter and thereby at least partly freed from solubilized dirt, in particular pigment dirt. The washing solution treated in this way can be reused - for example in the context of textile washing.

The use of appropriate PQAV or PQAV / surfactant complex compounds as from the reaction of PQAV with surfactant components, in particular anionic, amphoteric and / or nonionic surface-active agents, as dirt-absorbing weight-loss agents for reducing the need for conventional chemicals in washing and / or cleaning agents is the subject of said patent application DE 36 06 729.6 (D 7554).

The following general information, to be understood in particular by way of example, of the older applications cited relating to the PQAV to be used or the PQAV / surfactant complexes derived therefrom also apply to the teaching of the present invention:

Polyfunctional quaternary ammonium compounds (PQAV) are described and known in the most varied form in the printed prior art and also in commerce. An important area of use for such compounds is in the field of cosmetic preparations, in particular for the treatment or conditioning of hair. It is a known characteristic of the PQAV that they are capable of being coated on solid surfaces, this capability being possible in particular in the presence of customary surfactant components. Depending on the constitution, the absorbency and the adhesive strength of the PQAV on the solid base are different. In detail The respective constitution of the PQAV plays a decisive role here. For the behavior of PQAV under the influence of aqueous surfactant baths, however, interaction with anionic surfactant components in particular can also be of crucial importance. With stoichiometric or approximately stoichiometric amounts of the anionic surfactant components, the corresponding anionic surfactant salt generally forms on the quaternary ammonium group. Such PQAV anionic surfactant salts generally show a greatly reduced water solubility. Corresponding precipitates form, see for example the German Offenlegungsschrift 22 42 914. Such anionic surfactant salts from PQAV have been proposed as antistatic agents for application to fibers. In this context, however, it is also known that excesses, in particular considerable excesses of the anionic surfactant, can lead to a redissolution of the primarily precipitated PQAV / anionic surfactant salts, cf. the publication in "Soaps - Oils - Fats - Waxes" 1985, 529 to 532 and 612 to 614. In particular in the reaction diagram on page 530 op. cit. the formation of solubilized micelle systems of the anionic surfactant / PQAV complex is shown with an excess of the anionic surfactants.

In general, these previously known PQAV are oligomers and / or polymers which have a plurality or a plurality of quaternary ammonium groups on their oligomeric or polymeric matrix. Adequate water solubility of the PQAV is generally required for use in the field of cosmetics. The use of PQAV according to the invention, on the other hand, calls for the insolubility of the PQAV-based auxiliaries used as dirt collectors in the aqueous surfactant washing or cleaning solutions. The insolubility of the PQAV components used as dirt collectors in the sense of the invention is in fact an indispensable prerequisite, in particular for the field of textile washing. Will this critical precondition according to the invention is not met, then the washing result is reversed to its opposite. Soluble PQAV components sliding into the wash bath are absorbed onto the textile goods to be washed and there bind undesirably additional amounts of pigment dirt.

Nevertheless, in an important embodiment of the invention, all previously known, originally water-soluble PQAV components can be used for the application according to the invention. It is only necessary to convert the water-soluble and / or water-swellable PQAV components of the prior art into the required insoluble form or to fix and immobilize them on water-insoluble carriers so that they are removed from this carrier during the cleaning process not be washed off.

From the extensive relevant literature, the following publications may be named by way of example, the disclosure of which is hereby expressly also made the subject of the disclosure of the present description of the invention on the structure of the PQAV: US Pat. Nos. 3,589,978, 3,632,559, 3,910,862, 4,157,388, 4,240,450 and 4,292,212, GB-PS 1 136 842, DE-AS 27 27 255, and the US-PS 3,472,840 specified therein.

Suitable originally water-soluble or water-insoluble PQAV in the sense of the invention preferably have an average molecular weight of at least about 200, preferably at least about 300 and in particular at least about 1000. The upper limit of the PQAV is basically meaningless and is, for example, 50 million, for example 10 million. This is understandable from the requirement of the insolubility of the PQAV required according to the invention. If this is ensured, there are no upper limits to the molecular weight.

After suitable preparation, described below for the purposes of the invention, all polymers which carry quaternary ammonium groups either in the polymer chain or bound to the polymer chain are suitable as PQAV which are initially water-soluble but then immobilized on an insoluble carrier. Such quaternary ammonium groups can also be derived from cyclically bound nitrogen. Examples of such quaternary ammonium groups are corresponding members of 5- or 6-membered ring systems, e.g. of morpholine, piperidine, piperazine or indazole rings. Numerous examples of such water-soluble PQAV are e.g. in US Pat. No. 4,240,450.

Homopolymers or copolymers with cyclic units, as are known in detail from US Pat. No. 3,912,808, can be particularly suitable. Commercial products with this structure include Merquat ^(R) 100 and Marquart ^(R) 550 (Quaternium 41).

Further preferably suitable PQAV are, for example, cellulose ethers, the anhydroglucose units of which bear substituents with quaternary ammonium groups which are bonded via ether oxygen. Such polymers are known, for example, from US Pat. No. 3,472,840. A commercial product with this structure is, for example, the Polymer-JR ^(R) 400.

Other particularly suitable cationic polymers are, for example, the quaternary polyvinylpyrolidone copolymers known from US Pat. No. 3,910,862 and available, for example, under the trade name Gafquat ^(R) 734 and 755, and those known from US Pat. No. 4,157,388 and, for example, under the trade name Mirapol ^(R) A15 available quaternary polymeric urea derivatives. Suitable copolymers with a polycationic character are also the polyacrylamide copolymers described in the published European patent application 0 153 146, in particular in addition to contain at least 50 mol% of acrylamide units up to 50 mol% of a quaternized aminoalkyl ester of acrylic acid or methacrylic acid. These copolymers are water soluble. There they are applied to cloths based on cellulose fibers and are drawn up there due to their natural drawing power. Cloths of this type can be washed out and should then be used together with anionic surfactant-free surfactant systems for cleaning hard surfaces, in particular for cleaning glass. Under these conditions, they are characterized by an increased dirt absorption capacity. However, the cleaning wipes described in the publication are unsuitable for the use according to the invention in customary surfactant washing and cleaning liquors, which can also be exposed to temperature loads of up to about 95 ° C. Not inconsiderable proportions of the numerous PQAV copolymers described in the publication slip into the wash bath, pull onto the items to be cleaned and lead to increased pigment contamination. Only the conversion of such PQAVs to the physical state required according to the invention, as described below, makes them tools in the sense of the invention.

Preferred PQAV as starting material are those compounds which, in solid form, cause difficulties in dissolving in water. Such cationic polymers are especially the cationic polygalactomannan derivatives known for example from GB-PS 1 136 842.

in der R¹, R² und R³ z. B. Methyl- oder Ethylgruppen und R⁴ eine Epoxyalkylgruppe der Formel

oder eine Halohydringruppe der Formel

bedeuten und in welchen R⁵ eine Alkylengruppe mit 1 - 3 C-Ato­men, X = Chlor oder Brom und Z ein Anion wie z. B. Chlorid, Bromid, Jodid oder Hydrogensulfat ist. Der Substitutionsgrad sollte wenigstens 0,01 und bevorzugt wenigstens 0,05 sein und liegt typischerweise zwischen 0,05 und 0,5. Ein besonders geeignetes quartäres Ammoniumderivat eines Polygalactomannans ist z. B. das Guar-hydroxypropyl-trimethylammoniumchlorid, welches an die Sauerstoffatome der Hydroxylgruppen des Poly­saccharids gebundene kationische Gruppen der Formel

trägt. Solche kationischen Guar-Derivate sind z. B. unter der Handelsbezeichnung "Cosmedia Guar C 261" auf dem Markt. Der Substitutionsgrad (DS) von Cosmedia Guar C 261 liegt bei etwa 0,07. Auch die Handelsprodukte "Jaguar C-13" (DS = 0,11 -­0,13) und "Jaguar C 13 S" (DS = 0,13) gehören diesem Typ an.Galactomannans are polysaccharides that occur in the endosperm cells of many legume seeds, but which are obtained on an industrial scale only from locust bean gum, guar gum and tara gum. They are made up of a linear Mannan main chain consisting of beta (1.4) glycosidically linked mannopyranose building blocks to which individual galactopyranose residues are fixed in an alpha- (1.6) -glycosidic bond as a branch. The main difference between the individual polygalactomannans is the mannose-lactose ratio. The cationic derivatives of the polygalactomannans are produced by reacting hydroxyl groups of the polysaccharide with reactive quaternary ammonium compounds. Suitable reactive quaternary ammonium compounds are, for. B. those of the general formula

in the R¹, R² and R³ z. B. methyl or ethyl groups and R⁴ an epoxyalkyl group of the formula

or a halohydrin group of the formula

mean and in which R⁵ an alkylene group with 1 - 3 C atoms, X = chlorine or bromine and Z an anion such. B. is chloride, bromide, iodide or hydrogen sulfate. The degree of substitution should be at least 0.01 and preferably at least 0.05 and is typically between 0.05 and 0.5. A special one a suitable quaternary ammonium derivative of a polygalactomannan is e.g. B. the guar-hydroxypropyl-trimethylammonium chloride, which is bound to the oxygen atoms of the hydroxyl groups of the polysaccharide cationic groups of the formula

wearing. Such cationic guar derivatives are e.g. B. under the trade name "Cosmedia Guar C 261" on the market. The degree of substitution (DS) of Cosmedia Guar C 261 is about 0.07. The commercial products "Jaguar C-13" (DS = 0.11-0.13) and "Jaguar C 13 S" (DS = 0.13) also belong to this type.

Corresponding PQAV / surfactant complexes which are derived from the reaction of such PQAV components with one or more surfactants, in particular anionic surfactants, amphoteric surfactants and / or nonionic surfactants, are particularly suitable as dirt traps for the cleaning stage described using ultrasound. In this implementation, the originally present counter anion of PQAV may be at least partially replaced by surface-active agents. It may be preferred to use corresponding reaction products between the original PQAV and the surface-active agents, in which at least 50 equivalent% and in particular at least about 80 equivalent% of the quaternary ammonium groups are activated with regard to their counteranions by exchange with the surface-active agents. In the preferred embodiment of the invention, the activation of the quaternary ammonium groups by the use of at least equivalent amounts of PQAV on the one hand and surface-active agent on the other hand in the preparatory manufacturing stage of the dirt-absorbing Catcher made. Excess surfactants generally do no harm and may even be preferred. Particularly active scavengers have been obtained by using a multiple excess of the surfactant component in addition to the stoichiometrically required amount. This excess can be, for example, up to 10 times the stoichiometrically calculated amount or even more and, for example, up to 1000 times this amount. In a particularly interesting embodiment, tensides in amounts of 10 to 500 times - based on the stoichiometrically required amount - have been used.

Surfactant components which are capable of such an exchange are used in particular as surface-active agents. It is known that quaternary ammonium groups - depending on the type of quaternization reaction - usually contain e.g. Halide or a lower alkyl sulfate moiety. According to the invention, this counter ion is replaced, for example, by surfactants containing anionic groups or correspondingly reacting surfactants. Thus, the counter anion can be replaced by anionic, amphoteric and / or nonionic surface-active agents known per se, in particular by corresponding low-molecular compounds with surfactant character. It is known per se that PQAV components are accessible to such a reaction with in particular anionic surfactants and thereby form precipitation products with reduced solubility. The invention makes use of this known reaction because it has been shown that particularly active dirt absorbers are present when this reaction with the surfactant components has already taken place in the washing or cleaning solution before the dirt-collecting absorbers are used.

If the solubility of such PQAV / surfactant complexes has not been sufficiently reduced, so that with a retransfer these complexes must be counted towards the material to be cleaned, the desired insoluble state of this impregnating composition can be achieved by crosslinking the impregnating composition containing PQAV, for example by means of polyfunctional crosslinking components.

The insoluble catchers based on PQAV can - as described in detail in the older applications - in the form of flat supports with a large surface area, e.g. in sheet or foil form or in the form of a cloth used. In particular, however, it is preferred according to the invention to use these essential auxiliaries in the form of finely divided substances which enable their disperse fine distribution in the washing or cleaning liquors and thus ensure that, with the most homogeneous possible distribution of the dirt-adsorbing catcher components, every contaminated area of the material to be cleaned of catcher substance is washed around. The transport path of a detached dirt particle from its original location to the desired landfill location on the catcher surface is kept as short as possible in this way. By moving and mixing the cleaning liquid, new, adsorptive PQAV surfaces of the surface of the molded part to be unloaded from pigment dirt can also be made available in this way. For the appropriate mixing, the movement of the entire bath triggered by ultrasound can be sufficient if the finely divided capture material is sufficiently suspended, but an additional movement of the bath liquid can also be provided.

The facts described here relate to the embodiment in which the surfaces to be cleaned are kept in constant, direct contact with the strainer when exposed to ultrasound. However, it is also in a further embodiment, which is described below possible to carry out the cleaning process under the influence of ultrasound in the absence of in particular fine-particle undissolved dirt traps, instead first taking up the dirt particles detached under the influence of ultrasound in the fleet and batchwise or continuously guiding this fleet over separately stored or held dirt traps, in order in this way to guide the fleet to get rid of dirt, in order to then subsequently feed the cleaning liquor refreshed in this way to the cleaning process.

The catchers based on PQAV, which are present as a heterogeneous solid phase according to the invention, absorb, in particular, electrostatically charged portions from the dirt-laden liquor, for example correspondingly negatively charged particle dirt. In addition, due to other surface forces, the PQAV solid material can also have a cleaning effect or relieve fleets of other dirt components. In particular, the PQAV-based catchers are also able to remove considerable amounts of grease from the fleet. In order to reinforce the cleaning effect, it can be useful in this context to use substance classes other than dirt-absorbing catchers in the sense of the invention or to use them together with the PQAV-based catchers.

In an important embodiment of the invention, auxiliaries which are also present in a heterogeneous solid phase and are distinguished by high absorption capacity for oleophilic soiling are used. It is known that selected plastics, for example polyethylene or polypropylene or polyurethanes or also superficially highly hydrophobic finished insoluble solids of any origin, have the ability to pull the oleophilic dirt portion, which has been hydrophilized under the action of surfactants, from a surfactant wash liquor and to hold on to its surface. Especially in the field of Technical surface cleaning of solid molded parts, the binding of considerable amounts of greasy dirt can be an important task. So far, organic solvents of the type CHC and / or CFC have been used for this purpose, which act as solvents for the greasy dirt and which, in previously known processes, have to be subjected to a usually distillative workup in order to maintain the cleaning action of the sonicated bath. On the other hand, it is basic knowledge of the person skilled in the art that greasy soiling can also be detached by means of aqueous washing liquors containing surfactant and can be taken up in the liquor. This working principle is used in the preferred embodiment of the invention in which aqueous washing or cleaning liquids are used. Undissolved catchers of the type described are then used, which remove the fatty dirt from the aqueous-surfactant liquor loaded with fatty dirt.

In an important embodiment of the invention, the entire catcher system can be based on such predominantly oleophilic contaminant-binding systems. This becomes possible if the soiling to be removed from the solid molded parts is exclusively or by far predominantly greasy soiling. Since this prerequisite is relatively rare in large-scale technology, and pigment stains must generally be expected, the catcher substrate based on PQAV or PQAV / surfactant complexes is at least partly used in the more important embodiment of the invention together with such oleophilic catchers also used.

The collectors for oleophilic dirt can be used, for example, in the form of flakes, fibers or fiber structures such as cloths, tangled fiber tiles, poromer skins and the like. The same applies here that they are in direct contact with the cleaning bath cleaning solid surface can be used and / or that their storage separate from the cleaning process is possible with batch or continuous passage of the cleaning liquor to absorb the oleophilic dirt. In any case, the teaching according to the invention also applies with regard to these dirt traps, that a manual and / or mechanical separation between the material to be cleaned and the dirt collector and in particular also between the liquid phase and the dirt collector is ensured.

The auxiliary substances which collect oleophilic dirt can be used simultaneously with the treatment of the cleaning liquor by catchers based on PQAV and / or separately therefrom. The individual working conditions are determined by the nature of the pollution in the cleaning liquor and the expected load of the dirt-collecting auxiliary substances in the solid phase.

The insoluble PQAV-based scavengers used as dirt-absorbing slimming agents are preferably used as a finely divided solid which is dispersed in the wash liquor during the washing process, can be removed from the washed items after the washing process has ended and, if desired, can ultimately also be separated from the cleaned washing liquor, as described in detail in the above-mentioned older application DE 36 05 716.9 (D 7538). Any insoluble materials of an inorganic and / or organic type are suitable as insoluble carrier materials for fixing PQAV or PQAV / surfactant complexes and thus for the immobilization of these dirt-collecting active components, provided that they are otherwise inert in the washing solutions. Suitable organic materials can, for example, be of vegetable origin. However, preference is given to inorganic supports such as those mentioned in the older ones Registrations are described. These are mineral substances of natural and / or synthetic origin, which are in the form of finely divided solids. PQAV-coated carrier substances having a specific surface area of at least about 0.5 m² / g are preferably used according to the invention, this specific surface area in particular preferably being at least 1 m² / g. The specific surface is understood to be the area that can be covered with PQAV. Certain minerals, which are particularly suitable here, have additional surface areas inside the solid phase - be it due to their pore structure or their ability to swell - which, however, are not or only to a limited extent accessible with PQAV. However, the verifiable outer surface can reach considerable values, which can reach or exceed 10 m² / g and also 50 m² / g and lead up to the range of 100 m² / g or even up to for example 300 m² / g. Colloidal silicas may be mentioned as examples of such extreme surfaces that are accessible for covering with PQAV.

The maximum particle sizes of the PQAV-loaded fine particles are preferably not above about 100 μ, preferably not above about 40 μ - these numerical values are based on the absolute particle diameter and mean that all or at least the vast majority of the fine particles present meet these general conditions correspond. Particles which have an average particle size (volume average) of at most about 10 μ can be particularly useful for effective cleaning, the absolute particle size of at least the majority of all solid particles also being below this value.

Suitable inorganic carriers are in particular insoluble and finely divided salts, oxides, silicates and the like. Especially For example, aluminosilicates of the type of zeolites or zeolite-like compounds are suitable, in particular sodium zeolite A, which is widely used in detergents today. In its place, however, zeolite A can also be used in an exchanged form, for example as a calcium salt.

A particularly suitable mineral carrier class is swellable, finely divided substances of the type of clays and / or swellable layered silicates, in particular from the smectite class. Swellable inorganic minerals of this type are characterized by a particularly large surface when swollen. This can be used within the scope of the invention. The known smectite clays montmorillonite, hectorite and / or saponite are particularly suitable here. However, comparable synthetic materials are also suitable, and in particular corresponding synthetic materials with only limited swellability, as are described, for example, in the earlier application DE 35 26 405.5 (D 7031).

If catchers are used which contain the insoluble active component - for example the PQAV / surfactant complex and / or the strongly oleophilic coating - as surface finish per se of inert insoluble solids, it may be preferred according to the invention to use these active surface finishes in as much as possible provide a thin layer on the insoluble solid supports. This ensures optimal use of the dirt-collecting active materials. In this context, it can be preferred, for example, to work with layer thicknesses of PQAV or PQAV / surfactant complexes on insoluble supports which do not, or do not significantly, exceed the range of approximately 100 μ. In a preferred embodiment of the invention, however, much smaller layer thicknesses of such immobilized PQAV collectors are provided. If you work with finely divided coated carriers, for example mineral-based, high specific surface area, the thickness of the coating containing PQAV can reach into the range of monomolecular layers. Accordingly, layer thicknesses of the active substance on the carrier materials in the range up to about 1 μ and below can preferably be used.

In the method according to the invention, it is possible to work effectively with baths in which the capacity of the undissolved dirt traps for immobilizing dirt on the catcher is already largely exhausted but not yet fully utilized. This embodiment is particularly important for a continuous cleaning process in which stationary sound baths are used, the undissolved capture phase of which is regenerated batchwise or continuously, while the material to be cleaned is also passed batchwise or continuously through the sonicated cleaning stage. Here, for example, the cleaning can be carried out in such a way that the bath liquid together with the dirt-laden catcher is pumped through a separation stage in which at least portions of the dirt-laden catcher are separated off, while free catcher capacity is returned to the bath. In the other embodiment described above, the method of operation is possible in such a way that the surfaces to be cleaned are only treated with the washing solution under the action of sound and the dirt is first transferred to the washing solution, whereupon this washing solution is batchwise and / or continuously through a separately stored bed the strainer is guided and at least partially regenerated here. In general, especially for continuous processes of the type mentioned here, it is possible to work with catchers whose capacity for immobilizing dirt on the catcher is about 20 to about 98%, preferably not more than about 95% and in particular in the range from about 50 to Is 90% busy.

The amounts of undissolved catcher to be used in connection with the method according to the invention are matched to the expected contamination load. If it is intended to use these dirt absorbers only once, the smallest amounts of the catcher are often sufficient, provided that only minor contamination can be removed. In large-scale, in particular continuous, cleaning processes, however, comparatively large amounts of pigment and / or grease soiling are obtained and have to be removed. This fact can be countered by the total amount of catcher used and / or by preferably partially discharging contaminated catcher parts and correspondingly introducing fresh catcher parts. All in all, the catchers of the species concerned are able to bind the same to dirt, in particular pigment and / or grease dirt, up to a multiple of their weight - in particular due to the spreading of the PQAV-based catchers on the carrier substrate in the thinnest layer.

If dirt-absorbing scavengers are used in the context of the invention which contain an impregnation with PQAV or PQAV / surfactant complex or an appropriate hydrophobic equipment for absorbing oleophilic dirt on an organic and / or inorganic insoluble carrier, then it may be preferred to determine the amount of these Impregnation - based on the total weight of the impregnated solid - in the range from about 0.01 to 20 percent by weight and in particular in the range from about 0.1 to 10 percent by weight, preferably in the range from about 0.1 to 1 percent by weight.

The use of the swellable layered silicates of the smectite group mentioned above and in particular the use of swellable, finely divided montmorillonite, hectorite or saponite can be modified as follows: large surface ready for the absorption of PQAV / surfactant complex, the pre-swelling of these swellable materials is recommended. This pre-swelling is possible in a purely aqueous phase. In a special embodiment, however, the inner regions of the swellable materials can be designed such that they take on an additional function within the framework of the dirt collector according to the invention. In this embodiment, it is within the teaching of the invention to provide the swellable internal structure of these minerals with an oleophilic coating and to additionally coat layered silicates treated in this way on the outer surface with a very thin layer of PQAV / surfactant complex. The oleophilic interior areas of this solid phase are then able to soak up oleophilic dirt particles detached in the cleaning process and thus further intensify the cleaning effect of the chemicals. Monoquaternary ammonium compounds which have hydrocarbon radicals of limited carbon number on the quaternary nitrogen atom, for example with up to 18, preferably with up to 12, carbon atoms are suitable for the oleophilic finishing of such swollen dirt collectors. In addition to or instead of the previous or subsequent overlaying of such sheet silicates by the PQAV / surfactant complexes, suitably equipped sheet silicates can also be used as a mixture component together with the solids serving as pigment dirt collectors.

The temperature of the wash liquor in the ultrasound treatment can be up to about 95 ° C, but is preferably considerably lower and usually does not exceed temperatures of about 80 ° C. Effective cleaning is possible at room temperature. Lowering the process temperature toward room temperature is even preferred from the standpoint of promoting desired cavitation formation. On the other hand, it should be borne in mind that in the invention However, there is a certain interplay between conventional cleaning effects using surfactants and the known effect of ultrasonic cleaning. It has often proven to be expedient to carry out the washing step of the ultrasound treatment in the temperature range from approximately 30 to approximately 70 ° C. and here in particular in the temperature range from approximately 35 to approximately 50 ° C.

The frequency range for carrying out the method according to the invention in the stage of ultrasound treatment concerned here is the entire range known today and also partially used in cleaning methods. Particularly preferred frequencies of the sonication are in the range up to approximately 100 kHz, the lower limit for the ultrasound usually being specified as approximately 16 kHz. Accordingly, a range of about 20 to 60 kHz for the sound frequency used can be particularly suitable, although it is also known here that the tendency towards cavitation and thus the triggering of the desired cleaning forces becomes greater the lower the sonication frequency in the case mentioned here Area is selected. However, the effects of much higher frequencies are also known, e.g. up to the MHz range, which are characterized in particular by a stronger material penetration ability or force - even if the tendency to promote cavitation decreases.

It may be expedient to move the material to be cleaned continuously and / or discontinuously in the washing bath during the sonication step. This not only compensates for the disadvantages of any shadow areas, it can also significantly accelerate the removal of pigmented dirt.

The design of the sound reinforcement stage in the method according to the invention or of the devices suitable for carrying out this method stage is generally influenced by a plurality of parameters. As an example, his: composition and selection of the cleaning system, size and degree of loading of the cleaning bath, operating conditions of the cleaning bath, accessibility, durability and energy consumption of the sound reinforcement elements as well as expected degree of loading of the device in use, for example in the sense of a practically continuous use in the field of continuous commercial cleaning or periodic use only.

Such considerations ultimately also determine in the design of the cleaning devices that the cleaning step under ultrasound is carried out with a uniform frequency or with mixed frequencies and / or with sliding frequencies in the case of continuous or pulsating sonication. Values up to approximately 50 W / cm², in particular up to approximately 10 W / cm² and preferably values in the range from approximately 0.5 to 5 W / cm² have been found to be quite useful and effective as the power density, the power input into a bath, for example can range from at least about 20 W to the kW range. Larger amounts are also suitable for larger bathrooms.

Reliable washing results in the ultrasound stage are often obtained in the period from 0.01 to 60 minutes, in particular in 0.1 to 15 minutes, a period of about 1 to 15 minutes, in particular about 1 to 10 minutes, generally providing the desired cleaning action. As is known, there are special cases of shorter treatment times in the continuous cleaning of high-speed articles, for example wire.

For the cleaning method according to the invention, and in particular for the detachment of pigment and / or grease stains, which is facilitated and accelerated by the use of ultrasound, the general laws that apply to textile washing in the older patent applications mentioned and in particular in applications DE 36 06 729.6 also apply (D 7554) and DE 36 10 386 (D 7583) are described. The cleaning agent system for coping with the pigment dirt and / or grease dirt problem can be reduced to the suitable combination of the following two components: auxiliary means for detaching the dirt contamination from the items to be cleaned and dirt-absorbing insoluble or immobilized catchers in the sense of the invention.

The tools for detaching dirt and for transferring the detached dirt to the undissolved catcher are surfactants. Their nature and quantity can no longer be based on the fact that these surfactants used as washing aids are also of crucial importance for the solubilization of the detached pigment dirt in the liquor. The details of the earlier applications DE 36 06 729 (D 7554) and DE 36 10 386 (D 7583) mentioned apply here in detail.

In the method according to the invention, the cleaning stage using ultrasound can be combined in a manner known per se with additional work stages, for example pre-cleaning and / or with one or more subsequent rinsing and / or drying stages. Thus, the water-cleaned material can be dried in a manner known per se by subsequent treatment in an HFC bath in an energy-saving and stain-free manner at a relatively low temperature. In this context, reference is made, for example, to the published literature cited at the beginning.

example

Cleaning tests are carried out on complexly shaped motor vehicle carburetor elements which are covered with a thick, firmly adhering oil-pigment contamination due to several years of practical use. In the same bath, 3 such molded parts are treated in succession with the aqueous liquor described below under the action of ultrasound. About half of the molded parts are immersed in the bath liquid.

• 1. Fassungsvermögen des Reinigungsbottichs: 4 l; auf die Rei­nigungsflotte übertragene Ultraschallfrequenz: 35 kHz
• 2. Zusammensetzung der Waschflotte:
      0,5 g/l Fettalkoholethersulfat (2 EO) - "Texapon N25"
      1 g/l alpha-Sulfo-C₁₆/₁₈-Fettsäure-di-Natriumsalz
      0,6 g/l PQAV/Tensid-beschichtetes Schichtsilikat der nachstehend angegebenen Zusammensetzung
      1,5 g/l hydrophobierte Kieselsäure "Sipernat 50S"
  
    Das PQAV/Tensid-beschichtete Schichtsilikat - der erfin­dungsgemäß eingesetzte unlösliche Fänger - war wie folgt aufgebaut:
      unlöslicher Mineralstoff: quellfähiges Schichtsilikat "Dis-Thix-extra"
      PQAV: Cosmedia Guar C261
      Tensid: Texapon N25
      Gewichtsverhältnis Schichtsilikat/PQAV: 20/1
      Gewichtsverhältnis PQAV-beschichtetes Schichtsilikat/Tensid: 1/5
  
    Die die vorstehend aufgezählten Bestandteile enthaltende wäßrige Flotte ist auf Basis Leitungswasser (16 °dH) er­stellt.
• 3. Badbedingungen:
      Temperatur: 48 °C
      pH-Wert: 7 bis 7,5
      Beschallungsdauer pro behandeltes Formteil: 20 Min.

Subsequently, a cloth provided with standard soiling (dust / skin oil) based on a polyester fabric is exposed to the ultrasound in the dirty bathroom. The following applies in particular:

• 1. cleaning tub capacity: 4 l; Ultrasound frequency transmitted to the cleaning liquor: 35 kHz
• 2. Composition of the wash liquor:
  0.5 g / l fatty alcohol ether sulfate (2 EO) - "Texapon N25"
  1 g / l alpha-sulfo-C₁₆ / ₁₈-fatty acid di-sodium salt
  0.6 g / l PQAV / surfactant-coated layered silicate of the composition given below
  1.5 g / l hydrophobicized silica "Sipernat 50S"
  
  The PQAV / surfactant-coated layered silicate - the insoluble scavenger used according to the invention - was constructed as follows:
  insoluble mineral: swellable layered silicate "Dis-Thix-extra"
  PQAV: Cosmedia Guar C261
  Surfactant: Texapon N25
  Layered silicate / PQAV weight ratio: 20/1
  Weight ratio of PQAV-coated layered silicate / surfactant: 1/5
  
  The aqueous liquor containing the components listed above is based on tap water (16 ° dH).
• 3. Bath conditions:
  Temperature: 48 ° C
  pH: 7 to 7.5
  Sonication duration per treated molded part: 20 min.

The molded carburettor parts taken from the deep-dark gray cleaning liquor are rinsed with tap water and dried.

The dipped parts are surface-clean. The non-immersed parts are still dirty.

The wash test on the polyester rag in the dirt-laden liquor leads from an initial remission value of 29.5% to a wash remission value of 80.0%. The washed and rinsed test cloth is pure white.

Claims (26)

1. A method for cleaning the surface of solid moldings, in particular pigment and / or greasy soiling, by treating them in a washing and cleaning bath with at least temporary exposure to ultrasound, if desired in conjunction with washing and / or rinsing stages without the action of ultrasound, characterized in that for the ultrasound treatment is carried out with a bath which contains at least largely insoluble catchers for the absorption of at least part of the detached dirt in this bath. 2. The method according to claim 1, characterized in that work is carried out with insoluble dirt traps, which can be separated from the clean molded material parts - and, if desired, also from the cleaning liquid - manually and / or mechanically. 3. Process according to claims 1 and 2, characterized in that in the step of ultrasound treatment with aqueous baths containing dissolved surfactant components. 4. The method according to claims 1 to 3, characterized in that work is carried out with undissolved, solids catchers for pigment and / or grease soiling which prevent a substantial retransfer of the dirt particles taken up under the washing or cleaning conditions. 5. The method according to claims 1 to 4, characterized in that the dirt traps are used as a flat or finely divided material and are preferably applied to flat supports with a large surface area, for example as an immobilized coating on textile goods and / or foam material and / or in the form of a corresponding coating on finely divided supports which are insoluble in the washing and cleaning bath. 6. The method according to claims 1 to 5, characterized in that the ultrasound treatment takes place in aqueous baths, the pH of which can be in the weakly acidic to alkaline range, with working in the neutral range (about pH 6 to 8.5) may be preferred. 7. The method according to claims 1 to 6, characterized in that dirt traps are used, the organic or inorganic - in particular mineral - origin and have at least on their surface a pigment and / or grease dirt binding equipment immobilized. 8. The method according to claims 1 to 7, characterized in that insoluble polycationic, oleophilic and / or polyanionic dirt traps are used in the washing and cleaning bath, which contain appropriate equipment immobilized at least on their surface. 9. The method according to claims 1 to 8, characterized in that the surfactant and dirt trap in the washing or cleaning bath are matched to one another such that a direct transfer of the detached dirt to the catcher surface can take place without substantial retransfer to the surface of the molded part to be cleaned. 10. The method according to claims 1 to 9, characterized in that one works with a bath, the at least partially dissolved anionic surfactants and / or nonionic ten side together with an insoluble catcher containing polycationic elements. 11. The method according to claims 1 to 10, characterized in that insoluble dirt traps are used which have at least on their surface immobilized polyquaternary ammonium compounds (PQAV) or PQAV / surfactant complexes. 12. The method according to claims 1 to 11, characterized in that finely divided mineral solids, e.g. Insoluble metal oxides, carbonates, silicates and / or aluminosilicates are used, on the surface of which PQAV or PQAV / surfactant complexes and / or corresponding poly / tertiary amino compounds are immobilized. 13. The method according to claims 1 to 12, characterized in that the scavengers used for binding dirt have the equipment immobilized on the surface in a thin layer, preferably at layer thicknesses of not more than 100 µ, in particular in the range of 1 µ and below. 14. The method according to claims 1 to 13, characterized in that insoluble, finely divided dirt traps are used which have active surfaces of at least about 0.5 m² / g, in particular of at least about 1 m² / g. 15. The method according to claims 1 to 14, characterized in that in the stage of dirt detachment under the influence of ultrasound in addition to the insoluble dirt traps additional portions of finely divided solids in the bathroom liquid are used, which are preferably hydrophobic or have hydrophobic molecular components. 16. The method according to claims 1 to 15, characterized in that washing or cleaning baths are used, the hydrophobized very finely divided minerals e.g. contain correspondingly pretreated silica and / or surfactants which are sparingly soluble at the process temperature of the ultrasound treatment, partly undissolved. 17. The method according to claims 1 to 16, characterized in that surfactant mixtures are used which contain sparingly soluble surfactants together with readily soluble surfactants at the process temperature of the ultrasound treatment in an aqueous bath. 18. The method according to claims 1 to 17, characterized in that the ultrasonic treatment is carried out at temperatures up to about 80 ° C, preferably in the range from about room temperature to 70 ° C. 19. The method according to claims 1 to 18, characterized in that the ultrasound treatment is carried out at frequencies in the range up to about 100 kHz, preferably in the range from about 20 to 60 kHz. 20. The method according to claims 1 to 19, characterized in that work is carried out with static and / or sliding frequencies with continuous and / or pulsing sound, whereby mixed frequencies can also be used. 21. The method according to claims 1 to 20, characterized in that in the sonication with power densities up to about 50 W / cm² is used, preferably power densities up to about 15 W / cm² are used. 22. The method according to claims 1 to 21, characterized in that work is carried out with stationary sound baths, the undissolved capture phase is regenerated batchwise or continuously. 23. The method according to claims 1 to 22, characterized in that the bath liquid is pumped together with dirt-laden catcher via a separation stage in which at least portions of the dirt-laden catcher are separated, while free catcher capacity is fed back to the bath. 24. The method according to claims 1 to 23, characterized in that one works with undissolved dirt traps containing baths whose capacity for dirt immobilization on the trap is about 20 to 95%, preferably about 50 to 90%, utilized. 25. The method according to claims 1 to 24, characterized in that in a continuous process with stationary ultrasonic baths with batchwise or continuous regeneration of the capture phase and batchwise or continuous throughput of the solids to be cleaned. 26. Modification of the method according to claims 1 to 25, characterized in that the dirt trap is arranged at least partially spatially separated from the molded parts to be cleaned and the washing and cleaning liquid preferably containing dissolved surfactants is passed batchwise or continuously over the dirt trap, whereupon the liquid phase preferably the Cleaning process is fed again.