US3345123A - Drycleaning process in which garments are initially contacted with an organic solvent-water-deter-gent concentrate - Google Patents

Description

DRYCLEANING PROCESS IN WHICH GAR- MENTS ARE INITIALLY CONTACTED WITH AN ORGANIC SOLVENT WATER DETER- GENT CONCENTRATE James M. Chisholm, Cincinnati, Ohio,

Industries, Inc., Cincinnati, Ohio,

Ohio

No Drawing. Continuation of application Ser. No. 179,854, Mar. 15. 1962. This application Sept. 7, 1965, Ser. No. 485,526

3 Claims. (Cl. 8-142) This application is a continuation of my copending application, Ser. No. 179,854, filed Mar. 15, 1962, now abandoned.

This invention relates to a novel dry cleaning method of the type employed in coin-actuated and other units.

The dry cleaning operation with which this invention is concerned is one of the cyclic type wherein the soiled garments to be cleaned are charged to an empty, perforate cylinder rotatably mounted within a cleaning tub into which solvent solution is then pumped for contact with said garments as they are tumbled by the turning cylinder. The incoming solvent reaches an overflow level early during the cleaning phase of the cycle, thus permitting added quantities of the solvent to be continuously pumped into the tub while the overflow passes through a filter and is again returned to the tub. Once the cleaning phase is completed, the solvent is drained from the unit, after which the garments are extracted and then dried. The unit is then ready to repeat the cycle with a new ganment load.

While not specifically so limited, the invention finds particular utility in connection with dry cleaning units of the coin-actuated type. With the widespread introduction of such units, the industry has been faced with cleaning problems never heretofore encountered in commercial operations. In the latter operations the common good practice is to segregate the various garments received for cleaninto the loads of a generally similar kind, each load then being cleaned under conditions best adapted thereto. Goods of a heavily soiled variety, for example, are frequently handled together and receive an unusually intensive cleaning treatment. Again, woolens are handled sep arately and are processed under one set of conditions, while lighter goods such as cottons, synthetics, silks and the like are cleaned under still different conditions. The coin-actuated unit, as a practical measure, permits of no such segregation and of no variation in the quality, intensity or duration of the cleaning portion of the cycle. Such units must be prepared to handle mixed loads comprised of garments of every conceivable category and to thoroughly clean even heavily soiled items. Yet the action must be such as to avoid damage to the lightest and most fragile garments.

It is a general object of the invention to provide a novel cleaning method which makes it possible to achieve the foregoing results with a drycleaning unit operating in the cyclic fashion referred to above, and more particularly with a cyclic unit of the coin-actuated type.

In modern drycleaning operations it is customary to add from about 0.5 to of a detergent to the liquid hydrocarbon or halogenated hydrocarbon which is employed as the cleaning solvent. These detergents are essentially oil-soluble and have but slight solubility in the water which in many cases is added to the solvent to impart a measure of spotting" action thereto. The latter term refers to the action by which water-soluble stains or soil, such as sugar, perspiration, and similar residues, are removed from the garment by contact with moisture, preferably after the garment is wet by the cleaning solvent. The term drycleaning, on the other hand, refers to the assignor to Emery a corporation of action by which water-insoluble soil is removed by the detergent-containing solvent. While these conventional detergents are, as noted above, only slightly soluble in water, they do have the capacity to absorb or dissolve water and thereby disperse the same in the solvent to a limited degree. Under these conditions the dispersed water necessarily contains but a low concentration of detergent and, though absorbed on the clothes, can exert only a moderate degree of effectiveness. While any resulting spotting action may be adequate for many lightly soiled garments, it is entirely inadequate for such articles as carcoats and childrens clothing when heavily soiled with residues of the water-soluble type.

It is, therefore, another object of this invention to bring the spotting action of the drycleaning solution to the highest practical level.

Reference has been made above to the fact that water is in many cases added to the drycleaning solvent toobtain at least a limited degree of watercleaning, or spotting action, the Water also serving to dissipate static charges which build up on the clothes, particularly as they are tumbled during the drying phase of the cycle. Previously, any water so employed has been added to the total quantity of solvent in the tub in which a given load of clothes is being turned or premixed with the total solvent being circulated to the wheel for each load. While in such operations some of the water is absorbed on the clothes during the initial portion of cleaning phase, other quantities of the water are not absorbed until the terminal cleaning stages have been reached and can thus exert little effective action. Moreover, appreciable amounts of the added water never have an opportunity to be absorbed on the clothes but are swept out of the tub with the overflow stream. The presence of water in this stream may add to the difliculty of filtering said stream in some systems due to resulting higher pressures encountered. In view of these difiiculties, it is another object of this inven, tion to provide a method whereby the Water added to the system is rapidly and completely absorbed by the garments to be cleaned and is not allowed to overflow with the solvent recycle stream.

To do effective spotting in the presence of the conventional dry cleaning solvent, it is necessary that the amount of water absorbed by the garment be regulated within rather narrow limits. This amount ranges from about 0.1 to 1.5 ounces per pound of garment, the more heavily soiled materials requiring proportionately greater water contents than do those which are substantially free of water-soluble soil. A preferred range is from about 0.25 to 0.75 ounce of water/ lb. of clothes. Generally speaking, amounts of water within such ranges can be absorbed by any garment without wrinkling or shrinking the fabric provided that the water is absorbed evenly and in a manner which prevents largeramounts of water from being absorbed by local fabric areas. In one method of operation utilized by commercial cleaning establishments to effect adequate water emplacement, the more heavily soiled items are first dipped in solvent and then in water, the

principle being that the solvent-wet garments can pick up but little added water over that actually required. Again, in coin-actuated installations the user is cautioned to water-spray all spots and underarm areas of each garment before introducing the load into the cylinder. Both meth- Ods have obvious drawbacks, the former being cumbersome and inaccurate, while the latter must inevitably lead to wrinkling, color loss and shrinkage due to localized over-application, or else to inadequate water addition and poor spotting action.

It is a further object of this invention to provide a method whereby clothing placed in the empty cylinder of a drycleaning unit can rapidly and evenly be provided with the desired amount of water while simultaneously being wetted with solvent, the water being absorbed uniformly without in any way risking wrinkling or shrinkage of the garment fabric, or substantial contamination of the solvent overflow stream with water. A more particular object is to accomplish said result while also providing the absorbed water with an effective detergent capable of being readily dissolved (or dispersed) in the water, whereby the garments may be given a complete and balanced clean. ing treatment for the entire duration of the cleaning phase of the cycle.

In commercial operations wherein the solvent is provided with an oil-soluble detergent, an attempt is made to keep the concentration of detergent at the same general level by making periodic additions thereof. Similarly, water is added to the system from time to time to regulate its moisture content. However, it is common knowledge that the concentration of these materials in the system, particularly that of the water, varies widely from load to load and from one day to the next. It is an added object of this invention to provide a method whereby such water and detergent concentration variables may be entirely obviated, and whereby the solvent solution with which the garments are cleaned may have the same water and detergent concentration at the start of each operating cycle, thus permitting the unit to operate at peak efliciency with each new load.

The present invention rests on the discovery that the above and other objectives can be attained by wetting the garment load to be cleaned, early during the cleaning phase and before the solvent level in the tub reaches the overflow stage, with a solvent solution containing a predetermined quantity of dispersed water and a detergent of the so-called water-soluble" type. The total amount of water so introduced early in the cleaning phase is that calculated to provide the garment load with the desired content of water. This may range from about 0.1 to 1.5 ounces per pound of garment, with a preferred range being from about 0.25 to 1.25 ounces/lb. Such amounts are conveniently dispersed in the first few gallons of solvent which wet the garments. Stated otherwise, the invention comprises the improvement of adding all of the water required (based on the weight of the garment load) to a portion of the solvent initially contacting the garment load. This provides a temporarily high concentration of water and water soluble detergent relative to the quantity of solvent, and promotes exhaustion of the water onto the garment load.

The term water soluble referring to the detergent means one which preferentially dissolves in or is otherwise dispersed in the water phase and is but slightly soluble in the solvent phase. The content of the water-soluble detergent added along with the water and which dissolves or otherwise distributes itself essentially in the water phase (thus facilitating dispersion of the latter in the solvent and maximizing the spotting action of the system) may range from about 3 to 30%, based on the weight of water present.

Preferably, the solvent solution initially contacting the garments is also provided with additional, or make-up, quantities of an oil-soluble detergent of the type present in the entire volume of solvent circulating in the system. The amount of oil-soluble detergent preferably added to the solvent bath at the beginning of the cleaning cycle (over and above that contained in the incoming solvent stream from the solvent reservoir of the unit) is generally equal to that which will be removed from the system during a given cycle as a residue remaining on the dried, clean garments. This can readily be calculated by determining the amount of solvent left on the garments by a given unit at the conclusion of the extraction step, for all detergent then present in this residual solvent will remain on the finished garments as they are dried preparatory to being taken from the unit.

The method of this invention obviates critical concentration variables by replacing substantially the entire water and water-soluble detergent content of the solvent contacting the garments with each new operating cycle, that is, with the initial portions of solvent contacting each new load of garments. At the same time, replacements amounts of the oil-soluble detergent may also be added, if desired with each cycle. As indicated above, this is accomplished by providing the solvent entering the tub during the initial stages of each cleaning phase with the total quantities of water, water-soluble detergent and oilsoluble detergent required for the garment load to be cleaned. Substantially all of the water and water-soluble detergent so introduced are rapidly absorbed by the garments and are still present thereon (as is a certain amount of the oil-soluble detergent) at the completion of the extraction phase, the latter involving spinning the garments (from which the solvent has been drained) to express contained solvent. During the ensuing heating, or drying stage, the absorbed water is removed along with remaining solvent, the resulting vaporous effluent being condensed and passed to a water/solvent separator from which the water layer is discarded while the solvent is either directly returned to the solvent reservoir of the unit or is kept aside for later addition along with added detergent, along with residual amounts of the oil-soluble detergent, remains on the garment, these detergent residues acting to soften and otherwise improve the feel and appearance of the finished garment.

The present invention provides a controlled method whereby all the water and its accompanying (water-soluble) detergent required for a given cycle of operation are added on a load-by-load basis and are brought into effective working contact with the garments at an early stage of the cleaning phase. Addition of these components is substantially completed before the overflow stage is reached, with the result that the re-cycle solvent stream contains but trace amounts thereof. Moreover, by adding with each load an amount of the oil-soluble detergent calculated to be generally equal to that retained by the dried clothing, the concentration of this component may also be kept at a uniform, predetermined level.

One manner in which the present invention may be practiced can be illustrated by reference to the figure of the appended drawing which is a simplified flow scheme of a dry cleaning unit of the cyclic type. For the sake of greater clarity, said figure is described below in the example wherein details are given of a particular unit of the type adapted to receive and clean a small load of clothes on being actuated by the introduction of coins or otherwise.

Example A load of soiled garments Weighing approximately 10 lbs. is placed in the cleaning tub 10 of the unit, more particularly within the perforate cylinder 11 rotatably mounted therein. The door of the opening leading into the cylinder is then tightly closed and the unit is ready to commence its cycle of operation. At this initial stage the tub is essentially free of contained solvent, the same having been drained into the reservoir 12 at the close of the cleaning phase of the previous cycle of operation. As the unit is now actuated, the cylinder 11 begins to revolve, while solvent (such as perchlorethylene or a liquid hydrocarbon) is pumped into the tub through line 18 for contact with the garments.

The solvent, in passing to the cleaning tub, leaves the reservoir 12 and, after passing through line 13 and a deaeration chamber 14, enters line 15 and is impelled by pump 16 through a filter 17 and thence through line 18 into the tub 10, a portion of the solvent also reaching the tub via connecting lines 22 and 26. During this, the cleaning phase of the cycle, valve 19 in line 18 is open, while valve 20 in line 21 is closed, these valve settings being reversed during the ensuing portions of the cycle.

As the unit begins to pump solvent into line 18, a portion of the solvent passes via connecting line 22 into the reservoir 22' containing a charge of water and detergent (as previously accumulated therein) which is to be transferred to the tub for the cleaning operation then underway. The solvent entering the reservoir through line 22 sweeps this charge through line 26 and open valve 27 into the tub where said charge is rapidly dispersed in the solvent entering from line 18. In this particular operation, the tub reaches the overflow stage after about 10 gallons of solvent have been introduced. However, the charge contained in reservoir 22 is entirely transferred to the tub well before the overflow stage is reached, and normally by the time the tub contains ,but about 1-5 gallons of solvent.

The unit charge in reservoir 22 is made up of about 5 oz. of water, about 0.6 oz. of a water-soluble detergent (prepared by reacting 2 moles of diethanolamine with 1 mole of mixed coconut oil fatty acids, at a temperature of about 140 C. until the free acid content of the product is less than 4%), about 0.25 oz. of an oil-soluble detergent such as a petroleum sulfonate, and about 0.5 oz. of a material such as isopropanol which acts to reduce the viscosity of the charge and to impart compatability, or homogeneity thereto.

Under the conditions herein described, substantially all of the water and the water-soluble detergent introduced during a given cycle are absorbed by the garments and little if any is free to be carried out of the tub with the solvent stream which continues to pass out the overflow line during the balance of the cleaning phase once the solvent level reaches the overflow stage. On the other hand, the oil-soluble detergent component of the charge in reservoir 22' becomes a part of the solvent phase and thus acts to maintain the concentration of this component in the system at a generally uniform level, load after load.

Soil, lint and other particles released from the garments being cleaned are caught up in the solvent phase and are carried out of the tub in the overflow stream (to be cause in filter 17) as the cleaning phase progresses. At the end of this phase, valve 19 closes while valve 20 opens, thus permitting the recirculating solvent stream to pass through the filter and back to the reservoir 12 via lines 18 and 21. Valve 27 in line 26 remains open for a brief interval after the closing of valve 19 to permit the solvent accumulated in reservoir 22' to be siphoned out through line 26 and drain into the tub. Valve 27 then closes, while valve 25 in line 24 opens, said line connecting the reservoir 22' with that indicated at 23 used to contain a larger volume of the water/detergent charge. Valve 25 remains open until the vessel 22' is filled with said charge, whereupon this valve closes until the unit reaches the end of the succeeding cleaning phase.

At the end of the cleaning phase, the solvent in the tub, along with that expressed from the garments as the cylinder is turned at high speed, is drained through line 29 as valve 30 is opened, valve 30 being closed once drainage from the tub is complete. The garments are now dried as hot air is supplied to the tub via line 33. Solvent and water vapors thus driven off from the garments exit via line 34 and are condensed in condenser unit 35. The non-condensed gases from said unit are recycled to the heater via lines 36 and 31 (the entrant air line), while the condensate passes through line 37 to a liquid separator unit 38 from which the water is drawn oif through line 39 and the solvent phase through line 40 to the reservoir 12. The clothes, once dried and optionally freshened by a flow of non-heated air, are then removed from the unit. Valves 27 and 19 are then opened, valve 20 is closed, and the unit is ready to repeat the cycle with a new load of garments.

The mechanism which is illustrated in the drawing and referred to in the foregoing example forms no part of the present invention, and alternative means can be substituted for those shown. Thus, a proper amount of the water/detergent charge can be introduced into the tub along with the solvent in any convenient fashion, one such method being to inject the charge by means of a piston-actuated device or the like.

The water-soluble detergent employed in the present invention is, as indicated above, one which, though slightly soluble in the solvent, is capable of being readily dissolved or of otherwise being dispersed in the aqueous phase of the system, thus increasing the elfectiveness of the contained water as a spot remover, while also acting to disperse the water in the solvent. This detergent should be compatible with the oil-soluble detergent which is dis solved in the solvent. Thus, assuming the use of an oilsoluble detergent of the anionic or the nonionic type, or of a mixture of said types, the water-soluble detergent should also be one falling in this same category. On the other hand, if the oil-soluble detergent be of a cationic nature, then the water-soluble detergent should be cationic and/or nonionic. The oil-soluble detergent referred to in the foregoing example is anionic, while the watersoluble detergent is one of the mixed anionic-nonionic type.

In general, representative water-soluble detergents which may be satisfactorily used in this invention are: 1) the various alkali metal and amine salts of alkaryl sulfonic acids (preferably those wherein the substituent alkyl group contains from about 12 to 18 carbon atoms), as represented by sodium dodecylbenzene sulfonate, diethanolamine dodecylbenzene sulfonate and ammonium hexadecylbenzene sulfonate; (2) fatty acid alkylolamides such as those prepared by reacting an excess of an alkyl olamine with a C3 c13 fatty acid or fatty acid mixture, representative products being those prepared by reacting diethanolamine, monoethanolamine or dipropanolamine with mixed coconut oil fatty acids or with oleic, pelargonic or other normally liquid fatty acid of this class; and (3) ethoxylated fatty acids as prepared by reacting a C C fatty acid amide with an excess of ethylene oxide. The above materials are anionic and/ or nonionic in character. In the unlikely event that a cationic detergent is to be employed, an appropriate material would be cetyl pyridinium chloride.

Representative oil-soluble detergents are the so-called mahogany sulfonates formed in the oil, or layer in the refining of medicinal white oil and the like by the use of fuming sulfuric acid and/ or sulfur trioxide. Other oilsoluble detergents which can be used are the various products formed by reacting a condensate of a fatty acid and an alkanolamine with an alkaryl sulfonic acid or with some other acidic, surface-active agent of the type formed by reacting a polybasic acid of sulfur with an organic compound containing from about 12 to 20 carbon atoms. In forming representative products of the latter category, a fatty acid material made up of fatty acids of from 12 to 18 carbons atoms and having a titre not exceeding about 42 C. is reacted at elevated temperatures with an excess of an alkanolamine (e.g., diethanolamine) until substantially all the water of condensation has been evolved. This condensate, along with an excess of the alkanolamine, is then reacted at elevated temperatures with an acidic material such as dodecylbenzene sulfonic acid, sulfated oleic acid or oleyl sulfonate, for example, the latter compounds being added in an amount suflicient to bring the product to near-neutrality. This reaction is preferably concluded when the amide/ester ratio of the product is between about l/l and 2/1.

In many cases, particularly when the charge of water and detergent to be added to the tub is rather thick and viscous, it is desirable to incorporate therewith a small amount, usually of the order of about 2 to 15%, of a material capable of reducing the viscosity of the charge and of coupling the various phases thereof (if more than one phase be present) into a homogeneous system. Suitable additives of this character are the various 'alkanols of from 1 to 5 carbon atoms as well as alcohol ethers, e.g., methanol, ethanol, isopropanol, butanol, diethylene glycol monobutyl ether and ethylene glycol monoethyl ether.

I claim:

1. In -a drycleaning method wherein, at the start of the cleaning step, an organic solvent containing an oilsoluble detergent is pumped into a cleaning tub in which the soiled garments are being tumbled, wherein the solvent level in the tub first reaches a level sufficient to wet said garments and then an overflow level, and wherein further quantities of said solvent are pumped into the tub for substantially the balance of the cleaning step as like quantities overflow from the tub, and a small quantity of water (measured on the weight of the fabric load) is added to the solvent for each load cleaned therein, the improvement which comprises adding all of said quantity of water and a water-soluble detergent contained therein to a portion of the organic solvent initially contacting the fabric load to provide a temporarily high concentration of water and water soluble detergent in relation to the quantity of solvent.

2. The method of claim 1 wherein the amount of water added ranges from about 0.1 to 1.5 ounces/lb. of soiled garments in the tub, and wherein the water-soluble detergent is added in an amount of from about 3 to in terms of the weight of water added.

3. The method of claim 2 wherein there is added, along with the water and the water-soluble detergent, an oil-soluble detergent 0f the type present in the incoming solvent, said oil-soluble detergent being added in an amount generally equal to that which will remain on the garments then being cleaned after they have been dried and removed from the unit.

References Cited UNITED STATES PATENTS 2,709,908 6/1955 Altorfer et a1. 86l2 X NORMAN G. TORCHIN, Primary Examiner.

I. CANNON, Assistant Examiner.

Claims (1)

1. IN A DRYCLEANING METHOD WHEREIN, AT THE START OF THE CLEANING STEP, AN ORGANIC SOLVENT CONTAINING AN OILSOLUBLE DETERGENT IS PUMPED INTO A CLEANING TUB IN WHICH THE SOILED GARMENTS ARE BEING TUMBLED, WHERIN THE SOLVENT LEVEL IN THE TUB FIRST REACHES A LEVEL SUFFICIENT TO WET SAID GARMENTS AND THEN AN OVERLFOW LEVEL, AND WHEREIN FURTHER QUANTITIES OF SAID SOLVENT ARE PUMPED INTO THE TUB FOR SUBSTANTIALLY THE BALANCE OF THE CLEANING STEP AS LIKE QUANTITIES OVERFLOW FROM THE TUB, AND A SMALL QUANTITY OF WATER (MEASURED ON THE WEIGHT OF THE FABRIC LOAD) IS ADDED TO THE SOLVENT FOR EACH LOD CLEANED THEREIN, THE IMPROVEMENT WHICH COMPRISES ADDING ALL OF SAID QUANTITY OF WATER AND A WATER-SOLUBLE DETEGENT CONTAINED THEREIN TO A PORTION OF THE ORGANIC SOLVENT INITIALLY CONTACTING THE FABRIC LOAD TO PROVIDE A TEMPORARILY HIGH CONCENTRATION OF WATER AND WATER SOLUBLE DETERGENT IN RELATION TO THE QUANTITY OF SOLVENT.