US3101239A

US3101239A - Dry cleaning

Info

Publication number: US3101239A
Application number: US384644A
Authority: US
Inventors: Paul V Warren; Martin B Mathews; Hirschhorn Ernestine
Original assignee: RR Street and Co Inc
Current assignee: RR Street and Co Inc
Priority date: 1953-10-07
Filing date: 1953-10-07
Publication date: 1963-08-20
Anticipated expiration: 1980-08-20

Description

Aug. 20, 1963 P. v. WARREN ETAL DRY CLEANING Filed 001;. 7, '1953 45 H lll' water is not properly distributed through the organic solvent. Hence, it will be understood that when we speak herein of emulsions containing oil-soluble dispersing agents or detergents and ater, it will be understood that we mean such emulsions wherein the water is so finely dispersed asto form a substantially clear homogeneous emulsion in the water-immiscible organic solvent, as viewed by the naked eye. It'is also important, for the most effective practice of our invention, that the entire system to be charged with water so that the emulsified water passes through the filter.

Our invention is also based, in part, on a procedure, and simple and etfectiveequipment for use therein, involving determining the electrical conductivity of the aforesaid dry" cleaning emulsions at periodic or nonperiodic intervals and" if, during use of such emulsions in the cleaning of a batch or successive batches of soiled fabrics, the electrical conductivity'iias dropped to aputilizing Stoddard solvent as the dry cleaning organic solvent, dioctyl sodiurnsulfosuccinate as the dispersing agent or detergent, and distilled water as the source of water,

i it is possible to plot curves showing the relationship of preciably below 1(l 10 'lmhos an amount of water and/or oil-soluble dispersing agent or dry cleaning detergent is addedto the emulsion so as to bring the elect'rical conductivity thereof to not less than the aforesaid minimum value thereof.

Our invention is particularly advantageously practiced with the utilization, as the oil-soluble dispersing agent, of sulfate and sulfonate detergents containing an alkyl group of at least '8 carbon atoms and'usually between 8 and 18 carbon atoms, in the form of salts thereof as, for in- 'stance, the alkali metal, ammonium and amine salts. In

addition to the examples thereof described above, salts of higher alkyl aryl sulfonates such'as dodecyl benzene sul- 'fonate, octyl benzene sulfonate, nonyl naphthalene sulfonate, keryl benzene sulfonates, and the like can be utilized. It is also particularly advantageous, in the especially preferred embodiments of our invention, to utilize proportions of oil-soluble dispersing agent or detergent,

on the non-volatile basis, of not less than about 1.5

based on the volume of the organic solvent, "and desirably within the range of about 1.5% to about 3%, a good average being about 2%. In this connection, it will be understood that dry cleaning detergents are commonly marketed in the form of liquid or paste products and frequently contain diluents, volatile ingredients and'the like over and above the non-volatile dry cleaning detergents proper. When wespeak of, for example, 1.5% to 3% of the dry cleaning detergent, said percentages are on the non-volatile :active detergent basis.

The amount of Water added to the water-immiscible dry cleaning solvent should, in the particularly preferred embodiments of our invention, not be appreciably less than 0.2%, by volume, and most-desirably ranges from about 0.2% to about 0.4% it being relatively uncommon that this latter figure will be exceeded. So far as actual dry cleaning practice goes, these amounts of water are abnormally large but their use, under the conditions of the present invention, has been found to be most advantageous, cleaning of the fabrics being enhanced and "subsequent spotting operations being reduced to a substantial The optimum conditions under which the dry cleaning operation should be conducted, taking into account the over-all aspects, therefore, will, in general, involve the utilization of la water-immiscible dry cleaning organic solvent emulsion containing from about 1.5% to about 3%, with a good average of about 2%, of "an oil-soluble sulfate or sulfonate detergent containing an alkyl group of at least 8 carbon atoms, and from about 0.2% toabout 0.4%, with a good average of about 0.3%, of water, the

electrical conductivity of said emulsion being not less In the light of the foregoing description, it Will be and "detergent content of such emulsions, the greater the theirrefiecting the condition of the emulsion with respect to the content of water and detergent therein. In the usual case, the electrical conductivity readings of an emulsion containing a relatively high proportion of soluble impurities resulting from long continued use of the emul sion prior to distillation thereof will show a somewhat lower conductivity than a similar pure organic solvent solution containing only the same amounts of oil-soluble detergent and Water. Suitable extrapolations can be resorted to, if desired, in situations of this kind, if deemed advisable, to take into account the effect of soluble impurities on the electrical conductivity of repeatedly used dry cleaning emulsions. v

I While satisfactory results are obtained with electrical conductivities maintained at not less than about 10 x10 mlios, we prefer to operate at higher levels as, for example, from about 40 to about l20 l0' mhos or even higher, a particularly preferred range being from about 50 to about x10 rn-hos.

In the preferred manner of carrying out the present invention, in theso-called two bath system, for example, invdry cleaning systems which include a washer-filtertrap assembly reserved for the detergent emulsions and a separate rinse and filter system, and wherein said emulsion is continuously circulated through said washer-filter-trap assembly, the water-immiscible liquid organic solvent is activated with the requisite amount of oil-soluble nonvolatile dry cleaning dispersing agent or detergent and the resulting solution is circulated through said assembly to effect uniform distribution of said dispersing agent or detergent throughout the entire body of organic solvent in the assembly. The requisite amount of Water is then added and the resulting mixture is circulated through said assembly whereby to solubilize or emulsify the water throughout the system, so that the solubilized or emulsified water emulsion passes through the filter, and forms a substantially clear homogeneous composition having an electrical conductivity not less than about 10X 10* mhos'. The soiled fabrics to be dry cleaned are then subjected to the resulting dry cleaning emulsion in the usual way, successive batches of soiled fabrics being dry cleaned. The electrical conductivity of the emulsion is measured, for

instance, from time to time, and, if the electrical conductivity has dropped to below the aforesaid value, an addiwithin the predetermined'ranges. It will, of course, be

understood that after the fabrics are cleaned they are rinsed and dried and fluffed in accordance with standard practices in the art. I

It will be understood that the addition of oil-soluble dispersing agent or detergent to the organic solvent emulsions will occur.- far more infrequently than'the additions ofwater. In this connection, it will be appreciated that the solubility and stability of the oil-soluble dispersing.

agent or detergent are such that the content thereof diminishesquite slowly so that replenishing thereof is necessary at only relatively sporadic intervals. Hence,

when the electrical conductivity drops below about.

x 10'' mhosit will, in most cases, be necessary to add only water in order to increase the electrical conductivity to a value above said minimum figure. The content of oil soluble detergent in the dry cleaning emulsion can be determined from time to time by heretofore known procedures; It may be found, in certain instances, that when the electrical conductivity drops below the aforesaid minimum value there may be a deficiency of both detergent and water, and, in such cases, both detergent and water will be added to bring the amounts thereof within the desired or predetermined ranges as well as restoring the electrical conductivity of the dry cleaning emulsion to a value not below said minimum figure. In the-usual case, however, as stated, water additions alone will be sufficient and the detergent content can be determined and maintained at desired proportions by procedures already known in the art.

- In the drawing, FIG. 1 illustrates a conventional type of dry cleaning system, except as pointed out below, showin g only the cleaning system in schematic form and wherein the usual washer-filter-trap assembly is utilized, the rinse system being omitted since it is strictly conventional and forms no part of our present invention although, of course, it will be understood that the rinse system is utilized after the cleaning operation is completed. In FIG. 1, we show a simple unit which is utilized in the practice of the method of our invention.

FIG. 2 is a vertical section through the unit or device for determining the electrical conductivity of the dry cleaning emulsion.

FIG. 3 isja perspective view of the electrodes and supporting structure.

In FIG. 1, numeral 10' represents a conventional type of dry cleaning washer or wheel connected through drain. 7 pipe 12 to the usual trap 14, pump 16 and filter 18. Connected into the line between the filter and wheel is the conductivity measuring device 20*, hereafter described in detail. As shown in FIG. 1, the device 20 is shown positioned in the direct line between the filter and the return line to the washer in which case all of the filtered solvent passes through said device. If desired, however, said device 20 can be positioned in a by-pass line so that the filtered solvent will not pass through said device 20 except when an actual conductivity test is to be carried out.

The device 20 shown in FIGS. 2 and 3 provides a simple, effective means which enables the dry cleaner readily to determine the electrical conductivity of his dry cleaning emulsions at any desired stage of his operation. Itcomprises a chamber 22 open at its top and provided with a cover 24. Connected into the chamber 22 adjacent its top is an inlet pipe 26 through which the dry cleaning emulsion is admitted to said chamber 22. A flexible tube 28 made of a material, such as Neoprene, which is resistant to the action of organic solvents, leads toward the bottom of the chamber. The pipe 26 is provided with a valve 30-. A pipe 32, serving as an outlet from the chamber 22 connects into the bottom of the chamber and joins, through a valve 34, a T 36. Extending from the T is an outlet pipe 38 and overflow pipe 40, the open top of said overflow pipe being disposed just above the top of the electrodes.

The electrode assembly, denoted generally by numeral 42, is adapted to be inserted and removed from the chamstance, Luci-te or polystyrene. Ihe frame comprises

side members

50, 52 which are provided with notches 54,

, 56in which opposite edges of the electrodes fit. The electrodes are supported and fixed in vertical position by bottom and

top members

58 and 60* respectively. Reinforcing

members

62, 64 are provided on opposite sides of the side members to impart strength and rigidity to the frame. The transverse plates 66 land 68 serve to hold the electrode assembly against tipping in the chamber 22.

Vertical extension pieces

70, 72 provide convenient grasping means for lifting the electrode assembly out of the chamber, and they serve also to rest against the underside of the cover to aid in holding the assembly in position against movement.

Electrodes

44 and 48 are electric-ally connected by wire 74 the ends of which may be soldered to said electrodes. Wire lead-s 76, 78, connected to

electrodes

46 and 44 respectively, pass through

grommets

80, 82 in the cover 24, and are adapted to be connected to anelectrical conductivity meter or measuring device (not shown) of any suitable type.

' Although we have described a system wherein the required additions of water and detergent are made, for instance from time to time, by what may be called manual means, it will be seen that, if desired, equipment can be so arranged as to automatically measure the electrical conductivity of the dry cleaning emulsion and automatically control the addition of water and/ or detergent in response to changes in electrical conductivity of the emulsion. This can readily be accomplished by the utilization of a measuring device wherein changes in the electrical conductivity of the emulsion during the subjection of the fabrics to the action thereof during the dry cleaning operation are determined and, when the electrical conductivity falls below a predetermined value, valve means are opened to admit water and/or detergent, particularly water, to

the-washer so that it is admixed with the dry cleaning organic solvent emulsion to bring the detergent and/ or water content up to the desired value. When such value is reached, in response to the increase in the electrical conductivity resulting from such increased detergent and/or water content, the valve means close and the supply of detergent and/ or water is shut off.

The electrical conductivity values referred to above and in the claims represent the reciprocal of resistance values in ohms obtained when using the herein described cell with brass plates measuring 6 x 5 /2 inches spaced 0.160- inch apart and a standard ohm meter which employs a potential of 60 volts DC. It will be appreciated that, with different types of cells and different cell constructions, different values may be obtained and such values may be reflected in terms of electrical conductance, electrical conductivity or electrical resistance. In any event, however, whatever the values may be and whatever the unit of measurement may be,- to the extent that such values correspond to the herein disclosed and claimed electrical conductivity values obtained by measurement with a cell made as described above, they will, of course, fall within the scope of our present invention. We prefer to recite the values in terms of electrical conductivity for simplicity purposes since these values increase with addition of water j ble non-volatile dry-cleaning water-emulsifying detergent and (b) from about 0.2% to about 0.4% of water so finely emulsified in said organic solvent as to form a substantially clear homogeneous emulsion, said emulsion having an electrical conductivity between about 10 and about 120x 1O mhos, periodically measuring the electrical conductivity of said emulsion and, when said electrical conductivity drops below said lower aforesaid value, measuring the emulsifying detergent content of said emulsion, adjusting said emulsifying detergent content to bring it to within the aforesaid values, and, to the extent required to bring the electrical conductivity of said emulsion to within the aforesaid values, adding water in the requisite amount.

2. In the dry cleaning of soiled fabrics, the steps which comprise cleaning successive batches of said fabrics with a continuously circulating filtered water-immiscible dry cleaning liquid organic solvent containing (a) from about 1.5% to about 3% of an oil-soluble dry cleaning wateremul'sifying detergent selected from the group consisting of sulfate and sulfonate detergents containing an alkyl group of at least 8 carbon atoms, and (b) from about 0.2% to about 0.4% of water so finely emulsified in said organic solvent as to form a substantially clear homogeneous emulsion, said emulsion having an electrical conductivity between about 50 and about l 10- rnhos, measuring the electrical conductivity of said filtered emulsion and, when said electrical conductivity drops below said lower aforesaid value, measuring the detergent content of said filtered emulsion, adjusting said detergent content to restore it to Within the aforesaid values, and adding water in the requisite amounts to restorethe electrical conductivity of saidfiltered emulsion to within the aforesaid values.

References Cited in the file of this patent 1 UNITED STATES PATENTS Keeler Mar. 24, 1925 1,810,660 Kritchevsky et ai. June 16, 1931 1,935,264 Felix et al Nov. 14, 1933 2,024,981 Reddish Dec. 17, 1935 2,158,614 Reddish May 16, 1939 2,251,691 Richardson AugfS, 1941 2,271,635 Flett ,Feb. 3, 1942 2,475,023 Grimes July 5, 1949 2,552,088 Davis May 8, 1951 2,614,026 Lascari Oct.16, 1952 2,621,673 Hodgens Dec. 16, 1952 2,632,144 Borrell Mar. 17, 1953 2,715,833 Fulton et al Aug. 23, 1955 FOREIGN PATENTS 392,931 Great Britain May .15, 1933 OTHER REFERENCES BulletinNo. T-292, Natl. Institute of Cleaning and Dyeing, Silver Spring, Maryland, Oct. 30, 1952 (4 pp.). (Copy available at Natl. Institute.) 7 ASTM Bulletin, No. 192, September 1953, pages (TP153) 63 to (TPlSS) 68. (Copy available at ASTM Headquarters, Phila., Pa.)

Claims

2. IN THE DRY CLEANING OF SOLID FABRICS, THE STEPS WHICH COMPRISE CLEANING SUCCESSIVE BATCHES OF SAID FABRICS WITH A CONTINUOUSLY CIRCULATING FILTERED WATER-IMMISCIBLE DRY CLEANING LIQUID ORGANIC SOLVENT CONTAINING (A) FROM ABOUT 1.5% TO ABOUT 3% OF AN OIL-SOLUBLE DRY CLEANING WATEREMULSIFYING DETERGENT SELECTED FROM THE GROUP CONSISTING OF SULFATE AND SULFONATE DETERGENTS CONTAINING AN ALKYL GROUP OF AT LEAST 8 CARBON ATOMS, AND (B) FROM ABOUT 0.2% TO ABOUT 0.4% OF WATER SO FINELY EMULSIFIED IN SAID ORGANIC SOLVENT AS TO FORM A SUBSTANTIALLY CLEAR HOMOGENEOUS EMULSION, AND EMULSION HAVING AN ELECTRICAL CON-