IL22070A - Dry-cleaning of materials - Google Patents

Description

This invention relates to improvements in the cleansing or cleaning of materials with an organic solvent that is capable of solidifying or congealing at a relatively high temperature. In general, the invention is concerned with the simplification of cleaning materials with an organic solvent by the use of a composition which may exist in a solid state in one step of the procedure, together xfith the necessary steps and apparatus by which materials can be cleansed, and in which the solvent can be economically recovered.

The prior art practices of cleansing of materials with organic solvents have either embodied the use of inflammable solvents which are dangerous to handle, or where the more costly non-flammable solvents have been used, because of the various needs of recovering such solvents the procedures and apparatus are relatively complex, requiring the services of skilled personnel and relatively expensive installations.

In the present invention, it is contemplated using materials, procedures and apparatus by which the dry cleaning of garments and other textile materials, or the degreasing and cleaning of metal products can b e simplified and performed in a satisfactory manner with less expensive equipment than is currently used. This invention is, in part, based on the discovery that garments and textile materials, as well as metal parts can be satisfactorily cleaned with the use of a composition comprising a solvent that has superior cleansing qualities, and which may exist in a congealed or solid form during a part of the procedure. It has been found that some of the solvents of this class of compositions have exceptionally good cleaning properties, and by reason of their high congealing or freezing points, can be more easily recovered than in the case of prior synthetic solvents. Although the evaporation rates of some of the solvents contemplated in the present invention are relatively low, as compared to carbon tetrachloride, the vapors can be removed from textiles or other objects with air at relatively normal temperatures. Thus, it is possible to avoid the use of extensive amounts of heat in drying textiles or other objects, and thereby avoid the handicaps that accompany the use of some of the prior art solvents, such as perchlorethylene or other similar solvents having a relatively high boiling point. Also, since the solvents contemplated by this invention can be condensed or congealed at easily attainable low temperatures, it is possible to avoid the costly procedures and equipment necessary to purify and recover such solvents.

A particular feature of the present invention is that it simplifies dry cleaning of textiles to the extent that some forms of apparatus comparable in cost and simplicity of operation to home laundry equipment can be utilized* An object of this invention is to provide a relatively simple process for the cleansing of textile materials or metal objects which embodies the use of a cleansing composition comprising an organic solvent which may be solid in one step of the procedure and may be readily liquif ed for cleansin and vaporized for removal and subsequently condensed to a liquid form and also converted into a solid state at an easily attained low temperature.

Another object is to provide a method and means of dry cleanin textile materials which avoids many of the complicated procedures and equipment heretofore required with previously used solvents.

Another object is to provide a dry cleaning composition comprising an organic solvent having dry cleanin qualities and characterized by having a freezing point not substantially lower than that of water.

A further object is to provide apparatus suitable for dry cleaning garments and textile materials in the home o under similar circumstances in which the operation can be safely conducted and economically performed by relatively unskilled personnel.

Other and further objects may become apparent from the followin specification and claims, and in the appended drawing, which is a schematic illustration of one form of dry cleaning apparatus forming a part of the present invention.

A highly important feature of the present invention is in the selection of an appropriate cleaning or.cleansing composition having characteristics that make it appropriate for the intended uses. The composition must he composed of an organic material that forms an acceptable dry cleaning or.other type of eleansing solvents, and which also have the added characteristic of a relatively high congealing or freezing point. To be acceptable as a "dry cleaning solvent", the solvent must not weaken nor shrink ordinary textile fibers, nor bleed the common dyes from such fibers. It must have the ability to remove fats and oils; it should not impar objectionable odors to textiles; and it should be non-corrosive to metalsi The solvents selected for this invention have all of the desirable characteristics set forth hereinbefore, and in addition thereto, their cleaning qualities are equal to or superior to that of any prior art solvent, and they are relatively non-toxic. Mos important, the selected solvents all possess a relatively high congealing or freezing point.

The class of solvents with which this invention is concerned are those organic solvents having relatively high congealing or freezin points.

While there, may be a number of solvents that come within this class, I have found those most desirable are certain chloro-fluorohydrocarbons which contain at least two carbon atoms, one chlorine atom and at least two fluorine atoms to the molecule, and for practical purposes, have a freezing point not appreciably lower than listed, together with their boiling points and freezing points.

B.P.O. F.g.C. 1,1,2,2 tetrachloro-1,2 difluoroethane 92.8 26.0 (CC12FCC12P) 1,1,1,2 tetrachloro-2,2 difluoroethane 92.0 42.0 1,1,1 trichloro-2,2,2 trifluoroethane 45.7 14.0 (CC1,CF,) 2,2,3 72.0 -4.0 1,2,2,3»3 pentachloro-1,1,3 trifluoro- 152.0 -5.0 propane (CFgClCClgC Clg) The first two of the aforementioned solvents, which are preferred, have a relatively low latent heat of fusion, in the order of 10 Btu*s per pound, an evaporation rate of 35 as compared to 100 for carbon tetrachloride, and a vapor pressure of the liquified solvent at its meltin „ point of about 1.5 pounds per square inch.

These solvents may be used alone or in a mixture with each other, but when used for the dry cleaning of textiles or garments, are admixed with a small amount of a surface active agent that may be either anionic, cationic or non-ionic. An example of an anionic surface active agent is an alkyl aryl sulphonate; an example of a cationic agent is"a quaternary ammonium salt; and an example of a non-ionic agent is an alkyl aryl polyethylene ether. Any one or a mixture of these surface active agents in a small amount, not generally in excess of 2 , may be added to the solvent,, either as a preliminary ,treatment, or during the washing operation* A small amount of water may also be present in the cleaning composition to aid in the forming of an emulsion, and ordinarily, the amount of water should likewise not exceed about , 2% of the solvent, based on solvent weight.

Referring now to the drawing, which is merely illustrative of one form of apparatus, reference character 10 indicates a closed casing provided with a door 12 providing access to the interior of the casing* Within, the interior o casing 10, and illustrated in dotted lines, is a fKraininous cylinder 14v which is rotatably driven, preferably at two speeds by means no shown.

Disposed beneath casing 10 is a container 16 which is joined to casing 10 by a conduit 18 containing a valve 20,. While not shown, container 16 has a suitable access opening for admission of solvent, as well as suitable means for removing residue;, such as soil from the container.

Disposed above casing 10 is a container 22 which is joined to casing 10 by a conduit 24 containing a valve 26-. Δ small container 28 is also provided for adding surface active material to the cleaning compositio and is connected to casing 10 by a conduit ¾0 containing a valve 32,.

Extending in a closed loop between containers 16 and 22 is a duct designated by general reference numeral 34 , said duct having a right hand leg 36, and a left hand leg 38, In the right hand leg is a lint filter 40, ^l the left hand leg 38 is a fan casing 42 containing a fan or fclower 44 driven by a motor 46, In the lower extremity of the legs 36, 38, are valves or dampers designated as 48,50.

Within the upper extremity of the duct 34 is a reheating chamber 52. The interior of casing 10 is placed in communication with the duct 34 by conduits 54, 56» which are respectively provided with valves or dampers 58, 60, A refrigeration, or heat exchange system is provided fo the transfer and recovery of solvent.

This system includes a refrigerant compressor 62, a first condenser, or heating heat exchanger 64, located in container 16, a second condenser or heating heat exchanger 66 located in the reheating chamber 52, and an evaporator or cooling heat exchanger 68 located in container 22. A conduit 70 extends from the high pressure outlet of compressor ? ■to a cross 72. A conduit 74 containing a valve 76 extends from the cross 72 to the inlet end of condenser 64, A conduit 78 containing a valve 80 extends from cross 72 to the inlet end of condenser 66, A conduit 82 extends from the outlet end of condenser 64 to conduit 78 and may contain a valve 84. By this arrangement, the condensers 64,66 are connected in series relationship with each other, or xrtiere desired, condenser 66 may he operated as a heating heat exchanger separately from condenser 64. A conduit '86 extends from the outlet end of condenser 66 to the inlet end of the evaporator coil 68, and contains a control device 88, such as a restriction which regulates the flow of liquid refrigerant to the evaporator 68. A return 90 extends from the outlet end of evaporator 68 to the inlet side of compressor 62 to complete the refrigerant circuit. A hot gas conduit 92 containing a valve 94 extends f om the cross 72 to the inlet end of evaporator 68, and provides in a well known manner, means for defrosting said evaporator 68 when the proper conditions require such action.

It is the general function of the refrigeration, or heat exchange system t A typical operation of the process for dry cleaning textile materials or garments will nox* be described.

Any of the organic solvents described heretofore, in either a new or soiled condition at the outset of the operation is disposed in the lower container 16, and would ordinarily exist therein in a solid or semi-solid state. The garments or other textile materials are placed in casing 10, and the door 12 X3 closed. Valves 20 and 26, and dampers 58 and 60 are closed, and dampers 48 and 50 are open.

The refrigerant circuit .is set with valves 76 and 84 open and valves 80 and 94 closed. Fan 44 is energized, and compressor 62 is energized. The refrigeration feystem must have the capacity to evaporate the solvent in container 16, and to condense the vapors thereof in container 22. With the fan circulating the heated solvent in container 16 is transferred through the right hand arm 36 of the duct 3 to the container 22, and condensed to the liquid phase therein. The fan returns the gas through the reheating chamber 52 to container 16, and the procedure continues until a substantial quantity of solvent in a liquid state is present in the container 22. Assuming a sufficient quantity of liquid solvent feists in container 22 to form a washing charge, valve 26 is opened and the liquid the textiles, is added to container lo from container 28 by opening valve 32. The textiles are then washed within container 10 until the soluble and/or insoluble soil has been trnas erred to the solvent, whence valve 20 is opened to permit drainage of the soiled liquid into container 16.

The textiles are then rinsed with clean liquid from container 22, and the rinse liquid is thereafter also transferred to container 16 , and the cylinder 14 is rotated at its maximum speed to aid in the removal of any residual liquid.

To dry the textile material, they are retained in the casing 10 and, the , apparatus is adjusted so as to place dampers 48 and 50 within the duct 34 in a c£b¾ed position* and the dampers 58 and 60 in the branch conduits 54 and 56 are open. The refrigeration circuit is adjusted to open valve 80 and close the remainder of the valves in the system. Thence, the compressor and fan are energized, and cylinder 14 is rotated at its lowest speed. Under these conditions, the air within the system is passed through the closed loop, comprising casing 10 and the containers 22 and 52 with the coil 68 serving to remove vapors within container 22 and the coil 66 serving to reheat the air prior to repassage through the casing 10.

While the circulated gas initially contains a substantial amount of vapors, these will be condensed in container 22 -and subsequently the remaining vapors are solidified or congealed on the coil; 68. When the layer of solidified solvent . on the coil 68 reaches a depth sufficient to inhibit the cooling action of the coil, valve 94 is opened to permit hot refrigerant gases to pass through coil 68 for a period sufficient to melt the solidified solvent from the coil.i In the manner described, substantially all of the solvent may be recoveredj and the textiles may fa removed from casing 10 free of solvent and the odors thereof. After the removal of the textiles from casing 10, the residual solvent i.ft container 22 is returned through the system to container 16'.

It is recognized that instead of storing the solid solvent in container 16-, such solvent can be rectified in the manner disclosed heretofore, and stored in container 22,· but in that event, the initial operation will consist of melting the solid solvent either by a "defrosting" operation, or with the use of a auxiliary heater in container .22..

It is also recognized,, but not described herein, that the entire operation of the apparatus may be automatic, or semi-automatic under the direction of a conventional control system.

Representative examples illustrating cleaning and recovery tests follow: -EXAJCPLE I Samples of various forms of textile and garmen materials composed of wool, cotton and "Dacron" (synthetic polyeste fibers) were immersed in 1, 1,2,2 tetrachlor-1,2 difluoroethane. This solvent,, at room temperature (22°C. was in a solid state and was, therefore, heated to a temperature of approximately 30°C^. in order to convert it to a liquid state for washing purposes. The textiles were agitated in the solvent for 15 minutes, after which the free liquid solvent was removed. The textiles were rinsed in clean solvent, and after removal thereof, air at ambient temperature was passed through the container until the fabrics were dried. The air-vapor mixture coming from the container was passed into contact with a "condensing coil cooled to 5°C* and at that temperature, the solvent solidified on the condenser surface, and the air leavin the condenser bore only a faint trace of solvent vapor. The garment materials cleaned in the manner described were compared for cleaning capacity with identical samples of garment and textile materials washed with perchlorethylene. In all instances, the soil removal capacity and soil redeposition prevention capacity of the chloro-fluorohydrocarbon were equal to or superior to those obtained with perchlorethylene.

EXAMPLE II The test described in Example I was repeated, but in these tests; the soiled garment materials were pretreatcd by spraying onto soiled or spotted surfaces of the textiles a water solution of an alkyl aryl sulphonate The degree of cleaning obtained vras comparable to the results of Example lt and in addition thereto; the spots on the garment materials were removed; EXAMPLE III The tests described in Examples I and II were repeated; using 1^1;1;2 tetrachlor-2,2 difluoroetharie. The solvent was in a solid state at room temperature (22°C), and was heated to 49°C:. to melt the solvent and conduct the cleansing operations Air at ambient temperature was used to dry the textile materials, and it was observed that some of the solvent had congealed on the textiles before removal from the washing containers When these textile materials were exposed at . oom temperature-, the remaining solvent sublimed.. The cleansing quality of this solvent was compared with results obtained with perchlorethylene at room temperature', and at the same elevated temperature'. At room temperature, the cleansing quality of the chloro-fluorohydrocarbon was comparable to the results previously reported in connection with Example I·, but when comparable tests were made at an elevated temperature, it was found that perchlorethylene was more damaging to fabrics • EXAMPLE 17 .

The following. is a typical dry cleaning operation using apparatus of the type which is schematically disclosed in the drawing* A charge of "Freon 112% xihich consists of CCIgFCC^F plus varying amounts of the isomer CCLjCClF,-,, was placed in the lower container 16, and at normal ambient temperature 20°C. , it existed therein in a solid state. The refrigeration system, and the fan were placed in operation to transfer the solvent in vapor form to container 22. Although the boiling point of the solvent mixture is relatively high, the latent heat of evaporation for this solvent is relatively low in the nature of approximately 60 Btu per pound, and therefore,, it is possible to evaporate the solvent into the air stream with only a relatively small amount of heat being furnished by the refrigerant compressor to the condenser coil 64. Utilizing a 1 h.p. compressor approximately 6 gallons of the solvent, were transferred from container* 16 to container 22 in 30 minutes,. Fiv pounds of textile materials were placed in the casing 10, and 34 grams of a¾yl aryl sulphonate containing 5$ of water was added as the surface active agent. The material was washed by rotating cylinder 14 at 34 r.p.m. for 5 minutes. The soiled cleaning Solution was then transferred to container 16, and the textiles were rinsed with 5 gallons of clean solvent by solvent byrotat ng the cylinder for 5 minutes, after which solvent was also disposed textiles was removed by rotatin the cylinder at 68 r.p.m. for 2 minutes. The textiles were then dried within casing 10 by rotating the cylinder and ; circulating the gas throughout the upper portion of the circuit. The coil 68 was refrigerated about 5°C » and at that temperature the. apors whic -were liberated from the textiles became solidified on coil 68. The gas passing through the reheating chamber 52 was reheated . to a temperature of about 40°G.. After 30 minutes of drying in the manner described solvent-free odorless textiles were removed from the casing 10.

While not specifically described, this invention is equally applicable to the decreasing of metals or other non-poroujj objects. Degreasing is produced by subjecting the articles to vapors of the solvent at the boiling point thereof to remove the grease and soil. V/hen the articles are removed from the degreasing apparatus, the vapors carried by the articles, or displacedfrom the container, are collected in the same manner as disclosed hereinbefore by solidifying such vapors on an enclosed refrigerated surface, such as thejevaporater coil 68 within the container 22.

The principal advantage in the present invention is in the provision of effective and relativel simple eaas for cleaning or dry cleaning materials..

The solvents and cleansing compositions have good soil removal qualities¾ are nonflammable, relatively non-toxic, and therefore, quite safe to handle. An important factor in solvents of the class defined are that they can be evaporated into an ai stream at a temperature much below their boiling points, and when the air stream is brought into contact with a surface, the temperature of which approaches or is below the freezing point, the solvent can be condensed into liquid or solidified on the surface to fully recover the solvent from the air stream.

Moreover, should spillage of the solvent occur onto a floor surface whose temperature is below the freezing or congealin point of the solvent (the floor surface of a room o basement would generally be within this range) such solvent would quickly congeal and could be easily recovered or removed.

Another highly important advantage is that this invention makes home dry cleaning possible by a housewife using equipment which is comparable in cost and ease of operation to home laundry equipment.

Although the invention has been disclosed herein in connection with a type of apparatus that would form a home dry cleaning appliance, it should be understood that the disclosure is not intended as a limitation, and the invention is equally applicable to commercial use for the dry cleaning of textiles, or the degreasing of metal parts, or other non-porous objects.

The invention is defined in the terms of the appended claims.

Claims (5)

HAVING NOW particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is

1. A process of dry cleaning materials, particularly textiles and other garment materials, by washing said materials with a dry cleaning solvent composition compris ing a chloro- luorohydrocarbon having a freezing point in the. range of -5°C. to + 2°C.

2. A process as claimed in Claim 1, in which the solvent composition incorporates a surface active agent dispersed therein.

3. A process as described in Claim 1 or Claim 2, in which after the materials are cleansed the chloro-fluorohydrocarbon solvent is evaporated and the vapor bearing gas is passed into contact with a confined surface which is cooled to a degree sufficient to condense and/or congeal substantially all of said solvent from said gas.

4. A process as described in Claim 3» in which the chloro-gluorohydrocafebon solvent is evaporated at a temperature substantially below the boiling point of said solvent.

5. A process as described in Claim 1 or Claim 2, in which after the materials are cleansed, the excess liquid composition is separated from the materials, and the chloro-fluorohydrocarbon solvent contained in the materials is evaporated therefrom, and the vapor bearing gas is passed into contact with a confined surface which is cooled to a degree sufficient to condense and/or congJsaiiL substantially all of said solvent from said gas. for re-use in a subsequent washing operation. ¾· A dry cleaning solvent composition for use in the dry cleaning process as claimed in any of Claims 1 to j!f, comprising a chloro-fluorohydrocarbon having a freezing point in the range of -5°C. to +k2°C, and a surface active agent dispensed therein. iCj, A dry cleaning solvent composition as claimed in Claim g in which said chlorq- luorohydrocarbon contains at least 2 carbon atoms, at least 2 f.luo¾ine atoms and at least one chlorine atom in the molecule. 1-0· dry cleaning composition as claimed in Claim in which said chloro-fluorohydrocarbon consists wholly or essentially of 1, l,2,2-tetrachloro-l,2 difluoroethane . 1) A dry cleaning composition as claimed in Claim 10"" in which said chloro-fluorohydrocarbon consists wholly c essentially of 1 , .1 , .1 , 2- tetrachloro-2 , 2 difluoroethane . 1^,. A dry cleaning composition as claimed in Claim -tL- in which said .chloro-fluorohydrocarbon consists wholly or essentially of .1 , 1 , 1- trichloro-2 , 2 , 2 trifluoroethane . A dry cleaning composition as claimed in Claim 4Θ- in which said chloro-fluorohydrocarbon consists wholly or essentially of 2 , 2 , 3-trichloro-l , 1 , 1 , 3f 3 pentafluoreprepane . l^f. A dry cleaning composition as claimed in Claim in which said chloro-fluorohydrocarbon consists wholly or essentially of 1 , 2 , 2 , 3» 3-pentachloro- 1 , 1 , 3 trifluoropropane . lii. Apparatus for use in the process of dry cleaning volatile dry cleaning solvent composition— -s—defined, the solvent recovery apparatus inctoding conduit means connecting jaid enclosure and s^rird' container in a closed circuit, means for circulating vapors within said circuit, means for condensing vapors within said container, and means for reheating the condensed solvent in said container. IIP. Apparatus as claimed in Claim * * in which said cooling means comprises the low pressure heat exchanger of a refrigerant system. .18. Apparatus as claimed in Claim lip in which said reheating means comprises means for admitting hot refrigerant gas to said low pressure heat exchanger. . Apparatus as claimed in any of Claims ¾r6«18, in which a further container is operatively connected to said enclosure and adapted to form a receiver for soiled dry cleaning solvent composition from said enclosure, said further container being further connected in said closed circuit. Apparatus as claimed in Claim l^ in which said enclosure and said further container are connected in parallel by conduit means with said first named container. 2D. A process of dry cleaning textiles and other garment materials substantially as herein described with reference to any one of the accompanying examples. S2. A dry. cleaning solvent composition as claimed in Claim g and substantially as herein described. T 2 j. Apparatus as claimed in Claim 3r6" and substantially as described herein with reference to and as illustrated in the accompanying drawing. DATED THIS 9th day of September, 1964