US 3925010 A
Description (OCR text may contain errors)
United States Patent [1 1 1111 3,92
Barton 5] Dec. 9, 1975  DRY CLEANING PROCESS UTILIZING 3,530,073 9/1970 Clark et a1. 252/170 AZEATROPIC NONFLAWABLE VAPORS 3,692,686 9/1972 Barton et al...... 8/142 X 3,776,693 12/1973 Smith et al 1 8/142 Inventor: 3 3 n, Florham Park, 3,778,379 12/1973 Papannou 8/142 x 73 A OTHER PUBLICATIONS Sslgnee 521 g fi Corporatmn New Mellon, Industrial Solvents, Reinhold Publishing Co.
(1950), p. 79. k  Filed: Dec. 3, 1973  APP] NOJ 421,192 Primary ExaminerLeland A. Sebastian Assistant ExaminerP. A. Nelson Related Appllcatlon Data Attorney, Agent, or FirmJ. P. Friedenson  Division of Ser. No. 158,129, June 29, 1971, Pat. No.
3,794,590. 57 ABSTRACT 52 US. (:1. 8/142; 252/153; 252/DIG. 9 Mixtures comprising Water, tertiary amyl alcohol and 51 Int. Cl D06l 1/00 tetrachlorodifiuoroethane which Over Substantially [53 Fi f Search 42; 252/1316 1 DIG 9, the entire course of their evaporation or distillation,
252/153, 171 545, 557 form azeotropic nonflammable vapors containing tertiary amyl alcohol and tetrachlorodifluoroethane. 5 References Cited These mixtures are useful in dry cleaning textile fab- UNITED STATES PATENTS tics and fibers with reduced hazard of fire.
2,503,119 4/1950 McKinnis 252/1310. 9 4 l im N Drawings DRY CLEANING PROCESS UTILIZING AZEATROPIC NONFLAMMABLE VAPORS BACKGROUND OF THE INVENTION 2 pors of constant boiling mixtures, that is azeotropes, containing the flammable tertiary amyl alcohol together with tetrachlorodifluoroethane. I have unexpectedly discovered that on distillation (or evapora- 5 tion) of the present mixture the water component of This is a division of application Ser. No. 158,129, the mixture is evolved asa vapor containing about 87.2 filed June 29, 1971, now US. Pat. No. 3,794,590. weight percent tetrachlorodifluoroethane, about 7.5 It has been suggested to employ volatile mixtures of weight percent tertiary amyl alcohol and about 5.3 lower aliphatic alcohols and halogenated hydrocarbons weight percent water which mixture boils at constant in cleaning compositions. However, many of the possicomposition in the vapor and liquid phase at 7475C. ble mixtures of lower aliphatic alcohols and halogeat atmospheric pressure, that is, a pressure of about nated hydrocarbons suffer from at least one disadvan- 760 mm of mercury. After removal of the water comtage which prevents or seriously limits their use in the ponent, the remaining tertiary amyl alcohol and tetradry cleaning of textile fabrics and fibers. chlorodifluoroethane of the mixture distill (or evapo- In conventional dry cleaning of textile fabrics and f1 rate) to give a vapor containing about 1 1.4 weight perbers, the textile, after being contacted with the liquid cent of the tertiary amyl alcohol and about 88.6 weight cleaning mixture, is dried by allowing the cleaning mixpercent of the tetrachlorodifluoroethane which mixture adhering to the textile to evaporate. Furthermore, ture boils at constant composition in the vapor and liqspent cleaning mixture, that is cleaning mixture satuuid phase at a temperature in the range of about 89.0 to rated with soils removed from the textile, is usually dis- 897C. at atmospheric pressure. Surprisingly vapors of tilled to recover the constituents of the mixtures devoid both the tetrachlorodifluoroethane-tertiary amyl alof soils and non-volatile cleaning adjuvants such as decohol-water azeotrope and the tertiary amyl alcoholtergents. tetrachlorodifluoroethane azeotrope are substantially However, many of the possible mixtures of lower alinon-flammable. Accordingly, the fire-hazard in distillaphatic alcohols and halogenated hydrocarbons evapotion or evaporation of the present mixture is greatly dirate or distill to produce flammable alcohol containing minished as compared to the hazard encountered with vapors. Use of such flammable vapor-producing mixaqueous alcoholic halogenated hydrocarbon mixtures tures in textile dry cleaning constitutes a serious fire hawhich do not evolve non-flammable azeotropic vapors zard. over the entire course of their distillation or evapora- It is an object of the present invention to devise novel tion. Furthermore, the present azeotropic compositions alcoholic halogenated hydrocarbon mixtures which disare found to boil at lower temperatures than the pure till or evaporate with reduced hazard of fire. tetrachlorodifluoroethane, tertiary amyl alcohol and This and additional objects and advantages will be water components of the present mixture, that is, are apparent from the following description of my invenazeotropic compositions of the minimum boiling type. tion. Accordingly, in the cleaning of textiles, the formation of such minimum boiling azeotropic compositions on SUMMARY OF THE INVENTION distillation or evaporation of the present mixture facili- The above objects are attained and the aforementates both evaporation of adherent cleaning mixture tioned disadvantages of prior art alcoholic-halogenated from the cleaned textile substrate and the recovery of hydrocarbon mixtures are overcome, according to the the cleaning mixture by distillation as compared to the invention, in mixtures which are useful in cleaning texevaporation or recovery by distillation of either the tile fabrics and fibers and which comprise about 87.0 to pure components of the present mixture or of aqueous about 88.9 weight percent tetrachlorodifluoroethane, tertiary amyl alcohol-tetrachlorodifluoroethane mixabout 7.0 to about 11.0 weight percent tertiary amyl tures which do not form azeotropic vapors over the enalcohol and about 0.1 to about 6 weight percent water. tire course of their distillation or evaporation. The invention also includes a process of cleaning of textile fabrics and fibers such as those of wool, cotton, DETAILED DESCRIPTION OF THE INVENTION rayon, the nylons including polyhexamethylene adipa- AND PREFERRED EMBODIMENTS THEREOF mide and polyepsilon caprolactam, polyesters including cellulose acetate, cellulose triacetate and polyethyl- The pr nt novel mixtures are prepared by mixing ene terephthalate, and polyacrylonitrile, with the novel water, tertiary amyl alcohol and tetrachlorodifluoroemixtures of the i ve ti n thane in the prescribed amounts according to conven- The cleaning mixtures of the invention are surpristiollal hniq ingly effective in removing stains of both the water-sol- The etrachlorodifluoroethane component of the uble a d Organic Solvent l bl t fr t til f b present mixtures is available commercially as a mixture rics and fibers, of the symmetrically-substituted isomer, l,l,2,2-tetra- The cleaning mixtures of the invention are critically chloro-2,2-difluoroethane and the asymmetrically subch t i d i th i ti f concentrations stituted isomer, 1,l,l,2-tetrachloro-2,2-difluoroethane therein of tetrachlorodifluoroethane, tertiary amyl aln 3 H101 at o of about 69131. The melting and boiling h l d w t r 3 th t th r se t i t v b points of the two tetrachlorodifluoroethane isomers are stantially the entire course of its evaporation or distillamp r With O e 0 he Other Components of the tion at atmospheric pressure, forms non-flammable vapresent cleaning mixture in Table I below.
TABLE I Melting Boiling Point Compound Formula Point C. C., at 760 mm l,l,2,2-Tetrac1 c1 23.5 92.8 chloro-1,2- difluoroethane ClCCCl (American Society of Refrigerating Engineers F F TABLE I-continued Melting Boiling Point Compound Formula Point C. C.. at 760 mm Designation l 12 I l.l l .2Tetral Cl 40.6 91.0 chloro-2.2-difluoroethane (American ClC CF Society of Refrigerating Engineers Cl F Designation 1 12a) Tertiary Amyl CH 92.8 Alcohol CH CH CIOH CH Water H O I000 The azeotropes of tertiary amyl alcohol or aqueous tertiary amyl alcohol with either pure isomer of tetrachlorodifluoroethane have approximately the same composition, normal boiling point and properties as the corresponding azeotropes with mixtures of the pure isomers. Accordingly, my inve ition includes tetrachlorodifluomethane-containing mixtures derived from either the symmetrically-substituted or asymmetrically-substitued tetrachlorodifluoroethane or from mixtures of these isomers. Hence, reference in this specification and the claims appended hereto to tetrachlorodifluoroethane, unless otherwise indicated, is intended to include the pure isomers and/or any mixtures thereof. However, the aforementioned commercial mixture of tetrachlorodifluoroethane isomers, because of its ready availability, is the preferred tetrachlorodifluoroethane component of the invention.
The present cleaning mixture contains about 0.1 to about 6.0 weight percent water to solubilize textile soils which are soluble in water but insoluble in the organic components of the present mixture. Preferably, the concentration of water in the novel cleaning mixture is maintained at about 0.1 to about 1.0 weight percent to diminish shrinkage in cleaning wool-containing fabrics or to diminish wrinkling of rayon-containing fabrics. An especially good cleaning result is achieved in employing a mixture of the invention containing about 1.0 weight percent water.
The novel water-tertiary amyl alcohol-tetrachlorodifiuoroethane mixtures of the invention are substantially inert to synthetic organic textile fabrics and fibers such as nylon, polyacrylonitrile, and polyester and do not appreciably dissolve or swell these substances. Additionally, the present composition is non-toxic and substantially non-corrosive to metals such as aluminum and stainless steel, even on contact with such metals for periods as long as one month.
The process of cleaning textile fabrics and fibers with the novel water tertiary amyl alcohol tetrachlorodifiuoroethane mixtures of the invention is carried out by contacting the soiled textile fabric with the novel mixture in the liquid phase employing conventional techniques, apparatus and conditions.
For example, in the present process the conditions of cleaning temperature and contact time, the proportions of cleaning mixture and textile fabric and the distillation techniques for recovery of spent cleaning mixture are susceptible to wide variation but are conventional in the dry cleaning art.
In accord with conventional dry cleaning procedures, the cleaning of textiles with the present novel mixture is advantageously effected in the presence of an organic detergent which may be either dissolved or dispersed in the cleaning mixture. The particular type and structure of the organic detergent is not critical and any of a wide variety of non-volatile organic detergents can be employed in the present process including, for example, Aerosol OT, a dioctyl ester of sodium sulfosuccinic acid (an anionic detergent manufactured by The American Cyanamide Co.), Igepal CO-730, a nonyl phenoxypoly (ethyleneoxy) ethanol (a nonionic detergent manufactured by General Aniline and Film Corp.) and Emcol P10-59, an amine salt of dodecyl benzene sulfonic acid (an anionic detergent manufactured by Witco Chemical Corp.).
The concentration of the detergent in the cleaning mixture is also not critical and can be varied over a wide range depending, in general, upon the particular type of detergent employed. An especially good result is achieved in the present cleaning process in employing an anionic-type organic detergent at a concentration of about 1 to about 2 weight percent of the cleaning mixture.
It will be apparent tb those skilled in the art that other additives, which for specialized purposes are conventionally incorporated into dry cleaning mixtures, can also be incorporated into the present novel mixtures, including for example, textile lubricants, textile water-proofing agents, moth-proofing agents, soil release agents and the like.
In the following examples which serve to illustrate my invention, percentages and proportions are by weight unless otherwise noted and temperatures are in degrees Centigrade.
EXAMPLE 1 Preparation of Tertiary Amyl Alcohol-Tetrachlorodifluoroethane Azeotrope Part A A mixture of 60 g. of tertiary amyl alcohol and 240 g of tetrachlorodifluoroet hane (a commercially available mixture consisting of about 69 mol percent CFCl CFCl and about 31 mol percent CCl CF Cl) is heated to reflux in a conventional laboratory fractional distillation apparatus. After equilibrium is attained, the mixture is partially distilled to collect consecutively the fractions listed in Table II below.
TABLE I1 Boiling Point at 760 mm (Still Head Temperature Weight of Fraction at which fraction is collected) Fraction Forerun 8488 5.3 g. First Fraction 88-89" 39.5 g. Second Fraction 89 214.5 g.
On redistillation the major distillate fraction, that is, i Per/c,ent the Second Fraction above, shows no change in boiling Almho] point at a pressure of 760 mm of mercury or in compo sition. This constant boiling fraction, as analyzed by vapor phase chromatography, is found to have the following composition: A 1
Tetrachlorodifluoroethane Tertiary Amyl Alcohol This fraction when tested for flammability according to the Tag Open Cup Flash Point Test of Volatile Flammable Materials (ASTM-D-l3lO-63) is found to be non-flammable.
Part B Repetition of the procedure set out in Part A, above, but substituting an equivalent amount of substantially pure (99 mol percent) l,l,2,2-tetrachloro-difluoroethane for the tetrachlorodifluoroethane isomer mixture charged in Part A gives a non-flammable binary azeotrope of the alcohol and the halogenated hydrocarbon which boils at 892 at a pressure of 760 mm mercury and which contains substantially the same proportions of tertiary amyl alcohol and halogenated hydrocarbon as the constant boiling mixture obtained in Part A. Part C Repetition of the procedure set out in Part A, above but substituting an equivalent amount of substantially pure (97 mol percent) l,l,l,2-tetrachloro-2,2- difluoroethane for the tetrachlorodifluoroethane isomer mixture charged in Part A gives a non-flammable binary azeotrope of the alcohol and halogenated hydrocarbon which boils at 897 and which contains substantially the same proportions of tertiary amyl alcohol and halogenated hydrocarbon as the constant boiling mixture obtained in Part A.
The foregoing results indicate that azeotropic mixtures formed in accordance with the invention from substantially pure tetrachlorodifluoroethane isomers or from mixtures of these isomers have substantially identical compositions and have no significant difference in properties.
EXAMPLE 2 Preparation of Water-Tertiary Amyl Alcohol Tetrachlorodifluoroethane Azeotrope A mixture of 50 g. of tertiary amyl alcohol, g. of water and 50 g. of the tetrachlorodifluoroethane isomer mixture of Example 1 is heated to reflux in the fractional distillation apparatus of Example 1. After equilibrium is established, the mixture is distilled at a still head temperature of 7475 at 760 mm pressure to give about 60 g. of distillate which on redistillation shows no change in boiling point or composition. This distillate as analyzed by vapor phase chromatography is found to possess the following composition:
The distillate of the above-defined composition .is tested for flammability according to the Tag Open Cup Flash Point Test of Vol atile Flammable Materials (ASTM-D-l3l 0-63) and is found to be non-flammable.
Substantially identical results are obtained on repeating the foregoing procedure with either substantially pure (99 mol percent) l,l,2,2-tetrachloro-l,2- difluoroethane or substantially pure (97 mol percent) 1,1,l,2-tetrachloro-2,2-difluoroethane in place of the aforementioned tetrachlorodifluoroethane isomer mixture.
EXAMPLE 3 A test set of four 2.5 X 7 inches swatches of rayon fabric (National Institute of Dry Cleaning White Rayon Test Fabric) are each spotted by one of the following stains:
Lipstick Catsup Mustard Lanolin The stains are allowed to dry and to set for 24 hours at room temperature. A duplicate set of four stained rayon swatches are similarly prepared for use as a control. Each soiled swatch of the test set is then immersed for 30 minutes at room temperature (about 25) in 200 cc of agitated cleaning bath consisting of: About 98 weight percent of a mixture of l 1.4 weight tertiary amyl alcohol and 88.6 weight percent of commercial tetrachlorodifluoroethane wherein the mol ratio of CFCl CFCl and CCl CClF is about 69:31.
About 1 weight percent water About 1 weight percent of a dodecyl benzene sulfonic acid, amine salt anionic oil-soluble detergent. (Emcol Pl0-59 Witco Chemical Corp.).
Each swatch is raised from the bath, squeezed to express cleaning mixture and allowed to stand in the air at room temperature for 30 minutes to evaporate adherent cleaning mixtures. The cleaned test swatches are devoid of wrinkles.
The effectiveness of stain removal by the foregoing cleaning procedure is rated by visual comparison of the cleaned test swatches employing a rating scale of l to 10 with 1 being substantially about 10% stain removal and 10 being substantially complete stain removal, that is, about 100% stain removal. That portion of each test swatch which had not been originally stained is compared with the like portion of the corresponding control swatch to evaluate redeposition of stain during the cleaning operation. Redeposition of stain as indicated by discoloration of the fabric is rated according to the following ascending scale: slight, moderate, severe. The
results of this experiment are summarized in Table III below.
TABLE III Stain Removal Rating (Percent Stain Removed X 10) Lipstick Catsup Mustard Lanolin Stain Redeposition 9 9 2 l0 Slight 88.9 weight percent tetrachlorodifluoroethane, about 7.0 to about 1 1.0 weight percent tertiary amyl alcohol and about 0.1 to about 6.0 weight percent water in the liquid phase and evaporating the liquid which adheres to the textile fabric or fiber, thereby removing the tertiary amyl alcohol in a non-flammable azeotropic composition containing tetrachlorodifluoroethane.
2. A process as claimed in claim 1 wherein the mixture contains about 0.1 to about 1.0 weight percent water.
3. A process as claimed in claim 1 wherein the tetrachlorodifluoroethane is a mixture of 1,l,2,2-tetrachlorol ,2-difluoroethane and 1, l ,1 ,2-tetrachloro-2,2- difluoroethane in a mo] ratio of about 69:31.
4. A process as claimed in claim 1 wherein the textile fabric or fiber and the mixture are contacted in the presence of a non-volatile organic detergent.