Textile Cleaning Process For Simultaneous Dry Cleaning And Finishing With Stain Repellent

Abstract

A process for simultaneous cleaning and finishing of soiled textile material in which the textile is (A) exposed to a cleaning bath consisting essentially of a major amount of a textile dry cleaning solvent and minor amounts of water, and containing (1) a polyfluoroalkyl substituted stain repellent material and (2) an emulsifying agent which does not adversely influence the stain repellency of the treated textile material, and then (B) is dried.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improved process for cleaning textile materials and more particularly is directed to a process for simultaneous cleaning and finishing of textiles using a bath of dry cleaning solvent and water which contains a polyfluoroalkyl substituted stain repellent and an emulsifying agent.

2. Prior Art

Textile dry cleaning is based on the fact that most soiling matter is bound to textiles by a film of oil or grease, and dissolving the oil in a solvent releases the dirt.

The solvents in common use are: perchloroethylene, trichloroethylene, and the relatively recent introduction, trichlorotrifluoroethane.

The solvent may be used alone and will give reasonably good cleaning. The best results are obtained by filtering the solvent continuously during cleaning so as to remove the released particles of soiling matter and prevent redeposition. A proportion of the filtered solvent containing dissolved oil and grease is distilled after each load has been cleaned in order to prevent undue accumulation of contaminants. This system of dry cleaning is used less widely today because it is less efficient than other methods in removing stains attached by water-soluble films, such as food and beverage stains. In the alternative systems, small quantities of water are carried into the solvent in such a way as to minimize any harmful effects the water may have.

The latter system seems to be widely misunderstood outside the dry-cleaning industry and sometimes even within the industry. It involves the use of a solvent containing a moderately high concentration of dissolved detergent and a controlled concentration of dissolved water. The solution is used repeatedly in a process involving continuous filtration.

In practice, the concentrations used vary over the range 0.5 to 4 percent by volume of detergent as purchased, and the detergents commonly contain some 50 percent active material. Because of the high concentration of detergent and attendant high cost, the bath cannot be discarded after a single use. Continuous filtration to remove suspended dirt particles as soon as possible is helpful in almost any type of process, but it becomes essential when a bath is reused repeatedly.

When small quantities of water are added to such a system, they become solubilized and are held quite tenaciously. The partial pressure of the water vapor in the atmosphere in equilibrium above the solution is much below that of pure water at the same temperature, and the ratio of this to the saturation vapor pressure is known as the solvent relative humidity (SRH). At a given temperature and detergent concentration, the SRH depends on the water concentration, and it can therefore be controlled by controlling the addition of water.

When textiles are immersed in a charged system (solvent-detergent-water), an equilibrium tends to be set up between the water in the textiles and the water in the solvent in exactly the same way as an equilibrium is set up between textiles and the surrounding atmosphere. The moisture regain of fibers in equilibrium with a charged system with an SRH of 75 percent is the same as that which they would attain when in equilibrium with an atmosphere of 75 percent relative humidity at the same temperature.

The significance of this is that sufficient water can be added to the system to have a very marked effect in removing water-soluble soilings without increasing the moisture regain of the fibers beyond the level that they would have in contact with the ordinary atmosphere. The usual risks of wet treatment, including shrinkage, loss of creases, felting of woll, etc., can be avoided. The fact that water can pass in either direction is a considerable safeguard because, if a damp article is inadvertently included in a load, the solvent will rapidly take up water, and the article will be exposed to much less risk than would otherwise have been true.

The effect of adding water in this way may be judged from the fact that, after cleaning in solvent alone, on average some 45-50 percent of garments need no further treatment to remove stains, whereas, after cleaning in a charged system, the proportion may be 75 percent or more.

The dry-cleaning machine, although basically similar to a washing maching, requires much more accessory equipment, and this is generally built into the one assembly, which includes filter, still, condenser, separator, and pumps and storage tanks, possibly with control gear for the charged system. The machine serves not merely as a washer, of the drum can also be run at high speed to give centrifugal extraction and subsequently acts as a drying tumbler. In order to recover the solvent, there is a closed air-circuit. Hot air is blown through the load, and the solvent-laden air then passes over cooling coils (or, in some designs, meets a spray of cold water) to strip the solvent before the air is reheated to repeat the circuit. When substantially all the solvent has been removed from the load, the air-circuit is opened, and air is vented from the machine for a short time.

The solvent application of finishes to textile products can be performed in dry cleaning equipment by soaking the textiles in the treating bath and spinning off the excess fluid. Prior art use of such equipment, however, has merely adapted familiar application methods to the available mechanical devices. In these prior art methods, the application bath is prepared to contain about 0.1 to 10 percent by weight of solid repellent, whether in solution or suspension. The textile material is soaked or agitated in the treatment bath, then removed and freed of excess liquid by centrifuging so that the dry pickup (weight of dry polymer on the fiber) is about 0.1 to 10 percent of the weight of fiber. The active ingredient in the treatment bath does not exhaust onto the textile material. The concentration of repellent in the bath is not appreciably reduced by the treatment process, but remains essentially the same. So far as is known, there is no disclosure in the prior art of a process simultaneously combining the two functional treatments of dry cleaning and repellent or other finish application.

Prior art applications of water and oil repellent compositions do not combine the treatments, but rather apply the repellent in a separate step after the cleaning operation is finished. Such processes are disclosed for example in Italian Pat. Nos. 14308A/69, 14309A/69, 14310A/69, 14311A/69, 14312A/69, 14313A/69, and U.S. Pat. No. 3,657,173. It was usually necessary to apply a wash or rinse to remove the dry cleaning detergent, which, if present, interfered with application or performance of the repellent. In the process of this invention the two functions are combined satisfactorily through the use of a composition wherein an aqueous finishing composition is dispersed in dry cleaning solvent at a relatively low concentration such that the dry cleaning procedure can be carried forward in an essentially normal manner. The dry cleaning detergents normally used in that operation are not necessary in the process of this invention and can thus be omitted. If used, however, higher amounts of stain repellent should be used.

SUMMARY

In summary this invention is directed to a process for simultaneous cleaning and finishing of soiled textile materials in which the textile is

A. treated at from about 0.degree. to 100.degree.C. for from about 1 to about 30 minutes with a composition consisting essentially of

a major amount of a textile dry cleaning solvent;

a minor amount of water;

an amount sufficient to give add-on of 0.05 to 0.5 percent, based on the dry weight of textile of a polyfluoroalkyl substituted stain repellent; and

5 to 20 percent, based on the weight of stain repellent, of an emulsifying agent; and then

B. the treated material is dried.

DESCRIPTION OF INVENTION

The present invention provides a process wherein textiles can be cleansed of types of soil or foreign matter soluble in or removed by the usual dry cleaning solvents exemplified by halogenated low molecular weight hydrocarbon solvents and also the kinds of soil soluble in or subject to removal by water. At the same time the process applies polyfluoroalkyl substituted stain repellent to the article being cleaned. The entire process can be carried out in the absence of the usual dry cleaning detergents.

In carrying out this process, a water in oil type emulsion is first prepared by mixing an aqueous dispersion of a textile stain repellent agent into a relatively large amount of a halogenated liquid having a boiling point between 25.degree.C. and 150.degree.C. and a relatively small amount of an emulsion promoting agent which does not adversely affect the performance of the repellent on the textile. The resulting water in oil type emulsion is added to an organic solvent functioning as a cleaning agent for textiles to form a very dilute extended water-in-oil type emulsion. Textile material is then contacted with the dilute emulsion at ambient or elevated temperature, after which the textile material is dried. The treatment serves a plural function in that:

1. Soil or foreign material soluble in the organic solvent is removed from the textile.

2. Water soluble soil or stain is removed by the action of the water present.

3. The repellent is deposited on the textile to serve its designed function.

The invention has broad application in the processing and cleaning of textiles. Where organic dry cleaning solvents are used as cleaning agents the invention provides a method for accomplishing several desirable objectives in one simple step. The combining of a cleaning step and a stain repellent finish application is unique and very valuable to the cleaner and processor.

More specifically, in this invention textile material is cleaned and a polyfluoroalkyl substituted oil and water repellent is deposited thereon in regular textile dry cleaning equipment with very slight alteration of the normal cleaning cycle. The unique combination of cleaning solvent, water, oil and water repellent and emulsifier provides normal cleaning and significant stain repellent qualities to the textile products. Water soluble stains are removed and the objectionable necessity for "spotting" or hand removal of stubborn stains is lessened or completely obviated.

Another application is found in textile processing where a step involving exposure of the fabric to dry cleaning type solvent for the purpose of removing processing chemicals is involved. Stain repellents in the water-in-oil type emulsion are mixed with the solvent to provide stain repellency after the cleaning step.

For the purpose of this invention, "soiled" textile materials means textiles which are soiled or stained in use as well as new textiles which contain processing chemicals.

In preparing an emulsion of water based finishing agent in solvent, the usual dry-cleaning solvents are satisfactory, including tetrachloroethylene, trichloroethylene 1,1,2-trichloro-1,2,2,-trifluoroethane and trichloromonofluoromethane. Stoddard solvent and others based on petroleum fractions also function satisfactorily, however, the halogenated solvents named above possess the advantage of lack of flammability.

Any polyfluoroalkyl substituted or other textile finishing agent exhibiting lack of solubility in water and in the solvents employed can be used in the process of the invention. This group can include not only oil and water repellents but also members which additionally exhibit the quality of providing dry soil resistance, improved soil release during laundering and other desired properties to textile substrates. Since dry cleaning equipment does not normally provide temperatures above about 210.degree.F., those agents requiring a higher temperature cure for development of functional performance are not recommended unless the required cure temperatures can be otherwise provided, as for example in pressing or the like. Of course such agents can be applied in dry cleaning equipment where less than optimum performance is acceptable.

Oil and water repellent agents are exemplified by polyfluoroalkyl substituted compounds which contain perfluorinated alkyl chains of at least three and as many as 16 carbon atoms. Representative agents are polymers of fluoro monomers which can be copolymerized or "extended" with non-fluorinated monomers, and are listed below: ##SPC1##

where n can be 1 to 5 and R is H or CH.sub.3. These compounds are disclosed in U.S. Pat. No. 3,547,861. ##SPC2##

where n is usually 3 but can be from 1 to 5, and R is H or CH.sub.3. These compounds are disclosed in U.S. Pat. No. 3,544,663. ##SPC3##

where R is H or Ch.sub.3 is disclosed in U.S. Pat. No. 2,803,615. Useful polymers of such monomers are also disclosed in U.S. Pat. Nos. 3,068,187 and 3,574,791. ##SPC4##

where n has a value of 3 to 14; m is an integer of from 1 to about 12; and R is H or CH.sub.3 are disclosed in U.S. Pat. Nos. 2,642,416, 3,102,103, 3,378,609, 3,392,046 and 3,546,187. ##SPC5##

where R.sub.f is a perfluorinated alkyl group of 3 to 17 carbons, disclosed in U.S. Pat. Nos. 3,386,977 and 3,395,174. ##SPC6##

where n is .gtoreq. 1; X is --O.sub.2 C alkyl, --(CH.sub.2).sub.m OH, --(CH.sub.2).sub.m O.sub.2 C alkyl, OH wherein m is an integer of 0 to 10; and R.sub.f is perfluoroalkyl of from 3 to 21 carbons as disclosed in U.S. Pat No. 3,575,940, U.S. Pat. No. 3,514,420, Japanese Pat. Nos. 23923/67, 26607/68, 1994/69 and 2182/70. ##SPC7##

where R.sub.f is perfluoroalkyl of 4 to 18 carbons; m is an integer of 2 to 6; R is an alkyl group of 4 to 10 carbons; and R' is H or methyl as disclosed in U.S. Pat. No. 3,304,278. v,45/4

where R.sub.f is perfluoralkyl of 5 to 12 carbons and R is H or methyl as disclosed in U.S. Pat. No. 3,384,627.

The above list is not exhaustive, but merely exemplifies suitable fluorine containing monomers which are employed in some commercial oil and water repellent polymers for textile finishing. The polymers are available in the form of aqueous emulsions containing from 5 to 50 percent active ingredient (polymer).

In order to effectively disperse and emulsify the aforementioned fluorinated repellents in dry cleaning solvent, an emulsifying agent must be used which promotes dispersion but does not negate the functional performance of the repellents on the treated fabric. Conventional surfactants such as alkane sulfonates, long chain alcohol sulfates, ethylene oxide additives of alcohols, acids, amines and phenols, alkylnaphthalene sulfonates and the like can be used; however, they tend to diminish water repellency and otherwise interfere with the performance of the repellent. Where these or other dry cleaning detergents are employed, their deleterious effect can be largely overcome by increasing the amount of repellent used and deposited on the textile substrate.

A number of chemical species provide the desired emulsion promoting function. Preferred among them are:

1. water soluble salts of condensation products prepared by reacting

methylol compounds of

aminotriazines,

urea,

cyclic ureas or their ethers with low molecular weight alcohols

with

aliphatic compounds containing a carbon chain of at least 7 carbon atoms and a reactive hydrogen atom attached to a heteroatom

and

a primary or second amine,

a water soluble salt of a primary or secondary amine, or

a tertiary amine which contains a reactive hydrogen attached to a heteroatom;

2. acrylate and methacrylate polymers and copolymers; and

3. hydrocarbon copolymers of 80 to 20 mol percent ethylene and 20 to 80 mol percent aminoalkyl acrylate monomers of the formula ##SPC8##

wherein

R.sub.1 is hydrogen or methyl,

R.sub.2 is hydrogen or alkyl of 1 to 4 carbons.

R.sub.3 is hydrogen or alkyl of 1 to 4 carbons, and

n is a positive integer of from 1 through 4.

Of the above emulsifying agents the copolymers of ethylene and aminoalkyl acrylate monomers are most preferred. Suitable acrylate monomers include 2-(dimethylamino) ethyl acrylate and methacrylate, aminoethyl acrylate and methacrylate, 2-(diethylamino) ethyl acrylate and methacrylate, 2-(methylamino) ethyl acrylate and methacrylate, 2-(t-butylamino) ethyl acrylate and methacrylate and 3-(dimethylamino) propyl acrylate and methacrylate.

The water soluble salts of the condensation products and their preparation are described in U.S. Pat. No. 2,783,231 and preparation of the hydrocarbon copolymers is described in Canadian Pat. No. 900,650.

The emulsifying agent is present during the treating process in a weight ratio of from about 1:20 to 1:5 relative to the active component or components of the finishing agent. A ratio of 1:10 to 1:5 is preferred.

The preferred manner of introducing the stain repellent to the cleaning operation is in the form of a water-in-oil type emulsion. The emulsion is prepared by mixing the repellent (which is itself in the form of an aqueous dispersion) into a solution of the emulsion promoting agent in a solvent. The solvent can advantageously be the same as used in the textile cleaning operation. The product should be uniform in composition, stable and easily handled, so that it can be added to the cleaning system in accurately known amounts with no more than a preliminary stirring or shaking. It must be extendible in the cleaning solvent so as to form and maintain a uniform treating composition. The product is not limited so far as the concentration of water and repellent material in solvent is concerned, so long as the product is uniform. Normally the emulsion prodcut will contain from 1 to 25 percent of the polyfluoroalkyl substituted stain repellent, preferably from 5 to 15 percent.

For use in textile cleaning, the above emulsion product is greatly diluted in the cleaning solvent. The controlling factor is the amount of repellent agent which is to be deposited on the textile material. While easily discernible results are achieved even at very low add-on of stain repellent, the preferred add-on is from about 0.05 to about 0.5 percent of polymer solids on the dry weight of the textile. Practically, the amount of repellent agent used is determined by the weight of textile material to be processed and the concentration of solid repellent in the emulsion product. For 50 pounds of textile material, using a prepared emulsion containing 10 percent of polyfluoroalkyl stain repellent, there would be used from about 0.25 to about 2.5 pounds of the emulsion product whether the cleaning procedure required 100 gallons or 200 gallons of cleaning solvent. The concentration of repellent in the cleaning bath itself is thus very low, in the order of 0.01 percent by weight.

It is in this condition particularly that the process of the invention differs from prior art processes for application of stain repellents to textiles. Where the objective of a process is solely the application of an adjuvant to a garment or other textile product, a minimum amount of solvent or application medium will be employed, since the solvent or application medium will have to be purified, recovered or somehow handled for re-use. Where the process objective is solely cleaning, the greater amount of cleaning solvent used per unit weight of textile the better the cleaning will be. The process of the instant invention performs the two functions, and without the use of ordinary dry-cleaning detergents.

While the stain repellent and emulsion promoting agent are preferably introduced to the cleaning operation in the form of a water-in-oil emulsion product, they can also be introduced separately. That is, the emulsion promoting agent can first be dissolved in or added to the cleaning solvent, and the familiar aqueous emulsion of water and/or oil repellent added subsequently.

The cleaning bath containing the polyfluoroalkyl substituted stain repellent is applied to the textile material so as to provide thorough and efficient contact between the two for a period of at least about one minute. Agitation of textile material in a perforated basket through the cleaning composition as in a dry cleaning machine is quite satisfactory. Temperature of the bath during treatment is not critical and can range between 0.degree.and 100.degree.C. Ordinarily both temperatures will range between about 15.degree. and about 50.degree.C. In general, where the equipment affords the opportunity, it is best to mix the pure solvent cleaning liquid with the textile material first, before adding the repellent composition. In this manner particulate soil loosened from the textile fibers can be removed by filtration, as in the regular cycle of a dry cleaning machine, before introduction of the repellent composition. If the repellent composition is present while circulation and filtration of the cleaning fluid is in progress some of it may be carried along in particulate form and filtered out of the stream before it can be deposited on the textile substrate. Where such filtration is a part of the cleaning cycle, it is preferably omitted or by-passed during the period the textile material is in contact with the repellent-laden cleaning fluid. No other alteration is necessary in any of the well-known dry cleaning machine cycles. Drying of the cleaned and treated material can be carried out at any convenient temperature. Best results are achieved when cleaning fluid is completely removed before further processing of the textile.

While even better oil and water repellency is attained when the usual hot pressing is carried out, this step is not essential to the attainment of good oil and water repellency.

Textiles treated by the process of the invention exhibit a distinct improvement in water and oil repellency and stain resistance. Non-oily stains or "sweet spots" are effectively removed during the dry cleaning procedure, and no more hand removal of stains is required than with prior dry cleaning techniques. Where the instance of water soluble stains is higher than normal, additional water can be added with the fluororepellent composition. Water level can be controlled by employing the solvent relative humidity concept, as hereinbefore described. Redeposition of particulate soil from the cleaning solvent appears to be minimized also in the process of the invention.

Any of the well known commercial dry cleaning machines can be employed in the process of the invention. Transfer or dry-to-dry machines, drum types, open pocket and split pocket types are all usable. The usual ratio of solvent to clothes (which admittedly varies widely) can be used, for instance from about 0.5 to about 2 gallons per pound of textile being treated. The usual cycle times are satisfactory except that the repellent composition is best not introduced into the solvent until about one-half of the wash time has passed, and the particulate filter should be bypassed after the washing is resumed, as already mentioned.

The following examples illustrate the invention. Parts and percentages referred to therein are by weight unless otherwise indicated.

EXAMPLE 1

In a typical small commercial dry cleaning machine there were placed 25 pounds of a variety of soiled garments for dry cleaning and 2250 pounds of perchloroethylene. The machine was previously washed thoroughly to remove any residual detergents, which might impair the efficiency of the subsequent treatment. The cycle was started, and after about 4 to 5 minutes (1/2 the normal washing time) the filter was by-passed and 1/2 pound of a stain repellent composition was added. The composition contained 71.5 percent 1,1,2-trichloroethylene, 1 percent of a copolymer derived from 70 percent ethylene and 30 percent dimethylaminoethyl methacrylate, and 27.5 percent of an aqueous emulsion containing 77 percent water and 23 percent of a copolymer obtained by emulsion polymerization of a monomer mix containing (1) 75.0 parts of F(CF.sub.2).sub.n CH.sub.2 CH.sub.2 O.sub.2 CC(CH.sub.3)=CH.sub.2 where n is 6, 8 and 10 in the weight ratio of 3:2:1 with additionally less than 10 percent by weight of n = 12 and 14, (2) 25.0 parts of 2-ethylhexylmethacrylate, (3) 0.25 part of N-methylolacrylamide and (4) 0.25 part of 2-hydroxyethyl methacrylate. A detailed method for preparing this polymer is given in column 6, Example 1 of U.S. Pat. No. 3,462,296.

After addition of the stain repellent composition, the cycle was resumed. The garments were washed in the perchloroethylene stain repellent for about 5 minutes and then agitation was stopped. The liquid was drained away and the load spun and dried.

When tested for oil repellency and water repellency, very good results were shown. Water repellency tests were performed according to the AATCC Standard Test Method 22-1967 of the American Association of Textile Chemists and Colorists. A rating of 100 denotes no water penetration or surface adhesion, a rating of 90 denotes slight random sticking or wetting, and so on down to 0 which denotes immediate wetting and penetration of water spray. Oil repellency tests were carried out according to the AATCC Standard Test Method 118-1966, using clear undyed oil. Results on garments treated in this example ranged from 70 to 90 in water repellency and 3 to 5 in oil repellency. Tests on untreated material gave 0 in both oil repellency and water repellency. The incidence of "sweet spots" was at least as low as with the normal detergent process. There was no increase in wrinkling, and appearance of the garments after pressing was judged equal or superior to those treated by prior art processes. Handling and recovery of the dry cleaning solvent was carried out in the routine manner. There was no additional make-up or purification required.

Using the same composition and procedure, over 700 cycles were carried out successfully, with continued excellent performance in appearance, water repellency and "sweet spot" removal.

EXAMPLE 2

A cleaning composition was prepared by first dissolving 2 pounds of the copolymer derived from 70 percent ethylene and 30 percent dimethylaminoethyl methacrylate in 278 pounds of perchloroethylene, then mixing in, with rapid agitation, 120 pounds of an aqueous dispersion of a copolymer prepared by polymerizing a mixture of monomers containing 90 parts F(CF.sub.2).sub.n CH.sub.2 CH.sub.2 O.sub.2 CCH = CH.sub.2 where n is 3 to 14, 10 parts of trifluoroethylvinyl ether, 0.25 part N-methylolacrylamide and 0.25 part of 2-hydroxyethyl methacrylate. Preparation of this copolymer is disclosed in U.S. Pat. No. 3,546,187. A stable emulsion resulted.

In this application 70 pounds of 65 percent cotton-35 percent polyester clothing were scoured at ambient temperature with about 70 gallons of perchloroethylene. The fabric was first washed in a basket washer for about 5 minutes while particulate soil was removed by filtering the circulating solvent. The 1.4 pounds of the emulsified product described above were added to the perchloroethylene along with 2 pounds of water to aid in removal of water soluble soil. The fabric was then washed an additional 5 minutes while by-passing the solvent filter. After 1 to 2 minutes of centrifugal extraction the fabric was dried at 160.degree.-170.degree.F. The treated clothes were clean and exhibited good water repellency.

Claims

I claim:

1. A process for simultaneous cleaning and finishing of soiled textile materials in which the textile is

A. treated at from about 0.degree. to about 100.degree.C. for from about 1 minute to about 30 minutes with a composition consisting essentially of

a major amount of a textile dry cleaning solvent;

a minor amount of water;

an amount sufficient to give add-on of 0.05 to 0.5 percent, based on the dry weight of textile of a polyfluoroalkyl substituted stain repellent; and

5 to 20 percent, based on the weight of stain repellent, of an emulsifying agent which does not negate the stain repellency; and then

B. the treated material is dried.

2. The process of claim 1 in which the stain repellent is substituted with polyfluoroalkyl substituents containing from 3 to 16 carbon atoms, and the emulsifying agent is a hydrocarbon copolymer of ethylene and an aminoalkyl acrylate monomer.

3. The process of claim 2 in which the emulsifying agent is present in amounts ranging from 10 to 20 percent based on the weight of stain repellent.