US3374107A - Process for the treatment of textiles with aminoplasts - Google Patents

Description

United States Patent O 3,374,107 PROCESS FOR THE TREATMENT OF TEXTILES WITH AMINOPLASTS James F. Cotton, Columbus, Ga., assignor to West Point- Pepperell, Inc., West Point, Ga., a corporation of Georgia No Drawing. Continuation-impart of application Ser. No. 301,952, Aug. 14, 1963. This application Aug. 17, 1966, Ser. No. 572,906

11 Claims. (Cl. 117--139.4)

ABSTRACT OF THE DISCLOSURE Improved wet fixation of aminopla'sts in textiles through the use of a catalyst containing an acidic component and a salt component. The acid has a dissociation constant no smaller than at room temperature. The salt is an ammonium, amine or metallic salt of an organic acid showing an acidic reaction in aqueous medium. The wet fixed fabric may be dried and cured, for which a volatile acid is a preferred acid component. An epoxidized triglyceride may be fixed with the aminoplast.

Disclosure This is a continuation in-part of our earlier application Ser. No. 301,952 filed Aug. 14-; 1963, now abandoned.

The present invention relates to a chemical treatment of textiles and, more particularly, to a treatment using aminoplasts.

It has been known for a number of years that textiles, and particularly cellulosic textiles, may be treated with the reaction products of urea, melamine and similar materials with aldehydes, particularly formaldehyde, (referred to as aminoplasts) to increase resistance to creasing, for dimensional stabilization in laundering, to improve resistance to attack by microorganisms which can cause rotting,- for surface and novelty effects and for other purposes. The aminoplasts are applied to a textile and then are cured, a procedure which causes interactionbetween the cellulose and the aminoplast, e.g. cross-linking or interaction between aminoplast molecules, e.g. polymerization, or both. The mode of reaction is dependent upon the particular nature of the aminoplast being used and the conditions of curing.

It is known that curing may be accomplished in several ways. The most usual procedure, which will be referred to as dry curing, is accomplished at high temperature, eg 300 F. and higher, with the presence of acidic substances for catalysts. In the special case of urea-formaldehyde aminoplasts, the impregnated textile sometimes is merely dried without curing in the presence of an ammonium salt. Curing is then accomplished on extended holding of the treated fabric, e.g. thirty days and longer. Another known method, which will be referred to as wet fixation is accomplished with the fabric in the Wet state, either at room temperature for extended periods or at moderately elevated temperatures. A principal object of the present invent-ion is to provide for very great acceleration of the speed of the latter type of fixation.

As indicated above, the bulk of textiles treated by current processes are dry cured at high temperatures. Mos-t aminoplasts have required high temperature cures. In

addition, speed of operation is often great, necessitating short cure times and more precise control of treated textile properties is obtained thereby. But certain disadvantages are also attached to this type of curing. Of primary importance is loss of physical strength properties including tensile strength, tear strength and abrasion resistance.

3 ,3 74., l 0 7 Patented Mar. 1 9, 1 968 Aesthetic properties such as flexibility and fabric smoothness are generally affected also although these may be recovered, at least in part, by application'of softeners and other agents.

Dry curing on extended storage is usually confined to lower grade finishes. Strength and other properties suffer in the same fashion as noted for high temperature curing and, in addition, creases or folds in cloth so cured are usually fixed in thefabric.

Wet fixation Was developed as an alternate for dry curing in that it does not cause the same degree of loss in physical strength properties, although some stiffening of the fabric is usually observed. As described in Ruperti US. Patent 2,763,574, it has been employed primarily for the fixation of melamine polymeric materials in and on cellulosictextiles. This method requires that the fabric be maintained in the moist state untilthe aminoplast is converted to the insoluble state. As described by Ruperti, wet fixation may be accomplished by steaming of the impregnated textile. In practice this requires a minimum of eight minutes for light fabrics in the. case of a commercially used process, and more time for heavier fabrics. A more common wet fixation procedure is carried out in a batch process. A fabric, for example, is wound onto rolls which must be held in a moist state for one or more days. It isnecessary to provide means to prevent drying of the fabric as, for example, wrapping the rolls of fabric with a moisture barrier. Drying of the fabric prior to wet fixation will raise the possibility of dry cure occurring.

A continuous process is possible for the commercially available wet fixation treatments if steam is used and special equipment is employed to permit maintaining uniform steaming of the fabric for fairly long periods of time or if output of more commonly available steaming equipment is reduced extremely. The latter is not economically feasible since the output generally must be reduced by a factor at least ten or greater (e.g., in a dye steamer, Where normal dwell is thirty seconds for a medium weight fabric, increasing dwell to ten minutes reduces the output of the steamer by a factor of twenty). High speed continuous processing of fabric by the extaut wet fixation methods, therefore, is not generally possible.

The present invention overcomes the several difficulties enumerated above and has as a principal object a wet fixation process which does not require extended treatment of moist fabric or high temperature dry curing and which may be carried out on conventional processing equipment in a continuous, high speed operation. Properly executed, there is little or no loss in strength properties or stiffening of the fabric as is observed in the dry cure procedures enumerated above. The treated textile is resistant to shrinkage, resistant to rotting and tends to resist creasing. These and other objects are achieved by the use of a catalyst which contains a synergistic combination of critical components, viz., an acid and an acid salt. The aminoplast is applied to the textile from aqueous solution or dispersion and the catalyst introduced either with the dispersion or, wholly or inpart, after the aminoplast. The impregnated textile is heated until the resin is fixed while moist and then may be washed and dried. Various procedures for controlling the moisture level of the fabric during resin fixation will be referred to further herein. Surprisingly, it has been found that the highly active catalysts accelerate wet fixation of the aminoplasts at moderate temperatures, but they do not interfere with the stability of solutions or dispersions of aminoplasts at room and slightly elevated temperatures to any greater extent than catalyst systems which are presently employed in wet, fixation procedures.

The term aminoplasts refers to hardenable amine-aldehyde precondensates of the type which are either freely soluble in water or soluble therein to a limited but sub stantial extent. Included are reaction products of nitrogenous compounds, e.'g., nitrogenous bases with aldehydes which are either water soluble or water dispersible. Typical nitrogenous compounds are melamine, guanamines and other triazines, urea, ethylene urea, propylene urea, thiourea, guanadine, biuret, dicyandiamide, urons, triazones and various derivatives thereof. Also included in the term nitrogenous compounds are cyclic imines such as ethylene imine and propylene irnine. The aldehyde is selected from that group forming water soluble or dispersi-ble condensation products with nitrogenous bases, but formaldehyde is the preferred aldehyde. The aminoplasts may be etherified or partially etherified with methyl, ethyl 'or higher alcohols. Mixtures of aminoplasts may be used.

In accordance with one embodiment, there is added to other aminoplasts, a fatty acid derivative of melamine which has been condensed with formaldehyde. It may be described as a fatty acid derivative of melamine which is capable of self-condensation and reaction with cellulose which is available commercially under the name Phobotex f/t/c. Normally, this material is dry cured, e.g., at 300 F. to impart water repellency to the fabric. However, this is accompanied by the loss of strength discussed a-bove. By mixing with, say, a melamine-formaldehyde precondensate and wet-fixing in accordance with the invention, the difficulty is avoided.

Combinations of aminoplasts with various modifiers such as water repellents, fire retardants, hand modifiers, softeners, tints, etc., may be used provided only that no interference in the reactions of the aminoplasts should occur. The aminoplast may be capable of reacting to form repeating units and it may be reactive with other substances containing hydroxyl, nitrogenous, thio or oxirane groups. It has been determined that compounds containing these groups may exert a secondary synergistic effect. Thus, for example, epoxidized triglycerides have been found to cause an appreciably higher fixation of aminoplast in and on the fibrous substrate.

The curing agents contain an acidic component and a salt component. The acidic component may be'one or more mono-, dior polybasic acids, organic or mineral, which for the primary acid are no more weakly acidic than acetic acid or; stated in another way, which have a dissociation constant no smaller than at room temperature. Suitable acids include formic, sulfamic, glycolic, oxalic, citric, diglycolic, tartaric, sulfurous and orthophosphoric acids. These acids are preferred for low cost, ready availability, ease of handling, and the like, but other acids, within the above range may be used. Formic acid is particularly suitable. It possesses the advantage, in connection with one embodiment that it is volatile. In that embodiment, to be described further herein, after the fabric is subject to wet fixation, it is 'dry cured. During dry curing, the acid component may injure the fabric. However, formic acid rapidly evaporates and avoids this difiiculty.

The salt component is an ammonium, amine or metallic salt of an organic or inorganic acid which shows an acidic reaction in an aqueous medium at either ambient or elevated temperatures. Also included. among this group are those combinations of salts, a member of which, when isolated, will not show an acidic reaction but which in combination with another salt or salts will not so alter the characteristics of the combination as to prevent an acid reaction at'either ambient or elevated temperatures. By way of illustration, the broad range of salts which show utility include, but are not limited to, the ammonium, amine and metallic salts of hydrochloric and other halogen acids, sulfuric, thiosulfuric, sulfurous, sulfamic, phosphoric, phosphorous, fiuoboric, nitric, nitrous, carboxylic and sulfonic acids-either si g y O i combina n- Specific examples among these groups chosen for low cost and availability without intent to limit the present invention are ammonium chloride, ammonium sulfate, ammonium sulfite, ammonium bisulfite, ammonium thlosulfate, ammonium dihydrogen phosphate, diammonium phosphate, ammonium sulfamate, ammonium nitrate, ammonium acetate, ammonium citrate, Z-aminopropanol hydrochloride, magnesium chloride, magnesium sulfate, magnesium dihydrogen phosphate, aluminum chloride, aluminum acetate, aluminum sulfate, zinc chloride, zinc acetate, zinc nitrate, zinc fiuborate, calcium chloride, barium chloride, ferric chloride, stannic chloride, and chromic chloride. As may be appreciated, a broad diversity of salts may be used advantageously in the present invention. However, magnesium chloride is particularly suitable.

Amounts of catalysts may range from about 0.1 to 4.0% acid and about 0.1 to 4.0% salt based on the weight of aqueous medium plus aminoplast used to apply the resin but concentrations outside these ranges may be found useful in special cases. More usually, the preferred level of both acid and salt is in the range from about 0.5% to 1.5% based on the weight of said aqueous medium plus aminoplast.

Textiles which may be treated include, but are not limited to, textiles of cellulose fibers both natural and regenerated and blends thereof with other fibers, synthetic fibers, and blends thereof with other fibers including polyamide, polyester, polyolefin, acrylic and other fibers produced by chemical synthesis, animal fibers including wool and other fibers produced from agricultural sources where the fibers occur naturally or are produced from nonfibrous commodities.

The term textiles refers to, e.g., all that body of filamentary sheet materials including woven, knitted, nonwoven and similarly constituted textiles, yarns, threads and similar aggregations of fibers either spun, twisted or braided, roving, slivers, laps and similar aggregations of fibers whether disposed in an ordered or random manner and bulk fibers. Also included in this definition are paper and other products of the paper making system whether constituted of natural or synthetic fibrous materials.

In carrying out the treatment, the first step is impregnation of the textile with an aqueous solution or suspension of the aminoplast and the catalyst, either from a single bath or from a series of baths, by immersion, etc. Generally, however, the aminoplast and catalyst will be applied from a single bath maintained at room or slightly elevated temperatures, usually no more than F. Pickup of aminoplast will usually be about 1% to 15% on a dry weight basis but higher levels may be desirable for specific cases. Under some conditions, however, it may be advantageous to apply the aminoplast from one bath and the catalyst from a second. Separation of the components in this fashion provides much longer standing bath life for the aminoplast and allows higher operating temperatures to be maintained in the impregnation step. The maximum allowable temperature in the aminoplast will depend primarily upon the heat stability of the aminoplast being utilized, but for some aminoplasts, especially those which show no tendency to form insoluble residues when non-catalyzed solutions containing them are heated, any practical operating temperature may be maintained. For the catalyst solution, the temperature selected is usually from F. or higher but any practical temperature from room temperature to the boil may be utilized. After application of the aminoplast and catalyst, the aminoplast is fixed to the textile.

The wet fixation process is carried out by keeping the fabricmoist until the resin is fixed, the term moist referring to maintaining the moisture content of the fabric above. its normal moisture regain. This is the moisture content of the fabric in equilibrium with a standard atmosphere,'*i.e. air at 65% relative humidity and 70 F., as determined under ASTM D123 and D62959T. It is measured by comparing the weight of this fabric with the weight of fabric after drying in an oven under specified conditions. However, the moisture content of the fabric preferably is kept above about 15% based on the dry weight of the fabric, until the aminoplast is fixed.

The moisture content is maintained until the aminoplast is fixed to the fabric. Ordinarily, this means that at least about 70% of the applied resin is fixed to the fabric. However, adequate wet fixation can be determined, e.g. by following conversion of resin to a state of insolubility or by a dyeing test. Thus if the fabric is placed in boiling water after fixation for one-half hour, dried and then weighed, increase in weight compared to the unimpregnated fabric indicates fixation of aminoplast. It also is possible to dye a white fabric with a mixture of two dyes, one of which is a direct dye for the textile and the other of which is a dye for the fixed (or polymerized) aminoplast. For example, in the case of cotton, the mixture may be Pontacyl Fast Red AS (Color Index Acid Red 88) and Pontamine Sky Blue FF or Color Index Direct Blue 1. A typical solution for making a dye bath would contain 1% each of the dyes, 12.5% sodium sulfate, 2.5% acetic acid, 2.0% wetting agent such as Deceresol NI and the balance is water. A dye bath is made using two parts by weight of this solution to one part by weight fabric and enough water so that the volume of dye bath in ml. is 40 times the weight of the fabric in grams. The fabric samples are prewet, dyed in a preheated dye bath at 200 F. for 30 minutes and rinsed repeatedly until the rinse water is substantially free of color. The blue dye will color cotton, and it is a characteristic of wet fixation of aminopl'ast that the absorption of direct dyes by treated cellulosic textiles is not substantially reduced. On the other hand, dry curing does substantially reduce and often may essentially eliminate direct dye uptake, The red dye is an acid dye which is not taken up by the cotton but it does dye wet fixed or dry cured aminoplast.

The color of the dyed fabric therefore indicates the nature of fixation: the deeper the red dyeing, the more resin that is fixed; the loss of blue dyeing, compared to untreated textile, indicates dry curing. Shades of purple indicate wet fixation. Thus the color observed can be interpreted as follows:

Blue-No fixation Deep purple-Fair wet fixation Violet-Good wet fixation Red violet-Excellent wet fixation RedDry cure It also is possible to dye fabric samples separately with the individual dyes for more precise determinations. Dry cure can then be detected directly If the aminoplast is wet fixed, the depth of blue coloration will remain about the same, except for heavy impregnations. If a large amount of resin is used, there is a slight lightening. On the other hand, a dry cure leads to a white or pale blue fabric. In the separate dyeing with the acid dye, color formation indicates resin fixation or curing.

As indicated, the fabric is maintained moist at a suitable temperature until the resin is fixed, as indicated by one of these tests. Several different methods may be used:

(1) The treated textile may be steamed for from about 15 seconds or less to 5 minutes. In some cases as when yarn or fibers are treated in bulk, steaming times may be extended to insure that the entire mass has been steamed. However, for ordinary fabrics, the fixation temperature will be about 15 to 90 seconds, typically 30-60 seconds. The temperature of steam may be 212 F. or greater, typically 220 to 250 F.

(2) The treated textile may be simply dried under con- More specifically, a sample of fabric is first dried at 105110 C. until the weight of the sample remains constant at :.001 gram. Then it is exposed to the standard atmosphere until its Weight is constant to $001 gram. The difference in weight indicates the normal moisture regain, which ordinarily is expressed as a percentage of the dry Weight or the fabric,

trolled humidity conditions to induce a cure. Preferably, drying temperature is maintained in the range from 220 to 250 F. although temperatures outside this range may be utilized. For example, an 8 oz. cotton twill can be wet fixed on conventional drying cans at 15 p.s.i. gauge steam at about 240 F. (These are the temperatures of, e.g. the surface of conventional drying cans, measured by pyrometer. Sufiicient steam pressure is used in the cans to produce these temperatures.) However, the temperature of the fabric itself probably does not rise above 212 F. fixed, the evaporation of moisture acting as a kind of natural thermostat. In general, when drying cans are used, the temperature should not be too low. While water evaporation and the rate of wet fixation are both reduced at lower temperatures, the effects may not compensate each other, and there is a risk that the fabric will dry before the resin is fixed. The primary consideration to be observed of course, is that the treated textile is not heated beyond the stage of normal moisture regain at temperatures in excess of about 250 to 300 F. preferably not in excess of 212 F. before the resin is fixed. To do so induces dry cure instead of wet fixation. Time and temperature of drying will be dependent upon the conditions imposed by the system including treating equipment and textiles being treated. Further control can be achieved by flow of humidified air around the fabric.

(3) The treated textile may be cured by holding in the wet state. Although one of the principal advantages of the present invention is its adaptability to high speed continuous operations, in certain cases it may be found advantageous to treat textiles in batch operations. In such cases, cure may be obtained in as little as three hours at to F. although holding time can be extended without detrimental effect on the treated textile. Alternatively, holding time may be reduced if the temperature of holding is increased.

As a substitute for steaming, another embodiment of the process comprises passing padded textile including the solution or dispersion of aminoplast with or without the acid or salt through a solution of a salt, an acid or a solution of a salt and an acid which is maintained at elevated temperature, preferably F. or higher. Another embodiment of the present invention involves the application of an uncatalyzed aminoplast solution or of an aminoplast solution which contains one component of the acid-salt catalyst solution, either hot or cold, to a textile followed by the application of the catalyst system, or of the second component of the catalyst system, hot or cold, to the textile which may or may not be further fixed by steaming as previously outlined.

After wet fixation, the textile may then be washed with water, with or without a surface active agent and other washing auxiliaries and dried. Very little if any resin is removed from the fabric, clearly demonstrating that the resin has polymerized. It also may be given an odor control treatment as described in US. Patents 2,- 870,041 and 2,928,758.

It is possible to follow the wet fixation with a dry curing step. This tends to enhance the properties conferred by the wet fixation and can be achieved, under proper conditions, with little or no deleterious effects on the fabric. That is, the harmful effects of conventional dry curing on fabric strength are substantially reduced if the aminoplast is first subjected to Wet fixation. Thus, a treated textile may be simply dried at elevated temperature without washing, subsequent to wet fixation, to cause an improvement in properties generally. As indicated above, in this procedure, it is preferred that the acid catalyst component be volatile, e.g. formic acid, so that it does not injure the fabric. Of course, the salt component should itself be a catalyst for dry curing, e.g. magnesium chloride. Alternatively, the textile may be washed subsequent to wet fixation followed by application of conventional dry curing accelerators or catalysts such as, but not limited to, the ammonium, amine, magnesium, aluminum and zinc alts of hydrochloric, phosphoric, sulfuric, nitric, fluoboric and other acids or of an acid per se. In general, to prevent or minimize damage to the material subjected to a dry curing treatment, the textile is merely dried in the manner enumerated above after application of the dry curing agent although tem peratures and times of drying may be as high or long as desired with such temperatures and times selected to suit the conditions imposed by the system including treating equipment and textiles being treated.

This dry cure can be carried out after a treated fabric is manufactured into a textile article by cutting, sewing, etc, to provide durable crease features, as described in Getchell Patent 3,138,802. Thus, the textile article, such as a garment, is sewed and creases, curves and pleats are pressed .into it with or without prior moistening, and then the garment is dry cured, for example, up to about 350400 F. The same effect can be achieved by prolonged heating during pressing. For example, a cotton twill fabric weighing about 8 oz./sq. yd. when made into work pants may be given a permanent crease by pressing for 25-30 seconds at 350 F. or 3-5 minutes at 325 F. This will be adjusted depending on the weight of the fabric and the number of layers pressed together.

The sequence of wet fixation followed by dry curing permits a larger part of the resin to be bound to the fiber. Thus, wet fixation may insolublize 7080% (or even as high as, say, 93%) of the resin and the subsequent dry resin can increase this amount to almost 100%. On the other hand, ordinary dry curing causes attachment of only about 70% of the resin.

A surprising feature of the present invention for processes in which the textile being treated is in contact with the treating solution more than momentarily, as for instance in jigs, kiers, etc., the resin may be made to exhaust upon the textile being treated. Thus it is possible to treat the textile in a relatively low concentration of aminoplast and achieve a high concentration of aminoplast fixation on the treated textile. By way of illustration, when similar yarns were treated in a kier with a catalyzed solution containing 4.2% aminoplast and conditions were similar except that the temperature of the treating solution was varied from 80 F. to 120 F, the average fixation of aminoplast was as follows:

Temperature, F.: Percent aminoplast fixed 80 5.2 100 7.6 120 9.9

Similarly, exhaustion time will influence the degree of exhaustion of the resin as will other factors such as the particular catalyst combination being utilized, the aminoplast, and the previous history of preparation of the textile being treated. As those skilled in the art will realize, such processes and considerations are common in exhaustion dyeing.

Exhaustion times and temperatures are restricted only to the stability of the treating solution being employed. That is, the time and temperature of exhaustion are selected so that precipitation or coagulation of residual aminoplast within the body of the solution does not occur.

In accordance with this embodiment of the invention more rapid exhaustion is achieved by adding salts such as sodium chloride to the aminoplast bath. The concentration of sodium chloride is up to about A simple means for preliminary evaluation of the catalyst system for wet fixation of aminoplasts has been established. In the evaluation a measured amount of a solution or dispersion of the aminoplast containing the catalyst system under study is introduced into a test tube which had been previously immersed in and is at the temperature of a thermostated water bath maintained 'at 180 F. The time required for condensation of the aminoplast to occur as determined by a visible clouding or g precipitation and the temperature at which such clouding or precipitation occurs are used as an indication of the catalytic efficiency of the system being evaluated. By such means, for example, the relative efficiencies of a group of chlorides in effecting wet fixation was determined. In this group, a standard solution of a methylated melamine resin was catalyzed with formic acid and at equal concentrations in separate containers, combinations of formic acid and ammonium, magnesium, zinc, aluminum and ferric chlorides and hydrochloric acid. By the method above it was found that the relative reaction rates of these catalytic systems which include formic acid was of the following order:

NH4C1 MgOli FeCis ZnClz AlClz HCOOH HCL HOOOH HGOOEI HCOOH HCOOiI HOOOH it will be noted that the relative reaction rate of a salt in this system is not necessarily related to the acidic character of tie salt. This test is valid for those amino plasts which form insoluble polymers.

The following examples illustrate the practice of the invention:

Example I A cotton twill fabric weighing about 10.5 oz./sq. yd. which had been desized, scoured, dyed and washed substantiaily free of residues is passed in a continuous operation through a padder, steamer and wash box. The pad box of the padder contains an aqueous solution of:

Percent Methylated melamine 12 Magnesium chloride hexahydrate 1.0

Formic acid 1.0 Polyethylene oxide condensate of nonylphenol (wetting agent) 0.2

Warp Breaking Strength, Lbs/In. Shrinkage,

percent Warp Filling As may be seen, a substantial improvement in warp shrinkage is obtained with no deterioration of fabric strength. Further, the treated fabric dried fiat and smooth,

the others did not. The fabric was not stiffened by the treatment. Example 11 The procedure of Example I was followed for the same fabric except that the last part of the washing operation consisted of application of a 1% solution of magnesium chloride hexahydrate at F. followed by drying, as before, for two and one-half minutes at 300 F. The warp shrinkage of this fabric was 5.3%, the warp breaking strength was 140 lbs/in. and the filling breaking strength was 80 lbs/in.

Example Ill The procedure of Example 11 was followed for a fabric which contained yarns composed of a core of polyamide fiber covered with an outer layer of cotton. The treated fabric and a similar untreated fabric were subjected to heat setting at 380 F. for forty-five seconds under identical conditions. It was found that the shrinkage of the treated fabric in both warp and filling was less than 50% of the shrinkage of the untreated fabric and that the treated fabric did not yellow as did the untreated fabric in the heat setting operation. In a laundering operation subsequent to heat setting, shrinkage of the treated fabric was substantially lower than the untreated fabric. The treated fabric washed withontravelling and dried smooth and fiat while the untreated fabric ravelled badly in laundering and dried badly wrinkled.

Example IV As may be seen, the wickup absorbency of the treated fabric was slightly higher than the untreated fabric.

Treated Untreated Example V A cotton duck fabric was treated as in Example II except that the melamine concentration was 18% in the treating bath. Improved dimensional stability and smooth drying properties with no appreciable loss in strength is obtained and, in addition, the fabric retained all its strength when buried for two weeks in a soil burial bed of such potency that an untreated fabric is completely decomposed in the same length of time.

Tests have been performed on cotton fabrics treated with melamine-formaldehyde resins in accordance with the above process and these have indicated that as much as 90100% of the resin applied was fixed in the fabric. These tests include boiling in an aqueous solution containing 5.0% phosphoric acid and 1.5% urea. Boiling is continued until the fabric gives a negative test for formaldehyde, usually 30-60 minutes, and then weight loss is determined, the percentage of resin retained indicating the amount of fixation. By comparison, similar tests performed on fabrics treated in a known wet cure process indicated 70% fixation and dry curing normally fixes about 70% of the resin applied.

Example VI Mercerized cotton yarn was treated with a solution containing:

Polyethylene oxide condensate of nonylphenol (surfactant) in a kier. The solution at 100 F. was passed through the yarn for 30 minutes. Excess solution was extracted from the yarn, it was held for from three to sixteen hours at ambient room temperature and dried. The treated yarns were placed in dobby towel borders and subjected to shrinkage tests. It was found that the towel borders containing the borders were highly resistant to puckering whether the yarn was held three hours or sixteen hours prior to drying where towel borders containing similar untreated yarn puckered severely in shrinkage testing. On chemical analysis, it was found that the amount of resin fixed in processing was virtually the same for yarns held three, four, five, six, seven or sixteen hours prior to drying. Average resin content was 7. 6%. The durability of the resin was such that greater than 90% of that present in the dyed and finished towel border was still present after 30 launders.

Example VII The solution of Example VI was applied to greige cotton yarn, merccrized cotton yarn, bleached cotton yarn and mercerized and bleached cotton yarn. Conditions of application included 120 F. solution temperature and 30 minutes saturation time. The yarn was held wet for three hours or longer prior to application of a solution containing:

Percent Sodium metabisulfite 0.5 Tetrasodium pyrophosphate 0.25 Aqueous ammonia 0.1

at 180 F. followed by drying. It was found that towel borders containing these yarns were highly resistant to puckering due to shrinkage. It was further noted that the resin so eificiently stabilized the yarns that normal bleaching operation failed to remove the normal coloration of the greige and mercerized yarns. The bleached and mercerized and bleached yarns on the other hand suffered no discoloration due to processing and were: acceptably white in standard white towels. The resin fixation in these yarns ranged from 10 to 12%. After thirty simulated home launders, it was found that treated yarns retained and greater of the aminoplast present in the treated yarns of the finished towels.

Example VIII Skeins of 20s/2 ply mercerized and bleached cotton yarn were treated for 30 minutes in the solution of Example VI at F. The yarns were held for 2 hours at F. in a moisture impermeable cover and finally Example IX A 136 x 64 broadcloth, mercerized and bleached, was immersed in an aqueous media containing:

Percent Triazine resin 3.3

Epoxidized triglyceride 0.84

Zinc fluoborate 0.5

Citric acid 0.1

Ethylene oxide condensate of nonylphenol (wetting agent) 0.2

The fabric was treated for 60 minutes at 150 F., squeezed to approximately 60% solution pickup and held 2 hours at 150 F. in a sealed polyethylene cover. The fabric was dried at 220 F., washed in an alkaline media, rinsed and redried. By weight gain measurements 11.5% weight gain was achieved based on the untreated fabric. The epoxidized triglyceride also increases abrasion resistance.

Example X This example shows. that the epoxidized triglyceride is hydrolyzed to some extend in the treatment to'function as the acid component of the catalyst as well as a co-reactant.

The process of Example IX wasrepeated except that the citric acid was removed and 0.25% formaldehyde and 0.5% acetone were added to the aqueous system. All conditions of treatment were identical. By weight gain ii measurements 17.0% add-on based on the untreated fabric was found.

The following example illustrates the use of a fatty acid-melamine-formaldehyde precondensate which is i of a polyoxyethylene sorbitan monola'urate (Tween 20) and an alkylaryl polyether alcohol (Triton X45) prior to addition to the body of the mixture. The ammonia was added to the mixture to provide increased stability fixed to impart water repellency. of the mixture without inhibition of subsequent wet fuation at hi her tem eratures. Example X1 in a coi itinuous operation a vat dyed all cotton twill III a Continuous Operation, an 398 afmy duck work clothing fabric was padded through the mixture fabric was padded through an aqueous media containing: above, t a pickup of 55% on h dry i ht of th Percent fabric passed over steam heated drying cylinders heated Triazinc resin with 8 1 2 p.s.1.g. steam pressure, passed into a tes er Emuisificd fatty derivative of melamine formaldedryer a tempefature setting of 230 and rolled hyde (Water repellent) Operat1ng speed was ad usted to leave the fabric Magnesium Chloride hexahydrate L2 slightly damp to the touch. For the 001K111 twlll operat- Formic acid L2 mg speed was its yards per minute. The Labl'lc temperature at the exit of the dryer housing was 140 F. as The fabric was steamed for one minute at 226 F., washed measured by an optical pyrometen at and PaSSEd through a Solution at Next the fabric was given a compressive shrinkage mining grams P liter of magnesium chleridi treatment. Steam pressure on the cylinder was 40 p.s.i.g. y The fabric Was then barely dried at Operating speed was 82 y.p.m. Because the fabric entered This fabric Was f und to have a 109 p y ralmg damp it Was not sprayed with water or steam as is the (AATCC Standard Text Method and maimed usual practice to permit easier compression in this operaan its Strength in tWO Weeks Soil burial Where the 1111' lion. Fabric temperature as measured with an optical treated fabric was completely deteriorated in seven to pymmete; ranged f o 208 F. to 212 F at h paint nine y The p Shrinkage of the treated fabric was 25 of nearest measurement as the fabric left the cylinder. 4.4% compared to 9.9% for the untreated fabric. When The fabric was tesied analyzed (a) as prepared an inverted cone Of the treated fabric was Suspended fg treat ng t after 13 fixation and cg np gssive from its C n rs d filled With Water, leakage W shrinkage and (c) after pressing the Wet fixed and comfOund thr ugh a tW nty-four hour period. By Way f pressively shrunk fabric 15 seconds at 120 p.s.i.g. steam contrast, the untreated fabric, tested in a similar man- 30 pressure in a pressing machine followed by dry curing ner, leaked instantly. in an oven set at 325 F. for 15 minutes.

Prepared Comprcs- Pressed for Treat- Sive and Dry merit, Shrunk Cured Indicated Strong fabric, percent:

Warp Filling Nitrogen Content, percent:

1 Wash temperature was 140 F. Fabric was tumbled dried.

This example shows the efiicacy of including water re pellent in the present process.

Example XII This example illustrates one method for utilization of the above-described method in which the fabric is simply dried by heating under controlled moisture conditions to cause wet fixation of an aminoplast.

An aqueous mixture was prepared containing calculated levels on the total weight of the mixture of:

Polydimethylsiloxane oil (commercial emulsion,

Silicone LE-46) 0.1

The epoxidized triglyceride was emulsified with 10% on the weight of the epoxidized glyceride of a 1:1 blend As may be seen the fabric exhibited excellent retention of strength even through the severe dry curing imposed upon the wet fixed fabric, The indicated nitrogen content of the wet fixed fabric pressed and cured and given five home launders at 146 F. is about 94% of the nitrogen content of the wet fixed fabric which was not laundered. After laundering, the wet fixed fabric pressed and cured with the low angle lighting method of evaluation was actually smoother than the standard used for the maximum rating by the method. Also note that the wet fixation did not reduce moisture regain but that dry curing did cause a reduction.

A sample of white cotton twill fabric which was sewn in line with the principal fabric of this example and which was treated in the same manner was dyed with the combination of dyes as previously described. The fabric after compressive shrinkage dyed violet to red violet indicating good to excellent wet fixation. The fabric after pressing and curing dyed a bright red indicating dry cure.

In a further test of the wet fixed fabric simulated pant legs with cuffs were sewn from the wet fixed fabric compressively shrunk and pressed and oven cured as before.

This example further illustrates the efficacy of using dry heat to causewet fixation and compares drying to normal regain and partial drying in a wet fixation process.

In this case two separate standing mixes were made and combined proportionally as needed. In one mix were combined formic acid and zinc fiuoborate. In the second mix were combined all other components of the final aqueous mixture. The combining ratio of mix one to mix two was 1 to 10, This enabled the advance preparation of mixes which could be allowed to stand virtually indefiniely. The components of the final mixture and the calculated active concentration based on the total weight of the final mixture were:

Nonionic wetting agent (Deceresol Surfactant FW) 0.25

The cotton twill fabric of Example XII was padded through the aqueous mixture to a pickup of 55% and passed directly into a tenter dryer set at a temperature of 250 F. One sample was dried to 4.5% to 5.5% residual moisture as determined by a conductance type moisture monitor which had been calibratedto indicate moisture content of fabric treated by the wet fixation method. Operating speed was 50.yards per minute and fabric temperature at the dryer exit asmeasured by an optical pyrometer was 180 F.

A second sample of the cotton twill fabric was processed similarly except that drying was controlled to leave 20% to 24% residual moisture in thefabric as determined by a calibrated conductance type moisture monitor. Operating speed was 80 yards per minute and fabric temperature at the dryer exit at measured by an optical pyrometer Was 170 F. r i

Both fabrics were next compressively shrunk. The sample which had been dried to 4.5% to'5.5% residual moisture was sprayed with water as is usual practice; the fabric which had been dried to 20 to 24% residual moisture was not. All other conditions for compressive shrinkage were identical for both fabrics. Cylinder steam pressure was 50 p.s.i.g., operating speed was 75 yards per minute. For both samples fabric temperature as indicated by an optical pyrometer was near 210 F. at the nearest visible point as the fabric leftthe cylinder'and residual moisture content was in the range-from 3.5% to 4.0% with the conductance type moisture monitor.

Pieces of both sample fabrics were pressed for 15 seconds at a line pressure 120' p.s.i.g. steam on a pressing machine followed by dry curing 15 minutes at an oven setting of 325 F. The fabrics were tested (a) before treatment, (b) after compressive shrinkage and (c) after pressing and dry curing.

As may be seen, neither sample lost any significant strength through wet fixation and strength retention through a severe dry curing operation was excellent.

Nitrogen analyses by the Kjeldahl method were made on both sample fabrics as follows:

ssggvlashed according to Federal Specification COO-T-ltllb-Mcthod .It is readily evident that the bulk of the aminoplast applied was fixed in the wet fixation process without harm to the physical strength of the textile and that a comparatively minor portion was fixed in the dry curing step but it is also apparent that in combination a very high yield of total aminoplast fixed was obtained.

Both fabric sarnples were evaluated for fabric appearance ratings and crease retention ratings in the manner of Example XII after pressing and dry curing.

Sample 1 Sample 2 (4.55.5% (20-24% residual residual moisture) moisture) Appearance Ratings:

Low angle lighting. 5. 0 4. 9 Overhead lighting. 4. 4 4. 6 Crease Retention Rating 5.0 5.0 Warp Shrinkage in laundering, percent 1. 1 1.5

Norm-Appearance and crease retention ratings were considered excellent.

Other tests have compared the use of the catalyst components separately and in combination. Fabrics were impregnated with an aminoplast solution containing the acid component alone, the salt component alone or both components and then passed continuously from a padder containing the treating solution through a steaming chamher for 30-60 seconds, followed by washing. It was found that substantial wet fixation occurs only on the fabric which is treated with the solution containing both catalyst components, thus demonstrating their synergistic cooperation.

Because of the unique properties imparted by wet fixation, a broad range of effects can be achieved in various textiles. For'example, the tendency of textiles to shrink in laundering can be materially reduced or in some cases, eliminated by treating with an aminoplast by the present wet fixation process. The tendency of some textiles, notably polyamides, to shrink on heat setting can be materially reduced. Textiles may be colored by incorporation of suitable dyes and pigments in the resin Grab Breaking Indicated Strength Strength, lbs/in. Retention, percent 1 Warp Filling Warp Filling Fabric Sample 1-dried to 4.5% to 5.5%

residual moisture in wet fixation:

(b) Alter compressive shrinkage 159 98 96 (0) After press and dry cure... 134 77 81 79 Fabric Sample 2-dried to 20% to 24% residual moisture in wet fixation:

(b) After compressive shrinkage 164 97 100 100 (0) After press and dry cure 138 70 84 72 (a) Control-belore treatment 97 1 Strength retention expressed as a percentage of the control fabric strength to the nearest percentage point.

solution, these include even those textiles of synthetic fibers which are notably resistant to coloration. Alternatively, color may be developed in textiles as by use of ferric chloride in the aminoplast solution and an alkaline wash following fixation which precipitates an insoluble colored iron compound and provides color in situ. Cotton yarns may be given stretch properties by wet fixation of an aminoplast in and on a highly twisted yarn followed by backtwisting of the treated yarn. Towel border yarns, which due to fabric geometry apparently shrink to a much greater extent than do the ground and pile yarns, can be made resistant tolaundry shrinkage and inhibit the usual distortion of towels due to this shrinkage. Fabrics treated by this method, especially cellulosics, exhibit increased resilience and smooth drying properties without stiffness. Treated textiles are resistant to biological degradation. By incorporation of suitable agents in the impregnating media, the treated textile may be rendered water resistant, fire resistant, resistant to surface growths or resistant to actinic degradation.

It may be softened, stiffened or otherwise altered to enhance such properties as handle, seam slippage or sewability.

it will be appreciated that while various specific embodiments of the invention have been described, changes and modifications may be made in details of composition and mode of operation without departing from the scope of the invention as this is set out in the claims.

I claim:

1. In a process for the insolubiiization of aminoplast on a textile by wet fixation which comprises impregnating the textile with an aqueous liquid containing at least one aminoplast and a catalyst, and thereafter wet fixing the aminoplast by heating the textile to an elevated temperature while maintaining its moisture content above its normal moisture regain, until a substantial portion of the aminoplast is insolubilized, without substantial reduction of the dye receptivity of said textile to direct dyes;

the improvement which comprises using as said catalyst a synergistic mixture of at least one acidic substance having a dissociation constant greater than l and at least one salt which shows an acid reaction in aqueous medium and which is a salt of a member of the group consisting of ammonia, amines and metals with a member of the group consisting of organic and inorganic acids, thereby shortening the time required to fix the aminoplast to the textile,

the amount of said acidic substance being about 0.1

to 4.0% of said aqueous medium and aminoplast,

the amount of said salt being about 0.1 to 4.0% of said aqueous medium plus aminoplast, and the amount of said aminoplast applied to said textile being about 1% to of said textile on a dry weight basis.

2. A process for the application of aminoplasts to a textile as set forth in claim 1 in which the aminoplast is an at least partially water-soluble condensate of formaldehyde with melamine.

3. A process for the application of aminoplasts to a textile as set forth in claim 1 in which the aminoplast is an at least partially water-soluble condensate of formaldehyde with urea.

41. A process for the application of aminoplast to extiles as set forth in claim 1 in which the aminoplast is fixed to the moist textile by exposure to steam.

5. A process for the application of aminoplasts to a textile as set forth in claim 1 in which said acid is a member of the group consisting of formic, sulfamic, glycolic, oxalic, citric, diglycolic, tartaric, sulfurous and orthophosphoric acids.

6. A process for the application of aminoplasts to a textile as set forth in claim 1 in which said salt is a salt of a member of the group consisting of halogen, sulfuric, thiosulfuric, sulfurous, sulfamic, phosphoric, phosphorus, fiuoboric, nitric, nitrous, carboxylic and sulfonic acids.

7. A process for the application of aminoplasts to a textile as set forth in claim 1 in which the textile is cotton.

8. A process for the application of aminoplast to a textile, as set forth in claim 1 including the step of drying the textile, after the wet fixation of aminoplast, to below the normal moisture regain and heating the dry textile to an elevated temperature to effect curing.

9. A process as set forth in claim 8 in which the textile is dried and subjected to curing after said wet fixation but without intermediate washing, and said acidic substance is volatile so that it evaporates from the textile to limit injury to the textile during the curing step.

10. A process for the application of aminoplasts to a textile, as set forth in claim 8 in which said acid is formic acid and said salt is magnesium chloride.

11. A process as set forth in claim 1 in which said liquid contains an epoxidized triglyceride in an amount of 5 to by weight of said aminoplast, prior to wet fixation.

References Cited I UNITED STATES PATENTS 3,138,802 6/1964 Getchell 117-1394 X 2,093,651 9/1937 Widmer et a1. 117-1394 X 2,191,362 2/1940 Widmer et al. 117-1394 2,416,151 2/1947 Boulton 117-1394 2,709,141 5/1955 Burks 117-1394 2,763,574 9/1956 Rupcrti 117-1385 2,765,287 10/1956 Aycock 117-1394 X 2,859,136 1.1/1958 Marsh et al 117-1394 X 2,898,238 8/1959 Van Loo et al. 117-1394 2,899,263 8/1959 Neussle et a1. 117-143 X 3,212,928 10/1965 Hushebeck 117-1394 3,186,954 6/1965 Hushebeck 252-428 WILLIAM D. MARTIN, Primary Examiner.

T, G. DAVIS, Assistant Examiner.

James F. Cotton that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 8 line 30, "Meth I Methylolated melamine ylated melamine" should read Signed and sealed this 9th day of September 1969.

SEAL Attest:

Edward M. Fletcher, Jr. WILLIAM E. S HUYLER, JR- Atteating Officer Commissioner of Patents