US3434794A - Delayed cure of cellulosic articles - Google Patents

Description

United States Patent U.S. Cl. 8116.3 11 Claims ABSTRACT OF THE DISCLOSURE In manufacturing durable press garments or other articles from cellulosic textiles, the fabric is first impregnated with a resin finishing agent or crosslinking agent, a catalyst and a water miscible, non-reactive, high boiling swelling agent; the fabric is then cured in the presence of the high boiling swelling agent whereby the crosslinking agent is made insoluble by being chemically fixed in the fabric without however imparting any high degree of dry wrinkle recovery to the fabric and without interfering with subsequent manufacturing or shaping operations; the high boiling swelling agent is then removed from the fabric by washing or evaporation at an elevated temperature and the fabric is then manufactured into the desired shape and recured, whereby an article possessing excellent dry and wet wrinkle recovery is obtained.

This invention relates to textile articles such as permanent press garments. More particularly, it relates to an improvement in the well-known delayed cure process for making durably creased garments from cellulosic fabrics. It still more particularly relates to a process which comprises impregnating cellulosic fabrics with a finishing formulation comprising a resin finishing agent or crosslinking agent, a catalyst and a water-miscible nonreactive, high boiling swelling agent, curing the so impregnated fabric so as to render the crosslinking agent insoluble, but without imparting good dry wrinkle recovery to the fabric (i.e., without causing the fabric to resist subsequent shaping by tailoring, pressing, etc.), and finally re-curing the fabric after a garment of the desired size and shape has been tailored from it and after the high boiling swelling agent has been removed therefrom, whereby excellent dry wrinkle recovery is obtained.

There is an ever increasing demand for easy care, durable press garments, that is, for garments which have creases and pleats durably pressed in them, which remain substantially wrinkle-free in normal wear and which can be worn after washing without requiring much, if any, re-pressing. As is well-known, such durable press garments are obtained by applying to the textile material one or more of a wide variety of so-called crosslinking or resin finishing agents and curing the material after the desired garment has been fabricated therefrom. US. Patents 2,974,432 (Warnock et a1.) and 3,138,802 (Getchell) contain disclosures representative of such previously known processes. Such prior processes had the disadvantage, however, of requiring a carefully controlled, special drying or precuring step to avoid the premature imparting of a high degree of dry wrinkle recovery to the textile material prior to or during the fabrication of garments therefrom. Once imparted, such dry wrinkle recovery could cause objectionable puckering of subsequently made seams and make it difficult or impossible thereafter to form permanent creases, pleats, etc in a garment made from such a crosslinked fabric. Conversely, insuflicient insolublization of the finishing agent in the pre-curing step leaves the fabric excessively water sensitive during subsequent garment manufacture, may make the fabric unpleasant to work with because of offensive odors, etc.

It is an object of this invention to provide a process for the manufacture of permanent crease garments, especially cellulosic garments, in which the crosslinking agent can be readily affixed to the fabric without prematurely causing any undesirably high degree of dry wrinkle recovery and in which the desired permanent press properties are readily achieved by curing the finished, tailored garments.

Another object is to provide a process for making a flat finished cellulosic fabric that is substantially indefinitely stable in storage even at relatively high ambient temperatures, can be easily sewn and pressed without danger of discoloration or resin migration, and permitting garments tailored therefrom to be readily converted to the desired permanent shape-holding state by a delayed cure.

It has now been discovered that the foregoing objects can be achieved and durable press garments of excellent quality can be obtained by applying a conventional crosslinking or resin finishing agent to a cellulosic fabric in the presence of a high boiling, non-reactive, water-miscible liquid solvent or swelling agent (i.e., a liquid which boils above about C. and is non-reactive with cellulose and with the crosslinking agent but capable of maintaining cellulose in the swollen state), for example, a polyalkylcne glycol compound boiling between about 120 and C., drying the fabric to drive off water but not the swelling agent, and pre-curing it at a temperature lower than the boiling point of the swelling agent while the fibers are in the swollen state. In this state the fabric still has low dry wrinkle recovery and is therefore easy to sew, shape and press. However, after a finished garment has been tailored from the thus pre-cured fabric, the desired creases and pleats have been pressed into it and the swelling agent has been removed from it, the garment is cured in an otherwise conventional way to impart to it permanent dry wrinkle recovery.

The removal of the swelling agent from the fabric prior to the final curing can be accomplished in any conventional manner, e.g., by heating the fabric to cause evaporation of the swelling agent or by rinsing the fabric in water. In the case of removal by heating this may occur during the final pressing and curing. Removal by rinsing is most advantageously carried out at the mill following pre-cure. Additional catalyst is then reapplied by including it in the rinse water or by separate application following such rinsing, after which the" fabric is dried and finally made up into garments and after-cured to set the desired shape, creases, etc. Other methods of utilizing the invention can, however, be practiced. For example, it is possible to rinse out the swelling agent and catalyst following pre-cure and then reapply catalyst only'at the time of after cure by spraying the fabric or garment with an appropriate catalyst solution or by introduction of the catalyst into the vapor space of the curing oven or by other suitable means.

This invention is applicable for a wide variety of textile materials, especially cellulosic fiber materials containing cotton or viscose fibers, e.g., filaments, yarns, threads and, particularly, woven or non-woven fabrics. It is particularly effective with materials consisting of natural cellulose, such as cotton and linen, but is also applicable to regenerated cellulose such as viscose rayon and to fabric blends containing about 15 percent or more cellulosic fiber, e.g., blends of 35% cotton and correspondingly 65% polyester.

The invention is particularly useful in conjunction with the conventional crosslinking or resin finishing agents, known as creascproofing agents, such as the water soluble hardenable amine-formaldehyde condensates or aminoplasts. These include the well-known precondensates of formaldehyde and a melamine, a urea, or the precondensates of cyclic ethylene urea compounds. For instance, dihydroxy dimethylol ethylene urea, a wellknown commercial resin finishing agent, is suitable for use herein. However, the essence of the invention lies primarily in the conditioning of the textile material itself with a high boiling, non-reactive, water-miscible swelling agent while a crosslinking agent is affixed thereto prior to a delayed cure, rather than in the use of any particular crosslinking agent. Accordingly, the invention is similarly useful when other crosslinking or resin finishing agents, such as formaldehyde itself, ethyl or methyl carbamate-formaldehyde precondensates, triazones, triazines, phenol-formaldehyde precondensates, sulfones such as divinylsulfone, epoxy resins, etc. are used. A more complete disclosure of some of the more common types of crosslinking agents suitable for use in the present invention can be found, for instance, in U.S. Patent 3,138,802 (Getchell).

As is well-known, these agents are commonly applied to the textile material in the form of aqueous solutions by padding. For instance, the crosslinking agent, such as an aminoplast, is dissolved in water to form a padding solution containing from about 5 to 25 percent, e.g., percent, of the crosslinking agent. To facilitate the eventual curing of the agent in the material, an apropriate conventional catalyst, such as an acid-acting salt, e.g., zinc nitrate, magnesium chloride or ammonium chloride, or an acidic substance, e.g., formic acid, maleic anhydride, hydrochloric or sulphuric acid, etc., is also included in the solution or bath. The catalyst is commonly added to the bath in an amount equal to about 1 to 30 percent, e.g., about 5 to 10 percent, based on the weight of the crosslinking agent. An add-on of about 1 to percent by Weight, e.g., 3 to 12 percent of the agent (calculated on dry basis) is desirably built up on the fabric in such padding, the optimum amount of add-on of crosslinking agent depending somewhat on the particular kind of crosslinking agent used as is otherwise well-known in the art. Instead of applying the crosslinking agent by padding, other known techniques such as spraying can be employed.

In practicing the present invention, an aqueous padding bath as described above is used which, however, is modified by including therein a high boiling swelling agent in addition to the conventional components. More specifically, the present invention requires the use of a relatively high boiling compound which is miscible with water and capable of swelling the cellulosic fibers, i.e., capable of being occluded in the fibers after being carried into them by the water and after the water is removed. The solvent should be inert in the sense of not reacting substantially either with the cellulosic fibers to be treated or with the crosslinking agent or catalyst used in the padding bath. To permit easy drying of the textile material after it has been treated with padding solution, and also to give protection against unwanted premature crosslinking of the fabric, the solvent or swelling agent should have a boiling point higher than about 120 C. If its ultimate removal by heating is desired, it should not be too high boiling, e.g., it should have a boiling point lower than about 300 C., preferably lower than about 275 C. Particularly suitable are the various polyalkylene glycol ethers having a boiling point within the limits just indicated. However, when removal by rinsing is acceptable, higher boiling compounds having the required characteristics of relative nonvolatility, solubility in water, swelling action on cellulose, and chemical inertness in the fabric under precuring conditions can be used.

Thus, among the useable swelling agents are dimethyl ether of tetraethylene glycol (B.P. 260 C.), dimethyl ether of triethylene glycol (B.P. 220 C.), monomethyl ether of polyethylene glycol, average molecular weight 350 (BR higher than 400 C.), tetramethylene sulfone (B.P. 285 C.), n-methyl pyrollidone (B.P. 202 C.), dimethyl sulfoxide (B.P. 189 C.), as well as the lower dialkyl amides of C C alkanoic acids such as dimethyl formami'de and diethyl acetamide.

The swelling agent should be included in the aqueous padding bath in a concentration such as to result in a retention of from about 5% to of such swelling agent on the textile material after it has been dried to remove water. For instance, the swelling agent may be included in the padding bath in a concentration of between about 5% and 50% for 100% wet add-on.

Following padding in such a solvent-modified bath, the impregnated material is dried for a time and at a temperature such as to cause no substantial removal of the swelling agent, preferably below the boiling point of such agent, and still more preferably at a temperature not higher than about C. Thereafter, while the material remains swollen by means of the retained high boiling swelling agent, the crosslinking agent is fixed therein by pre-curing the material in a conventional manner, again at a temperature below the boiling point of the solvent. For instance, when a high boiling swelling agent such as tetraethylene glycol dimethyl ether is used, satisfactory fixation of an aminoplast such as dimethylol ethylene urea can be obtained by heating the dried material in an air oven for five to ten minutes at to C. If desired, the thus cured fabric can then be rinsed in water to remove the swelling agent and any residual soluble crosslinking agent, and dried. Before this latter drying step, unless a spray or a gas phase catalyst is used in the final cure, it is also often convenient to apply additional catalyst to the material, as for example by giving it a final rinse in water containing about 0.1 to 5% of an acidic catalyst such as zinc nitrate hexahydrate. Of course, if the pre-cured material is not washed, the swelling agent will be retained therein automatically.

The precured, dried fabric, preferably with the added latent catalyst present therein, is then shaped into the desired product. This may involve continuous pleating of the cloth for subsequent use in making curtains or ladies skirts, etc., or it may involve cutting and sewing the cloth to make desired garments therefrom and creasing and pleating the resulting garments by pressing. Finally, the tailored or otherwise shaped finished articles are re-cured, after removal of the high boiling swelling agent therefrom. As already indicated, such removal may be achieved by washing the precured material prior to tailoring. However, when solvent removal at such early stage is not practiced, the swelling agent must be removed by other means prior to the final cure. For instance, one may heat the finished garment at a temperature high enough to cause rapid evaporation, preferably above the boiling point of the swelling agent, to drive it off either in the initial stages of the final curing step itself, or in a separate operation preliminary thereto. For instance, when tetraethylene glycol dimethyl ether is used as the swelling agent, it can be removed from the fabric by heating garments tailored therefrom at C. for 20 minutes, whereby the swelling agent is driven off and the fabric becomes cured or wrinkle resistant.

As will be shown hereinafter, the initial curing in the presence of the swelling agent results in fixing the crosslinking agent in the fabric such that the crosslinking agent becomes insoluble and the thus cured fabric becomes insensitive to moisture. This initial cure or fixation step brings about a substantial increase in the wet wrinkle recovery of the fabric as compared to untreated fabric, but dry wrinkle recovery is not much better than that of the untreated fabric and remains far short of what is required of a commercially desirable permanent press fabric. Because of this low level of dry wrinkle recovery, the precured fabric can be readily cut and tailored into garments and creases can be introduced into such garments under essentially the same conditions and using essentially the same techniques as in the case of untreated fabrics, avoiding any puckering of seams that otherwise tends to be a troublesome problem when conventionally crosslinked fabrics are used. The introduction of creases into the fabrics precured in accordance with this invention requires neither excessive temperatures, nor high pressures, nor spraying with chemical solutions. Consequently, the present invention avoids the dangers of fabric spotting and discoloration, resin migration, and fiber embrittlement that are often encountered when tailoring conventionally crosslinked cotton fabrics. On the contrary, when garments are made from fabrics precured in accordance with the present invention, any faults in pressing the precured fabric can be corrected substantially as easily as in the case of an untreated fabric, due to its relatively poor dry wrinkle recovery. When, however, the high boiling swelling agent is removed from the precured fabric and the garment made from the latter is then recured in an otherwise conventional manner, a garment possessing excellent wrinkle recovery, both wet and dry, is obtained.

Various advantageous modifications of the procedure described above are of course possible. For instance, when a substantially odorless creaseproofing agent is used or when its odor is not objectionable during garment manufacture, such creaseproofing agent may be deposited on the fabric in the presence of the swelling agent and the resulting fabric used directly in garment manufacture after simple drying, without eflfecting any cure of the agent at this stage. Heretofore, in the delayed cure technique, deposition of a Creaseproofing agent on cotton and its retention in the reactive state in the fabric during subsequent manufacturing operations prior to final cure has been generally considered undesirable because of the danger of premature reaction and consequent loss of the interim handling properties which a delayed cure is supposed to provide. However, when the fabric is swollen by a high boiling solvent as taught in accordance with the present invention, a premature cure of a creaseproofing agent in such swollen fabric results in no serious loss of desired handling properties.

In accordance with another modification, instead of effecting the final curing of the present process in an air oven, it can be carried out in a steam chamber wherein steam of appropriate temperature, e.g., at 150 to 170 C., is used both to strip the swelling agent from the garment and to re-cure the fabric in the finished garment to give it the desired wet-and-dry recovery. When such a steam cure is practiced, it can be advantageous to incorporate a vapor phase catalyst, e.g., hydrochloric acid when an aminoplast isused as the crease-proofing agent, in the steam being fed to the steam chamber to assist and accelerate the final cure.

The present process can of course be modified in still other ways. For instance, in accordance with practices otherwise known in the art, the described process can be adapted to permit the introduction of conventional polymer-forming additives, softeners, etc. if these are desired to improve strength retention, wear life or other desirable properties of the fabric.

The following examples are illustrative of the process of the invention and of the results obtained thereby, but are not to be considered as limiting. On the contrary, it will be understood that persons skilled in the textile treating art will be able to make many variations and modifications of this invention, not specifically described herein, without departing from the spirit of this invention or from the scope of the appended claims. Unless otherwise indicated, all percentages and ratios of materials are expressed herein on a weight basis.

EXAMPLE 1 To illustrates the manner of use and effectiveness of the present invention an 80 x 80 unmercerized cotton print cloth was treated as described below. Dimethylol ethylene urea, purchased in the form of an aqueous solution containing 50% solids (Rhonite R-l) was used as the creaseproofing agent.

The novel padding solution compounded for use in the present invention had the following composition:

. Parts Creaseproofing agent (DMEU, 50%) 20 Catalyst, Zn(NO -'6H O 0.5 Swelling agent (dirnethyl ether of tetrathylene glycol, Ansul 181) 40 Water 40 For control purposes a conventional padding solution containing 20 parts of the same creaseproofing agent (DMEU, 50%) 0.5 part of zinc nitrate hexahydrate catalyst and parts of water was used.

In carrying out the treatment, samples of the print cloth were conventionally padded to 75% wet add-on (with either the novel solution or with the control solution); framed, dried, and cured for 10 minutes at 150 C.; rinsed to remove the swelling agent and any residual water soluble resin and catalyst; dried, conditioned at 55% relative humidity, and tested for wrinkle recovery, wet and dry. In testing wet wrinkle recovery, the samples were thoroughly wet with water and lightly blotted to remove any excess drops.

The results obtained are summarized in Table I-A wherein each tabulated value is an average of three readings:

TABLE IA.WRINKLE RECOVERY (DEGREES MONSANTO) As can be seen from the tabulated data, a total dry wrinkle recovery of 267 (136 warp and 131 fill) was obtained in the case of the conventionally treated samples after the initial cure. This wrinkle recovery value is too high to permit such fabric to accept a durable crease by ordinary pressing, making such a fabric relatively diflicult to tailor into garments. On the other hand, the pre-cured samples which has been treated with the solution that contained the glycol ether solvent in accordance with this invention had a dry recovery of only 227 warp and 112 fill), which value is representative of a state wherein the fabric accepts a crease quite readily upon ordinary ironing and is otherwise easy to tailor. At the same time, the pre-cured samples treated with the polyglycol ether-containing solution as well as the control samples had quite similar wet recovery values.

The precured samples were then repadded to 75% wet pick-up in a 0.5% aqueous solution of Zinc nitrate hexahydrate, dried for 20 minutes at 60 C. and given an aftercure at 150 C. for 10 minutes. After washing to remove residual catalyst and conditioning at 55% relative humidity the wrinkle recovery values shown in Table I-B were obtained.

Aftereure, 10 minutes at 150 C. Invention Control Dry warp 131 Dry fill 127 135 Total dry 257 266 Wet warp 126 129 125 127 Total Wet 251 256 As shown in Table I-B, the aftercure had no significant effect on the wrinkle recovery of the conventionally treated control samples. On the other hand, in the case of the samples which had been precured while swollen by the high boiling solvent in accordance with this invention the aftercure raised the initially low dry wrinkle recovery to 257. Thus, the samples treated in accordance with this invention, when aftercured, had substantially the same dry wrinkle recovery as the conventionally treated control. In this state the fabrics possessed good shape holding properties and a good resistance to wrinkling and good crease retention. The wet recovery of the aftercured samples was substantially the same after the initial cure, both in the case of the control samples and in the case of the samples treated in accordance with the invention.

EXAMPLE 2 The same basic procedure was used as in Example 1, but two different concentrations of the swelling agent and two different methods of removing the agent were used. The final curing conditions also were somewhat different. The results are reported in Table II.

TABLE II.WRINKLE RECOVERY (DEGREES MONSAN'IO) Test No Concentration of swelling agent ("Ansul 181") in bath, percent None Wrinkle. recovery Wet Dry Wet Dry Wet Dry Preoure at 100 C. for 10 minutes-.. 276 Postcure at 170 C. for 10 minutes,

after rinsing out swelling agent 298 290 300 Postcure at 170 C. for 10 minutes,

vaporizing swelling agent during cure 281 EXAMPLE 3 The same procedure was used as described in Example 1, but with the 40% dimethyl ether of tetraethylene glycol replaced by 40% tetramethylene sulfone. In this case the print cloth was padded to 100% wet add-on, precured at 100 C. for ten minutes, rinsed, conditioned, and tested for wrinkle recovery. The results are shown in Table III-A.

TABLE IIIA.WRINKLE RECOVERY (DEGREES MONSANTO) Initial cure 10 minutes at 100 C. Invention Control Total dry (warp and filling) 184 282 Total w et (warp and filling) 232 264 The precured samples were then repadded to 100% wet pick-up in a 0.5% aqueous solution of zinc nitrate hexahydrate, dried for 20 minutes at 60 C. and aftercured at 170 C. for 10 minutes, rinsed, conditioned, and tested for wrinkle recovery as shown in Table III-B.

TABLE III-B.-WRINKLE RECOVERY (DEGREES MONSANTO) After-cure, 10 minutes at 170 C. Invention Control Total dry (warp and filling) 298 298 Total wet (warp and filling) 286 282 It is to be understood that the foregoing detailed description is given merely by way of illustration and that variations and modifications of the described invention may be made without departing from its scope or spirit. The invention which is to be secured by US. Letters Patent is particularly pointed out in the appended claims.

What is claimed is: 1. A process for forming a shape-retentive textile article from a cellulosic fabric, which comprises:

applying to said fabric an aqueous solution containing (a) creaseproofing agent selected from the group consisting of formaldehyde, amine-formaldehyde precondensates, C -C alkyl carbamate-formalde- 1 hyde precondensates, triazones, triazines, phenolformaldehyde precondensates, sulfones and epoxy resins, (b) a curing catalyst for said creaseproofing agent and (c) an inert water-soluble oxygencontaining organic solvent which boils at above about C. and is capable of swelling cellulosic fibers, thereby incorporating at least 5% (on a water free basis) of said solvent in said fabric, drying and precuring the resulting fabric in the presence of said incorporated solvent at a temperature below the boiling point of said solvent,

manufacturing the desired textile article from the precured fabric and removing the swelling agent from the fabric, and

thereafter recuring the manufactured textile article to impart to it durable shape-holding properties.

2. A process according to claim 1 wherein solvent is removed from the precured fabric by volatilization at elevated temperature.

3. A process according to claim 1 wherein the solvent is removed from the precured fabric by rinsing with water.

4. A process according to claim 3 wherein the water used for rinsing the solvent from the fabric contains a curing catalyst for said recuring step.

5. A process for forming a shape-retentive garment from a cotton-containing fabric which comprises:

padding said fabric in an aqueous solution containing a curable amine-formaldehyde resin finishing agent, an acidic curing catalyst, and an inert water soluble oxygen-containing organic solvent which boils above about 120 and below about 300 C. is capable of swelling cotton fibers, thereby incor porating at least 5% of said solvent in said fabric calculated on a water-free basis,

drying and pre-curing the resulting fabric in the presence of said incorporated solvent at a temperature below the boiling point of said solvent,

washing said pre-cured fabric to remove therefrom residual soluble resin finishing agent, catalyst and solvent,

drying the washed fabric, cutting, sewing and pressing the fabric to form a tailored garment therefrom, and

re-curing the fabric after a garment has been completed and said solvent removed from the pre-cured fabric.

6. A process according to claim 5 wherein the solvent is a water soluble alkyl ether of a polyethylene glycol having a boiling point not in excess of 200 C.

7. A process according to claim 5 wherein the solvent is dimethyl ether of tetraethylene glycol.

8. A process according to claim 5 wherein the fabric is padded in an aqueous catalyst solution after it has been precured and washed.

9. A process according to claim 5 wherein the resin finishing agent is dimethylol ethylene urea and the catalyst is an acid-reacting inorganic zinc salt.

10. A process according to claim 5 wherein the catalyst is zinc nitrate.

11. A process according to claim 6 wherein the resin finishing agent is a C -C alkyl carbamate-formaldehyde condensate.

9 10 References Cited 'Porter et al.: Survey of Cotton Fiber Swelling in Vari- UNITED STATES PATENTS ous Liquids by Use of the Yarn Untwisting Test, Textile J 5 v a 2,974,432 3/1961 Warnock et a1. 3s-144 fi i f f v01 35 N0 2 February 1965 341384802 6/1964 Getchen 117 '139-4 XR Frick et al.: Modification of Cross-linking Effects in OTHER REFERENCES Cotton Fabrics by Swelling and Methylation, Journal of Angelil: Addition of Polyglycols to Cross-Linking Applied Polymer Sclence 2311-2318 (1965) Reagents for Cotton, masters thesis submitted to Lowell MAYER WEINBLATT, Primary Technological Institute, Mar. 24, 1960, see pp. 9-11.

Valko et a1: Textile Research Journal, vol. 32, pp. 10 331-337 (1962). 8116, 116.4, 120; 38144; 117139.4