US3536648A - Treatment of cellulosic textile materials to impart crease resistance thereto - Google Patents

Description

United States Patent Office 3,536,648 Patented Oct. 27, 197i) US. Cl. 260-29.4 5 Claims ABSTRACT OF THE DISCLOSURE Cellulosic textiles are treated with a curing catalyst and a crease proofing composition comprising the product of the interaction of a lower alkyl sulfonamide, urea, and formaldehyde. After a conventional heat-curing step, the impregnated textile has wash-wear and durable-press characteristics.

This invention relates to a novel composition adapted as a finishing agent for cellulosic textiles, to the method of treating cellulosic textile materials with said composition to impart crease resistance and wrinkle-recovery properties thereto, and to the crease-resistant textile produced thereby. More particularly, this invention is concerned with a creaseproofing agent for cellulosic textiles which comprises the product obtained by interacting a lower alkyl sulfonamide, urea, and formaldehyde, said product further characterized by having a free formaldehyde content within the range of about to about 50%, based on the total weight of said interactants. This invention is also particularly concerned with the application of said product to a cellulosic fabric and the curing of the treated fabric with heat to impart wash-wear and durable-press characteristics thereto.

As used herein, the terms cellulosic textile, cellulosic textile material, and cellulosic fabric refer to fabrics, whether woven or nonwoven, containing at least about of cellulose fiber, prepared from cotton, mercerized cotton, rayon, linen, flax, cellulose acetate and like cellulosic materials. These cellulosic materials may be employed in fabric as blends, i.e., in combination with other natural or synthetic non-cellulosic materials such as, for example, wool, nylon, acrylic fibers, polyester fibers and the like, and it is to be understood that these blends are subject to treatment according to this invention with good results.

In recent years there has been extensive experimentation and commercialization of methods for treating cellur losic fabrics with various creaseproofing substances and reaction products to impart so-called wash and wear properties to said fabrics. Said wash and wear properties include dimensional stability and crease or wrinkle resistance, wherein said resistance is retained by the fabric through repeated launderings. These finishing agents are generally compounds which contain at least two functional groups (such as a plurality ofCH OH groups) which react with and cause cross-linking between the molecular chains of the cellulose when the fabric is subjected to a catalyzed heat-cure treatment.

The cellulosic fabrics which are treated in accordance with this invention have, in addition to excellent wash and wear characteristics, a combination of other desirable properties. Firstly, there is a marked advantage noted in the processing of the fabrics. Despite the fact that there is free formaldehyde present in the reaction product embodied herein, there is relative freedom from obnoxious odors during the treating and curing of the fabrics as hereinafter described, in comparison to a greater level of irritating fumes evolved in these operations using some of the finishing agents heretofore available. The cellulosic fabrics which are treated according to this invention have good color, which advantage is exemplified by the relative initial whiteness of the treated fabrics and their resistance to yellowing after numerous launderings. The cellulosic fabrics treated according to this invention also have high resistance to acid hydrolysis and minimal loss of tensile strength subsequent to chlorine bleaching and scorching. It is very significant that these good properties can be attained with a smaller amount of textile finishing agent than is normally used for wash and wear fabrics.

PREPARATION OF THE CREASEPROOFING PRODUCT The creaseproofing agent of this invention comprises the product obtained by the interaction of a lower alkyl sulfonamide, urea, and formaldehyde in certain specific proportions. The lower alkyl sulfonamides are those having an alkyl group, branched or unbranched, of 1 to 4 carbon atoms, e.g., methanesulfonamide, ethanesulfonamide, n-propanesulfonamide, isopropanesulfonamide, nbutanesulfonamide, isobutanesulfonamide, etc. Methanesulfonamide is the preferred compound. The preferred urea reactant is unsubstituted urea; however, in lieu thereof, carbamyl urea (biuret) or mixtures of urea and biuret in any proportions may be used as the urea component in the interaction. The formaldehyde reactant is generally used as the commercially available 37% aqueous solution (Formalin), although the 55% solution of formaldehyde in methanol (Methyl Formcel) or the polymeric form of the compound known as paraformaldehyde, which is also commercially available, can be employed with good results. An aqueous solution of formaldehyde, which is preferred, may or may not contain the conventional inhibitor additives.

The creaseproofing agent embodied herein is obtained by interacting one mole of the alkylsulfonamide, from about 0.2 mole to about two moles of the urea and from about three to about ten moles of formaldehyde. The preferred range of formaldehyde is from about 4 to about 6 moles per mole of alkylsulfonamide. It is preferred to employ from about 0.5 to about 1.5 moles of urea per mole of alkylsulfonamide and, in general, it is most preferred that this ratio be essentially equimolar because it has been found that fabrics treated with product so pre pared have the best resistance to loss of strength caused by chlorine bleaching. The interaction of the three foregoing components to prepare the unique reaction product is most conveniently and desirably carried out in aqueous solution wherein the proportions of reactive ingredients and water are such that the final reaction product solution contains from about 30% to about 50%, based on the total weight of the solution, of product solids (i.e. total dissloved interactants). Other solvent systems for the reactants and the product can be used instead of water, for example, a lower alkanol, e.g., methanol, ethanol, isopropanol; dimethylsulfoxide, dioxane, alphatic ethers, aliphatic glycols, glycol ethers and the like.

It is desirable to carry out the reaction in alkaline media, preferably at a pH in the range of about 8 to 9. The pH is conveniently adjusted by adding small amounts of aqueous alkaline material to the reaction mixture prior to interaction of the components and, usually, alkaline material is added incrementally during the reaction period to maintain the alkaline conditions. Suitable alkaline additives include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like.

The interaction of the alkylsulfonamide, urea and formaldehyde to produce the product of this invention is favored by supplying heat to the reaction mixture, and therefore, the interaction is generally conducted for from about two to about twelve hours at temperatures within the range of about 50 C. to about C., preferably about 90 C. to 100 C. Although lower temperatures, e.g,. as low as about 25 C., may be used, the reaction period then required is so extended that lower-temperature interaction is not recommended. Moreover, the performance of the lower-temperature interacted product as a creaseproofing agent will not be as effective as that of the product prepared at the higher temperatures.

The interaction of the three components is sustained until there is a specific level of free formaldehyde present. By free formaldehyde is meant that formaldehyde which is not chemically bound to the other constituents of the reaction product. The percent of free formaldehyde in the aqueous reaction product is conveniently determined by the following procedure (however, other acceptable analytical methods may be used). A few drops of a 0.1% solution of mixed indicator (1 part methyl red and parts bromcresol green) is added to a weighed 1 ml. or 2 ml. sample of the aqueous reaction product. The sample is neutralized by gradually adding 0.5 N HCl or H 80, to the indicator end point. Then 20 ml. of hydroxylamine hydrochloride solution is added and the mixture is allowed to stand for minutes. It is then titrated to the mixed indicator end point with 0.5 N NaOH solution (the color will change from orange-pink to nearly colorless). A blank titration with the NaOH is run separately on a ml. sample of hydroxylamine hydrochloride solution. The free formaldehyde in the product is calculated as:

determine the chemical structure of this dried solid have also failed. Moreover, elemental analysis of the product to determine the sulfur, nitrogen and formaldehyde group content thereof does not permit a postulation of a specific chemical structure which could be assigned to the possible condensation products of the interactants.

APPLICATION OF THE PRODUCT TO CELLULOSIC TEXTILES As aforementioned, the reaction product solution, as synthesized, usually contains from about to about 50 weight percent of dissolved solids (interactants). The fabric treating solution is prepared by diluting the aforesaid solution to a solids concentration of from about 7 to about 15 weight percent. The pH of the treating solution is usually adjusted to the acid side, before the addition of the curing catalyst, preferably within a pH range of from about 3 to about 5. The pH control is accomplished by adding a small but sufficient amount of free acid to the solution. Suitable free acids include the inorganic acids such as hydrochloric, sulfuric and phosphoric acid and the organic acids such as formic, oxalic, acetic, citric acid, etc. A conventional acidic curing catalyst or accelerator is then added to the solution. Preferred catalysts are certain metallic salts, for example, magnesium chloride, zinc chloride, zinc nitrate, aluminum chloride, zinc fluoborate, magnesium fluoborate, magnesium hydrogen phosphate, and the like. The concentration of the catalyst normality of NaOH soln. (ml. titration sample-ml. titration blank) 300 Percent free OH O (based on interactions in sample on solvent-free basis) It has been found that to obtain good cellulosic fabric finishing the reaction product of this invention should contain from about 10% to about 50%, preferably from about 12% to about of free formaldehyde, based on the weight of total dissolved interactants in the treating solution. (Total dissolved interactants is defined as the total amount of alkylsulfonamide, urea, and formaldehyde charged to prepare the product.)

The interaction of the three component system may be carried out using either one-step or two-step techniques. In the one-step technique the total charge of all three components is initially mixed together in solution and the mixture is heated and the reaction sustained until the free formaldehyde level is within the above-mentioned range.

In the two-step technique, of which there are two embodiments as hereinafter discussed, an initial interaction is conducted between, for example, one mole of alkylsulfonamide, the urea, and about two moles of formaldehyde. This mixture is advantageously heated until the free formaldehyde content is from about 5% to about 15% based on interactants charged. Then to this product is added the additional formaldehyde to bring the overall molar ratio to from about 3 to about 10 moles, preferably about 4 to 6 moles, of formaldehyde per mole of alkylsulfonamide. The interaction of the reactants in this second step may be carried out at elevated temperatures, as above-described, or at ambient temperatures, i.e., about 20 C. to 40 C. Whether or not heat is applied, the product will have the free formaldehyde content within the range as previously set forth.

The manner in which the three components of the aforesaid reaction mixture interact to form the textilefinishin-g product of this invention is not known, nor has the chemical structure of the final product been ascertained. Attempts to analyze the products chemical structure while in aqueous solution have proved fruitless, and when evaporated to dryness, the product appears as a transparent, slightly tacky film. Attempts to analytically wt. sample (gms.) percent of interaetants in sample can range, depending on the particular catalyst chosen, from about 10% to about and is generally from about 20% to 30%, based on the weight of the dissolved solids in the treating solution. In lieu of the aforementioned metallic salts, other acidic curing catalysts well known in the art may be used, such as a free acid, for example, phosphoric, tartaric or oxalic acid, or an amine salt such as diethanolamine hydrochloride or the hydrochloride of 2-amino-2-methyl-l-propanol. Other conventional additives may be added to the padding bath to impart particular end use characteristics to the fabric, for example, optical brighteners, softeners, hand builders, water and oil repellents, and biocides and biostats.

The creaseproofing agent of this invention is applied to the cellulosic fabric by contacting the fabric with the described solution in the padding bath employing techniques well known in the art. This operation is usually performed at ambient temperatures, e.g. about 20 C. to about 40 C. The amount of pickup of the finishing agent on the fabric depends to some degree on the type of fabric; however, the amount of add-on of creaseproofing agent can be largely controlled by the concentration of the solution and the extent to which excess solution is squeezed out of the fabric by its subsequent passage through squeeze rolls. Generally, in accordance with this invention, the add-on of creaseproofing agent is on the order of about 2 to about 8 weight percent of solids based on the weight of dry fabric. The lower range of about 2 to 5 percent of solids add-on is regarded as a surprisingly small amount of a finishing agent for imparting good wash-wear properties to cellulosic textiles.

The outstanding stability of the padding bath solution of the product of this invention is another advantage of its use. It has been observed that the solutions are stable after standing for periods of from 3 days to as long as several weeks, without any apparent precipitation of solids. In contrast, some commercially available finishing agents will develop a haze or show a precipitate after only a few hours of standing in the padding bath.

Following the above-described application of the agent, the impregnated fabric is subjected to a drying and then curing operation to effect the chemical cross-linking reaction between the finishing agent and the cellulose in the textile which imparts the wrinkle-resistant properties to the fabric. The temperatures required to accomplish these steps vary and are influenced to some degree by the catalyst used and the mutual reactivity of the fiber-re actant-catalyst system. The times required to complete the drying and curing operations are inversely related to the temperatures used. The drying operation is generally carried out at from about 60 C. to about 120 C., preferably about 90 to about 105 C. for about to 30 minutes. The curing is effected at from about 140 C. to about 190 C. for from about 2 to 15 minutes. Care must be taken when the higher temperatures are used not to prolong the curing period so as to cause injury to the fabric. The curing is usually carried out at from about 160 C. to about 170 C. for from about 2 to 3 minutes.

The products of this invention are also useful in the production of press-free, crease-retained garments as described in U.S. Pat. No. 2,974,432 to W. K. Warnock and F. G. Hubener. The method therein-described involves a post-cured (i.e. deferred cure) technique whereina garment fabric is impregnated with a solution of the textile fiinishing material, the fabric is partially dried below the curing temperature, the fabric is cut to the garment dimensions and sewed and creased into the shape of the completed garment, and thereafter the garment is cured at elevated temperatures to impart the press-free properties thereto.

EXAMPLES The examples of the invention that follow are set forth to illustrate the invention and are not to be interpreted as limitative of the scope thereof.

Example 1 60 parts by weight (1 mole) of urea and 60 parts (2 moles) of formaldehyde (168 parts by weight of a 35.7% aqueous solution) are mixed together. NaOH solution is added to make the solution alkaline to a pH of about 8.5. 95 parts of methanesulfonamide (1 mole) is dissolved in 200 ml. water and this solution is added with stirring over a period of 30 minutes to the previous solution at about 30 C. The reaction is somewhat exothermic. The total mixture is heated to from 50 to 60 C. and held with stirring at these temperatures for six hours during which period 10% NaOH is added incrementally to maintain the alkaline conditions. The free formaldehyde concentration in the solution of the interactants is about 12%, based on dissolved solids.

Two more moles of formaldehyde are added to the foregoing parent reaction product. The solution is then refluxed (ca. 100 C.) for 4.5 hours while maintaining an alkaline pH. The free formaldehyde in the product is about 15% based on the reactant solids present.

Example 2 The procedure of Example 1 is repeated except that the additional formaldehyde charged to the parent reaction product is four moles per mol of methanesulfonamide initially charged. The free formaldehyde content of the aqueous product is about based on the reactant solids present.

Example 3 One mole of methanesulfonamide, one mole of urea, and four moles of formaldehyde are reacted in aqueous solution at 60 C. at a pH of 7.5 to 9 for six hours. The aqueous product contains about 40.2% of dissolved solids and about of free formaldehyde based on these solids.

Example 4 The procedure of Example 3 is repeated except that the reaction is carried out for two hours at about 100 C.

' e The free formaldehyde concentration in the aqueous product is about 25 based on dissolved product solids.

Example 5 The procedure of Example 1 is repeated except that the source of the formaldehyde is Methyl Formcel instead of Formalin. The final product contains about 27% of free formaldehyde.

The above-described solution of the creaseproofing agent are diluted with water to padding bath concentrations of about 10 to 20 weight percent and curing catalyst is added in an amount of from about 20 to 30 weight percent based on the solution solids. Standard x 80 print cotton fabric swatches are treated in the padding bath with these solutions and squeezed through rolls until there is about a Wet pick-up in weight by the fabric. The swatches are pin-framed to constant dimensions and dried for 10 minutes at 200 F. and cured for 3 minutes at 330 F. After curing, the speciments are given an afterwash which consists of washing and rinsing in an automatic Washer at -125 F. for a 3-5 minute normal cycle using such quantities of sodium carbonate, sodium perborate, and Nonic 218 (a nonionic detergent) to give solution concentrations of 0.01, 0.1 and 0.05 percent, respectively. The specimens are tumble dried in an automatic drier for 30 minutes at a wash and wear setting. The afterwash serves to remove uncombined, water-soluble, excess finishing materials. The cured and afterwashed fabrics, which have an average add-on of about 5% of solids, are evaluated according to the following test procedures.

WASH AND WEAR APPEARANCE Test Method AATCC 88A1964T, p. B99, 1965 Technical Manual of the American Association of Textile Chemists and Colorists.This test (low-angle viewing method) is designed to evaluate the retention of original smooth or surface textured appearance of Wash and wear fabrics after repeated home launderings. The test specimen is ordinarily given a relative evaluation rating of from 1 to 5 equivalent to its appearance; the higher the evaluation rating, the better the appearance. A rating of less than 4 is considered as unacceptable; a rating of 5 is considered good; extrapolated ratings greater than 5 are regarded as excellent wash-wear characteristics, such evaluations being superior to the best of the rating standards.

DAMAGE BY RETAINED CHLORINE An accelerated test to determine the potential damage caused by retained chlorine in the fabric. Test Method AATCC 114-1965T, p. B-106 (multiple sample method), 1965 Technical Manual of the American Association of Textile Chemists and Colorists.

BREAKING STRENGTH OF FABRICS Test Method ASTM D1682-59 T for measuring the breaking load and elongation of textile fabrics.

The results from the foregoing tests and evaluations of fabrics treated with the compositions of Examples 1-5 are summarized in Table I.

When Dacron polyester-cotton blend fabrics containing from about 20% to 50% cotton are treated with the compositions of this invention in the same manner as the fabrics of the foregoing examples, it is found that the wash-wear properties and strength retentions of the blended fabrics are somewhat better than those of the straight cotton. Alkane sulfonamides having 2 to 4 carbon atoms, and a mixture of urea and biuret, are substituted for the methanesulfonamide and urea constituents, respectively, without an appreciable decrease in the quanity of the product as a creaseproofing agent.

Comparisons of the performance of the composition of this invention are made with textile finishing products (referred to as Samples A-E) containing only two of '2 the three critical components; to similar products whose component molar proportions are not within the scope of the invention; and to commercial creaseproofing agents that are widely used in the industry.

SAMPLE A 120 grams of a 50% solution of the methylol derivative of glyoxal monourein having the formula H(]?Cll HO 011 (a commercial creaseproofing product sold under the trademark Permafresh 183), is diluted to 420 ml. with water and mixed with 180 ml. of a (weight/volume) solution of MgCl -6H O.

SAMPLE B 110 grams of a 45% solution of a urea-formaldehyde condensation product (a commercial product sold as Permafresh 424) is diluted with Water to a volume of 350 ml. and mixed with 150 ml. of a 10% solution of MgCl 6H O.

SAMPLE C This example is the partial condensation product of methanesulfonamide and formaldehyde prepared as follows: 50 grams of methanesulfonamide are mixed with 85 grams of 37% aqueous formaldehyde and diluted with water to a volume of 350 ml. The solution pH is raised to 8 with dilute NaOH. The solution stands for minutes and then acetic acid is added to lower the pH to 4.0.

150 m1. of a 10% solution of MgCl '6H O is mixed therei with. The free formaldehyde concentration of the pad bath solution is about 30% based on dissolved product solids.

SAMPLE D for 20 minutes, acetic acid is added to lower the pH to 4.0, and 150 ml. of 10% MgCl -6H O solution is added thereto.

SAMPLE E This example is the reaction product of methanesulfonamide, urea, and formaldehyde, but the proportions of said reactants are not within the boundaries of those required to give an acceptable product in accordance with this invention.

60 parts by weight (1 mole) of urea and 60 parts (2 moles) of formaldehyde (168 parts by weight of a 35.7% aqueous solution) are mixed together. 10% NaOH solution is added to make the solution alkaline to a pH of about 8.5. 95 parts of methanesulfonamide (1 mole) is dissolved in 200 ml. water and this solution is added With stirring over a period of 30 minutes to the previous solution at about 30 C. The mixture is stirred at 50 to 60 C. for six hours, 10% NaOH solution being added incrementally to maintain the alkaline conditions. The free formaldehyde concentration of the product solution is about 12% based on dissolved solids. A slight precipitate is noted after 24 hours in the padding bath prepared from a 20% solution of this product.

Samples AE are used to impregnate cotton swatches using the techniques described in the preceding examples. The specimens are similarly dried, cured, and evaluated. The data is summarized in Table I. The results show that the wash-water properties of the fabrics treated in accordance with this invention are significantly better than those of the compared samples.

*Strcngth retention ratings:

Poor. 35% loss in strength. Fair.2035% loss in strength. Good.520% loss in strength. Excellent. 5% loss in strength.

While there have been described herein what are considered at present to be preferred embodiments of the invention, it will obvious to those skilled in the art that many modifications and variations thereof may be made without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims. It is therefore understood that all modifications that come within the meaning and ranges of equivalencies of the claims are intended to be included therein.

I claim:

1. A composition comprising the product of the interaction in aqueous media at temperatures within the range of about C. to about C. for from about two to about twelve hours of one mole of methanesulfonamide, from about 0.2 mole to about two moles of a urea selected from the group consisting of urea and carbamylurea and mixtures thereof, and from about 3 to about 10 moles of formaldehyde, said product characterized by having a free formaldehyde content of from about 10% to about 50% by weight based on the combined weight of the methanesulfonarnide, urea and formaldehyde.

2. A composition according to claim 1 wherein there is interacted 1 mole of methanesulfonamide, from about 0.5 mole to about 1.5 moles of urea and from about 4 to about 6 moles of formaldehyde.

3. A composition comprising the product of the interaction in aqueous media at temperatures within the range of about 50 C. to about 100 C. for from about two to about twelve hours of 1 mole of methanesulfonamide, from about 0.5 mole to about 1.5 moles of urea, and from about 3 to about 10 moles of formaldehyde, said product characterized by having a free formaldehyde content of from about 10% to about 50% by weight based on the combined weight of the methanesulfonamide, urea and formaldehyde.

4. A composition in accordance with claim 3 wherein essentially one mole of urea and from about 4 to about 6 9 10 moles of formaldehyde are interacted with the methane- FOREIGN PATENTS sulfonamide, and the free formaldehyde content of the 470 519 8/1937 G tB product is from about 12% to about 40% by weight. 1 082885 6/1954 is n 5. A composition in accordance with claim 3 wherein the interaction of said components is in alkaline aqueous d 5 JOHN C. BLEUTGE, Primary Examiner me 1a. I

References Cited US. Cl. X.R. UNITED STATES PATENTS 8116.3; 117-139.4, 161; 26070, 849 2,160,196 5/1939 Bruson et a1. 260--70 2,374,648 5/ 1945 Burke et a1 260-70 10