Permanent press fabric resin and process therefor
United States Patent 11 1 Tracy et al.  
 [ Apr. 8, 1975 PERMANENT PRESS FABRIC RESIN AND PROCESS THEREFOR [75] Inventors: James E. Tracy, Bernardsville; Alan L. Peterkoisky, Newark; William Lindlaw, Westfield, all of NJ.  
 [73] Assignee: Celanese Corporation, New York,  
 [22] Filed: Apr. 25, 1973 [21] Appl. No.: 353,835  
  Related U.S. Application Data [62] Division of Ser. No. 53.028, July 7, 1970. abandoned.  
 [52] U.S. Cl. 1l7/139.4; 8/115.6; 8/115.7; 8/185; 8/186; 8/189; 117/143; 117/138.8 A; l17/138.8 F; 260/676 C [51] Int. Cl. D06m 13/38; D06m 15/58 [58] Field of Search 260/676 C, 67.7, 67.5; 117/1394; 8/185, 186  
 [56] References Cited UNITED STATES PATENTS 2.264.400 12/1941 Ott et a1 260/69 X 2.600780 6/1952 Kohler 8/185 X 3.329.519 7/1967 Mills 106/165 3.350.162 10/1967 Beck 8/185 X 3,386.940 6/1968 Tuites 8/185 X 3,539,286 11/1970 Bowers et al. 8/185 X 3.634.019 1/1972 Beaumont et a1 8/185 X 3.651.139 3/1972 Feinauer et a1 8/185 X 3,660,010 5/1972 Georgoudis et a1 8/185 X 3.771.950 11/1973 Schwartz et al. 8/185 X Primary Examiner-P. E. Willis, Jr. Attorney, Agem, 0r Firm-John A. Shedden; Kenneth A. Genoni; Thomas .1. Morgan [57] ABSTRACT Crotonylidenediurea is reacted between about 2.80 molar proportions and about 5.0 molar proportions of formaldehyde in aqueous medium to produce an aminoplast material. When applied to a fabric and cured. the aminoplast material forms a finish which imparts permanent press properties to the fabric.  
 2 Claims, N0 Drawings PERMANENT PRESS FABRIC RESIN AND PROCESS THEREFOR This is a division of Ser. No. 53,028, filed July 7. 1970, now abandoned.  
 BACKGROUND OF THE INVENTION This invention relates to a novel aminoplast material. The invention also relates to a process for producing the aminoplast material and to the method for using same to impart permanent press properties to fabrics, particularly cellulosic fabrics.  
  The term permanent press resins&#34; is understood to mean substances which, when applied to fabrics, impart to the fabrics properties of wrinkle resistance and durable press&#34;. The property of wrinkle resistance (which is synonomous with terms such as wrinkle-recovery, crease resistance,&#34; and the like) refers to the ability ofa fabric to resist wrinkling and to retain smoothness of shape and hand upon repeated wear and laundering. The property of durable press (which is synonomous with terms such as crease retention and the like) is understood to mean the ability of a treated fabric to drip-dry without loss of crease and to be worn without ironing, although fastidious wearers may insist on some touch-up&#34; ironing.  
  Various methods are known for imparting permanent-press properties to fabrics, particularly fabrics derived from cellulosic materials (e.g., regenerated cellulosic materials such as rayon and natural&#34; cellulosic materials such as cotton and cotton-polyester blends and the like). However, these prior art techniques suffer a number of disadvantages. Thus, for example, some processes heretofore employed to impart permanent-press properties to cellulosic fabrics result in finished products which retain an undesirable amount of chlorine. thereby causing damage to the fabrics. Moreover, it is generally recognized in the fabric finishing art that fabrics treated with heretofore known permanent press resins tend to be discolored and will experience further substantial and unsightly discoloration on scorching. Accordingly, the overall performance of heretofore known textile finishing agents leaves much to be desired. Thus, for permanent press white cottons, textile finishing agents should impart to the substrate fabric a finish which does not suffer nor otherwise cause acid damage to the substrate fabric as a result of hypochlorite bleaching, and should be durable to alkaline conditions normally encountered in laundering.  
 Therefore. it is an object of the present invention to provide a novel composition ofmatter which, when applied to a fabric, particularly a cellulosic fabric, imparts a colorless, permanent press finish thereto, said finish having improved resistance to acid and alkaline degradation normally encountered under ordinary bleaching and laundering conditions, which does not retain an undesirable amount of chlorine, and which does not cause substantial and unsightly discoloration of the fabric upon scorching.  
  Another object is to provide a process for producing a novel composition of matter which, when applied to a fabric, and particularly to a cellulosic fabric, imparts a colorless, permanent press finish thereto, said finish having improved resistance to acid and alkaline degra dation normally encountered under ordinary bleaching and laundering conditions, which does not retain an undesirable amount of chlorine, and which does not cause substantial and unsightly discoloration of the fabric upon scorching.  
  Another object is to provide a permanent press fabric finish having improved resistance to acid and alkaline degradation normally encountered under ordinary bleaching and laundering conditions, which does not retain an undesirable amount of chlorine, and which does not cause substantial and. unsightly discoloration of the fabric upon scorching.  
  Yet another object is to provide a process for applying to a fabric, and particularly to a cellulosic fabric, a permanent press finish, said finish having improved resistance to acid and alkaline degradation normally encountered under ordinary bleaching and laundering conditions, which does not retain and undesirable amount of chlorine, and which does not cause substantial and unsightly discoloration of the fabric upon scorching.  
  These and other objects of the present invention, as well as a fuller understanding of the advantages thereof can be had by reference to the following detailed description and claims.  
 SUMMARY OF THE INVENTION The above objects are achieved according to the present invention by the discovery of a novel composition of matter which, when applied to a fabric, particularly a cellulosic textile fabric, forms a coating or fabric finish which imparts excellent permanent press properties to the treated fabric. More particularly, this novel composition of matter is produced according to the present invention by contacting crotonylidenediurea which has the following formula:  
 H-N N-II l l jl with a specific amount of formaldehyde under carefully controlled reaction conditions. The product resulting from the reaction of crotonylidenediurea with formaldehyde according to the present invention is an aminoplast material comprising trimethylol crotonylidenediarea which has the following structural formula:  
 HOH2CN N-CH2OH O Hue omort A H H The material crotonylidenediurea can be made by reacting urea with acetaldehyde in an acidic hydroxylic medium, for example, as described in US. letters Pat. No. 3,190,741.  
  It is a feature of the present invention that the crotonylidenediurea starting material must be employed in a high state of purity, i.e., in crystalline form. In addition, it is especially important that the crotonylidenediurea be free of color bodies or substances which give rise to color bodies which become noticeable when the aminoplast is applied to a fabric, or during the lifetime of the treated fabric. In this connection, it has been discovered that the novel aminoplast material of the present invention is not produced when formaldehyde is contacted in situ with the crude reaction product of urea and crotonaldehyde as described in US. letters Pat. No. 3,329,519. Since crotonylidenediurea has been postulated in the literature, e.g., 37 Kunststoffe 165 (1947), as a product of the reaction between said urea and crotonaldehyde. the formation of the herein novel aminoplast material according to the present invention is a suprising and unexpected result.  
  Crotonylidenediurea suitable for use in the present invention is conveniently and preferably prepared according. to the following procedure, it being understood, of course, that other methods of synthesis can be used without departing from the spirit of the invention: Thus, 270 parts by weight of urea are added to a mixtureof 99 parts of acetaldehyde and 600 parts of distilled water in a suitable-conventional reaction vessel. The resultant solution is heated to a temperature of about 60C. Thirty parts of phosphoric acid (catalyst) are then added and the temperature is thereafter maintained at between about 60C. and about 70C for 1 hour. The reaction mixture is subsequently cooled to ambient temperature whereupon the crotonylidenediurea crystallizes. This product is separated from the supernatant liquid by filtration, washed with water, and dried in vacuo. The yield of white, solid, crotonylidenediurea (135.3 grams) is 66.9 percent of the theoretical based on the weight of urea. Elemental analysis of the product corresponds to the formula C,;H ,O N and the infrared spectrum thereof (nujol mull) is identical to that reported in the literature (cf. Japanese letters Pat. No. 492,348).  
  The reaction of crotonylidenediurea with formaldehyde to produce the novel aminoplastic material of the present invention is accomplished by contacting crotonylidenediurea with between about 2.80 and about 5.0 molar equivalents of formaldehyde in a hydroxylic medium. The hydroxylic solvent used should be capable of dissolving the reactants and also capable of being separated from the aminoplast material formed in the reaction by evaporative means. The preferred solvent is water. The concentrations of the reactants in the hydroxylic medium are not critical provided the dissolution of the reactants can take place. However. in applying the novel aminoplast material of the present invention to a fabric, it is advantageous to do so by simply immersing the substrate fabric into an aqueous solution of the aminoplast material, said solution being simply the aqueous reaction mixture in which the aminoplast material is formed, modified, of course, by the addition thereto of suitable curing catalyst of the type described hereinbelow. Accordingly, the concentrationsof reactants are preferably those which result in a concentration of aminoplast material which in turn determines the amount of resin pickup&#34; experienced by the fabric within the pad bath.  
  In an especially preferred mode of the present process the reaction is conducted in formalin, i.e., an aqueous solution of formaldehyde in which the concentration of the latter is between about 35 and about 40 percent. The amount of formaldehyde used can range between 2.80 and 5.0 molar proportions, and preferably between about 2.90 and about 3.05 molar proportions per molar proportion of crotonylidenediurea. The use of formaldehyde in amounts such that the molar ratio of formaldehyde to crotonylidenediurea is less than about 2.80:1 is undesirable because the trimethylol crotonylidenediurea would in such case be contaminated with substantial quantities of materials which tend to inhibit the performance of the aminoplast material as a permanent press resin. On the other hand, the use of formaldehyde: crotonylidenediurea molar ratios in excess of about 3.05:1 is less desirable, and the use of ratios in excess of about 5:1 is paticularly undesirable. The reason for this is believed to be that when a quantity of formaldehyde is present which substantially exceeds that which is stoichiometrically required for the formation of the trimethylol crotonylidenediurea, such excess tends to contaminate the aminoplast material with formaldehyde and with by-products therefrom during the course of evaporative distillation to remove the excess formaldehyde or during curing operations, these being processes which generally require elevated temperatures.  
  The reaction between crotonylidenediurea and formaldehyde according to the present invention is catalysed by acid or base. In aqueous media, the reaction can be conducted at a pH of less than or greater than 7. Desirably, the reaction is conducted under basic conditions. Preferably, the reaction is conducted at a pH of greater than about 8 and less than about 12, with a pH of between about 9 and about 10 being especially preferred.  
  The temperature and pressure at which the crotonylidenediurea and formaldehyde are reacted are not critical. Desirably, the reaction is conducted at an elevated temperature and atmospheric pressure, with a temperature corresponding to the atmospheric reflux temperature of the reaction menstruum being preferred. The time required for completion of the reaction is generally less than 1 hour. The exact time required depends upon the reaction temperature, concentration of the catalyst (i.e., the pH) and reactants. A conventional titration method for determing when a particular reaction system has reached equilibrium is referred to in connection with Example 1 hereinbelow.  
  The aminoplast material of the present invention is water-soluble, and is conveniently applied to a fabric as an aqueous solution. Accordingly, the reaction mixture, and preferably the aqueous reaction mixture, in which the aminoplast material is formed, can be used directly as the pad bath solution into which the fabric to be treated is immersed or dip treated. The fabric is then wrung out by conventional means (e.g., be-  
 tween a pair of rollers) to remove excess liquid, and.  
 subsequently cured.  
  The curing of the aminoplast resin on the substrate. fabric is performed according to the present invention under conditions of elevated temperature and acid catalysis. A temperature of between about 50C and about 200C is generally effective in curing the instant aminoplast material to form a permanent press finish on the treated fabric. Preferably, a curing temperature of between about C and about 200C is employed. The time required for curing depends upon the curing temperature and catalyst concentration. Desirably, the curing step is completed between 1 and about 30 minutes and preferably between about 3 and about 15 minutes. Substances suitable for catalysing the curing process include any conventional acidic catalyst or catalysts heretofore known to be useful in catalysing the curing of conventional aminoplast materials. Such acid catalysts are employed in conventional amounts e.g., at a concentration of between about 1 percent and about 50 percent by weight based on the weight of aminoplast materials and includes as a general category those water-soluble inorganic salts which behave as so-called Bronsted acids. e.g., ammonium chloride, magnesium chloride, zinc nitrate, and the like.  
  According to a preferred mode of carrying out the fabric treatment process of the present invention, the aqueous reaction mixture containing the novel aminoplast material dissolved therein is cooled to ambient temperature, brought to a pH of about 7.0, and filtered to remove any insolubles which may or may not be present. Then, a conventional amount of an acidic curing catalyst is dissolved in the filtrate, and the fabric to be treated is immersed therein. The amount of resin picked-up&#34; by the substrate fabric is determined in large measure by the concentration of the aminoplast material in the aqueous pad-bath solution. Generally, the concentration of the aminoplast-material in the pad bath solution (which can be determined gravimetrically) ranges between about 2 percent or less and about 65 percent by weight or more for cellulosic fabrics. Preferably. a pad-bath concentration of between about 5 percent and about 45 percent is used, with a concen tration of between percent and about percent being especially preferred. The particular desired concentration of aminoplast material in any given instance is conveniently achieved by appropriate adjustment of the concentrations of reactants (i.e., fofmaldehyde and crotonylidenediurea) or by the judicious addition of water to an initially relatively highly concentrated solution of aminoplast material.  
  After saturating the fabric with the pad-bath solution, the treated fabric is withdrawn from the bath, wrung between rollers made of an inert material (e.g., metal, ceramic, and the like), preferably stainless steel rollers, and simultaneously or subsequently heat cured at a temperature within the aforementioned range. The heat curing step can. if desired, be conducted by contacting the fabric with heated metal rollers, preferably heated stainless steel rollers, which rollers can be-the same or different than the rollers used in the wringing operation.  
  Fabrics, particularly cellulosic fabrics, treated with the aminoplast material according to the present invention exhibit excellent permanent press properties. In addition, such fabrics are free of undesirable amounts of chlorine, and white fabrics so treated are not discolored nor does appreciable discoloration occur upon aging or scorching.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples are presented for the purpose of illustrating (but not limiting) the present invention. In the examples, parts and percentages are by weight unless otherwise indicated.  
 EXAMPLE 1 This example illustrates the novel aminoplast of the present invention and the process for producing same.  
  To a suitable reaction vessel equipped with conventional agitation means are charged 239 grams (2.94 moles) of 37 percent formalin (uninhibited&#34;) and 15 grams of a 10 percent aqueous solution of sodium carcrotonylidenediurea. The reaction mixture, which has a pH of between about 9 and about 9.5, is heated to reflux temperature over the course of about 20 minutes and maintained at the reflux temperature for about 5 minutes. The reaction mixture is then cooled to ambient temperature, the pH is adjusted to 7.0, and the reaction mixture filtered to remove insolubles. The clear filtrate contains 2.8 percent free formaldehyde as determined by the sodium sulfate method&#34; described in Walker, Formaldehyde, 3d ed.., p 486 (Reinhold, NY. 1964). The concentration of aminoplast material in the aqueous filtrate is 60 percent by weight as determined gravimetrically, i.e., by evaporating an aliquot sample of the solution at C. for 6 hours and weighing the residue.  
 EXAMPLE 2 This example illustrates a variant of the procedure used in Example 1 to produce the trimethylol crotonylidenediurea aminoplast material of the present invention.  
  To a suitable reaction vessel equipped with conventional agitation means are chared 4,055 grams (50 moles) of 37 percent formalin (uninhibited&#34;) and grams of a 10 percent aqueous solution of sodium carbonate. To the resulting mixture are added, with agitation, 1720 grams (10 moles) of crystalline crotonylidenediurea. The reaction mixture is then heated at reflux temperature for 5 minutes and cooled to ambient temperature. An additional charge of 150 grams of 10 percent aqueous sodium carbonate and 1204 grams (7 moles) of crotonylidenediurea are added and the reaction mixture is again heated to reflux temperature and maintained thereat for 30 min utes. Upon recooling the reaction mixture to ambient temperature, neutralizing the pH, and filtering, a solution of trimethylol crotonylidenediurea is obtained which contains 2.7 percent unreacted formaldehyde.  
 EXAMPLE 3 This example illustrates the process of treating a cellulosic fabric (100 percent cotton) with the trimethylol crotonylidenediurea aminoplast material of the present invention.  
  The pad baths used in this evaluation were prepared at two different concentrations, namely, 10 percent by weight permanent press resin and 25 percent by weight permanent press resin. Twenty percent Zinc nitrate (curing catalyst) based on the weight of aminoplast material was also included in each pad bath.  
  Four samples of light-weight cotton fabric were treated with each pad bath solution for a total of 8 samples. Four addition samples served as controls.&#34; The odd-numbered samples were cured for three minutes at C. and the even numbered samples were cured for 6 minutes at 165C. Of the two odd numbered samples that were treated with each solution, one sample was laundred (in Tide) one time and the other sample was laundered 25 times. The fabric samples were rated for hand, appearance, tear strength and wash-wear appearance. The results are summarized in Table l.  
 Table I Permanent Press Treatment of I Percent Lightweight Cotton Fabric Wash-Wear Tear Strength Appearance Hand (2) Appearance After Sample Number of After After After After After Laundering (3) No. Treatment Luandcrings Curt Laundering Cure Laundering Laundering (2) Warp I No Treatment I OK no change I l l 4.4 4.2 2 do. 1 do. do. I l l 3.0 2.2 3 do. 25 do. do. I l l 2.6 3.6 4 do. 25 do. do. I I 2 3.5 3.0  
 5 &#39;71 Pad-Bath 1 OK. do. I l 4 3.7 3.5 6 do. I V.Sl.Ycllo\\ do. 1 1 4-5 3.5 3.3 7 do. O.K. do. I I 4-5 3.7 2.6 8 do. 25 V.SI.Yellow do. I I 5 3.6  
  9 2571 Pad-Bath l O.K. do. 1-2 l 5 2.9 10 do. I SLYeIlow do. I-2 I 5 3.3 I I do. 25 O.K. do. l-2 I 5 2.6 I2 do. 25 SLYellow do. 1-2 I 5 2.6  
 (I A rating of l is \ery wrinkled and a rating of 5 is wrinkle-free (excellent durable press). The test procedure used is described in AAATC No. l24-I967 (2) A rating of l corresponds to an acceptably &#34;soft feel: a rating of 5 corresponds to an undesirably stiff feel.  
 (3) Measurements of tear strength (in pounds) are made on an Elmendorf Tear Tester.  
 EXAMPLE 4 The aqueous pad bath used in this example has the We claim: 1. A process for imparting a permanent press finish to a fabric comprising:  
 a. contacting the fabric with an aqueous solution of an aminoplast material comprising a compound having the following structural formula:  
 ollowrng composition: -HOH2C-N N-CHzOH CHQOH o t... Aminoplast 20 percent H H 5 b. conducting step (a) 1n the presence of an acid curzinc nitrate (curing catalyst) 4 percent (i.e.. 20 mg catalyst; and  
 Psrcem a the c. subsequently exposing the fabric treated in step percent of ammoplast I 0 present) (b) to a temperature of at least about 50 C. to cure the aminoplast material. Emersoft 7777 (softener) 3 percent 2. A process according to claim 1 wherein:  
  the fabric is a cellulosic fabric; Trim&#34; X4000 05 percent the concentration of the aminoplast material in the aqueous solution used 1n step (a) IS between about d d 2 percent and about 65 percent by weight; Three 5amples (Nos; 7 9) 0ff1bnc are treats decor the acid curing catalyst used in step (b) is selected mg to the present mvemlon l three. sampkis T from the group consisting of inorganic salts which 1-3) are used as a control. After immersion, t e behave as Bronsted acids; and samples are wrung and cured for five minutes at 170 C. the temperature employed in Step (c) is between Test results for the treated fabric are summarized 1n about 100C and about 200C. Table TABLE II Permanent Press Treatment of 50/50 Polyester/Cotton Poplin Blend Tear Strength Hand Appearance After Laundering Sample Number of After After After After After Warp Fill No. Treatment Launderings Cure 1 Wash 25 Washes Cure Laundering 1 No Treatment 25 2 l l O.K. O.K. 7.5 6.5 2 do. I 2 l do. do. 8.6 6.6 3 do. I 2 I do.  
 7 20&#39;71 Pad-Bath 25 3-4 2-3 2 do. O.K. 5.6 5.4 8 do. 1 3-2- do do. 6.8 5.3  
  2-3 9 do. 1 3-4 2-3 do.