Process for improving abrasion resistance of resilient fabrics and the product produced
United States Patent Vail et al.  
 [ Apr. 15, 1975 PROCESS FOR IMPROVING ABRASION RESISTANCE OF RESILIENT FABRICS AND THE PRODUCT PRODUCED Inventors: Sidney L. Vail, New Orleans, La.;  
 Alvin H. Young, New York, N.Y.; Gerald B. Verburg, Metairie, La.  
 The United States of America as represented by the Secretary of Agriculture, Washington, DC.  
 Filed: Oct. 6, 1972 Appl. No.: 295,778  
 Related US. Application Data Continuation-in-part of Ser. No. 772,386, Oct. 31, 1968, abandoned.  
 Assignee:  
 US. Cl. 8/183; 8/1 15.6; 8/186;  
  8/187 Int. CL... D06m l/00 Field of Search 8/1l5.6, 116.4, 181, 183,  
 [56] References Cited UNITED STATES PATENTS 3,434,794 3/1969 Tovey 8/116.4 X 3,451,763 6/1969 Weiss 8/1 16.4 X 3,658,458 4/1972 Gale 8/1 16.4 X  
 Primary Examiner -Stephen J. Lecher&#39;t, Jr. Attorney, Agent, or FirmM. Howard Silverstein; Max D. Hensley [57] ABSTRACT 4 Claims, No Drawings PROCESS FOR IMPROVING ABRASION RESISTANCE OF RESILIENT FABRICS AND THE PRODUCT PRODUCED A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government. with the power to grant sublicenses for such purposes. is hereby granted to the Government of the United States of America.  
  This is a continuation-in-part of application Ser. No. 772,386, now abandoned, filed Oct. 31, 1968.  
  The search for improved methods of treatment of cotton to produce commercially acceptable durablepress fabrics has resulted in several new processes. One of the more promising, a wet-fixation process. was first introduced by the National Cotton Council of America in 1966 [Textile Research Journal 37. 70 (1967)]. It involves the fixation of a polymer-former and a crosslinker to cotton fabric under aqueous, acidic conditions. In this laboratory process the fabric, padded with the solution of reagents at a pH of 2, is heated in a sealed container (plastic bag) to achieve fixation of the resins. The first or fixation step appears to be the more important phase of the process. Part of the resin content is firmly fixed in the cotton fibers and the fabric, after rinsing and application of catalysts and softener, can be used in the production of durable-press garments.  
  A major advantage of the process is that an essentially odorless, sensitized fabric is produced for use in the manufacture of durable-press garments. in addition, the cured fabrics are smooth drying with less impairment of tearing strength and Stoll flex abrasion than conventionally treated fabrics with equivalent smooth-drying properties.  
  The purpose of the present study is to improve the process in a practical sense. Laboratory procedures have been studied which are potentially more adaptable to commercial finishing. More specifically, this application deals mainly with a major process variation of the treatment, i.e., fixation of the resins in a semi-dry state in the presence of an inert additive. The fixation step, as described in this invention, may be carried out using conventional equipment used for drying textiles. The fixation can be carried out rapidly in an open state and no bag or container is required. Further, the amount of resin required on the fabric is much lower than conventional treatments, i.e., resins add-ons in this invention are from about 3 to 6 percent.  
  These and some of the other advantages of this process are seen in the following general description.  
  1 Cellulosic fabric is padded through a resin bath at a pH of about 2 which contains 10-20 percent of a methylated methylolmelamine (hereafter abbreviated MMM), -20 percent of another cross-linking agent, and -20 percent of an inert additive.  
  2 In the fixation step, the wet fabric is partially dried in an oven to remove part of the water present. Time and temperature for this step will depend upon the weight of the fabric used. Satisfactory conditions for a 3.0-3.5 02. printcloth are three minutes at 58C.  
  These conditions must be such that the resin add-on (calculated after step 3) is less than 8 percent. Also these conditions must be such that a high degree of polymerization of the reactants is not achieved. i.e., the materials fixed in the fabric must be highly capable of further crosslinking of the cellulose. Conditions which favor the polymerization reaction at this point produce a boardy fabricwhich cannot be used to produce a durable press fabric with acceptable strength and resistance to abrasion;  
  3 The partially dried fabric is neutralized, washed, and dried.  
  4 Curing catalyst and softeners (or other auxiliaries) are added to the fabric in a conventional manner.  
  5 Fabric is dried and treated as a sensitized fabric for durable press.  
  Many MMM resins are satisfactory for this process. However, those resins which contain from at least one to six methoxymethyl groups and one or two methylol groups (where possible) appear to be preferred. The methylation of the methylolmelamines should be carried out under conditions which keep polymerization at a minimum.  
  The second crosslinking agent can be selected from a number of agents but N,N-dimethylol carbamates or N,N&#39;-dimethylol dihydroxyethyleneurea (DMDHEU) generally are preferred.  
  Inert additives were selected from a group of materials which were expected to keep the cellulosic fiber (cotton, for example) in a swollen state. Such materials include tetraethylene glycol dimethyl ether (abbreviated TDM). Zinc nitrate or magnesium chloride has been found to be satisfactory as curing catalyst. Emulsified polyethylene was used as softener when a softener was desired.  
  Valko, et al. [Textile Research Journal 37, 253 1967)] have recently discussed the use of nonreactive and co-reactive additives for the purpose of obtaining an improved abrasion resistance-wrinkle-recovery angle relationship. Our work with the same twocomponent system (melamine plus cross-linker) was performed under different conditions than those used by Valko and has produced different effects. A highly wrinkle-resistant, abrasion-resistant cotton fabric can be obtained from the fixation of a two-component system which has a swelling agent present. The aqueous resin mixture-TDM solution at pH of about 2, is padded onto cotton fabric, and the wet fabric is heated in an oven until it is barely moist to the hand. From this point on, it is treated in the same manner as any other wetfixed fabric. Our process is different from Valkos double cure of two-component systems in at least two important respects: (1) A higher percentage of reactants are required, and (2) the fixation conditions or first cures&#34; are much milder, e.g., 58C. for 3-4 minutes rather than C. for 15 minutes. For simplicity the process of this invention will be called moist fixation.  
  Table I compares various fixation conditions and their effect upon the physical properties of the fixed and the cured fabric.  
 Fixation for 15 minutes at 82 provides the equivalent of a harsh, conventional pad-dry-cure finish. Abrasion resistance of the cured fabric is very poor. The milder fixation conditions of 3 minutes at 58 provides a sensiin the art. In the examples, all parts and percentages are by weight unless noted otherwise. The fabrics were tested by the following methods: Wrinkle recovery an,  
 gle, Monsanto method, American Society for Testing for the production of an acceptable finished textile. Many variations or additions within these procedures can be made, as will be readily apparent to those skilled tized fabric which can be used to produce an abrasion 5 Materials (ASTM) test D l295-6OT; tearing strength, and wrinkle-resistant fabric with only a moderate add- Elmendorf method, ASTM test D 1424-63, Stoll flex on of resin. The moderate wrinkle resistance can be imabrasion resistance, ASTM test D l l75-64T; Both proved through the use of more reagents and/or use of abrasion and tearing strength are reported as percent. softeners as shown in Table II. of theoriginal, untreated fabric which had been:laun- TABLE ll Procedures Wrinkle and Paid Recovery Bath Abrasion Angle Tearing Concentrations Fixation Resistance (W+F) Strength as in: Conditions (/1 of orig.) (deg) (/1 of orig.)  
 Example 3 3 min/58 H4 285 98 Example 4 (1 min/50 72 295 82 The effects of the use of polyurethanes (an elastof f Once- Thls noted m the moles as fl mer) in the various treatments are noted in Table III. EXAMPLE 1 The polyurethane was obtained from Wyandotte Chemicals Corporation and was identified as E-406A. 25 An 80 X 80 cotton printcloth (3.4 oz/sq. yard), which The material may be further described as anionic, had been desized, scoured, and bleached. was padded emulsifiable, high molecular weight polymers that form in the usual manner with two dips and two trips in the strong elastic films upon drying and heat-fusing the following aqueous pad bath which had been adjusted to polymer particles at elevated temperatures. pH 2 with hydrochloric acid:  
 TABLE III Procedures Wrinkle and Pad Bath Abrasion Recovery Tearing Concentrations Fixation Resistance Angle W-i-F) Strength as in: Conditions (71 of orig.) tdeg.) (/2 of orig.)  
 Example 1 5 min/58 [54 27l 92 Example 6 l 5 min/58 3ll 293 98 Example 7 &#39;4 5 min/58 262 299 96 No polyurethane pretreatment In Examples 6 and 7 the polyurethane was applied to First Pad Bath the cotton&#39;fabric before moist fixation. However. if the R I P polyurethane emulsion is compatible with the softener- Cree&#34; curing catalyst system, it can be added at this point. MMM The polyurethane is particularly useful in situations SS 3 where the wrinkle recovery angles of the treated fabrics from a process are in need of being increased. If the I The wet fa nc w polyurethane (or other, elastomer) is used prior to b as h l q on a pm fiame and I heated under the fixation conditions shown in the tamoist fixation, then the elastomer must be able to resist bles Fonowin fixation the fabric was Washed imm di hydrolysis under the acidic (pHzz) Conditions of the ately to remofe the acid and any unreacted mater ials d bat containin the ol mer-formers and crossq, f h g p y and then dried. The fixed fabric was then padded as lmkers&#39; before in an aqueous pad bath with the following com- The processes of this tnventlon can be used to treat Osition substantially any hydrophilic fibrous cellulosic material p (including blends) such as cotton, rayon, ramie, jute. 5mm! PM and the like. Reagent Percent The following examples are given by way of illustration and&#39;not by way of limitation of the invention. The Magnesum chlmdc hcmhydw&#39;c 4 detailed procedures given below in the examples are illustrative, and are not the only or specific conditions ,5 The wet fabric was again pinned on a pin frame and dried in an oven at 60C. for seven minutes. Final curing of the resins was obtained in a second oven by heating the fabric on a pin frame for three minutes at 160C. The fabric was washed and dried prior to testing. See the appropiate table for testing results.  
 EXAMPLE 2 Same as Example 1 except the concentration of TDM in the first pad bath was 20 percent.  
 Second Pad Bath Zinc nitrate hexahydrate Poly-ethylene solids EXAMPLE 4 Same as Example 3 except the second pad bath had the following composition:  
 Second Pad Bath Reagent Percent Magnesium chloride hexahydrate 4.0 Polyethylene solids 2.0  
 EXAMPLE 5 Same as Example 4 except a seven ounce twill fabric was used instead of the printcloth and the percentage of magnesium chloride hexahydrate in the second pad bath was 2.0 percent EXAMPLE 6 Same as Example 5 with the following changes:  
  The fabric was given a pretreatment prior to padding in a second pad bath. In this pretreatment the fabric was padded with an aqueous emulsion containing 12 percent polyurethane (E-406A, supplied by Wyandotte Chemicals Corporation) and the wetted fabric was dried for ten minutes at 60C.  
 EXAMPLE 7 Same Example example 6 except that the second pad bath contained:  
 Second Pad Bath Reagent Percent MMM 20 Dimethylol isopropyl carbamate 20 TDM 20 We claim:  
 . l. A process for treating a cellulosic fabric to produce a commercially acceptable durable-press fabric which process consists of:  
 padding the cellulosic fabric through a resin bath at a pH of about2 which bath contains from about 10 to 20 weight percent of a methylated methylolmelamine, from about 5 to 20 weight percent of a crosslinking agent selected from a group consisting of N,N-dimethylol carbamates and N,N&#39;- dimethylol dihydroxyethyleneurea and from about 10 to 20 weight percent of tetraethylene glycol dimethyl ether,  
 b. heating the padded cellulosic fabric in an open state at a temperature of about 58 C- for a period of about 3 minutes to permit unrestrained evaporation of moisture from said fabric and, without any further heating, then neutralizing, washing and drying the cellulosic fabric,  
 . padding the washed and dried cellulosic fabric from step (b) with an aqueous solution free of crosslinking agent and containing from about 0.5 to 4.0 weight percent of an acid catalyst selected from a group consisting of magnesium chloride hexahydrate and zinc nitrate hexahydrate and from about 0 to 2 weight percent of emulsified polyethylene,  
 d. drying the cellulosic fabric from step (e) for a period of about 7 minutes at a temperature of about 60 C., and  
 (e) curing the fabric from step (d) for a period from about 3 to 5 minutes at a temperature of about C.  
 A process for treating a cellulosic fabric to produce a commercially acceptable durable-press fabric which process consists of:  
 padding a cellulosic fabric in an aqueous solution containing about 12 weight percent of an anionic. emulsifiable, high molecular weight polyurethane.  
 b. drying the padded cellulosic fabric for a period of about 10 minutes at a temperature of about 60 C.,  
  padding the cellulosic fabric from (b) through a resin bath which bath contains from about 10 to 20 weight percent of a methylated methylolmelamine. from about 5 to 10 weight percent ofa crosslinking agent selected from a group consisting of N,N- dimethylol carbamates and N,N&#39;-dimethylol dihydroxyethyleneurea and from about 10 to 20 weight percent of tetraethylene glycol dimethyl ether,  
 (1. heating the cellulosic fabric from (c) in an open state at a temperature of about 58 C. for a period of about 3 minutes to permit unrestrained evaporation of moisture from said fabric and, without any further heating, then neutralizing, washing and drying the cellulosic fabric,  
  padding the washed and dried cellulosic fabric from step (d) with an aqueous solution free of crosslinking agent and containing from about 0.5 to 4.0 weight percent of an acid catalyst selected from a group consisting of magnesium chloride hexahydrate and zinc nitrate hexahydrate and from about 0 to 2 weight percent of emulsified polyethylene,  
 drying the cellulosic fabric from step (e) for a period of about seven minutes at a temperature of about 60 C., and  
 g. curing the fabric from step (f) for a period from about 3 to 5 minutes at a temperature of about l60.  
 3. The product produced by the process of claim 1. 4. The product produced by the process of claim 2.