Walter D. King

Reagent Migration and the Performance of Durable-Press Fabrics

In order to delineate the effects on reagent migration on the textile-performance properties of durable-press fabrics, dimethyloldihydroxyethyleneurea (DMDHEU) and N-methylolpolyethyleneurea, degree of polymerization = 2, were applied to cotton printcloth under slow and rapid drying conditions, which effected uniform and nonuniform crosslink distributions through the fabric thickness. These reagents are representative of conventional and network polymer forming cross-linking reagents, respectively. The crosslink uniformity (or nonuniformity) was measured in the DMDHEU series with a negative Direct Red 81 staining technique. Fabrics with a uniform distribution of crosslinks throughout the fabric thickness were the point of reference. The concentration of crosslinks on fabric surfaces effected by reagent migration during rapid drying resulted in a) comparable development of resilience, b) slightly better retentions of breaking strength, tearing strength, and elongation, c) greater weight losses in Accelerotor abrasion, and d) comparable retention of Stoll-flex abrasion resistance. These trends occurred with both reagent systems and were detected at both the low and high levels of reagent incorporation. The results are discussed in relation to the distribution of crosslinks.

Pore Structure of Cotton Fabrics Crosslinked with Formaldehyde-Free Reagents:

Pore structures of cotton fabric crosslinked with several formaldehyde-free durable press reagents are elucidated, and results are compared with those for the industry standard, DMDHEU (dimethyloldihydroxyethyleneurea). The formaldehyde-free reagents were BTCA (butanetetracarboxylic acid), DHDMI (dihydroxydimethylimidazolidinone), and the glyoxal/glycol system; the fabric was an 80 × 80 cotton print-cloth. Treatments were designed to impart the same degree of conditioned wrinkle recovery (WRA) to the fabric. A reverse gel permeation chromatographic technique was used to follow changes in pore size distribution. Columns were prepared by settling water slurries of the ground cotton in a conventional manner. Two series of water soluble solutes, which were series of oligomeric sugars and ethylene glycols, were used to study the elution characteristics of the unmodified and crosslinked samples. Internal structure differences were also elucidated by means of moisture regain, considered to be a measure of the internal surface of the cotton fiber in the conditioned state, and water of imbibition, a measure of internal volume in the water-swollen state. Formaldehyde-free crosslinking reagents effect a lower level of collapse of the internal pore structure of the cotton fiber than does DMDHEU at generally comparable levels of resilience.

Reagent Migration in Fabric Thickness in Pad-Dry-Cure Finishing

Migration of dimethyloldihydroxyethyleneurea in the thickness direction of fabric was examined under conditions of forced-draft drying at temperatures from 40°C to 160°C. The subsequently cured fabrics were subjected to de Boer migration mea surements to clarify extents of migration of reagent residues to fabric surfaces. Migration was a primary function of forced-draft drying; differences in temperature of drying exerted no additional distinguishable effect. Unhalanced and variable migrations were observed for forced-draft drying in common laboratory ovens. Durable-press ap pearance rating is discussed in relation to add-on of reagent for the products of these treatments.

EFFECT OF CATALYST ON THE PORE STRUCTURE AND PERFORMANCE OF COTTON CELLULOSE CROSSLINKED WITH BUTANETETRACARBOXYLIC ACID

Pore structures of cotton crosslinked with butanetetracarboxylic acid (BTCA) and different catalysts were assessed. The catalysts included NaH2PO2.H 2O, Na- H2PO 3.2.5H2O, Na2HPO3.5H2O, NaH2PO4.H2O, Na2HPO4, Na4P2O7, and Na2CO3. Treatments were applied to all-cotton printcloth using a pad-dry-cure process. Textile performance properties were determined for the treated fabrics. Pore size dis tribution was assessed on Wiley milled fabric using a reverse gel permeation chro matographic technique. The water soluble molecular probes employed were sugars and ethylene glycols. Plots were prepared of V, , the accessible internal water, versus the molecular diameters of the probes. In addition, internal structure differences were elucidated by moisture regain, considered to be a measure of the internal surface of the cotton fiber in the conditioned state, and water of imbibition, a measure of internal volume in the water-swollen state. There were definite patterns in textile performance with the different catalysts. The total volume in residual small pores was inversely related to the resilience level achieved, and retained breaking strength was directly related to the volume in residual small pores. Patterns with respect to abrasion resistance were more complex. Because BTCA add-ons were comparable, the data suggest that the more effective catalysts, NaH2PO2 and NaH2PO3, are effecting either a greater number of crosslinks in the cotton or producing crosslinks that differ in actual structure.

Assessment of Fabric Performance Versus Reagent Location from Lick Roller Application of DMDHEU

The balance of textile performance properties and the distribution of crosslinking reagent residues throughout fabric were studied in relation to lick roller application of DMDHEU. Features of the lick roller treated fabric were compared to the con ventional pad(immersion)-dry-cure product and to a corresponding product designed to have a high degree of uniformity of reagent residue distribution throughout the thickness of the fabric by minimizing migration. A special Osnaburg-fabric was used to facilitate several aspects of the study including the measurement of distribution of reagent residues. The fabric treated to a high degree of uniformity of reagent residue distribution exhibited substantially higher abrasion resistance than the con ventional product when compared at equal levels of durable press appearance rating; it was slightly lower in strength properties. The product from lick roller treatment at optimum liquor pickup approached the high uniformity standard in uniformity of reagent residue distribution throughout the fabric thickness and in abrasion resistance. In breaking strength, tearing strength, and elongation (especially in the warp), this product from lick roller treatment performed close to the high uniformity standard. The performance of another product from lick roller treatment that involved lower liquor pickup is also described, Performance properties and distributions of reagent residues are discussed in detail.

Migration and Location of Reagent Residues in Cotton Fabric

To delineate the effect of migration to fabric surfaces during rapid drying on translocation of resin between warp and fill yarns, DMDHEU was applied to a series of fabrics with increasing fill thread count. Treated fabrics were dried under slow and rapid drying conditions which effect uniform and nonuniform distributions through the fabric thickness, respectively. The degree of crosslink uniformity (or nonuniformity) was measured with a Direct Red 81 staining technique. A fabric characterized by uniform crosslink distribution served as the point of reference. Nitrogen contents of the fabrics and of the isolated warp and fill yarns were determined. Translocation of resin during rapid drying was assessed by comparing these fabrics to the reference samples. Rapid drying caused translocation of resin towards those yarns that pre dominate in the effective evaporation surface. An extensive analysis of the relationship between resin translocation and fabric structure is reported.

Durable Press Performance and Reagent Distribution from Foam Application of DMDHEU

Textile properties of a special 30 × 30 Osnaburg-type fabric treated by foam ap plication of DMDHEU were studied in relation to durable press (DP) appearance rating and distribution of reagent residues in fabric samples. The foam treated fabrics were compared to a high uniformity DP fabric and to a DP fabric from conventional laboratory scale, pad-rapid-dry-cure treatment. The products from foam application of DMDHEU were generated under two sets of conditions designed to minimize migration and realize high uniformity of wicking and spreading of reagent liquor into fabric, and to realize near maximum economy in energy by minimization of wet pickup. Fabric performance, the distribution of reagent residues in the fabric, and, primarily, the interrelationship between distribution of reagent residues in fabric and fabric performance are considered and discussed in detail.

Effect of Drying Rate on the Location of Durable Press Reagents in Fabric

The effect of various drying conditions on the location of DMDHEU or MgCl2·6H2O in fabric samples was assessed. A nonsubstantive dye/grid technique was developed for following solute movement during drying.

A Simple Density Method for the Analysis of Fabric Blends of Cotton and a PET Polyester

A practically linear relationship has been found to exist between the polyester content of a cotton/PET polyester fabric blend and the ml of n-heptane, called the B value, that must be added to 100 ml of carbon tetrachloride in order to prepare a solution in which the cotton/polyester blend will neither sink nor float. It is a simple matter to determine the polyester content of a fabric blend from its B value.

Distribution of Crosslinks in DMDHEU-Treated Fabrics from Measurements on Warp and Fill Yarns

Dimethyloldihydroxyethyleneurea (DMDHEU) was applied to cotton fabrics via immersion padding followed by fast (I-FD) and slow (I-SD) drying and via lick roller (LR20, LR35) and foam (FM20, FM35) applicators at 20% and 35% wet pickups. The fraction of cuene-soluble cellulose, distention index (DI), water of imbibition (WI), and moisture regain (MR) were determined on the fabric or the separated warp and fill yarns to elucidate the effect of processing conditions on crosslink distribution. The slowly dried fabric served as the standard for uniformity. Samples were compared at the same level of bound nitrogen. High DIs, WIs, and MRs were associated with a less uniform crosslink distribution at the same overall crosslink density. Uniformity of crosslink distribution was found to decrease in the order I-SD > FM35 > LR35 > I-FD > FM20 > LR20. The fraction of cuene- soluble cellulose increased with increasing bound nitrogen in the LR20 samples, whereas the WI and MR of these fabrics exhibited U-shaped behavior. These trends are attributed to decreasing spreadability of liquor with increasing reagent concen tration. The result is that progressively larger portions of the cotton fabric are left untreated. Foam application at the 20% pickup level resulted in enough penetration to the backside of the fabric to impart cuene insolubility at all but the lowest DMDHEU add-on level. Indications are that the spreading mechanism for foam is substantially different from and more efficient than that for the liquid film from the lick roller. Crosslink distributions differed in the warp and fill yarns in all but the I-SD samples.