Dimethyloldihydroxyethylene Urea Research Articles

Crosslinking of Cotton Cellulose in the Presence of Mixed Catalysts

A crosslinking treatment is reported for cotton fabric with dimethyloldihydroxy ethyleneurea (DMDHEU) in the presence of mixed and conventional catalysts using a pad-dry-cure process. The crosslinked fabric and a control were studied for various physicochemical properties by standard methods. The distribution of crosslinks per anhydroglucose. unit and length of crosslinks were calculated from formaldehyde and nitrogen content values. The data on formaldehyde and nitrogen content, physical properties, number of crosslinks, and length of crosslinks are discussed. The number and length of crosslinks increase with increased resin concentration in the pad bath. Self-condensation of resin is evident for fabric treated in the presence of the mixed catalysts; in addition, this phenomenon in the presence of aluminum sulfate/tartaric acid is higher than with aluminum sulfate/citric acid. The relationships between various fabric properties are also considered.

Reaction Equilibria and Textile Performance from Low Formaldehyde Release Carbamate Finishing'

Durable press finishes for cottons based on carbamate agents have certain advantages over those based on other amides, including superior resistance to both acidic and alkaline hydrolysis and absence of yellowing on white goods. A disadvantage has been the tendency of these finished fabrics to release unacceptably high levels of formal dehyde in the unwashed state, a result of the equilibrium between the methylolcar bamate and the free carbamate and formaldehyde, which favors the free carbamate and formaldehyde. We have taken advantage of the stability imparted to the methylol- amide by etherification to design low formaldehyde release carbamates. We discuss the influence of reaction conditions such as temperature and pH on formaldehyde release in preparing these agents. We report on the textile performance of treated cotton, including formaldehyde release, for fabrics finished with the low formaldehyde release carbamates, and we compare this to a finish from dimethyloldihydroxyeth yleneurea.

Improving the Wrinkle Recovery of Wool/Cotton Blends by Simultaneous Treatment with Synthappret BAP and DMDHEU

A simple pad-dry-cure procedure is described that significantly improves the dry (conditioned) wrinkle recovery of fabrics made from a range of intimate blends of wool and cotton. The method involves simultaneous application of a mixture of a cellulose crosslinking agent dimethyloldihydroxyethylene urea (DMDHEU) and the carbamoyl sulphonate-terminated poly (ether) urethane Synthappret BAP from pad liquors containing a nonionic surfactant. The latter is necessary to prevent precipitation of the magnesium salt formed from Synthappret BAP by the magnesium chloride catalyst used to crosslink cellulose with DMDHEU. The two reagents act, by different mechanisms, by improving the dry wrinkle recovery of only the cellulosic component of the fabric. DMDHEU acts by increasing the resilience of the cotton fibers and Synthappret BAP by reducing the frictional component of wrinkling that is due largely to the cotton in the blend. When applied simultaneously, the effects of the two reagents are additive. This permits higher levels of wrinkle recovery than are possible by treat ment with either compound alone, with only small accompanying adverse effects on abrasion resistance. A simultaneous treatment with low levels of the reagents also controls shrinkage in laundering and improves the wet wrinkle recovery properties of the wool/cotton fabrics.

Highly Active Mixed Catalyst System for Producing Durable Press Cotton Textiles

In this study cotton fabric samples were crosslinked with 10% N-methylol compound 4-5, dimethyloldihydroxyethylene urea in the presence of a mixed catalyst system consisting of varying proportions of aluminium sulfate, glycolic acid, and tartaric acid. Resin finishing was by the pad-dry-cure method and curing was done at 160°C for 3 minutes in most cases and in few cases at 180°C for different periods. Treated and control samples were evaluated for various properties. Wrinkle recovery and durable press ratings of the crosslinked fabrics increased and breaking strength decreased as the concentration of glycolic acid in the mixture increased up to 2.0%. Further increases in the concentration of glycolic acid in the mixture did not have pronounced effect on fabric properties. The fabric samples treated in the presence of the mixed catalyst system of glycolic acid and aluminium sulfate exhibited better resilience than those treated in the presence of either citric or tartaric acid and aluminium sulfate. Fabric samples cured at 160°C exhibited better textile properties than the samples cured at 180°C. Fabric samples crosslinked in the presence of the mixed catalyst system showed higher WRA and DP ratings and better tensile properties compared to the samples treated by the conventional process.

Concurrent dyeing and finishing: V. One-bath dyeing and easy-care finishing of cotton fabrics with acid dyestuffs and N-methylol compounds using different catalytic systems

A number of catalysts have been used for effecting concurrent dyeing and easy-care finishing of cotton fabric with acid dyes and N-methylol finishing agents. Factors affecting the process, such as the nature and concentration of catalyst, the finishing agent, the additive and the dye as well as curing temperature, were investigated. Evaluation of the simultaneously dyed and finished fabric was made with respect to colour strength, wrinkle recovery and fastness properties. The results obtained indicate that, of the eleven catalysts used, ammonium persulphate is the best for effecting concurrent dyeing and finishing of cotton fabric using acid dye and dimethyloldihydroxyethylene urea (DMDHEU).

Factors Controlling Formaldehyde Release from Durable Press Cotton

Formaldehyde release from durable press fabrics treated with dimethyloldihy droxyethyleneurea (DMDHEU) has been investigated in an effort to understand the physicochemical equilibria that control the generation of formaldehyde and its transport from the fabric to the environment. Fabric pH plays a major role in the generation of pendant N—CH20H groups and of formaldehyde by affecting the rates of hydrolysis of the crosslinks formed between cellulose and the finish and of the pendant N—CH2OH groups, respectively. Specific rate constants for the hydrolysis of C-O and C-N bonds have been determined and found to go through a minimum at pH 7, suggesting that formaldehyde release under neutral conditions is very low. Under acid conditions, a high rate of crosslink hydrolysis (C-O scission) and a proportionately low rate of N—CH20H hydrolysis lead to the generation of additional N-CH2OH groups, increasing the formaldehyde release potential of the fabric. Under alkaline conditions, on the other hand, a combination of high C—N and low C—O hydrolysis rates leads to the elimination of N—CH2OH groups, the potential sources of formaldehyde release in the fabric. The sorption equilibrium does not play a major role in formaldehyde release into water, but in a confined gas phase, formaldehyde release to the environment is controlled by the distribution coefficient of formaldehyde between cellulose and air. At ambient temperatures, the distribution coefficient is very large, reflecting the high affinity of formaldehyde for cellulose at low temperatures. Heats of sorption obtained from sorption studies at various temperatures suggest chemisorption of formaldehyde, possibly involving the formation of hemiacetals with cellulose. Since hemiacetals are hydrolytically unstable, formaldehyde is released under conditions of high humidity. At high treatment temperatures, formaldehyde binds with cellulose in an irreversible manner, forming a product that is stable to mild hydrolytic conditions, and is thus removed from the sorption equilibrium.

Effect of Synthappret BAP on the Wrinkle Recovery of Uncrosslinked and Crosslinked Cotton

The dry and wet wrinkle recovery angles of a cotton fabric are increased by treatment with the carbamoyl sulphonate-terminated poly(ether) urethane, Synthap pret BAP. This product cures best under alkaline conditions, but in the presence of an organometallic catalyst, it can also be cured under the acid conditions used to crosslink cotton with dimethyloldihydroxyethylene urea (DMDHEU). Synthappret BAP improves wrinkle recovery by decreasing the frictional component of wrinkling, probably through the formation of interfiber and interyam bonds. This contrasts with DMDHEU, which acts largely by changing the viscoelastic properties of the fibers. When the treatments are done separately, the improvements obtained with the elastomer and fiber crosslinker are additive for both dry and wet wrinkle recovery. Even better results are obtained however, when the treatment with Synthappret BAP, DMDHEU, and magnesium chloride catalyst is done from a single bath, provided a nonionic surfactant is present. The surfactant is necessary to prevent precipitation of the magnesium salt of Synthappret BAP. The practical significance of these results is that fabrics with dry and wet wrinkle recovery angles similar to those produced by treatment with a high level of DMDHEU alone can be produced by a pad-dry-cure method, using low concentra tions of Synthappret BAP (<1.0% solids omf) plus DMDHEU (1-2% solids omf). These fabrics have better abrasion resistance and tear and tensile strengths than fabrics treated solely with a high level of the crosslinker.

A Comparison of Aftertreatments to Lower Formaldehyde Release from Cottons Crosslinked with Various Finishing Agents

Acidic, basic, oxidative, and reductive aftertreatments were investigated on cot ton finished with methylolamide crosslinking agents, including dimethylol dihydroxyethyleneurea (DMDHEU), methylated dimethylol dihydroxyethyleneurea (Me-DMDHEU), dimethylol ethyleneurea (DMEU), and dimethylol methyl car bamate (DMMC). The value of aftertreatments to lower formaldehyde release from the finished fabrics without excessive adverse effect on smooth-dry performance was determined. The responses of the finished fabrics to aftertreatments were compared and contrasted with those of methylene-crosslinked cotton. A range of effectiveness of aftertreatments existed among the finishes. Aftertreatments diminished formaldehyde release from some finishes by 90% or more compared with that from unwashed, finished fabric.

Scavengers and pH Control in Aftertreatments for Reducing Formaldehyde Release from Durable Press Cottons1

Recent studies from this Center have demonstrated the influence of the pH of washing and of application of buffered solutions on the amount of formaldehyde released from finished fabrics in the standard AATCC sealed jar test. This work has been extended to include investigation of the effect of aftertreatments, and the in terrelated influence of pH, on formaldehyde release from durable press cottons. In cluded in the study were application of aftertreatments from solutions of salts, acids, and bases that produce various pH levels; formaldehyde scavenger agents; and scavenger agents in conjunction with pH control. Also, aftertreatments with ammonium hy droxide and ammonium salts were explored for condensing ammonia with free form aldehyde in the finish to give hexamethylenetetramine and thus reduce formaldehyde release. Fabrics were investigated that had been finished with dimethylol dihydroxyeth yleneurea, dimethylol ethyleneurea, and dimethylol isopropyl carbamate. Effectiveness of aftertreatments and scavenger applications for controlling formaldehyde release varied as a function of pH and the chemical nature of the finish. Depending on the particular finish, aftertreatments yielded formaldehyde release values ranging from considerably below that of the unwashed, finished fabric to several times that value.

7—THE EFFECTS OFN-METHYLOLATED RESIN FINISHES ON THE FLAMMABILITY OF 67–33 POLYESTER-FIBRE–COTTON FABRICS PART I: THE DIMETHYLOLDIHYDROXY ETHYLENE UREA–MAGNESIUM CHLORIDE SYSTEM

Dimethyloldihydroxy ethylene urea (DMDHEU) is adsorbed more rapidly from aqueous solution by 67–33 polyester-fibre–cotton fabric in the presence of magnesium chloride. This has been attributed to the structure-breaking effect of the magnesium cations. Relatively small increases in limiting-oxygen index (LO1) are observed for magnesium-chloride-treated fabrics, and these are increased by the presence of DMDHEU, but the magnitude of the improvements in LO1 are dependent upon the add-on and approach limiting values in both cases. The mean fabric-burning rate measured for a descending flame at specific LO1 values decreases with increase in add-on for both treatments studied. Thermogravimetric-analysis studies demonstrate that magnesium chloride leads to a significantly greater loss of fabric weight with increase in temperature. Efficient removal of residual catalyst is therefore essential if the effects of resin finishes on fabric flammability are to be critically evaluated.

Unusual Effects of Some Zwitterion Compounds as Catalysts in Easy-Care Finishing 1

Aminoalkanesulfonic acids and amino acids are internal organic salts or zwit terions. In pad-dry-cure processing to impart durable press properties to cellulosic fabrics, they may be used as catalysts. Aminomethanesutfonic acid (AMSA), in particular, is about as effective a catalyst as magnesium chloride. Because of its zwitterion structure, AMSA is unlike most sulfonic acids which produce durable press fabrics with high strength losses. Mixed catalysts of magnesium chloride and the zwitterions AMSA, taurine, or glycine can be employed with dimethylol dihy droxyethyleneurea to produce fabrics with a good combination of smooth drying appearance, wrinkle resistance, serviceable strength, and moderate formaldehyde release values.

Chemical factors affecting soiling and soil release from cotton‐containing durable press fabric. VI. Effect of introduction of carboxymethyl groups in the cotton component of polyester/cotton blend

AbstractPartial carboxymethylation of the cotton component of polyester/cotton blend prior to durable press finishing with dimethyloldihydroxyethylene urea in presence of MgCl2·6H2O was carried out under different conditions to control the carboxyl content as well as alteration of the blend components accompanying the chemical modification. The susceptibility of these modified blend samples before and after crosslinking to aqueous and nonaqueous oily soiling and their ability to release the soil was examined. The general indications are that introduction of carboxymethyl groups in the molecular structure of the cotton component of the blend imparts soil release characteristics of the blend provided that (a) the condition of partial carboxymethylation is not accompanied by profound changes in neither the microstructure of the cotton component nor in the polyester content of the blend and (b) the carboxymethyl content should not be so high. It is proposed that the anionic nature of the modified cotton component of the blend during washing helps in repelling the negatively charged soil particles from the blend surface. In addition, a reduction in the interfacial tension at the soil–water interface assists in rolling up the soil and subsequent removal. This can be turned to the opposite if the electrostatic repulsion is masked through creation of soft swollen environment by significantly increasing the carboxymethyl content, decreasing the polyester content, and/or increasing the swellability of cotton component of the blend.

Polyelectrolyte behavior of chemically modified cotton cellulose

AbstractIon exchange and sorption of charged molecules such as dyes, crosslinking agents, etc., by cotton cellulose very much depend on the charge on cellulose, which in turn is known to depend on the external pH of the medium. In order to understand the role of various fixed groups in cellulose in its polyelectrolyte behavior, the standard cellulose was deliberately oxidized with nitrogen dioxide and sodium periodate, and the sorption of formaldehyde and dimethylol dihydroxyethylene urea by these oxycelluloses as well as by alkali‐treated nitrogen dioxide–oxycellulose was investigated. The results obtained are interpreted in terms of polyampholyte behavior of oxycellulose. The nitrogen dioxide–oxycellulose is positively charged and is a polycation in acidic medium due to protonation of aldehyde groups while it is negatively charged and acts as a polyanion in slightly acidic to alkaline medium due to dissociation of carboxyl groups.

Reduced Formaldehyde Release with Nitro Alcohols

Residual formaldehyde was lowered by 59% when an alkyl nitro alcohol (ReForm™ brand textile reactant modifier) was substituted for 35% of dimethyloldihydroxyethyl eneurea (DMDHEU) on an active weight basis. The textile reactant modifier was added directly to the pad baths. The catalysts used, with a buffered and a nonbuffered DMDHEU, were "hot" magnesium chloride and zinc nitrate. Substantial lowering of formaldehyde was observed in all formulations; however, a lower level of formalde hyde was achieved with the zinc nitrate catalyst in both the buffered and the nonbuffered systems. The durable press properties of the fabric treated in a nitro alcohol modified pad bath were not significantly different from the fabric treated in an unmodified pad bath. There was no increased discoloration of the fabric when it was treated with the nitro alcohol. The textile reactant modifier (ReForm™) used in the formulation is nonsensitizing and nonmutagenic.

Graft copolymerization of vinyl monomers on modified cottons. XVIII. Grafting of methyl methacrylate and acrylonitrile on cotton treated with N‐methylol crosslinking agents using tetravalent cerium as initiator

AbstractCeIV‐induced grafting of methyl methacrylate and acrylonitrile on cotton fibers crosslinked with dimethylol ethylene urea, dimethylol dihydroxyethylene urea, and dimethylol carbamate was investigated. The graft yields obtained with crosslinked cotton were signifcantly lower than the untreated cotton, irrespective of the crosslinking agent and the monomer used. However, the extent and rate of grafting depended upon the degree of crosslinking and the nature of monomer. Based on the magnitude of grafting and CeIV consumption during grafting and oxidation of the untreated and crosslinked cottons, the different reactions occurring during grafting of vinyl monomers on these modified cottons were elucidated.

Crease-Recovery and Tensile-Strength Properties of Unmodified and Modified Cotton Cellulose Treated with Crosslinking Agents

Cotton fabrics were oxidized with nitrogen dioxide and sodium periodate and crosslinked with dimethylol urea (DMU) and with dimethylol dihydroxy ethylene urea (DMDHEU) by the pad-dry-cure process. The effect of pre- and post-oxidation to resin treatment on the crease-resistance and tensile properties of cotton fabrics have been investigated. The results show that crease-recovery angle increases with degree of oxidation, and further periodate oxidation causes the release of strain in cellulose structure, thereby lowering the loss in tensile strength. Resin treatment, on the other hand, improves alkali sensitivity of periodate oxycellulose. Periodate oxidation and resin treatment therefore seem to complement each other.

Improved Durable-Press Cotton by a Two-Step Poly-Set Process

A crossrinking treatment on scoured, bleached, mercerized, and desized cotton fabric with dimethyloldihydroxyethylene urea (DMDHEU) by a two-step poly-set process is reported. The fabric was also treated with DMDHEU by the conventional pad-dry-cure tecnhique. The resin-finished fabric, along with a control, were studied for various physiochemical properties by standard methods. The number of crosslinks (expressed as CL/GPU) and length of crosslinks were calculated from formaldehyde yields and nitrogen values. The data on resin add-on, CL/GPU, and length of crosslinks of cotton crosslinked with varying concentrations of the resin in the presence of polymerization catalysts is discussed. The add-on values in the case of the sample treated by zinc acetate was much higher compared to the similar sample treated in the presence of magnesium acetate. The number of CL/GPU and length of crosslink increased with the increase of resin concentration. Homopolymerization of resin was evident in step 1. The fabric processed in step 2 showed marked improvement in wrinkle-recovery angle and other properties such as strength, elongation, abrasion, and toughness, compared to the samples treated by the conventional process. The relationship between various properties of the fabric is also dealt with.

Carbohydrazide as a Formaldehyde-Scavenging Agent in Durable-Press Finishing

Carbohydrazide has been demonstrated to be an efficient formaldehyde-scavenging agent, particularly with dimethyloldihydroxyethylene urea (DMDHEU) resins. With a given level of carbohydrazide, a lower level of free formaldehyde was achieved with the buffered DMDHEU resin than with the unbuffered. The nature of the catalyst also had a significant effect on the formaldehyde-scavenging ability of the carbohy drazide. Although the free formaldehyde is reduced on the fabric initially, it increases after washing. A solution of the carbohydrazide in the methylated DMDHEU has long-term stability. This property would permit a preformulated product by the resin manufacturer.

Performance Properties of Cottons at Two Levels of Durable-Press and Conditioned Wrinkle-Recovery Angles

Polymerization-crosslinking reagents such as N-methylolacrylamide, N-methylol- methacrylamide, and N-methylolpolyethyleneurea (dp = 3) (NMP-2) and conven tional crosslinking agents such as dimethylolethyleneurea, dimethyloldihydroxyethyl eneurea, and formaldehyde were used to treat cotton twill fabrics. A concentration study with these reagents was carried out, and physical and chemical properties of the finished fabrics were compared. Strength and abrasion properties of treated fabrics at two levels of DP and conditioned WRA were also determined. The results indicated that the experimental reagents capable of undergoing polymerization as well as crosslinking within the cellulose substrate afford a superior balance of strength and abrasion properties. NMP-2 appears to be most stable to loss of formaldehyde among the polymer-forming reagents studied and most sensitive to loss of breaking strength from scorching following treatment with chlorine bleach.

Comparative study of the properties of differently decrystallized and crosslinked cotton fibers

The physical, structural, and mechanical properties of decrystallized cotton fibers prepared by preswelling in different concentrations of alkali followed by partial substitution—to nearly the same extent irrespective of the preswelling alkali concentration—by acetylation or cyanoethylation have been compared. The decrystallized fibers have been crosslinked with dimethylol dihydroxy ethylene urea (DMDHEU), along with the swollen controls, and the mechanical properties have been measured on these samples. It was found that preswelling in NaOH solution of lower concentration (12–15%) prior to cyancethylation results in better decrystallized fibers which also possess better strength uniformity, whereas a higher concentration of NaOH (15% or above) is necessary for acetylation to obtain fibers with nearly similar characteristics. On crosslinking, the swollen and substituted fibers show a better strength retention and a higher strength uniformity than the swollen control, for the same degree of crosslinking.