Wilson A. Reeves

Cotton Cross-Linked at Various Degrees of Fiber Swelling

Wet and dry density measurements were made on a wide variety of wash-and-wear cotton fabrics and some interpretations of these values are given. Methylenated cotton was selected for more extensive fundamental study because of the simplicity of the formaldehyde cross link and the fact that formaldehyde can be reacted with cotton under greatly different conditions. Formaldehyde was used to cross link cotton print cloth at various degrees of fiber swelling by reacting in systems ranging from completely aqueous to anhydrous using hydrochloric acid as catalyst. The amount of water in the system at the time of reaction is related to the extent of fiber swotting. The extent of swelling at the time of cross-linking and the extent of cross-linking influence wet density, which may be considered to be a measure of the water swellability of a fiber. Cross-linking tends to fix or stabilize a fiber in a given state of swelling: the stabilization is more effec tive when the cross-linking is done in nearly anhydrous systems. The state of swelling at the time of cross-linking modifies moisture regain, water of imbibition, dyeabitity, and wet and dry wrinkle recovery. There seems to be an optimum water content in the reaction system at the time of cross-linking for maximum dry and wet wrinkle recovery. As the water content in the reaction system is increased beyond the optimum, the amount of dry wrinkle recovery becomes much less than wet wrinkle recovery. This phenomenon leads to vastly different wash-and-wear ratings of fabric. A mechanism is presented diagrammatically to explain wet and dry wrinkle recovery. The mechanism is based upon hydrogen-bond cross links, covalent-bond cross links, and the position of the two types of cross links.

Some Chemical and Physical Factors Influencing Flame Retardancy

Information is given to explain why or how bromine or nitrogen contributes to phosphorus-containing flame retardants. Amide and amine nitrogen generally increase flame resitance, whereas, nitrile nitrogen can detract. Essentially, all of the phosphorus in a flame retardant is accounted for in the char or solid phase and this is also true when amide or amine nitrogen is present. Nitrile nitrogen can cause a significant reduction in percent phosphorus accounted for in the char. The amount of nitrogen accounted for in the char is dependent upon the type of nitrogen and the atomic ratio of N to P in the flame retardant. When large proportions of amide or amine nitrogen are present they also contribute to flame resistance in the gas or vapor phase. Bromine makes its contribution to flame retardants by acting mainly in the vapor phase, and its action appears independent of phosphorus.

Flame Retardants for Cotton Using APO and APS-THPC Resins

A new group of polymers made by reacting tris(1-aziridinyl)phosphine oxide, referred to as APO, or tris(1-aziridinyl)phosphine sulfide, referred to as APS, with tetrakis- (hydroxymethyl)phosphonium chloride, referred to as THPC, are good permanent-type flame retardants for cotton. All three of the compounds are water-soluble crystalline materials. The application of APO- or APS-THPC resins to textiles consists of padding fabric in an aqueous solution of the compounds, drying the fabric, curing it at about 140° C. for about 5 min. to polymerize the compounds, and then rinsing the fabric to remove any unpolymerized material. About 8% of the resins in 8-oz. cotton twill or sateen is adequate to make the fabric pass the vertical flame test before or after 15 launderings with synthetic detergents, followed by an acid fluoride sour after each laundering. The flame resistance is also very durable to boiling alkaline soap solutions. The properties of fabric treated with these new polymers are, in general, excellent. The hand and strength of the fabric is only slightly different from that of untreated fabric. The flame-resistant fabrics are resistant to rot and mildew.

Chemical and Physical Properties of Aminized Cotton

curing with 2-aminoethylsulfuric acid in the presence of sodium hydroxide. Fabric may be conveniently aminized in a practical manner using standard cotton chemical finishing equipment. Sliver aminized by the process described may be opened, recarded, and converted into yarn. Experiments dealing with the effect of various processing conditions on the aminization of sliver are reported. It is shown that 30%

Conventional Pad-Dry-Cure Process for Durable- Flame and Wrinkle Resistance With Tetrakis (Hydroxymethyl) Phosphonium Hydroxide (THPOH)

A durable-flame retardant based on tetrakis (hydroxymethyl ) phosphonium hydroxide (THPOH), urea, and trimethylolmelamine has been developed and applied to cotton fabric. The process is accomplished by padding fabric through a water solution of the three components to a wet pickup of about 75%, drying at moderate temperature, and curing at an elevated temperature. Solutions of 25-34% total solids containing the three components in a molar ratio of 2 : 4 : 1 (THPOH: urea : methylolmelamine), when applied to cotton fabrics of 8-9-oz weight, imparted flame resistance, and only minimal losses in breaking and tearing strength. The treated fabrics retained 91-95% break strength and 73-80% tear strength. Wrinkle recovery angles (W + F) of treated fabrics ranged from 280° to 306°. Wash- wear and durable-press properties are discussed. Little or no yellowing of treated fab rics was observed when bleached with sodium hypochlorite solution and scorched between heated plates. Resin add-ons of fabrics treated in this manner ranged from 15 to 19%. Flame resistance of fabrics treated by this process is retained after boiling the treated fabrics in a soap-sodium carbonate solution for 3 hr or after 15 laundering cycles.

Effects of Temperature on Oxygen Index Values

The oxygen-index (01) test [1 ] is finding widespread application for determinations of fabric flammabilities [2, 3, 4, 5, 6]. Effects of environmental temperatures on 01 values have not been reported. This is perhaps because of the original assumptions of Fenimore and Martin [2] or because the logical expectation is that conditions are unfavorable for convective heating of the sample during testing. While determining 01 values for textile specimens, we observed that the glass chimney of the apparatus gets quite hot to the touch. We also observed that, when successive tests were made

Formaldehyde Treatment of Partially Swollen Cotton

Two processes for producing wash-wear cotton fabrics by treatment with formaldehyde are described. One of these processes consists of reacting the fabric in a wet swollen condition in an aqueous solution of formaldehyde and hydrochloric acid. This fabric has good wet wrinkle recovery only and is therefore referred to as the Form-W process. It has good strength retention and is suitable for line-drying after washing. The other process consists of reacting the fabric in a wet, partially swollen condition in a solution of acetic acid,. water, hydrochloric acid, and formaldehyde. It is referred to as the Form-D process because the fabrics have good dry (as well as wet) wrinkle recovery. These fabrics are suitable for either line-drying or tumble-drying. It is very important in both processes that the fabrics be well mercerized if adequate strength is to be re tained. Softeners also improve the tearing strength. Laboratory and pilot-plant appli cations are described, and data on the physical properties of the fabrics presented. Reaction rates of the Form-D process at various temperatures are given. Also, preliminary work on other solvents and catalysts is discussed briefly. Cross-linking with formaldehyde at various degrees of fiber swelling is discussed briefly from a theoretical standpoint.

Poly-Set Process for Producing Durable-Press Cotton Goods 1

Much remains to be done to test out fully this new wet-fixation process for durable-press use. The abrasion studies to date on finished all-cotton fabrics indicate a real improvement over pad-dry-cure processes, but studies on full garments still need to be performed. There are some characteristics of the process which make it especially interesting from the standpoint of cotton finishing. Because the resin is combined with the cotton in the wet, swollen state, it is possible to dye and resintreat at the same time, provided the resin mix and dyes are compatible. The amount of resin added to the cotton is, of course, quite substantial, so that it

Aminization of Cotton

A FEW YEARS AGO it was found that amino groups could be attached to the cellulose of cotton by reacting it with 2-aminoethylsulfuric acid in the presence of sodium hydroxide [2]. A degree of aminization represented by 0.3 % to 0.4% nitrogen may be readily obtained by this method. Although this level of aminization is adequate for demonstrating the unique dyeing characteristics and for some experimental work, a number of potential applications of aminized cotton require a higher degree of aminization.

Application of Mechanisms for Wet and Dry Wrinkle Recovery to Fabric Exhibiting the Unusual Combination of High Dry and Low Wet Recovery

By use of polyethyleneglycols and cross-linking agents in a conventional pad-dry-cure process, fabrics have been produced with the unusual combination of high dry wrinkle and low wet wrinkle recovery. These fabrics and others with the various combinations of dry and wet wrinkle recovery have been examined in terms of the mechanisms for dry and wet wrinkle recovery. On the basis of certain textile properties, an explanation is offered for this unusual combination of high dry and low wet recovery.