Cotton fabric processing

THPC—Amide—PoIy(vinyI bromide) Finish. A flame retardant based on THPC—amide plus poly(vinyl bromide) [25951-54-6] (143) has been reported suitable for use on 35/65, and perhaps on 50/50, polyester—cotton blends. It is appUed by the pad-dry-cure process, with curing at 150°C for about 3 min. A typical formulation contains 20% THPC, 3% disodium hydrogen phosphate, 6% urea, 3% trimethylolglycouril [496-46-8] and 12% poly(vinyl bromide) soUds. Approximately 20% add-on is required to impart flame retardancy to a 168 g/m 35/65 polyester—cotton fabric. Treated fabrics passed the FF 3-71 test. However, as far as can be determined, poly(vinyl bromide) is no longer commercially available. 

An important chemical finishing process for cotton fabrics is that of mercerization, which improves strength, luster, and dye receptivity. Mercerization iavolves brief exposure of the fabric under tension to concentrated (20—25 wt %) NaOH solution (14). In this treatment, the cotton fibers become more circular ia cross-section and smoother ia surface appearance, which iacreases their luster. At the molecular level, mercerization causes a decrease ia the degree of crystallinity and a transformation of the cellulose crystal form. These fine stmctural changes iacrease the moisture and dye absorption properties of the fiber. Biopolishing is a relatively new treatment of cotton fabrics, involving ceUulase enzymes, to produce special surface effects (15). 

CP esters are generally prepared as the ammonium salt [9038-38-4] by the reaction of cellulose with phosphoric acid and urea at elevated temperatures (130—150°C). The effects of temperature and urea/H PO /cellulose composition on product analysis have been investigated (33). One of the first commercially feasible dameproofing procedures for cotton fabric, the Ban-Flame process (34,35), was based on this chemistry. It consists of mixing cellulose with a mixture of 50% urea, 18% H PO, and 32% water. It is then pressed to remove excess solution, heated to 150—175°C for 5—30 minutes, and thoroughly washed (36). 

When exposed to heat, cotton fabrics, like most substances, increase in temperature to an extent that is proportional to their specific heats. Altering the chemical composition of the fabrics such that large amounts of heat are absorbed and released in repeatable cycles of controllable temperature ranges produces fabrics that are described as temperature adaptable. The process insolubili2es poly(ethylene glycol)s cross-linked with methylolamides in the cotton fabric (78). As with flame-retardant cellulose, attachment is through an ether linkage to the cellulose at a relatively low DS. 

Phosphine, which is produced in small quantities in the Silicol process for making hydrogen, has under certain conditions a deteriorating effect on cotton fabrics, not as an immediate action but as a secondary reaction. The examination of a balloon envelope which burst at Milan in 1906 showed that at some spots the material could be easily torn, while over the greater portion it... 

The introduction of rayon, nylon and other manmade fibers with their greater strengths per unit cross sectional area compared with cotton fabric has led to the use of rubber coated fabrics in the manufacture of various engineering products such as tyres, beltings and hoses and also several specialty products for the chemical process industries. The arduous service conditions prevailing... 

A vapor phase grafting process based on the ozonization of polymer films and fabrics followed by a treatment with vapors, such as acrylonitrile, dichloroethylene, and vinyl acetate, has been patented by Polyplastic (66). Also cotton fabrics can be used as substrates. 

Improved Comfort Properties. Wear comfort generally means cotton-like properties, The ability lo absorb moisture from the skin and ihe softness of cotton fabrics are considered to be the two key properties for comfort. The extremely line denier of cotton fibers accounts for its softness. Both properties can be achieved in acrylic fibers. Improved moisture retention can be achieved by incorporating hydrophilic comonomers that decrease ultimate fiher density, by modifying the fiber spinning process, ur by using after-treatments such as modified finishes. 

Permanent press, 100% cotton fabrics are produced via a licensed process involving mercerization in a bath of liquid anhydrous ammonia. This Sanfor-Set process was commercialized in 197557. 

Dean, J. D., Chemical Changes in Cotton Fabrics During Processing and... 

Since Mercel discovered the process of the so-called mercerization of cellulose (a process leading to cotton fabrics by treating cellulose under tension with an aqueous alkali solution), the swelling phenomena of cellulose in an aqueous alkali solution have been studied in detail, by many investigators. For example, for natural cellu-... 

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