Dyeability Modifiers

When modified fibres of type 5 are treated with hydroxylamine, oxime groups are also easily formed. The interaction with a protein affords a sandwich polymer22. Fibres modified in this way have enhances dyeability. When copolymer fibres are treated with diamine solutions or in acid medium with Fe+3 salts, intermolecular chemical bonds are formed, which results in a considerable increase of the temperature of zero strength and of the heat resistance of fibres. These conversions are shown in Scheme 2. 

One of the earliest fibre pretreatments for improving the dyeability of cotton is of course mercerisation (section 10.5.4). However, more recent research interest in this area has been generated by environmental concerns about reactive dyeing, aiming to enhance substantivity for the modified fibre so that higher absorption and fixation are obtained. This results in less dye (hydrolysed or still active) in the effluent. A further objective is to minimise the usage of electrolyte in the application process. This area has been thoroughly reviewed [392,393]. 

Recently, nitrilases have been applied to polymer modification, specifically to the modification of polyacrylonitrile (PAN). Nearly 3 x 106 tons of PAN are produced per annum and used in the textile industry. However, there is a great need to improve moisture uptake, dyeability with ionic dyes, and feel of this acrylic fiber. The cyano moieties of PAN have been successfully modified to carboxylates with the commercial Cyanovacta nitrilase, thus enhancing the aforementioned properties of PAN [98]. Nitrilase action on the acrylic fabric was improved... 

Polyamide fibers, 19 739-772. See also Synthetic polyamides applications for, 19 765-766 chemical properties of, 19 745-747 cross-section shape of, 19 756 dyeability of, 19 758-760 early reactive dyes for, 9 468-470 electrical properties of, 19 745 manufacture of, 19 748-749 modified nylon-6 and nylon-6,6, 19 760-764... 

More controlled and efficient fixation is possible when the reactant is applied as a pretreating agent [146]. If nylon given such a pretreatment is subsequently dyed with the conventional chlorotriazine dye Cl Reactive Red 3 (7.2), the substantivity and fixation of the latter are markedly lowered because the anionic XLC residues have reacted with N-terminal amino groups in the fibre. Treatment of the modified nylon with ammonia, however, restores some degree of dyeability. Opposite effects are observed if Cl Reactive Red 3 is reacted with ethylenediamine to form an aminoalkyl derivative (7.131). This nucleophilic dye exhibits a high degree of fixation only on the modified nylon that has been pretreated with XLC. 

As earlier noted, PET has no dye attachment sites for chemically active dyes. It is possible to add ionic dyeability by forming copolymers of PET with monomer species that possess active sites, for example, on a pendant side chain. The most common of these has been the incorporation of a sodium salt of a dicarboxylic acid, e.g. of 5-sulfoisophthalic acid (Figure 12.14). The acidic sulfo group allows the attachment of cationic dye molecules. If both the modified and the unmodified fibers are put into a dye bath containing a mixture of disperse and cat dyes, they will emerge with two different colors. This is useful in the creation of specialty fabrics, e.g. when two different dye types are woven into fabrics with a predetermined pattern. The multicolored pattern emerges upon dyeing. 

Since the basic structure of the modified fiber is a copolymer, more rapid disperse dyeing is also gained with these cat-dye fibers. Losses in fiber strength, temperature stability and increased hydrolytic degradation are the prices paid for the dyeability enhancement. 

Since disperse dyes diffuse very slowly into PES fibers, efforts have been made to increase the rate of dye strike by chemical or physical alteration of the fiber. The fiber is also modified to reduce the pilling tendency, to increase shrinkage and elasticity, and to reduce flammability. Such modified fibers exhibit improved dye receptivity. Fibers with improved dyeability can be dyed with disperse dyes at boiling temperature without a carrier or with basic dyes when they are modified with acidic components (5-sulfoisophthalic acid). Fibers of this type are used if dyeing cannot be carried out easily above 100°C (e.g., in the case of floor coverings, articles made of PES-wool blends, stretch materials, and cord). Strongly crimped PES bicomponent fibers are produced for special purposes. These fibers are normally also dyeable at the boil and without a carrier [136, 137, 138],... 

Modifications of the organochemical properties of cellulosic fibers by graft polymerization with selected monomers impart new chemical properties. The microbiological and light resistances of cellulosic fibers to degradation are increased by grafting (3). Surface properties of modified fibers are changed to impart soil-release (35), dyeability (36), and flame-resistance (37, 38) properties. 

Polyester. The most common polyester in use is derived from the homopolymer poly (ethylene terephthalate). Many types of this fiber contain a delustrant, usually titanium dioxide. Optically brightened polymers are quite common. The optical brightener, such as specially stabilized derivatives of either stilbenes or phenylcoumarins, can be added to the polyester before formation of the fiber (107). Some commercial fibers contain minor amounts of copolymerized modifier to confer such properties as basic dyeability. A wide range of polyester fibers is used for consumer end-uses. Both staple fiber and filament yarn are available. Filament yarns with noncircular cross-sections are made (107). 

A recent report by Fan et al. [267] claimed that the incorporation of nanosized clay modified with quaternary ammonium salt in polypropylene imparted dyeability. The technique... 

CAS 5205-93-6 EINECS/ELINCS 226-002-3 Uses Adhesion promoter, mfg. of quats, improves dyeability of textile fibers, photopolymer plates, photoresists, paint resins and emulsions, oil additives, electro dipcoats, rubber modifiers, dental compds. Properties Pt-Co 50 max. clear liq. ester-like odor m.w. 170 sp.gr. 0.94 vise. 28 cps (20 C) b.p. 134 C flash pt. 140 C ref. index 1.478 (20 C) 98.5% min. purity 0.1% water content Toxicology TSCA listed Storage 3 mos shelf life 30 C max. 

Synthetic fibers do not contain natural impurities although there are added impurities such as sizing materials and oil stains. Therefore, their pretreatment process is simpler than other natural fibers. However, synthetic fibers such as polyester and acrylic have poor wettability, dyeability, and antistatic behavior. After plasma treatment, the fiber surface gets physically altered, and hydrophilic functional groups are introduced to the fiber surface, which improves the wettability of the fiber significantly. In recent years, many researchers have studied ways to modify polyester textile materials, and good results have been obtained (Morent et al., 2008). 

Deep-dyeing variants - ver-e-ont n. Polymers that have been chemically modified to increase their dyeability. Fibers and fabrics made there from can be dyed to very heavy depth. 

Besides these fields of applications, Wulff and co-workers (307,308) investigated the potential ability of glycopolymers to modify surface properties. Thus, they copolymerized several isopropylidene-protected vinyl sugars with styrene, methyl methacrylate, and acrylonitrile. After eliminating the isopropylidene protecting groups from the copol5uner surfaces by acid hydrolysis, these surfaces were shown to become hydrophilic with improved dyeability and surface conductivity. 

---