Often fibers in textile substrates are deficient in one or more properties or improved properties are desired for the substrate. Textile finishing provides a method whereby deficiencies in the textile can be corrected or specific properties can be introduced. Physical finishing techniques (dry finishing processes) or chemical finishing methods (wet finishing) are used. Physical finishing is usually carried out on the yarn or formed textile substrate, whereas chemical finishes can be added to the spinning bath prior to fiber formation for man-made fibers or applied to individual fibers, yarns, or completed textile structures.
Softening Finishes in Textile
To change the hand properties of a fabric, we can apply mechanical, physical, chemical or combined techniques. As a general rule, the softening agents are hygroscopic or lubricating agents, which facilitate the fiber sliding within the fabric structure, thus granting easier deformation and creasing of the fabric. Softener is an auxiliary that, when applied to textile materials, brings about an alteration in the handle, resulting in the goods being more pleasing to the touch.
Softening finishes are among the most important of textile chemical after treatments. With chemical softeners, textiles can achieve an agreeable, soft hand (supple, pliant, sleek and fluffy), some smoothness, more flexibility and better drape and pliability. The hand of a fabric is a subjective sensation felt by the skin when a textile fabric is touched with the finger tips and gently compressed. The perceived softness of a textile is the combination of several measurable physical phenomena such as elasticity, compressibility and smoothness.
During preparation, textiles can become embrittled because natural oils and waxes or fiber preparations are removed. Finishing with softeners can overcome this deficiency and even improve on the original suppleness. Other properties improved by softeners include the feeling of added fullness, antistatic properties and sewability.
Disadvantages sometimes seen with chemical softeners include reduced crock-fastness, yellowing of white goods, changes in hue of dyed goods and fabric structure slippage.
Mechanisms of the Softening Effect on Fabric
Softeners provide their main effects on the surface of the fibers. Small softener molecules, in addition, penetrate the fiber and provide an internal plasticization of the fiber forming polymer by reducing of the glass transition temperature Tg. The physical arrangement of the usual softener molecules on the fiber surface is important and shown in Fig. It depends on the ionic nature of the softener molecule and the relative hydrophobicity of the fiber surface.
Cationic softeners orient themselves with their positively charged ends toward the partially negatively charged fiber (zeta potential), creating a new surface of hydrophobic carbon chains that provide the characteristic excellent softening and lubricity seen with cationic softeners. Anionic softeners, on the other hand, orient themselves with their negatively charged ends repelled away from the negatively charged fiber surface. This leads to higher hydrophilicity, but less softening than with cationic softeners. The orientation of non-ionic softeners depends on the nature of the fiber surface, with the hydrophilic portion of the softener being attracted to hydrophilic surfaces and the hydrophobic portion being attracted to hydrophobic surfaces.
- Chemical Finishing of Textiles by W. D. Schindler and P. J. Hauser
- Principles of Textile Finishing By Asim Kumar Roy Choudhury
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.