Nano-Finishes Based on Natural Ion Generating Minerals having Healing Properties

Recently textile finishes based on negative ion generating pyroelectric minerals such as Tourmaline (Illustration VI) have been developed by embedding the nanoparticles of tourmaline in a polymer emulsion.

The finish is applied by the pad-dry-cute method. Tourmaline particles emit negative ion and near IR radiation on heating or rubbing. These ions combine with airborne water molecules and stabilize in air. Therapeutic effects, such as stress reduction, recovery from fatigue and mental and/or physical relaxation, are expected if negative ions are taken into the body by breathing or through the skin.

Tourmalines are naturally occurring minerals (found in Rajasthan in India) with the general formula XY3Z6 (B03)3Si6018 (O, OH, F) 4 where usually X = Na, Ca, or a vacancy, Y = AI, Li, Fe²⁺, FeH, and many other cations, and Z = AI, Mg, and FeH. It has been known for centuries that tourmaline crystals are pyroelectric materials that develop an electrostatic charge when heated or cooled. When tourmaline crystals are heated, a positive charge develops at one and a negative charge at the other. These charges reverse themselves when the crystal cools. This is referred to as a pyroelectric property. A piezoelectric charge can be developed if pressure is applied to the ends of the crystal.

Finishes Based on Natural Bio-molecules such as Chitosan and Sericin

Chitosan and sericin are natural polymers (of value) available as by-products. Chitosan is a non-toxic biodegradable polycationic polymer with low immunogenicity. Because of the amino groups, chitosan carries cationic charge under acidic conditions, which give it the ability to lower plasma triglycerides and antimicrobial activity. Chitosan is produced commercially by deacetylation of chitin, which is the structural element in the exoskeleton of crustaceans (such as crabs, shrimp, etc.). It is a by-product of the shrimp and crab production industry. Low molecular weight chitosan (produced by enzymatic hydrolysis) that is soluble in water is a useful textile finish that modifies the handle and also acts as a natural antimicrobial agent.

Sericin generated as by-product of the degumming process of silk goes into effluent. It has been reported that sericin has high moisture absorbing, antimicrobial and UV [protection properties. Suitably tailored sericin is used as a textile finish to improve moisture, UV absorption and antimicrobial properties of treated fabrics.

The polymers can act as handle modifiers with added properties as antimicrobial, UV protection and cell rejuvenation.

Another natural product nano-silver is also finding considerable use in treatment of textile products such as socks etc to make them less smelling and requiring less frequent washing there by make them more sustainable. A combination of nano-silver and chitosan or sericin will make it an effective value added multifunctional finish. Such finishes need to be developed and evaluated.

Finishes based on Aloe Vera and Neem extracts

Aloe Vera (Aloe barbadensis, Miller), belongs to the family Liliaceae, has been used in traditional medicinal practices as well as cosmetic uses. Aloe Vera has excellent skin care properties which includes anti-inflammatory and anti-aging. Application of Aloe Vera on textiles as an anti-ageing and moisturizing agent has been patented by Kimberley-Clark Inc. Ltd. DyStar Auxiliaries GmbH has developed a textile finishing product containing a combination of vitamin E, Aloe Vera and jojoba oil in a silicon matrix for moisturizing and UV protection effect. This finish can also be applied on silk fabrics.

Neem (Azadirachta indica), belongs to the plant family Meliaceae (Mahogany). Neem oil has been applied on the textile material using micro encapsulation technique. An aqueous formulation based on Neem oil has been patented by Bayer AG, for textile and related products. The textile material treated with neem oil show very good antibacterial and moth repellent properties.