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.
