In Japan, functional finishes to textiles for apparel and technical use
are increasing, and the requirement for apparel use is the sensitivity and the
compatibility to surrounding circumstances.
The human skin has moisture absorbency and repellency to water, oil and soiling,
and release them easily. To give such performance to the textiles is a strong
research sector for Japanese technical experts.
Reviewing the history of the development of functional finishes on textiles
in Japan, we have cultivated the advantages and covered the disadvantages of
natural and synthetic fibers to meet the customers’ needs. One of the defects
of 100% cotton woven fabric is a high tendency to crease, then its blends with
washable polyester were developed competing with overseas textile manufactures.
Since 1945, wash and wear finish and permanent press finish for preventing
creasing in cotton woven fabrics has become popular, but these technologies were
first developed in the US. However, shape stabilizing finishes on cotton developed
in Japan are globally accepted in the apparel industry.
On the other hand, new synthetic fibers which give the advantages of natural
fibers, such as good hand, appearance and water and sweat absorbency, have been
progressively developed, still keeping their inherent properties.
One of the examples is called “Bionature” developed by Kurabo
(Japan). This fiber consists of hydrolysable/biodegradable polyester, and its
characteristic is beyond the classification between natural and synthetic fibers.
This fiber has been put on sale for 2006 Spring/Summer apparel.
Bionature is made from “Biomax” hydrolysable/biodegradable polyester
resin (Du Pont) and can be blended with cotton or wool to produce polyester/cotton
or polyester/wool environment-friendly textiles. This may be a profound collaboration
of ideas both from DuPont and Kurabo.
This technology belongs to a chemically based one.
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Characteristics of Bionature |
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hydrolysable/biodegradable properties
Bionature can be gradually biodegraded through hydrolysis, where sufficient water,
temperature (warmth) and microorganisms exist, and finally produce water and
carbon dioxide. The rate of degradation is very slow and has no adverse effect
on the environment. |
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Inflammability
The amount of carbon dioxide generated from incineration of Bionature is less
than that of other fibers, and the heat of incineration is also less, that means
a lesser burden to the incinerator. No harmful substances has been detected in
the ash. |
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Physical properties
The heat stability of Bionature is high enough because its raw material is polyester
resin. Where the hydrolysis does not happen, no biodegradation occurs, then,
there is almost no degradation in practical use. |
A lot of functional finishes will be developed in future in Japan, and Prof.
Joukou of Kyoto Women’s Univ. presented a classification of functional
finishes at a meeting of the Japan Dyers’ Association in Osaka in June
2005 (Figure-1).This classification includes physically based technology and
chemically based technology, the former is the improvement of potential function
by modification of the inner part of the fiber, and the later is the settlement
of additional function by modification of the surface of the fiber5).
He explained that the former includes crease-resistant finish, wash-and-wear
finish, permanent-press finish, shape-stabilizing finish, shrink-proofing finish,
mercerizing, imitation-linen finish, hardening finish, softening finish, salt-shrinking
finish, weighting finish, deep-coloring treatment and weight-reducing treatment,
and later includes water-repellent finish, oil-repellent finish, hydrophilic
finish, soil-repellent and release finish, antistatic finish, stretching finish,
mothproofing finish, antimicrobial and smell-proofing finish, ultraviolet-protection
finish.
According to our investigation, the process of incorporating active chemicals
into the fiber in its manufacturing stage is increasing and the product obtained
is called “functional fiber”, but functional finishes (physical and
chemical) are still major at present.
Some famous textile finishers who are active in their operation have established
many kinds of basic finishing technology for the aftertreatment of polyester
fabrics to allow the customer to feel safety and comfort in the clothes.
One example is graft polymerization on the fiber surface to improve moisture
absorbency in order to give physiological comfort to the customer. For improving
sweat absorbency, surface polymerization and polymer coating of fiber surfaces
are employed.
For breathable waterproofing finish, a surface modification using porous film
and conjugated polymer is commercially produced. New technology of improving
the penetration of active chemicals into the fiber, combined with skillful utilization
of polymer film technology was established in order to promote the antimicrobial
and smell-proofing effect. For an effective antistatic finish, new surface modification
technology using grafted polymer film was also established. For making the fiber
electro-conductive, some metals are skillfully adhered to the fiber. This technology
is also included in surface modification.
The purpose of the functional finish is to confer not only physiological comfort,
but also give safety and durability to the textiles.
To make fibers noninflammable and polyester fiber nonmeltable, a combination
of three basic technologies, those are thorough penetration into fiber, graft
polymerization and polymer film technology, is successfully employed. This technology
is characterized by the simultaneous effect of the modifications of the inner
structure and the surface of the fiber.
Most of those technologies are summarized as surface modification technologies.
Other finishers also concentrate their activity on surface modification technologies.
In Japan, functional finish using a photocatalyst is developing although this
technology is still under discussion. In these circumstances, major Japanese
textile processors utilize some surface modification technologies and have applied
for some patents concerning smell-proofing of synthetic fiber, preventing the
adsorption of smell and improving the durability of these effects to washing.This
technology is characterized by using a photocatalyst of the visual light response
type and preventing the dye and the fiber from degradation.
Summary of physical and chemical modification of the fiber
As mentioned above, functional finishes are divided into two categories, named
physical finish and chemical finish. Prof. K. Joukou of Kyoto Women’s Univ.
explained at the Japan Dyers’ Association meeting held in June 20056) ; “The
nature of physical finishes is noncontact and nonaqueous treatment.At present,
physical modifications based on UV, laser and low temperature plasma attract
high attention, and are studied aggressively. One of the advantages of this surface
modification is that the modification is restricted only to the surface, without
influencing any fundamental properties of the fiber. These modification effects
come from chemical and/or physical reactions, but their classification is difficult.”
Reference
5-6) Lecture meeting by K-Jouko at Japan Dyer’s Association meeting |