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A cool approach to well-being with textilesDr Raymond Mathis and Dr Annette Mehling of Cognis introduce the concept of cosmetotextiles
Speciality Chemicals Magazine November 2007 27
www.specchemonline.com
Leather & textile chemicals
Textiles are an important inter-
face between human beings
and the surrounding world and
can contribute considerably to feeling
protected and comfortable.
Conventionally, they do this via a
good fit, proper thermal and moisture
management and a pleasant handle.
Today, however, modern finishes can
transform textiles into delivery sys-
tems for cosmetic or sensorial active
ingredients, thus making them truly
‘active’ players that increase our sense
of well-being.
The name ‘cosmetotextiles’ has
been coined for textiles with cosmetic
properties, but these types of textiles
can also harbour other actives, such
as mosquito repellents, odour reduc-
ers, UV- p r o t ection agents or fra-
grances. At Cognis, Skintex technolo-
gy and products are used as cosmetic
finishes for textiles.
Rules of the game
Cosmetic products are defined in the
Seventh amendment of the European
Cosmetics Directive, 76/768/EEC, as
‘any substance or preparation intend-
ed to be placed in contact with the
various external parts of the human
body ... or with a view exclusively or
mainly to cleaning them, perfuming
them, changing their appearance
and/or correcting body odours and/or
protecting them or keeping them in
good condition’.
This implies that the cosmetic
ingredients built into garments must
be transferred to the wearer’s skin to
be considered a cosmetotextile.
Furthermore, the amounts transferred
must be sufficient to ensure that cos-
metic benefits are possible.
Therefore, cosmetotextiles will gen-
erally be characterised by the following
features, which shows that developing
and producing effective cosmetotex-
tiles that will have a strong appeal for
consumers is not an easy ta s k :
• Large volumes of built-in cosmetic
ingredients (up to several % of the
weight of the textile, depending on
functionality)
• Explicit cosmetic performance
claims
• S c i e n t i f i cally substa n t i a t ed claims
via cosmetic efficacy and/or con-
sumer tests
• A finish registered and labelled in
compliance with the Cosmetics
Directive and with a full cosmetic
dossier
Many cosmetic ingredients are
heat-sensitive or prone to oxidation
whereas others, such as perfumes, are
volatile. This is the reason why
micropackaging via microencapsula-
tion is such a key technology for cos-
metotextiles.
Tr a p p ed in microencapsules, sen-
sitive cosmetic ingredients are pro-
t ec t ed from degradation (oxidation,
p o l y m e r i sation, etc.) and can with-
s tand drying and heat-setting
processes. Volatile ingredients (such
as perfumes, essential oils and
coolants) are protec t ed from evapo-
ration, which can increase their
shelf-life.
Microcapsules suitable for cosme-
totextiles have diameters in the range
of about 0.2-10 µm. These miniature
spheres can be customised in terms
of their size, mechanical robustness
and permeability in such a way that
the release profile of their contents is
just right for their intended functional-
ity on the consumer.
Although covalent grafting of
microcapsules especially onto natural
fibres is feasible, the most common
fixation involves the use of a binder
with good skin compatibility. Th e
amount and type of binder used
depends on the textile and must be
adequate to bind the microcapsules
effectively to the fibres and minimise
their loss during laundry.
The release rate of the encapsulat-
ed cosmetic ingredients can be tai-
l o r ed with additional amounts of
binder. The binder to microcapsules
ratio can be selected as needed.
Exhaust application, which is stan-
dard on hosiery and garments, is a far
more complica t ed process, which
requires a very precise steering of
temperature and pH. Another role of
the binder is to secure other more
classic but nevertheless importa n t
properties of the final garment, such
as resistance to aqueous spills or
moisture management, the latter
being critical in modern functional
first layer sportswear.
Performance criteria
The three key elements to be expec t-
ed in the performance of cosmeto-
textiles are sa f e t y, s y n e r g y a n d
q u a n t i t y.
Cosmetotextiles need to be as safe
as cosmetics. A significant part of the
cosmetic dossier that has to be gener-
ated in accordance with the Cosmetics
Directive and later amendments deals
with product safety.
Qualified professionals make sure
that toxicological data for the cosmet-
ic ingredients and the textile auxil-
iaries used in the cosmetotextile’s fin-
ish are available and their toxicologi-
cal profile is satisfactory for use as a
cosmetic ingredient. Risk assessments
are made using end points including
acute oral toxicity, dermal irritation,
mucus membrane irritation, skin sen-
sitisation and mutagenicity.
The absence of a sensitising poten-
tial is generally verified with the help
of a human repeated insult patch test
on 100 or more volunteers. It is per-
formed with a textile sample treated
with a maximised level of finish.
The top performing cosmetotextiles
are those designed in an integ r a t ed
fashion. Fabric composition and con-
struction, garment design and cosmet-
ic finish all work in synergy to generate
the best effects. The Skintex range, for
example, offers different synergies with
different types of textiles.
Skintex Slimming has better effica-
cy in a pair of elastic and tight jeans
SEM image of Skintex microcapsules on polyamide knitwear
Spray reloading of cosmetic effects in textile
Leather & textile chemicals
28 November 2007 Speciality Chemicals Magazine
www.specchemonline.com
which provide a close conta c t
be t w een the fabric and ‘problem’
zones, Skintex Anti-heavy-legs gives
its best performance with pantyhose
featuring a certain level of progressive
compression and Skintex Supercool
will refresh the wearer of a sports shirt
more efficiently if there is a large area
of body contact and moisture absorp-
tion is secured, e.g. with a seamless
microdenier polyamide/elastane con-
struction.
As far as the duration of the cos-
metic functionality is concerned, one
has to distinguish between effects like
moisturising and slimming, which
require large amounts of ingredients
on the skin, and those produced by
minute amounts, as is the case for
perfumes.
One single daily dose of an effec t i v e
skin moisturising formula requires 4%
w/w cosmetic finish/textile for a 20
denier pantyhose and efficacy after
washing is successively lost over time.1
On heavier textiles, moisturising,
slimming or cooling efficacy, for
example, can be expected for five to
20 days of wear and five to ten mild
machine or hand washes. The exact
durability can only be determined
through extensive cosmetic efficacy
testing or consumer testing.
However, the duration of such cos-
metic effects can be increased by
reload systems. Depending on the
type of textiles or the actives, for
example in the case of perfumes and
essential oils, efficacy for ten to 30
machine washes has been demon-
strated.
The general philosophy is quite
simple. Whatever property is claimed
should be perceived by a large major-
ity of consumers. At Cognis, each
Skintex concept is designed to gener-
ate a high level of enjoyment and sat-
isfaction. After internal verification that
clear effects are obtained, scientific
confirmation is generated at inde-
pendent research institutes.
Cool as menthol
The refreshing feeling of the wind
caressing our skin, the shocking feel-
ing of cold when ice cubes glide
down our backs or the painful sensa-
tion of touching a hot object are all
generated by an intricate network of
nerves, and receptors that transmits
signals to our brains.
Most external stimulants act on
r eceptors that in turn trigger the
nerves which then transmit the sig-
nals. The types of signal, their intensi-
ty and the area of the brain involved
in processing the signal then deter-
mine how we perceive the sensation.
The skin has three major classes of
receptors: temperature receptors (hot
and cold), nociceptors (for pain) and
contact receptors (for touch, vibration,
pressure and tickle). Contact with skin
usually activates multiple classes of
receptors which act in concert to gen-
erate a total pattern of responses
resulting in a sensation.
Due to its highly valued properties
for providing a refreshing and cooling
s e n sation on the skin and mucus
membranes, menthol and its deriva-
tives have been used for many years in
cosmetic and pharmaceutical products.
In this context, it should be noted
that they do not bring about physica l
cooling, in which a cooling sensation is
i m p a r t ed by the decrease of the out-
side temperature, but physiologica l
cooling, in which a cooling sensa t i o n
on the skin is imparted via the stimula-
tion of receptors, without the tempera-
ture of the skin actually being lowered .
Skintex Supercool is ba s ed on
e n ca p s u l a t ed menthol along with
emollients and synthetic, long-lasting
coolants. Tests were carried out on 24
healthy and informed volunteers to
evaluate the efficacy of T-shirts treated
with it, guided by the principles of
Good Clinical Practice. Prior to testing,
toxicological clearance was obtained.
The test volunteers were asked to
assess the cooling effect of a treated T-
shirt subjectively when exercising. The
wash-and-wear efficacy was assessed
using polyamide/elastane sport shirts
treated with the standard hydrophilic
formula for Skintex Supercool.
The volunteers wore one each of
the test T-shirts (which had variously
undergone no, two, four or six
machine washes with the ISO
normed ECE detergent at 40°C) ran-
domised at each session during a 30
minute treadmill run and then filled
out an extensive questionnaire after
each run at an independent research
institute. Over 60% of the volunteers
still noticed the cooling effect after the
sixth wash (Figure 1a).
Another important aspect is when
the cooling effect starts. Figure 1b
depicts the results of the self-perceived
e f f ects evaluated via the questionnaire.
Most subjects noticed an effect in the
first minutes after starting to exercise
or when sweating began. The effec t
was most noticed on the back, shoul-
der, armpits and chest, i.e. those areas
most prone to sweating.
Outlook
Bringing perceivable cosmetic per-
formance to textiles is a quite a chal-
lenge. Skintex Supercool is just one
example of the challenge being met,
although further optimisation is possi-
ble. New functionalities, made possi-
ble by the constantly evolving world
of cosmetic ingredients, can be intro-
duced year after year.
Much needed norms are in prepa-
ration at EU level, which will give ori-
entation to textile brands and con-
sumers, putting them in a position to
make clear choices for serious solu-
tions for cosmetotextiles. The concept
of cosmetotextiles with proven per-
ceivable effects should make textiles
more attractive again by adding value
and more fun.
For more information, please
contact:
Dr Raymond Mathis
Cognis GmbH
Rheinpromenade 1
D-40789 Monheim, Germany
Tel: +49 2173 4995 430
E-mail: raymond.mathis@
cognis.com
Website: www.cognis.com
References:1 . R. Mathis, Proceedings of the 10th
International Izmir Textile & Apparel
Symposium, 2 0 0 4
Efficacy tests with Skintex Supercool
Figure 1 - Efficacy tests to assess the cooling effects of Skintex Supercool
after washing (a) & the time of onset of the cooling effect (b)