A Cool Approach to Well-being With Textiles

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)