Performance Apparel Markets - Grado Zero Espace Srl
Performance Apparel Markets - Grado Zero Espace Srl
Performance Apparel Markets - Grado Zero Espace Srl
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<strong>Performance</strong> <strong>Apparel</strong> <strong>Markets</strong>, 1st quarter 2006<br />
Seamless knitting and stitch-free technologies<br />
polymer types include polyurethane, polyester, nylon and<br />
polyolefin.<br />
—the thickness or gauge—<br />
—the film’s softening<br />
point, at which it begins to<br />
melt and flow—<br />
—and the melt flow index,<br />
indicating how an adhesive<br />
flows once it has melted<br />
A heat seal press may be<br />
used<br />
During production three<br />
key factors must be met<br />
precisely and monitored—<br />
—heat—<br />
—pressure—<br />
—and time<br />
Ultrasonic welding<br />
involves channelling high<br />
frequency vibratory waves<br />
to build up heat in fibres<br />
It is fast, accurate and fabrics<br />
stay soft and breathable<br />
Ultrasonic welding can be<br />
used on nylon—<br />
● A second property is the thickness or gauge of the film, which<br />
helps to determine its weight. Heavier fabrics require a thicker<br />
film for optimum bonding while lighter weight fabrics require a<br />
thinner film.<br />
● A third property is the film’s softening point—or the temperature<br />
at which it begins to melt and flow. As a general rule, the<br />
minimum set temperature to activate a thermoplastic film is 15°C<br />
above its softening point. Importantly, the film should have a<br />
lower melting temperature than the fabrics being bonded.<br />
● A fourth property is the melt flow index. This is an indication of<br />
how the thermoplastic flows once it has melted. A thermoplastic<br />
with a high melt flow index will flow rapidly after melting<br />
(similar to water) whereas one with a low melt flow index will<br />
flow more slowly (more like honey). High melt flow<br />
thermoplastics penetrate more quickly into fabrics than do low<br />
melt flow thermoplastics, resulting in a better mechanical bond.<br />
In order to activate thermoplastic films, a heat seal press may be<br />
used.<br />
During the production process, three key factors must be met precisely<br />
and monitored to ensure a strong and durable bond: heat, pressure and<br />
time.<br />
● Heat: during production the critical temperature is the glue line<br />
temperature (GLT)—which is the temperature at the interface<br />
between the two fabrics.<br />
● Pressure: this is usually applied by a pneumatic cylinder.<br />
● Time: for the thermoplastic to melt and flow into a fabric<br />
adequately, heat and pressure need to be applied for a precise<br />
amount of time.<br />
WELDING BY ULTRASONIC HEATING<br />
Ultrasonic welding involves channelling high frequency vibratory<br />
waves (typically 20 KHz or more) so that they cause a rapid build-up<br />
of heat in synthetic fabrics. The heat can be used to weld or cut the<br />
fabrics.<br />
Proponents claim that ultrasonic welding is fast, accurate and efficient.<br />
Also, fabrics retain their softness and breathability.<br />
Ultrasonic welding can be used to cut or weld materials such as:<br />
● nylon;<br />
24 © Textiles Intelligence Limited