ALPATEC MG 2.1 Manual de usuario descargar pdf (Pagina 7)

UNITEX nr. 1 - 2014

Figure 4: weight loss of 100% UV coating containing

0, 5, 10 or 20% sol-gel additive after sandpaper test

It can be seen that the addition of already 5% sol-gel

additive signicantly improves the abrasion resistance,

with similar results for the two sol-gel systems. Without

sol-gel additives the weight loss is 7.6% while adding

5% sol-gel additive the weight loss can be reduced

to approximately 3%. By adding 20% very good

resistance is obtained as the weight loss is only 0.9%

after 500 cycles.

For water-based systems very good results were

obtained with Laromer PE 55 WN (polyester acrylate,

BASF). The results for the abrasion testing described

above are shown in gure 5.

Figure 5: weight loss of water-based UV coating containing

0, 1, 5 or 10% sol-gel additive after sandpaper test

Similar as for the 100% systems, the presence of 5%

or more of sol-gel additive increases the abrasion

resistance signicantly, reected in a decreased weight

loss of the coating. For 10% sol-gel additive the weight

loss is half of that of the coating without additive.

Low-viscosity formulations – textile ﬁnishes

It was only possible to prepare low-viscosity

formulations from water-based binders. Here Laromer

PE 55 WN, Bayhydrol XP 2649 (urethane acrylate,

Bayer) and Bayhydrol 10777 (urethane acrylate, Bayer)

were found suitable for nishing PES fabrics by pad-

bath application (gure 6).

Figure 6: set-up for pad-bath nishing of fabrics

After padding, water was removed by drying in a thermal

oven at 100° C for 2 minutes, followed by UV curing

(4s illumination). For improving the abrasion resistance,

the water-based sol-gel system (F3) was found most

suitable. For the nished polyester fabrics the abrasion

resistance was evaluated by the Martindale test (ISO

12947 part 2), with testing being stopped after 100’000

cycles or when two yarns were broken. The results are

summarized in table 1.

In the rst column, the result for an untreated polyester

fabric is shown. No yarn breakage was observed after

100’000 cycles, but the fabric shows severe thinning,

being almost translucent.

Table 1: abrasion testing (Martindale) of polyester fabrics nished with hybrid

sol-gel and UV curable formulation

While looking at the results of the nished fabrics, it

can be seen that at low sol-gel concentrations (1%),

the resistance against abrasion is decreased, with no

signicant difference between the different binders. At

a sol-gel concentration of 5% the resistance to abrasion

is substantially improved. This is not reected in the

number of cycles but in the fabric remaining opaque,

indicating that less material is being removed. The effect

of the sol-gel concentration observed here follows the

results obtained for the fabric coatings (gure 5).

Conclusions and further research

The results of this study show that sol-gel

functionalization of fabrics by UV curing is feasible

for 100% coatings, water-based coatings and water

based nishes. The combination of UV curing and sol-

gel leads to substantial improvement of the abrasion

resistance.

From these results, it can be concluded that UV curing

is an eco-friendly technology suitable for application in

the textile industry. In the follow-up project LEDcure,

the adaptation of the curing formulation to different

types of UV lamps, especially new developments in

LED lamps, is being studied, focussing not only on

textile coating and nishing but also on impregnation

for use as composite pre-pregs.

The conventional UV light emits harmful UV-C radiation

together with high amounts of IR radiation (heat).

UV-C light produces toxic ozone and is dangerous to

human skin. As a result, respective UV lamps must

be shielded and ozone removal must be provided to

protect employees. On the other hand, the IR radiation

can be a problem for heat sensitive substrates.

By replacing the conventional UV lamp by an UV-LED

lamp, these problems are mostly annihilated. UV-LED

lamps only emit small-band UV-A radiation in a less

dangerous frequency range meaning that no ozone is

formed and no heat radiation occurs. However, due

to the narrow frequency band of the emitted light,

the chemistry of the formulations must be adapted

(especially the choice of photo-initiator).

Acknowledgements

The authors would like to thank Cornet and IWT

Flanders for supporting the research projects Hybritex

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