A single square meter of Luquafleece™, which is only a few millimeters thick when dry, can absorb 26 liters of water.
In shoes, nonwovens ensure dry feet in the wet and full air permeability in dry conditions.
Whether in rain or sunshine, children prefer to play outside. But splashing around in puddles is no longer fun when shoes are wet through. Rubber boots keep the moisture out, but they rapidly turn into foot saunas.
So how can a shoe keep the rain out, yet provide sufficient air circulation for delicate young feet? Luquafleece™ is incorporated in a ventilation component produced by IQTEX. On contact with water, the tiny polymer granules of the superabsorber, which are bound to the nonwoven fibers, absorb up to 500 times their own weight of liquid and swell proportionally.
This massive absorbency is due to the molecular structure of the superabsorber, which is based on acrylic acid. BASF chemists form long chains with widely spaced links out of these countless small molecules. The result is a loose molecule bundle, which absorbs water like a sponge. However, it is the strong ion charge in the material that is responsible for the high absorbency. It builds up osmotic pressure, which sucks the surrounding water into the polymer network. Water is absorbed until the polymer network offsets the osmotic forces through its elastic resilience. The ventilation component exploits the enormous thirst of the small particles to seal the inside of the children’s shoe against water from outside: two honeycomb-shaped grids stop the small Luquafleece™ particles from spreading upwards or downwards. The only exit for the swelling superabsorber particles is to the side, where they soon meet and seal off all the cavities of the nonwoven. On contact with water, the previously highly permeable Luquafleece™ thus very rapidly becomes absolutely waterproof. Once the environment is dry again, the water absorbed by Luquafleece™ evaporates, the pores open at a speed that depends on temperature and air moisture – and the air can circulate freely again.
Shoes are just one of numerous potential applications for the new miniature “flood barrier”, which can be widely varied in size and positioning. There are numerous potential uses for ventilation openings that seal automatically when it rains, above all in the outdoor sector: tents, sleeping bags and jackets, which otherwise become mini greenhouses, can be made much airier, while providing full protection against moisture.