Hook and loop fastener

The Velcro fastener is mainly a fabric, almost any number of times to be solved closure means, which is based on the principle of Velcro fruits. The bionic realization consists in the typical form of two woven synthetic fiber strips, one of which is flexible barbs that has other loops. Pressed Together they create a stress-resistant, but reversible snap closure. The Velcro woven made ​​of polyamide, polyester and polyolefin fibers. For special products, fibers from polyaramides be used. When the hook strips, the hooks are incorporated during the weaving or later. To test textile Velcro fasteners DIN EN 12242:1999 serves. Characteristic values ​​are the tensile shear strength, tensile strength [ Stirnabreißfestigkeit ] and the peel resistance. Velcro and snap fasteners (see below) can be coated with adhesive and pressure sensitive adhesive on the back.

History

The Swiss engineer Georges de Mestral took his dogs often walks in nature. Again and again ( Arctium lappa ) some fruits of burdock came with the fur of the dogs in contact and got stuck in it. He put the fruits under his microscope and discovered that they wear tiny elastic hooks that do not break even with violent removal from hair or clothes. Mestral examined their condition and saw an opportunity to combine two materials reversibly in a simple way. He developed the textile Velcro and announced his idea in 1951 for a patent. The product was marketed for the first time under the name Velcro, composed of the French words velours ( " velvet " ) and crochet ( "hook" ).

Varieties

Different variants have been developed in the meantime from the abgeschauten of the natural principle:

• Hook and loop tape ( Filzband ) ( typical application for clothing)
• Mushroom headband and velor band ( stronger adhesion )
• Mushroom head band and loop tape ( high holding forces at shear stress)
• Mushroom head band mushroom head band ( typical industrial application, with a defined pressure point, high holding forces in shear and tensile stress )
• Extruded hooks / mushrooms on knitwear ( a diaper closure )

Applications

Be used Velcro fasteners example of shoes and clothing, blood pressure cuffs, to diapers, to fix artificial turf surfaces, carpets, plan attachment to backpacks and bags at trade fairs, in tools, in cars, in space suits of astronauts and as cable ties.

A loop tape can also be used for bondage.

• Application Examples

Velcro on a bracer

Cable tie with Velcro on one power supply

Development

• There have been approximately 1986 Velcro straps with metal hooks and loops and a floor made of Kevlar, which were intended for use in high temperature areas, but have been the high price is not often used due. After the Apollo disaster in 1967, caused by a cabin fire, NASA called for a completely non-flammable Velcro glass fiber, which was then produced and used.
• For firefighters and racing clothing, there are also Velcro fasteners that are completely made ​​of Nomex and are not flammable. Special Velcro strips are also used in the aviation industry. This involves taking specially impregnated velcro strips that are self extinguishing in case of fire.
• Since 2009 it is also under the brand name Metaklett detachable connections from stamped, thin chromium -nickel sheets, which operate on the principle of Velcro. These are characterized by high holding forces and high resistance to thermal and chemical influences. The product was awarded the 2009 Steel Innovation Award.

• The 3M company developed a " mushroom head " Velcro, what with only one component of the Velcro works. Instead of the hook smallest hemisphere heads ( 26, 40, 62 or 110 stems per square centimeter on a short punches) are made from polyolefins, these are arranged wavy or parallel and ensure optimum holding power and removability. The mushroom caps slide over each other until they are anchored by pressure into each other. The zip lock closure with a thickness of about 4 mm, can be claimed by both perpendicular to train as well as shear. The train and shear strengths of the pressure locks are very different and are on the number of mushroom heads / cm ², which can be combined, depending. Through a peeling motion of the shutter will open. With a compound version of the thinnest thickness of 1.7 mm, is transparent and carries on 3M the designation " Dual Lock SJ4570 ". Now 0.87 mm thick combinations of a mushroom head and a Velcro band are also provided for closures of packagings.

Velcro can be sewn or welded onto textiles, rigid surfaces, the Velcro straps are also glued. To accomplish this, the backs of adhesive coatings, the shear forces are usually greater than the shear forces of the hook and loop fasteners.

Trivia

As a result, Carbon Creek ( 2002) TV series Enterprise is called one of the companions of volcanic T'Mir ( the great-grandmother of T'Pol ) Mestral. This naming understood the screenwriter as a tribute to the inventor George de Mestral. T'Mir sold at the end of the episode the velcro closure, which is a volcanic invention in the series, to a company, to a young man to finance her studies. Mestral remains as a single Vulcan on earth.