Gore-Tex
Gore-Tex (pronunciation: [ 'go: ɐ̯tɛks ], also common in German [ ' go: rɛtɛks ]) is the trade name of WL Gore & Associates for a microporous membrane ( moisture barrier membrane ) made of expanded polytetrafluoroethylene (ePTFE), the windproof, waterproof, but water vapor permeable and thus breathable, whereby the breathability is set limits during great efforts. This membrane has about 1.3 billion pores / cm 2 , the diameter of which is one 20,000th of a water drop, but about 770 times the size of a water vapor molecule . This keeps rainwater outside, but steam can escape. Because of these properties, it is suitable for processing in functional textiles such as sports, leisure and protective work clothing.
Similar membranes are Sympatex and Hipora .
Manufacture of the membrane
According to information from WL Gore & Associates , Robert W. Gore discovered in 1969 that PTFE was not destroyed when stretching quickly , but that the stretched (expanded) ePTFE was solid and highly porous. This discovery was the starting point for numerous product developments by the company based on ePTFE. The membrane can only be produced by paste extrusion. This requires a mixture of the PTFE granulate with a lubricant (for example high-boiling aliphatic hydrocarbons ). The lubricant is removed from the PTFE film by heating to a maximum of 327 ° C (melting point of the PTFE). The film is then stretched uniaxially or biaxially, creating the microporous structure. The basic product and process developments for microporous PTFE products by inventor Robert W. Gore were laid down by WL Gore & Associates in US Patents 3,953,566 and 3,962,153.
functionality
A small amount of the polymer is sufficient to create the airy, lattice-like structure . ePTFE is used in gas and liquid filtration, sealing technology and as medical implants. The best known are the Gore-Tex functional textiles.
Water droplets are 20,000 times the size of the pores in a Gore-Tex membrane. This is why the membrane is impervious to liquid water and wind. However, body moisture is let through as water vapor. When they were launched on the market in 1976, Gore-Tex textiles were the first waterproof and windproof textiles that were permeable to vapor and allowed the evaporation of sweat, which is important for regulating the body's temperature, to be removed.
Gore-Tex-XCR (extended comfort range), which was introduced commercially in 2000, is suitable for an area of application with higher requirements in terms of durability and breathability. In contrast to Gore-Tex clothing, a more powerful membrane technology and particularly durable textiles are used here. In the meantime, XCR has been replaced by Gore-Tex Pro Shell .
The undergarment must also support the membrane by allowing sweat to be transported instead of being absorbed. Cotton is not recommended; synthetic fibers or fine wool such as merino wool are better .
Production of the laminates
In the manufacture of the multi-layer Gore-Tex textile laminates, the ePTFE membrane is permanently and flexibly glued ("laminated") to textiles, mostly polyester or polyamide . These Gore-Tex laminates are processed into garments. The seams are sealed with special sweat tapes. Gore-Tex laminates are only sold to certified processing companies.
Gore-Tex products and their care
Five different variants are available for integrating the membrane into the tissue. The Gore-Tex Windstopper membrane is a windproof layer that, unlike the following membranes, is not waterproof.
Gore-Tex Performance Shell
The membrane and the outer fabric are firmly connected to each other, the (mostly mesh) lining hangs loosely inside. Performance Shell is characterized by a high level of comfort.
Gore-Tex Paclite Shell
Instead of a lining, the membrane has a breathable protective layer on the inside. This makes Paclite very light and packable, but the fabric is much less abrasion-resistant, making it e.g. B. not suitable for heavy backpacks.
Gore-Tex Pro Shell
The membrane is laminated with the outer material and the inner lining to form one layer. This makes the fabric a bit firm, creating the typical “rustling” of a hardshell.
Gore-Tex Soft Shell
In Softshell is a three-layer construction. The laminated inner lining consists of a thin fleece or flannel layer. The main advantage is a very high level of comfort due to the soft lining, as well as the less rustling compared to a hardshell. In addition, thanks to the lining , Soft Shell is the only Gore-Tex laminate that really warms. However, this makes it really only suitable for cold seasons. Breathability is somewhat limited by the rather thick construction.
Gore-Tex Active Shell
By integrating the inner lining in the membrane, increased breathability is achieved. The membrane is thinner, which reduces weight. Another advantage is that it is more comfortable to wear when the garment is worn directly on the skin (“next-to-skin comfort”).
maintenance
The pores of Gore-Tex clothing could be closed by residues of powder detergent . It is therefore recommended to use liquid detergent. Gore-Tex clothing can be sensitive to tumble dryers .
Other uses
Bicycle technology
In bicycle technology , the Gore company offers low-friction and low-maintenance gear and brake cables , in which there is a layer of Teflon between the Bowden cable and the outer shell , which is intended to protect against splash water and make the cables particularly smooth.
medicine
In medicine , Gore-Tex implants and patch materials are used in cardiovascular surgery for vascular prostheses , for hernia sac formation and in ophthalmic surgery for deep corneal ulcers .
Instrument strings
There are various coatings for strings from Gore . They should guarantee protection against moisture and dirt and ensure a longer durability of the strings.
criticism
As with all materials that contain halogenated hydrocarbons, disposal is problematic with Gore-Tex .
The properties of Gore-Tex are only evident when it is significantly colder or drier on the outside than in the clothing, i.e. when there is a sufficient vapor pressure gradient. This is not the case, for example, under backpack straps or when the air humidity or temperature is high.
The short and long-chain fluorocarbon compounds in particular have been shown to be harmful to the environment and health. These can be carcinogenic and mutagenic . Gore has recognized the problem and is already doing without the long-chain perfluorinated and polyfluorinated alkyl compounds . Short-chain connections are also to be dispensed with in the coming years.
swell
- ↑ Petra Knecht (Ed.): Functional textiles . Deutscher Fachverlag, Frankfurt am Main 2003, ISBN 3-87150-833-0 , pp. 287, 279
- ↑ See 1969 on the WL Gore & Associates company timetable . Retrieved November 18, 2014
- ↑ Klaus Ohlrogge, Katrin Ebert (Hrsg.): Membranes - Fundamentals, processes and industrial applications . WILEY-VCH Verlag, Weinheim 2006, ISBN 3-527-30979-9 , pp. 16/17
- ↑ US patent 3953566 “Process for producing porous products” . Retrieved November 18, 2014
- ↑ US Patent 3962153 “Very Highly stretched Polytetrafluoroethylene and process therefor” . Retrieved November 18, 2014
- ^ Page on Gore-Tex in housekeeping.
- ↑ ELIXIR® Strings - guitar strings from Gore , in: http://www.gore.com/de_de/products/consumer/elixir/index.html Status: 7.9.2016
- ↑ Contaminated outdoor clothing: Back to Chemistry - Spiegel Online from October 30, 2012.
- ↑ "Outdoorseiten.net"
- ↑ Gore-Tex: miracle material or chemical club? In: Trekkinglife. January 25, 2018, accessed on January 18, 2020 (German).
