Japanese Fire Protection Materials Made Of Paper-Thin Material

A fire sometimes seems to arise out of nowhere and can spread so quickly that the people present can hardly be rescued. This is one reason why good fire protection properties for materials used in public areas (aircraft, ships, railways, cars and public buildings such as hotels and theatres) are absolutely essential. Weserland offers halogen-free and low-smoking flame retardant compounds for these areas, which are specially adapted to the respective requirements and applications. In addition to requirements regarding flame protection, smoke gas density and toxicity – the ’classic‘ requirements, such as good cutting edge strengthening or pole and knob integration, as well as antistatic properties can also be met.

Our development teams are happy to look beyond their own horizons and have discovered new material Gulfeng from Toray (Tokyo), which combines very good fire protection properties with very good mechanical properties.

What makes Gulfeng interesting are its mechanical properties and the variety with which the fibres can be processed. Where classic materials tend to be thick and stiff, Gulfeng is thin, light and flexible. It can be woven into fabric, knitted or felted into soft mats. The material is paper-thin (0.06 mm at 60 g/sqm) and can therefore even be used in bedding. Corresponding tests were very successful and showed a good flame retardancy.

The flame-retardant effect of Gulfeng is based on the combination of two materials - polyphenylene sulphide (PPS) and oxidised polyacrylonitrite (Ox-PAN), a non-melting, temperature-resistant fibre made of thermally stabilised PAN.

Carbonization Under Exclusion Of Oxygen

When the material is exposed to a flame, all variants react in the same way: the fabric heats up and begins to melt at 285 °C. The material is then exposed to a flame. The liquid plastic then forms a thin skin around the oxidized fibres, which absorb the heat of the flame in the absence of oxygen and therefore do not burn. This leads to carbonization – the fibres are converted into resistant graphite. The molten material fills the gaps and also carbonizes, creating a closed carbon membrane that forms an excellent barrier against the flames.

Thanks to the good material properties of Gulfeng, a high level of comfort and very thin padding can be achieved. Many airlines fight for every millimetre, especially when it comes to aircraft seating.  

Another interesting development is a base material for artificial leather. Together with a Japanese artificial leather manufacturer, a light and thin material was created - and since it uses Gulfeng as the base fabric, the flame retardant is already built in. Normal artificial leather requires an additional layer as a flame blocker between the outer material and the seat upholstery. This can be omitted with the special leather or be significantly thinner, which saves weight overall and facilitates manufacture.



Functional Coating: Atmospheric Pressure Plasma Treatment On 3D Printed Polymer Surfaces

3D-printed components have an unmistakable advantage: they have a very free shape. But when it comes to coating, especially when other materials are subsequently functionalized, this free form may become a problem. The free form of the 3D components makes them inaccessible to many coating processes, especially low-pressure ones. In addition, it is difficult to combine 3D printing processes such as fused deposition modelling (FDM) with low-pressure coating processes such as sputter deposition, evaporation, plasma-assisted chemical vapour deposition.

The actual material surface is an important influencing factor that significantly determines the usability of many plastic materials. The aim is to change surface chemistry through coating and functionalisation processes. In the case of coatings, the layer-forming material brings the required chemical groups with it, while functionalization causes the chemical groups to couple directly to the surface.

The aim is to create surfaces that strengthen or reduce adhesion to other coatings or materials, reduce migration of plasticizers and improve mechanical or chemical resistance to environmental influences.

Dr Thomas Neubert, project manager at the Fraunhofer Institute for Thin Films and Surface Technology in Braunschweig, Germany, writes in an article in the journal 'Plastverarbeiter' that one solution could be to use the atmospheric pressure plasma process, which can be integrated into FDM systems in the form of plasma jets.

Combination Of 3D Printing And Plasma Jet Coating

At the Fraunhofer Institute, so-called dielectrically impeded discharges (DBE) are used. High voltages lead to an electrical gas-discharge in a gap between two electrodes, which serves as the actual energy source. It has been shown that the combination of 3D printing and plasma jet coating also successfully coats the inner surfaces of the polymer implants. Depending on the structure density, the working gas flow and the precursor vapour pressure, the coatings penetrated several millimetres into the polymer structure. It is also possible to pulse the electrical power of the plasma jet, thereby possibly increasing the density of the nucleophilic groups on the substrate surface.

The concentration on such a process becomes clear when one considers that atmospheric pressure plasma processes - compared to other gas-phase coating processes - are characterized by low investment costs, high treatment speeds and good scalability. In addition, there are various industrially established treatment sources for flat, curved or three-dimensional substrates.

Transparency And Traceability Of Products Through Pigment Signatures

75 per cent of all consumers in surveys typically state that they would buy sustainable products if they were clearer about the positive effect or could believe the claims. For the industry, this means creating comprehensive and completely transparent traceability in order to convince the customer, even the consumer, and not only to rely on his 'blind' trust. It must clearly state what is happening in the value chain and where the raw material originates.

The aim of such an 'optical fingerprint' is always to become a part of the product to be protected as early as possible in the existing production process, without influencing either the product characteristics or the manufacturing process. With pigments such as 'Cotton 4.0' from Tailorlux, this hurdle seems to have been overcome.

Particularly in the area of certified organic cotton, certain additives to cotton are viewed extremely critically, as Matthias Funke of Tailorlux reports in 'Melliand Textilberichten 1/19'. The Münster-based company's optical fingerprinting process is based on luminescence, inorganic substances that are chemically inert and non-toxic. Due to the extremely high emission intensity for UV light, an extremely low concentration of pigments is required to enable reliable measurement by sensors.

Traceability Without Influencing The Product

The decisive factor in this form of marking is that the introduction of limited quantities of foreign fibres during the spinning process only has a minimal effect on the physical properties of the semi-finished product and the finished products.

How can this be achieved? Now, for marking, the pigments are inserted into a prepared fibre. This fibre can consist of different base materials, identical marker fibres are then introduced into the batch of cotton to be marked employing a fibre dosing machine in the cotton mill.

Due to the minimal concentration, these are not sorted out by systems for the detection of foreign fibres, but are further processed like the cotton itself. The marking is thus distributed extremely homogeneously in the raw material and can de facto be traced at every point of the finished fabric. In fact, by using an appropriate sensor technology, it is possible to verify the marking in 1-3 seconds.

Testing At Every Point In The Value Chain

In this way, tests can be carried out at virtually any point in the value chain and it's as simple as can be. A decisive point compared to technologies that rely on laboratory analyses is that they are practically unsuitable for use in the field. One reason for this is undoubtedly that the processing of the raw mass is generally carried out at a speed that ensures that no intervention – based on measurement results – is possible at any point.

With modern methods such as 'Cotton 4.0', the measurement data is loaded directly into a cloud, which means that the verification of the certificates is permanently available – for producers, traders and consumers alike.

New Polyamides: Better Flame Resistance And Improved Physical Properties

A typical textile sample does not flare up suddenly as usual, but only hesitantly begins to melt. At first, the fabric only contracts and dark polymer droplets fall off very late ... An excellent result for flame retardancy, which was made possible by a new development by the "Deutschen Institute für Textil- und Faserforschung [German Institutes for Textile and Fibre Research]" (DITF). As the trade journal "Melliand Textilberichte" reports, it was possible to achieve a kind of intrinsic flame resistance for the first time, because the properties are directly part of the polymer chains of the material.

Flame retardant phosphorus compounds are usually added to the polymers as additives. However, large quantities of phosphorus compounds are required to achieve a good fire protection effect. And this is usually done at the expense of the physical and physiological properties of the textiles.

Contrary to the usual methods of adding flame-retardant properties to the polymer using phosphorus compounds as an additive, the researchers from Denkendorf with this new method were able to incorporate these directly into the polymer chains at low concentrations. This takes place directly during polycondensation, i.e. the synthesis of the plastic in reactor vessels.

In general, the aim here is to produce molecules with as long a chain as possible in order to guarantee good properties for later spin ability of the polymer granulate into textile fibres.

Fewer Phosphate Compounds With The Same Properties

One problem of traditional manufacturing processes is that when larger amounts of phosphorus compounds are added as additives, they prevent the formation of long molecular chains - they thus act as chain breakers. The resulting plastic is very difficult to process into fibres, and in addition, due to ageing and washing processes, the additive emerges from the fibre over time.

The new process allows compounds to be chemically coupled to the molecular chains and thus achieves a much stronger bond to the polymer - more than would be possible with additive blends.

The reduction of the required flame retardants makes it much easier to control the achievable molecular weight during synthesis, according to the journal. In this way, the viscosities can be precisely adjusted to guarantee the optimum spin ability of the polymer into fibres.

In addition, the chemical bonding of the flame retardants to the polymers prevents migration and leaking from the fibres due to ageing, which is common with the use of additives.

In their application, such textiles made of intrinsically flame-retardant polyamides show their advantages, especially where high flame-retardant requirements are placed on the materials. This is usually the case in home textiles like carpets, upholstery and seat covers or curtains.

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