Nonwovens And Nanofibers: New Manufacturing Processes For Reinforcement And Finishing

The production of smallest structures from micro- to nanofibers enables a highly efficient application in areas such as acoustics and filtration. Special emphasis is increasingly placed on promoting the development of environmentally friendly, solvent-free and ultimately cost-efficient manufacturing processes. The aim is to produce modern processes for nanofibers from polypropylene and other thermoplastics.

Harry Albus of JX Nippon, respectively of the JXTG Nippon Group, presents some current examples in his report in the trade journal "Technische Textilien" (3/18): Cross Laminated Airy Fabric (CLAF), Milife and nanofibers from multifilaments.

CLAF is used to reinforce nonwovens, foils, paper, etc. High tensile and tear strength, breathability, water and chemical resistance and dimensional stability in further processing are the "core competencies" of reinforcing fabrics. The aim is to increase the performance of the textile and reduce production costs. Bonding with other materials can be carried out thermally or by ultrasound, as well as by all other common laminating processes and by needle or water steel bonding.

High tensile and tear strength, good breathability, dyeability, printability and dimensional stability in further processing characterize the polyester nonwoven fabric "Milife". The molecular orientation of polyester melt-blown continuous filaments gives this melt-blown nonwoven high tensile strength combined with low basis weights and material thicknesses. During the process, a silk-like surface is created using a special process.

In addition to reinforcing other textiles, the aim of this development is particularly to optically and haptically refine the resulting final textile. Applications include interior design (e.g. pleats and wall coverings), packaging, medicine, adhesive tapes and other materials.

Nanofibers, Fanned Out By Vacuum And Melted By Laser

Solvent-free production of nanofibers from polypropylene is another focus of development at JXTG. The development of the laser-supersonic-stretching method makes it possible to produce nanofibers solvent-free, more homogeneous, more productive and, in addition to many other thermoplastics, also from polypropylene. The starting products from which the nanofibers are made are multifilaments that are drawn into a production chamber by means of a vacuum.

The vacuum causes the multifilaments to vibrate and they fan out. The individual filaments now released are melted - hit by a CO2 laser. The permanent vacuum draws the nanofibers from each individual filament, which are then homogeneously deposited on a freely selectable nonwoven carrier.


Sustainability: The industry change in the textile industry is unstoppable

Over the next few years, manufacturers and suppliers - from the chemical industry to the producer of the end products - will have to increasingly address the issue of sustainability. Start: Now. Because the environmental impacts of the textile industry are all too well known - from pesticide pollution and high water requirements during cultivation, to high C02 emissions during the production of synthetic fibers, to the unsafe handling of chemicals that are harmful to health and the environment during the manufacturing process, and the pollution of water bodies due to inadequate wastewater management. And consumers - the users - are increasingly demanding that this situation ist to be changed sustainably.
Criticism already starts at the conceptual level, so a reorientation must offer a clearly changed design approach for industrial and organisational problems - and is closely linked to a cradle-to-cradle design principle. This universal approach to sustainable design transforms linear production chains into closed material cycles and ultimately calls for the emergence of new business models.
The days when sustainability was more of a 'nice to have' are clearly over. Today it is a clear 'must have', a trend that is unavoidable all in all, and thus also a competitive advantage - which does not have to be a disadvantage on many levels, but on the contrary promises good turnovers and profits. In addition to the complete elimination of the waste problem through the cradle-to-cradle principle mentioned above, there are other approaches to raising recycling processes and products to a new quality standard.

Transparency And Identification As Characteristics

Nevertheless, further research and in-depth industrial restructuring are needed to make such technologies suitable for large-scale deployment. This does not only apply to the product as such, but also to all preliminary stages and resources. What is decisive for the quality of the novel recycling products is what takes place at the beginning of the textile value chain. And here the choice of fibres comes first. Some fibres or fibre blends are easier to transfer into a closed material cycle - because not all products can be produced from easily recyclable natural fibres.
The first promising approaches for clear and forgery-proof labelling and identification of fibres are chemical markings with pigments, identification via QR codes and the blockchain technology, which is becoming increasingly popular. In fact, traceability and transparency are becoming more and more important.

3-D Textiles Protect Against Extreme Heat Loads

The ideal complement to conventional protective clothing are functionalized, so-called three-dimensional undergarments. This newly developed protective clothing consists of a multi-layer structure in which the different layers assume different functions. The central role is played by a spacer fabric.

The protective effect of this spacer knit is based on the one hand on the avoidance of skin contact with the layers of protective clothing above, in order to prevent scalding caused by one's own body sweat, and on the other hand on a cooling effect produced by moisture removal. The knitted fabric works particularly well by producing locally different stiffnesses. The stiffness can be adjusted precisely on the machine side via the pile yarn and changed flexibly during the process.

In Germany, around 10 percent of the workforce are exposed to high temperatures at their workplaces, write the authors Lukas Lechthaler, Kristina Simonis, Marie-Isabel Popzyk, Christoph Peiner, Thomas Gries from the Institute of Textile Technology at RWTH Aachen University (ITA), Aachen and Markus Tutsch from STS Textiles GmbH & Co. KG, Grunbach, in their article in Technical Textiles. And complement them: In addition to intense physical exertion, an increased ambient temperature can lead to an increase in body temperature and thus to life-threatening heat shocks (from 40° C body temperature). This danger can and must be countered with the use of suitable protective clothing. It also shows the need to develop new materials.

A New Approach To Heat Protection

Within the framework of the research project "Development of heat-exposed occupational safety textiles", the focus is on the deeper layers of clothing. As a rule, conventional cotton underwear is used to absorb moisture, while the outer layers protect against heat radiation and burns. The cottonis in direct contact with the skin and can absorb and store large amounts of moisture due to its good absorption properties. The problem with this is that the stored moisture leads to a strong warming due to heating from the outside, which is not absorbed by protective clothing. This can actually lead to scalding and overheating due to the body's own perspiration.

The share of this heat damage in all accidents at work is about 50 percent for heat-exposed workplaces in Germany. The aim is to reduce this proportion to 10 percent by using 3D underwear.

Pressure-loaded areas in particular are reinforced locally in order to reliably prevent contact between the skin and the layer of protective clothing above it. In highly stressed areas such as knees, elbows or shoulders, local reinforcements must therefore be provided via stiffer pile threads that keep the needed distance. According to the current state of research, however, there is no possibility of changing the stiffness of the pile yarn during the production process.



Lower Pollutant Load Due to the Use of Thermoplastic Elastomers in Vehicle Interiors

For most people, the most conspicuous type of emission from a car is usually found in the interior - the smell. The substances in the air can come from a wide variety of interior components. In the past, plastic parts, in particular, have often attracted attention due to an unpleasant odour. It is interesting to note that in Europe and America a 'new car smell' is predominantly rated as pleasant, whilst in Asia it is often perceived as disturbing. The use of new types of elastomers is intended to significantly reduce the load in the future.

Air quality is generally a major issue in the automotive industry, but in addition to CO2 and nitrogen emissions to the environment, indoor air quality is now also of great importance – ultimately for both manufacturers and customers. In some countries, such as China, Japan and Korea, legal standards have even been introduced in recent years that clearly regulate the maximum concentration of some pollutants in the interior. It is therefore very likely that such or similar standards will also be applied in Europe and America in the same way in the future.

Emission values are among the most important material properties for automotive interiors, as they also make a significant contribution to driving comfort. For this reason, components must not release any substances into the air over a long period of time that could attract attention through unpleasant odours or impair the health of the occupants, write Florian Dresel and Dr.-lng. Thomas Köppl of Hexpol TPE in Lichtenfels in an article for the magazine ‘Plastverarbeiter’.

Emission And Solution Approaches

High-quality thermoplastic elastomers (TPE) are actually perceived positively by people with four of the five classic senses and are therefore increasingly being used in automotive interiors. This makes it particularly clear how important it is to select the right solutions. Mixtures and raw materials must be chosen carefully and with great effort.

In addition to the technical properties of materials, great importance is now also attached to the origin and sustainability of the raw materials. For this reason, the production of plastics from fossil raw materials is increasingly criticized. As an environmentally friendly alternative, products are therefore being developed that contain large amounts of plant-based raw materials. Moreover, these renewable raw materials, such as sugar cane, often originate from certified sustainable cultivation (e.g. ISCC+) and thus contribute to reducing the CO2 footprint. Depending on the hardness of the material, even a bio-based content of up to 90 per cent is possible.

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