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.

New Water-Based Latex Dispersion For Abrasive Carrier Textiles

Abrasives such as abrasive belts, fibre discs, flap discs, abrasive sleeves and polishing tools are available in a wide variety of designs, sizes and formats. They are not only used for sharpening, but also for smoothing and polishing objects and for dimensional stability. Textile-based industrial abrasives are one of the key segments of abrasives.

For decades, aqueous polymer dispersions have increasingly been used to manufacture such products – to improve mechanical and thermal resistance as well as adhesion between layers as muchas extending the service life of the material.

Aqueous latex dispersions give industrial abrasives on textile substrates important properties such as flexibility, heat resistance and durability during the actual grinding process. Typically, the abrasive consists of an impregnated fabric made of cotton, polyester or a blend as carrier. The backing is lacquered on the back and the abrasive particles sit on the backing, fixed with phenolic resin.

The use of aqueous polymer dispersions to impregnate and coat the backing allows modifications to the stiffness of the fabric. It improves the mechanical properties and adhesion between the abrasive particle layer and the backing. It also improves heat resistance and durability to coolants. And it also acts as a barrier to prevent the phenolic resin from damaging the backing through the top layer, write Michael Karnop and Sören Butz of Synthomer Deutschland GmbH in the trade journal Melliand International.

Optimisation And Quality

Newer products have better peel strength and higher thermal resistance and are clearly more environmentally friendly.
 The parameters of the polymerization process are optimized to ensure a clean, low VOC product with low CO2 emissions.

One of the key functions of such a polymer dispersion in textile-based abrasives is to improve the mechanical bond between the abrasive particles and the backing, regardless of the fibre type. This contributes directly to the durability and life of the abrasive.

Grinding and polishing is usually carried out at a very high speed. Thermal resistance is therefore a decisive property that must be taken into account when developing a high-performance dispersion for industrial abrasives. The composition of this polymer dispersion, in particular the monomers and crosslinker components, has a significant influence on the thermal resistance.

New products also have good compatibility with phenolic resin, which is often used to grind the sand fixation on the surface. By mixing a small amount of these products with the resin, a change in flexibility is achieved so that the final product can withstand the bending process towards the end of production. This involves stretching and bending abrasives at different angles to better match the abrasives and substrates.

By optimizing process parameters and modern quality control, current products can be developed that contain ten percent more solids with a constant particle size distribution than their predecessors.

Fibre-Plastic Composites As High-Performance Products And Smart Materials

Technical textiles are assigned more and more properties. Fibre-plastic composites (FKV) are already being used as promising smart materials. These belong to a special type of functional materials that perceive environmental stimuli, react to them and can return to their original state once the stimulus has subsided.

For 20 years now, FKV have enjoyed increasing popularity in the field of resource-efficient mobility. Due to their high stiffness and low weight compared to traditional materials such as aluminium, steel or magnesium, FKVs are used as load-bearing structures in aircraft, automotive, rail and marine traffic.

By integrating functional materials into layered structures, they are provided with structure-integrated functions, such as lighting, de-lcing or continuous structure monitoring, as well as guidance and activation functions. They thus become said smart materials.

Particularly promising smart materials are shape memory alloys (FGL), which are characterized by a high energy density, a high force generation potential and enormous formability and stability in the high-temperature phase. The integration of the FGL during the manufacturing process of reinforcing fabrics guarantees long-term stability, reproducibility and cost reduction with regard to adaptive FKV (AFKV for short), according to the report by Moniruddoza Ashir, Jan Hindahl, Andreas Nocke and Chokri Cherif (Technical University of Dresden) in the technical journal Technische Textilien.

The research of the Dresden scientists shows promising approaches in lightweight structures with morphing capabilities - thanks to the development of AFKV based on FGL actuators. A structural integration of FGL wires in reinforcing fabrics was implemented fully automatically in a single process step and with the aid of weaving (textile) technology.

Further research activities of the Dresden researchers from the "Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik" (Institute for Textile Machinery and High-Performance Textile Technology) will in future aim to promote the development of adaptive, tapered FKV with locally adjustable bending stiffness in order to ultimately achieve an even greater degree of deformation. Exemplary applications for the developed AFKV include aerodynamic flaps or rudders, for example, but also medical applications for humanoid kinematics and various technical applications for clamping and gripping devices.

Digital printing with pigment inks allows high colour fastness

Printing results in digital textile printing with qualities such as excellent edge sharpness, good colour fastness and a soft touch require a good prepress as well as corresponding pigment inks. However, it is not trivial to meet and reconcile these requirements. The German Institutes for Textile and Fiber Research (DITF) in Denkendorf have set themselves this task and are developing a chemical product preparation system for inkjet printing. Textilchemie Dr. Petry GmbH, together with the DITF, is researching the pre-treatment with "Pericoat" and "Perijet" for inkjet textile printing with these pigment inks and their properties.

The printing result in inkjet printing does not only depend on the resolution of the inkjet printer and the print heads used. Rather, the print quality depends primarily on the quality of the print pre-treatment. With a good pre-treatment and ideally matched textile auxiliaries, however, low-viscosity inks can be used to produce the desired properties such as sharp edges, clear contours and good colour fastness. At the same time, the thickener and binder systems used in pretreatment should not impair the fabric handle.

For good fastness results, a relatively high concentration of binder must be applied in pigment printing. It is not possible to formulate pigments plus binder completely in the ink at will. With higher binder quantities, the viscosity of the ink would increase so much that it can no longer be printed. The binders must therefore be applied in a separate process before printing with the pigment inks.

The market already offers a wide range of binders and pretreatment chemicals that are suitable for modifying the surface of the textile printing substrate and improving it for inkjet printing. However, due to the wide range of available chemical additives, each with its own mode of action, it may be difficult to achieve targeted improvements in digital printing results.

Setting process parameters

A screening of the chemicals in question makes it possible to identify particularly suitable active substances. In the subsequent development phase, these chemicals were therefore optimally adjusted with regard to their use as pretreatment chemicals in the injection pressure. Both the concentrations and the mixing ratios of the individual components were adjusted. Particularly important here was the adjustment of the flowability so that the chemical active ingredients were neither too thin nor too thick for application to the textiles.

The next step in development was to set the process parameters for applying the pretreatment chemicals. The number of chemicals applied, the type of application and the adaptation of intermediate drying phases – all these process steps ultimately have an effect on the printing result. According to the authors Reinhold Schneider and Ulrich Hageroth, the pigment inks used in the research project were developed in-house by DITF.

Finely divided pigment dispersions are produced from organic colour pigments. The addition of binding agents enables the pigments to adhere well to the textile substrate. The addition of additives can also influence other properties of the pigment inks, such as their hygroscopic or rheological characteristics.