IGF-AiF 17424 BR
Personal protective equipment (PPE) makes an essential contribution to safety in the workplace. Depending on the field of application, there are work clothes with special protective functions that usually protect effectively, but often do not meet all the requirements expected of them in terms of wearer comfort and clothing physiology. To improve the protective and wearing functions, the production of 3D knitted fabrics with integrated cut and impact protection was investigated. The new cut and impact protection knitted fabric is characterised by a low weight per unit area, high flexibility and good wearer comfort in terms of clothing physiology. It thus combines the well-known advantages of 3D knitted fabrics with important protective functions.
The joint project of the TITV Greiz, the Saxon Textile Research Institute Chemnitz e. V. (STFI) and other industrial partners developed the basics for multifunctional 3D textile constructions.
3D knitted fabrics were to be produced from a combination of high-strength textile yarns with metal yarns for protective textiles with integrated cut and impact protection. The materials were selected according to the requirements of the use. The pattern structures are to be used as partial surfaces or as inserts in the protective equipment. In addition to high frictional properties, metal yarns have low elongation elasticity and thus properties that are challenging in terms of machine and processing technology. In order to assess the characteristics of the different metal yarns and to compare them with textile yarns, a suitable testing apparatus was developed and tested. The tests provide the basis for statements on the bending flexibility and friction behaviour of special yarns under real-life conditions.
The processing of the yarns into spacer fabrics was carried out by the research institutes. Both institutes have different types of machines with different needle pitches for processing materials and ensuring yarn and product fineness.
The TITV Greiz used a double-faced warp knitting machine with a gauge of E 22 to incorporate metallic yarns in both the cover and pile areas of 3D knitted fabrics (cf. Fig. 1 and Fig. 2). In order to be able to evaluate the running characteristics of different metallic yarns in comparison with textile yarns, a corresponding test apparatus was additionally developed. With the help of this test apparatus, statements are made regarding the bending flexibility and the friction behaviour of the special yarns under practical conditions. Based on the test results, the yarn infeeds as well as the yarn guides on the warp knitting machine were modified in such a way that the metal yarns obtain a very good mesh shape. The fineness of the loops contributes significantly to high flexibility and drapability - a very important requirement for good wearing comfort. Additional cut protection is achieved by the high-strength aramid yarns that are incorporated at the same time. In order to achieve a high and durable impact protection, polyester monofilaments were mainly incorporated in the pile area. Due to the high needle pitch of the machine, a high material density is realised in the warp-knitted fabric, so that the mesh composite is reminiscent of a classic ring mesh of chain mail (cf. fig. 3). The new cut and impact protection warp-knitted fabric is characterised by a low weight per unit area, a high degree of flexibility and good clothingphysiological wearing comfort. It thus combines the known advantages of three-dimensional spacer fabrics with the protective effects.
Fig. 1: Microscopic image of a 3D knitted fabric with incorporated metal yarn (top view)
Fig. 2: Microscopic image of a 3D knitted fabric with incorporated metal yarn (cross section)
Fig. 3: Insertion of cut protection in work trousers
Results and Application
Protective textiles are very suitable for workers in the glass industry, demolition and construction, fire brigade, military and applications for the sport sector. Especially glass processing companies and construction companies working in demolition need lightweight and comfortable protective clothing due to the physically exhausting activities. In addition to the cut protection function, impact protection also plays a major role. Relevant standards and regulations have not yet been defined for these sectors, in contrast to forestry, for example. Further use of the project results is found in the textile and clothing industry. The 3D cut protection textiles with their completely new properties are of great interest to both fabric manufacturers and clothing companies. With the integrated cut and impact protection functions in 3D knitted fabrics, they offer a product that is optimally suited for the protective textile market segment. Textile machine manufacturers are able to offer new modules for the production of dense 3D knitted fabrics. Companies producing wire and metal yarns will find new sales areas in the field of protective textiles.The need for protective textiles is made clear by the following latest surveys: In Germany on average every 18 seconds there is an accident at work. Across the EU, 7 million accidents at work are counted annually.
Dipl.-Ing. (FH) Monika Weiser