Villa Nova - Portuguese knitted fabric manufacturer Tintex Textiles has been working with finishing machine specialist Brückner Textile Technologies to develop a new process for coating bi-elastic knitted fabrics.
Tintex is located in Villa Nova, not far from the Spanish border in northern Portugal. The company was founded in 1998 in the Porto region and now offers a range of functional, tricot fabrics for well-known fashion, sports and lingerie brands.
A key element of the circular knitter's strategic thinking is that the fashion and textile sector can make a significant difference in tackling climate change. As a result, the company says it is constantly developing new strategies and environmentally friendly concepts throughout its whole production process. As well as knitting, this include dyeing and finishing techniques as well as the coatings part of the production process.
Part of its ability to develop and produce intelligent, functional and high-performance textiles led Tintex to work closely with Brückner, whose product range includes machines and complete lines for coating and finishing of textiles, technical textiles, nonwovens and floor coverings.
With a production site in the south of Germany, which was completely rebuilt in 2018, the family-run company was founded in 1949 and is today managed by the second generation of the family - Regina Brückner and her husband Axel Pieper. "Still valid today, the values and visions of the company founder are the key to success: the production of high-quality lines, the development of sustainable and innovative technologies and the competent and comprehensive advice of our customers," Brückner says.
Key to Tintex's vision was a desire to achieve completely new effects on bi-elastic knitwear and the production of fabrics that the industry had not previously seen.
Following numerous tests at the Brückner Technology Centre in Leonberg and on a Brückner line at a textile institute in Stuttgart, the two companies developed a process that takes into account the requirements of temperature uniformity, the thermal treatment of synthetic fibre blends and other constructive issues. The finishing technology ensures that even knitted fabric with a high elastane content can be directly coated, a procedure that until now was only possible via an indirect coating process.
The heart of the new line is the proven Power-Frame stenter frame dryer. Key here is the inlet and outlet components are specially designed for sensitive fabric and ensure a tensionless fabric run. A special, newly developed coating unit is integrated in the in-feed stand of the stenter frame, which, due to its variable design, allows two different application processes to be run on the same line.
In the so-called screen coating process, water-based pastes and stable or unstable foams are applied onto the fabric with high precision by means of a driven, cylindrical screen and a squeegee system integrated in the screen. For paste coating, the machine parameters can be adjusted in such a way that a single-side coating is possible, even on light knitwear made of cotton or viscose, provided the paste is of a suitable viscosity. For the stable foam coating, the coating medium is mixed to foam with an exact foam/litre weight of 150 to 300 g/l. With an integrated feed pump, this foam can be precisely dosed and applied to the textile through the screen. Furthermore, in the case of unstable foam coating, the coating medium is foamed up with a mixer and applied to the textile in exact doses. Here the foam/litre weight is 30 to 100 g/l.
As the unstable foam collapses shortly after leaving the screen, a single-side functionalization with a very low pick-up of less than 10-20 per cent can be achieved, says Brückner. This is a minimum application with the corresponding benefits, e.g. considerable energy and therefore cost savings in the subsequent drying process.
If knitting mills wish to coat somewhat more stable fabric or apply higher coating weights, the unit can be quickly and easily converted from screen coating to a knife-over-cylinder system. The counter pressure roller is then used as the coating cylinder.
The system also includes a laminating/embossing calender which, integrated in the outfeed of the stenter, allows various effects to be achieved on the fabric, e.g. a leather grain.
If the applied stable foam coating has a certain layer thickness, this effect can be achieved after the drying passage in the laminating calender by means of a fed release paper or an appropriate embossing roller. Even with sensitive, directly coated knitted fabric, this calender can be used to apply a film, a membrane or even a second textile web onto the fabric. For this purpose, the calender is additionally equipped with an electric short-wave infrared dryer.
For simple heat-setting processes, meanwhile, a special roller has been developed which can be inserted into the coating unit instead of the screen and therefore acts as the upper infeed roller. Even very tension-sensitive knitwear can be run with an overfeed of up to 60 per cent before heat-setting.
This new multifunctional line can therefore be used for heat-setting, drying and coating processes. It can be used to manufacture products comparable to those previously produced with indirect coating - but without having to rely on cost-intensive release paper.
At Tintex, production on this line has already been running for some time and research into completely new types of textiles is continuing. Fabrics made using this bespoke process have also been honoured with a number of industry awards such as the Hightex Award at Munich Fabric Start and the Innovation Award at Techtextil.
"Brückner is very proud to have customers like Tintex who act with foresight and do not strive for short-term profit optimization," Brückner said. "The goal is always to think and act with a long-term perspective, because this is the only way Brückner and their customers can be successful in the long run."