Nowadays fabrics containing elastomers are widely used and in great demand but their manufacturing is not that simple due to the fact that they contain silicon oils and feel the effects of residual knitting tensions that may appear in the form of weight or surface irregularities. Bianco HS was developed for the preparation of knitted fabrics made of synthetic fibre and elastomer - which are the most sensitive to shrinkage and have got the highest oil content - and can be successfully applied to all kinds of fabrics which need to be washed before heat setting.
Until today the systems used for the preparation of knitted fabrics with elastomer consisted of washing in perchloroethylene solvent or in water; however, both systems need high investment costs for machinery and very expensive operating costs regarding energy consumption and maintenance. Being unwilling to incur such costs, in many cases fabrics are directly heat-set, with poor quality results in terms of uniformity and fabric handle.
Thanks to Bianco Happy Scour® is now possible to obtain an excellent quality with much lower costs than those incurred in traditional washing. The washing unit Bianco Happy Scour® mounted in front of a stenter and combined with a traditional squeezing padder allows continuous in line preparation.
The chemicals for washing and rinsing are prepared in the mixing tanks. Liquids are heated by means of indirect heat exchangers through steam coils in order to eliminate contamination of the chemicals. Once the temperature is reached, the prepared chemical recipe is pumped to the mixing tank, the product is delivered to the first tank section where it is sprayed on the fabric by means of nozzles, automatically ensuring continuity in the production process.
The tank is made of 100% stainless steel AISI 316, heated and equipped with the latest generation of probes to control the fluid level. The spray nozzles placed across the fabric width play a key role by directing the water jet to a specific point set between fabric and roller thus creating a delicate and uniform water cushion along the fabrics’ full width.
Due to the chemical characteristics of the oils which are removed in the first tank section, mean they float on the water surface and are carried to the special disk filter from where they pass in to a collecting tank. The rinsing tank in the second section is built separately to avoid any contamination. This guarantees a perfect rinsing by means of nozzles positioned across the width of the fabric and combined with a small amount of drainage, will ensure the necessary water cleanness.
Why Synthetic Fabrics?
Burning off during heat setting of spinning and knitting silicon oils present in synthetic fabric with elastomer alters the fabrics elastic properties and creates inner oxidisation which result in uneven dye absorption and formation of excessive yellowing which may affect the achieving of pale shades. Happy Scour® guarantees an optimal and economic fabric preparation by avoiding the above-mentioned disadvantages and by preserving the properties of the different yarns.
Why Cellulose Fibres?
Cotton and Viscose fabrics are equally susceptible to oil oxidation. The paraffin oils contained in cotton produces substantial "patchy" yellowing when burnt at high temperatures which can be hard to eliminate during the bleaching process and will require long processing times. The preparation with Happy Scour® allows dyeing very dark shades directly without any further treatment, while permitting for mid and light shades, which still need a bleaching oxidative process, a significant reduction both of the processing time as well as of chemical consumption. The viscose fabrics prepared with Happy Scour® are dyed directly in all colour ranges and without any other type of preparation.
Process
Essential for the correct preparation of elastomeric fabrics are the scouring of oils and the recovery of the residual tensions, which result in the best fibre relaxation.
Scouring
Bianco Happy Scour® utilizes a product for the scouring of oils expressively developed for this purpose, which contain: natural water-soluble solvent, cleaning agent, dispersing agent and sequestering agent.
The water-soluble solvent of natural origin dissipates silicon oils and mineral weaving lubricants cutting them down - according to their concentration of use - up to 99%. The main aim of the cleaning agent is to remove traditional spinning enzymatic treatments (i.e. antistatic and spinning oils) from the fabric. The dispersing agent prevents oils from settling back again on the fabric surface keeping them in dispersion in the bath before being removed by means of a filter. The sequestering agent cuts down both water hardness and possibly improves fabric handle.
Relaxation
Bianco Happy Scour® guarantees an absolutely tensionless process and furthermore the special treatment in the washing tank with nozzles helps create a gentle and effective relaxation.
Advantages of The Whole Process
No smoke at stenter’s entry and exit: heat-setting fabrics without prior scouring besides overstressing fume treatment plants also causes a high saturation of sublimated oils inside both at stenter’s entry and exit resulting in a big quantity of acrid and pungent smoke. Scouring with Bianco Happy Scour® eliminates this drawback, while reducing at the same time the smoke quantity going to fume treatment plants.
Handle: after heat setting, fabrics scoured with Bianco Happy Scour® have a soft and natural handle, as all the oils are removed before entering the stenter and are not burnt into the fabric.
Smell: the smell of knitting oils inside untreated fabric is unmistakable. After processing them in Bianco Happy Scour® this smell disappears thus confirming that oils have been removed.
Yellowing: after heat setting, the fabrics which have been scoured in Happy Scour® will incur far less yellowing and have a better uniform tone compared to partially scoured fabrics or fabrics simply eat set.
Dyeing test: this is the most effective among all indicators, i.e. if printed or dyed fabrics appear uniform, compact and with a soft handle without adding softeners, this means that the process was successfully completed. Fabrics scoured improperly will never give a perfect dyeing result.
Results
Bianco HS offers its best performance when placed in line with a heat-setting stenter; fabrics produced in such way do not need any other washing before dyeing. Therefore it is not recommended to install this unit out of a line, thus creating in fact a non-continuous preparation process which could create oxidation and creases in fabrics due to their wet storage, as it regularly occurs with the classic continuous washing machines, which are rarely placed in line with stenters due to their bulky dimensions.
Thanks to Bianco Happy Scour® well-cleaned and uniform fabrics with an excellent handle can be achieved. The shortening of the dyeing time due to the absence of fabric pre-treatment will incur minimal damage to fibre, which will therefore keep their properties almost unchanged.
Cost Saving
The process performed with Bianco Happy Scour® guarantees the best recipe in terms of performance and cost saving.
Water Consumption Saving
The consumption of the different chemical products inside the washing tank is only given by the fabrics’ absorption. The second rinsing tank gives excellent results thanks to the innovative nozzles washing fabrics on both sides by extremely reduced water consumption in the range of 4-6 litres each kg of water.
Happy Scour® PLUS
In its new “PLUS” configuration, Bianco Happy Scour® makes it possible to amplify the application range which is always focused on cost, time and energy consumption saving. The application of optical white for printing as well as for finished goods can be achieved directly through Happy Scour® PLUS on such fabrics as 100% Nylon and Polyester, Nylon/Elastomer and Polyester/ Elastomer, Viscose and Viscose/Elastomer as well as well as preparing for dyeing fabrics in Viscose/Elastomer and yarn dyed fabrics.
Construction
A BIANCO high-performance squeezing padder together with a second BIANCO impregnation padder with chemical recirculating system can be added to the basic Happy Scour® configuration to secure the best uniformity of application, if necessary the trough can be heated for better results on optical white. Fabrics are relaxed, scoured and re-washed in the Happy Scour® to allow a better absorption of the chemicals.
Controlled squeezing through the first padder ensures the best residual water uniformity in the fabrics; in the following impregnating padder the chemical product is recycled and always kept to the maximum level by means of sensors controlled by the machine’s software. Fabrics come then to the final passage inside the stenter by maintaining the usual heat setting or drying conditions. At the stenter’s exit the fabric can then be sent for inspection or for packing where an inspection has already occurred at the stenter exit.
The Happy Scour® PLUS solution really turns out to be very profitable compared to the traditional preparation lines both for printing and for fabrics with pre-dyed yarns. The energy and water consumption is reduced drastically; the processing time only consists of the simple passage in line with the stenter with controlled increase of the production capacity in connection to the dyeing process. All that without compromising the results of excellent fabric quality.
