Dyeing, Printing & Finishing
Textile World AsiaSpecial ReportAutomated DissolvingTermoelettronica unveils Termodye-M powdered dyestuff dissolving system for dyehouses and chemical auxiliaries in small quantities. In identifying priorities within the dyehouse, Italy-based Termoelettronica S.p.A. emphasizes recipe repeatability and reduced number of lots rejected due to offshading, which is the unequal tonality of color from dyeing to dyeing. Termoelettronica has demonstrated this emphasis through its dyeing solutions. Without making large investments in automatic dosing systems, it is possible to reach such objectives as recipe repeatability and a reduced number of rejected dye lots through the monitored weighing of dyestuffs using the company’s Termodye-M semi-automatic dissolving system, according to Termoelettronica.Dissolving the dyestuff can easily be managed in a centralized area in order to eliminate the problems related to the transporting of dyestuff near individual machines, which can lead to contamination and above all, misdosing — the possibility of dosing the recipe in a machine for which it is not intended. The system essentially consists of a series of dissolving tanks, equipped and prepared for dissolving the dyestuffs, the number of which is determined by the number of dyeing machines to be fed.Choosing The Most Suitable InstallationTo help determine which plant installation best fits a company’s needs, Termoelettronica offers several suggestions.An installation might be considered on dyeing machines with only a preparation tank — without a supervision system — with an average load capacity of 600 kilograms. In this case, Termoelettronica would suggest a single dissolving tank for every five to six machines in order to save time and avoid delay of dyeing operations. Obviously, if there is a supervision system in place that allows the preplanned applications of various dosings, the number of machines that could be fed can be increased. However, it is important to consider that the latest-generation dyeing machines, such as the MULTIFLOW® from Italy-based MCS Group, have significantly reduced the dyeing times so that they take less than half of the time of earlier dyeing cycles. So, even with modern and fast machines, a company should consider installing a dissolving tank for every five to six machines.Regarding the capacity of the single dissolving tank, Termoelettronica typically supplies several tanks — one of 300 liters and the other of 500 liters — to allow flexibility of options. (Consider that the dissolution and/or the dispersion of a dyestuff is effected, if not in particular cases, with a liquor ratio that varies in the range of 1:5 and 1:10.)The particular design of these dissolving tanks allows one to dissolve minimal dyestuff quantities in 20 to 30 liters of water. Nevertheless, the distance the dye must travel must be considered. A “food electrocleaned type”pipeline with an external diameter of 28 millimeters (mm) and a thickness of 1.55 mm is used to distribute dye to the various machines. Termoelettronica uses air to reduce the volume of water necessary to wash the line, so a minimum amount of water is required to clean the tanks. The dissolving system is managed by microprocessors linked by a barcode reader to additional dyehouse supervision system safety devices. Different size dissolving tanks are equipped with a mixer, three level probes, indirect/direct steam water and safety proximity devices.Hot WaterConsideration of the water temperature might seem a little trivial, but it is of notable importance in the dissolving process of powdered dyestuffs. To obtain the best dissolution, it would be ideal to use demineralized water, but sweetened water of various degrees of purification certainly is acceptable.Termoelettronica recommends using warm water at the correct temperature linked to the class of dyestuffs that must be dissolved. The method proposed by Termoelettronica enables the monitored mixing, managed by a microprocessor, of two water flows constantly maintained at two temperatures of 40°C and 90°C (using indirect steam). In this way, an appropriate volume of water immediately is available at the desired temperature. This procedure allows a rapid dissolution of the dyestuffs and allows the solution to be fed to different machines using a single dissolving tank.
Editor's Note: This article was provided by Termoelettronica SpA. It has been edited for clarity and space.
May/June 2005