Dyeing Processes

Textile material may be dyed using batch, continuous, or semicontinuous processes. The type of processes used depends on several things including type of material (fiber, yarn, fabric, fabric construction , garment ) , generic type of fiber, sizes of dye lots, and quality bblrequiredments in the dyed fabric.

Machinery for dyeing must be resistant to attack by acids, bases, other auxiliary chemicals, and dyes. Type 316 stainless steel is usually used as the construction material for all parts of dyeing machines that will come in contact with dye formulations.

Batch Dyeing Processes

Batch processes are the most common method to dye textile material . Batch dyeing is sometimes called exhaust dyeing because the dye is gradually transferred from a relatively large volume dyebath to the material being dyed over a relatively long period of time. The dye is said to exhaust from the dye bath to the substrate. Textile substrate can be dyed in batch processes in almost any stage of their assembly into a textile product including fiber, yarn, or garment. Generally, flexibility in colour selection is better and cost of dyeing is lower the closer dye application is the end of the manufacturing process for textile product.

Some batch dyeing machines operate at temperatures only up to 100 ℃ . Enclosing the dye machine so that it can be pressurized provides the capability to dye at temperatures higher than 100 ℃ , Cotton ,rayon, nylon, wool and some other fibers dye well at temperatures of 100 ℃ or lower . Polyester and some other synthetic fibers dye more easily at temperatures highter than 100 ℃ .

The three general types of batch dyeing machines are those in which the fabric is circulated , those in which the dyebath is circulated while the material being dyed is stationary, and those in which both the batch and material are circulated . Fabric and garments are commonly dyed in machines in which the fabric is circulated . The formulation is , in turn, agitated by movement of the material being dyed. Fiber , yarn, and fabric can all be dyed in machines which hold the material stationary and circulate the dyebath. Jet dyeing is the best example of a machine that circulates both the fabric and the dyebath. Jet dye machines are excellent for knit fabrics but woven fabrics may also be dyed using jet machines.

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