Knit dyeing is a technique of dyeing the knitted fabrics. The dyeing of knitted fabrics occurs in the exhaust method or in batch-wise process. Generally all type of single jersey, double jersey and their derivatives are dyed by the following process.
Machines used in dyeing process of knitted fabrics
Dyeing through winch dyeing machine
Knit goods are generally dyed in the roller piece form and slit(To cut lengthwise into strips) lengthwise after dyeing. Warp knits have the tendency to curl at the edges,hence several rolls are tied together so they are dyed in tubular form. Forming along chain, the number of rolls to the chain being dependent on the weight of the fabric. When dyeing of tubular fabric is carried out in winches, air bubbles are
Dyeing Of Knitted Fabrics inside the tube form immediately below the jockey roll. The bubble discontinuously pushed back along the rope by the jockey roll. The dyeing machine employed consist of a tub provided with a revolving winch on top. The winch is makeup of wood. The chains of cloth are passed over the winch and circulated through the dye liquor in the tub below. Usually from eight to twelve chains are run in one machine side-by-side. As the goods come up from the liquor they are passed from asset of small squeeze rollers and then run on the revolving winch. The squeeze roller sand the winch should be so set and run at such relative speeds that there is as little tension on the cloth as possible, as the tension while the cloth is running in the dyeing operation tends to stretch the goods out of shape and also materially reduce their elasticity. The speed of the squeezing rollers is somewhat high than that of the winch. The winch is fluted so that less surface area of the fabric touches the winch and hence low tension is created on the fabric.The machine employed for the dyeing process is similar in every respect to that employed for wetting-out or scouring process. Unless a number of lots to be dyed,the goods may be rinsed off in the machine used for dyeing, by simply running off the dye liquor and refilling with fresh water.
Piece dyeing occurs in the winch dyeing machine. Most textured polyesters is piece-dyed which are manufactured through knitting. Some continuous scouring machines are built to handle knitted fabric with controlled tension. Although one machine is more suitable than other, the depends on many factors, including the type of fabric to be processed, machine tension, method of extraction and efficiency of oil and dirt removal. This last factor is especially important.High temperature dyeing units generally operates at temperatures between 230 Andean F. This makes possible shorter dyeing cycles with little or no carrier cost. It also improves quality, barre and shading piece to piece. In spite of high capital costs,there are definite advantages to high temperature dyeing