4 quality problems when dyeing with rope dyeing machines

Rope dyeing machine, also known as rope dip dyeing machine. It is a kind of equipment for weaving thin silk, wool, cotton and chemical fiber materials with loose rope dip dyeing at normal temperature. It is suitable for many textile printing and dyeing operations, including scouring, dyeing, washing and other loose ropes. (An additional rope drying machine used in the denim plant is not considered in this article.)

Types of rope drying machines

Wool, silk, cotton and their mixed knitted textiles, and chemical fiber imitation fabrics, which are not suitable for tensioning and pressing, are the main materials that rope drying machines are used for.

In addition, it canUsed to scrub, bleach, soap and launder various silk, cotton and cotton blend knit fabrics This is due to the stretching, friction and loosening that certain textiles are prone to. Dyeing and converting machines should meet the special requirements of these low-tension, low-friction fabrics.

There are several types and variations of this device. There are typically four types of drying devices

Currently, there are several types and variations of this device. There are usually four types of drying equipment:

Normal temperature and normal pressure skein dyeing machines.Normal temperature and normal pressure overflow dyeing machines.High temperature and high pressure overflow dyeing machines.Jet dyeing machines.Quality problems in dyeing

Knit fabrics are mostly pre-treated , dyed and finished in rope dyeing machines. The short duration of this processs distinguishes him. In tubular form, the knitted fabric can be pretreated and dyed directly. During processing, the tension on the fabric is minimal. And the hank-dyed knit fabric feels good.

However, due to the influence of the dyeing process and the structural characteristics of the hank-dyeing machine itself, this kind of method also has a comfortable touch quality problems when dyeing. Dyelot chromatism, tube differences, streaks and folds are some examples.

1. Dyelot Chromatism

Rope dyeing of knitted materials mostly uses batch dyeing equipment suitable for small batches and a wide range of ONL products. Like the continuous dyeing machine, the batch dyeing machine has a limited one-time fabric capacity. If the capacity of a single machine is exceeded by a batch of the same dyed fabric, it will be dyed in different cylinders or batches.

Dyelot chromatism also occurs when the same tank is batch stained or the same staining procedure is performed in different tanks of the same model. The reason for this is that the conditions of use are different. Differences in water, steam, electricity and industrial processes are examples. And the operating conditions of the equipment of several machines at different times or different machines at the same time. Even the characteristics of different main circulating pumps of the same type, as well as the production and performance of components, can differ.

Of course, in actual applications, the dye chromatism generated for this reason must be kept in a range invisible to the naked eye.</p

In order to eliminate the influencing elements in this regard, the current machine for dyeing knitted fabric ropes tends towards a multi-tube or multi-dyeing tank design. TheDye chromatism is present both in the same tank and in other tanks of the same model.

However, in actual applications, dyeing with separate cylinders (dyeing the same fabric with your fingers) is unavoidable. Instead, it should be studied how to better control the color chromatism of the dye lot within the allowable range.

The chromatism of the dye lot can be regulated within the prescribed range if the appropriate drying process and specified operation technique are used with a dyeing machine good structural performance and sophisticated control combined, and the whole drying process is controlled fully automatically.

2. Tube difference

The batch hank dyeing machine connects the hank textiles end to end in a loop for a periodic cycle operation. Since the average residence time in a tube (trough) is 2-3 minutes, the length of the substance is in one tube (trough) is limited.

Multiple tubes (trough) are often used for dyeing in the same bath to improve the fabric capacity of a single machine.

The unique fabric capacity The Increased the power of the multi-tube (trough) dyeing machine. According to the batch size of the dyed fabrics, it can be set in a dyeing machine with an appropriate basic capacity, and the dyeing process can be completed at one time as possible to avoid the occurrence of Dyelot chromatism.

However, when the multi-tube (trAlthough ) the dyeing machine is not operated properly or the structure and performance of the equipment is affected, tube discrepancy will also occur.

There are several causes of the tube discrepancy, which can be summarized as follows:

Equipment shape and Structure Size

To ensure that the stock in each tube (trough) follows the same flow path, the nozzle (or weir) that guides the stock is providedpipe, the cloth storage tank and other shapes and structural specifications of each pipe required must be the same, otherwise there will be pipe deviations.

The flow rate and pressure of the circulating dyeing liquor

The flow rate and pressure of the circulating dyeing liquor are in the nozzles or overflow openings of each tube inconsistent. This refers to the structural design of the main distribution line of the dye liquor, as well as the flow rate and head of the main circulating pump.

The length of the cloth

The length variation between the individual tubes (slits) supporting the cloth is too large, what The ratio between the individual fabric tubes and the dyeing solution leads to irregular contact frequencies. At the same fabric speed and nozzle pressure, the color of the small capacity tube will be darker, while the color of the large capacity tube will be lighter. In general, the length varies between each tubecloth should be no more than 5%.

Nozzle pressure and line speed of the lifting roller

The nozzle pressure of each tube and the linear speed of the lifting roller are uneven, resulting in the same length of fabric and the same contact frequency, because the dyeing liquor cannot be reached

Fabric blocking

Fabric blocking occurs during the dyeing process, especially at high temperatures where dyeing occurs rapidly. In addition to the tube difference, the blocked tube may have chromatic aberration. In order to reduce the phenomenon of fabric blocking, the speed after fabric feeding should be kept low, and then gradually increase the required line speed after the fabric flows smoothly. The linear speed of the knitted fabric should be no more than 300m/min.

3. Stripes

Stripes of knitted fabrics are turned into weft (horizontal) stripesand warp strips (lengthways). Warp streaks are common in knitted fabrics made from pure cotton because the knitted tube is not inflated as it exits the guide roller. And the stripes appear in places that have not been opened and folded for a long time. Another problem is that the nozzle orifice is too small, resulting in the fabric being too narrow when passing through in a bundle. This creates the cross - the cross-sectional area of ​​the rope-like knitted fabric should ideally not exceed two thirds of the nozzle diameter.

Weft and warp stripes occur with polyester knitted fabrics. The reasons lie not only in the cylindrical expansion and nozzle diameter, but also in structural stresses that arise during the weaving process. These structural stresses are released during the initial wet work at a certain temperature. With a rope-like pre-treatment, weft orthe warp imprints. And there will also be streaks during the dyeing process.

This shows the real experience. When used as an initial wet treatment, open width prevention has the ability to completely relax the structural tension of receding knitted materials, thus preventing streaking during rope drying. In most cases, this operation can be carried out at the same time as refining.

4. Wrinkles

Wrinkles from rope dyeing occasionally appear in knitted materials.

Wrinkles are classified as either temporary or permanent. Tensioning can remove temporary creases, but stubborn creases cannot be removed even after tensioning. The creases are markings This is mostly about permanent creases.

Wrinkles are mainly caused by the following factors:

Cooling down too quickly

The usual chemical fiber knitted fabrics are at the fixing vprocess above the glass transition temperature is complete. In the dyeing tank, the rope textiles are stacked irregularly. If the temperature drops too quickly at this point, the cThe material cools, sets the staple folds and forms permanent creases.

The cloth sticks and knots

The cloth sticks and knots during the dyeing or fixing process and can are no longer used. It needs to be cooled and stopped to be removed, and during this time creases will quickly form at the knots.

The fabric will be unduly stressed.

Towel capacity of the rope drying machine refers to the maximum fabric capacity of a specific gram weight. It is often made of medium-thick materials. In practical applications, the respective load must be determined based on the actual grammage of the fabric.

Fabrics with a Maximum Fabric Capacity greater than the Reference Gram Weight may exceed the Nominal Fabric Capacityin. a weight less than the guideline, the maximum sling capacity should be less than the nominal sling capacity. This is because a shawl shorter than the specified grammage is too long. It is possible to produce raises if it stays in the groove for too long (more than 3mn).

This blog is a reproduction of 4 dyeing quality problems of a rope dyeing machine.