Causes and preventive measures of dyeing creases

Causes and preventive measures of dyeing creases

Textile fabrics boiled bleaching and dyeing processing is generally done in the overflow tank, the entire process of fabric are kept rope, fiber bending deformation continuously in the dyeing machine, the original hydrogen bonding has been destroyed, the new hydrogen bond formation, sometimes newly formed hydrogen bonds can't reply, thus formed in the surface of the fabric, chicken paw prints, dead crease.

How to prevent "chicken foot marks" on fabric when dyeing by overflow machine?

When all kinds of fiber fabrics are dyed on the overflow machine, whether at normal temperature (100℃) or high temperature and high pressure (130℃ / 0.19 MPa), it is possible to form "chicken foot print" (hereinafter referred to as folding print). The formation of folding factors for the following factors.

PART 1

Potential factors in spinning weaving

For example, uneven yarn and difference in twist shrinkage, tension and density during weaving, especially for high count and high density fabrics, will directly affect the following process.

In the process of hot and humid treatment, often due to the contraction of the fiber (yarn) different beauty formed fold. Therefore, to overcome the folding printing, the fabric is best to go through mercerization and pre-shrinkage treatment, especially after mercerization to rearrange the cotton fiber molecules, improve the crystallinity, in order to reduce the folding printing caused by spinning weaving.

PART 2

The thermal shrinkage of two or more fibers in blended fabrics is inconsistent

In some cases, although a predetermined shape was added after the pretreatment, there was still residual stress, especially at 130℃, the difference in thermal shrinkage was more significant. Therefore, two or more types of fibers will be folded because of their different thermal shrinkage rates, although the predetermined shape sometimes does not help (see figure below).

PART 3

The dyeing bath ratio is too small, forming creases in the dyeing cylinder

Bath than small, not only easy to dye flowers, more easy to form fold print, especially light and high density fabric, such as polyester flat spinning, spring sub-spinning and so on. The main factors causing crease of elastic knitted fabric in dyeing cylinder are: pressure of nozzle and running speed of lifting roller; Wrapping car, pressing cylinder, blocking cloth; Dyeing increases cooling rate.

A. Nozzle pressure and lifting roller speed

In the dyeing process, the coordination between the pressure of the nozzle of the dyeing machine and the speed of the lifting roller is controlled and mastered by the dyeing operator according to the technological practice and different cloth types. The pressure of the nozzle of the heavy fabric dyeing machine should be appropriately increased, and the speed of the lifting roller should be slowed down a little, so as to promote the normal operation of the fabric smoothly; On the contrary, it is necessary to adjust the nozzle pressure appropriately, increase the speed of the lifting roller, reduce the tension between the water flow and the lifting roller and the fabric, so as to reduce the crease phenomenon caused by the fabric surface stretching in the dyeing VAT.

B. Car wrapping, cylinder pressing and clogging

Cloth crease caused by wrapping car, pressing cylinder and blocking cloth in dyeing cylinder is generally caused by the following reasons:

First, the amount of dyeing VAT is too large, the bath ratio is small, the fabric cycle is long in the VAT, folding and squeezing each other, and the cloth is easy to generate chicken foot marks or creases. Dyeing cylinder must pay attention to the size of the cylinder, generally arranged according to 60% ~ 70% of the cloth capacity production, to avoid the crease phenomenon caused by poor operation of the fabric in the cylinder;

Two is the broken yarn weaving or into the cylinder before the joint is not strong caused by the broken cloth blocked in the cylinder, long time under high temperature conditions, plus water to form the blocking cloth crease. Operators are required to stick to their posts, pay attention to observe the running state of the grey cloth in the dyeing VAT, find it as soon as possible, and deal with it in time;

Three is the wet strength of the regeneration of cellulose fiber, such as Modal, viscose fiber, bamboo fiber fabric, in the dyeing VAT color, color repair time is too long caused by broken cloth, caused by the pressure cylinder crease; When it is found that the color difference is large, the product should be washed out of the cylinder first, and the color is close to the cylinder before dyeing; Color flower serious consultation with customers to change to dark, try not to take peeling color after repair, in order to avoid fiber wet strength is poor and broken in the cylinder phenomenon.

PART 4

The rising/cooling rate is too fast

Dyeing on the overflow machine, heating and cooling will directly affect the shrinkage of the fiber, thus forming a fold. For polyamide and other thermoplastic fibers, once formed fold, will be irreversible. Therefore, in dyeing, special attention should be paid to the fiber glass temperature before and after 10℃ should be slowly rising/cooling, generally 1℃ / rain speed is appropriate.

The rate of rise and drop in dyeing process not only affects the evenness of dyeing, but also restricts the hand feel and crease degree of dyed fabric. If the thermal processing temperature is not controlled properly, the surface temperature of the fabric will be heated or cooled, and the fabric will be creased because of the thermal contraction of the fiber. Production practice has appeared, because the operator violates the rules of the process will rise and fall from the computer automatic control to manual, cloth crease phenomenon, sometimes even serious crease. Therefore, the dyeing process strictly according to the computer program, slow rise and cooling is not only conducive to uniform dyeing, but also conducive to reduce cloth creases. Therefore, it is necessary to strengthen the staff's process discipline education to control the crease in the dyeing process.

Of course, the glass temperature before and after 10℃ can generally increase the speed of cooling, in order to shorten the processing time. Sometimes in order to speed up the rise of cooling speed, but to prevent folding printing, in addition to the addition of uniform dyeing agent when dyeing, can also add anti-wrinkle agent in the bath or bath softener 2-3 g/L, by reducing the rigidity of the fabric, improve softness, reduce the probability of crease when dyeing. Such as polyester/cotton and polyester/polyester superfine fiber made of leather thick fabric, in addition to the selection of superfine fiber special disperse dye series, in order to prevent the formation of folding in the overflow dyeing, the two additives can be added in the dyeing bath.

There are more varieties of this kind of additives, and attention should be paid to the selection:

(1) affinity and mixture of dyes;

(2) require low bubble or no bubble, in order to prevent clogging or consumption of defoaming agent;

(3) to be resistant to high temperature and weak acid medium;

④ Need to be selected after the test.

PART 5

Heat-treated fabrics cannot be cooled instantaneously

Practice has proved that no matter what kind of fabric, from the beginning of the previous treatment to the end of dyeing, after each heat treatment can not stop the discharge of residual liquid, and then change cold water for cleaning, otherwise piled up in the machine very hot fabric, instant cold will form folding, especially the composite fiber and its blended interweave is more significant.

Therefore, after the termination of dyeing, do not rush to drain, but should gradually add cold water in the operation of the fabric to overflow the dyeing machine, flow water for a moment, until the fabric and the body temperature has dropped before draining, or even change the liquid cleaning. This method can also reduce the production of "loose plate printing" if used in the roll dyeing machine. Hot and cold buffering is beneficial to dyeing process.

PART 6

Reasonable selection of processing equipment

For fabrics that can be processed by open-width equipment, such as nylon spinning, polyester taff, cotton high-count and high-density fabrics, the overflow machine should not be used as far as possible. In fact, all kinds of fabric dyeing and finishing processing has its applicable equipment, should be selected according to the performance of the fabric and the final use.