Causes And Avoidance Methods Of Fabric Wind Printing

Generally refer to

A dyeing defect produced during processing and drying of textiles.

Compared with the normal dyed blank, the wind print will show a gray or white shadow in the zonal direction of the entire width of the door.

The defect can not be seen before finalizing, and will be generated after typing.

Polyester fabric is not easy to produce wind printing when it is in continuous production (long car production line), while intermittent production (high temperature and high pressure overflow dyeing) is prone to wind printing.

Polyester fiber

Most of the wind printing is produced in this link after the cloth is dehydrated and finalized, and appears in the reciprocating and folding printing place of the storage of the cloth cart.

In severe cases, there will be dozens of zonal directions, and the spacing between them is exactly the distance between folded and folded fabrics.

Causes of wind printing on non woven polyester woven fabrics or knitted fabrics

After the opening of the fabric, the reciprocating folding place is exposed to the air. The flow of air causes the moisture to evaporate at first.

Due to capillary effect, the free water of other parts will flow towards the folded places.

However, the addition of antistatic agents, lubricants and levelling agents and detergents in spinning and weaving will still have a small amount of residual water remaining in fabrics and fabrics. Most of these auxiliaries are nonionic auxiliaries.

Like the principle of dye migration, when the free water flows towards the folding place, the residual aid dissolved in free water also flows towards the folded place.

With the further volatilization of water, the concentration of auxiliaries in reciprocating folds is much larger than that in other parts.

In the process of high temperature setting, the Thor mo-migration of disperse dyes produced by reciprocating folding parts is significantly larger than that of other parts.

The thermal migration of disperse dyes is due to the dissolution of auxiliaries outside the fiber at high temperatures. The dye moves from the fiber to the surface of the fiber through capillary tubes, causing the dye to accumulate on the fiber surface, resulting in a series of effects.

Such as color change, friction, water washing, sweat, dry cleaning, light fastness and so on.

But the fatal effect is the severe color difference between the reciprocating fold and other normal parts, that is, wind print.

Cause of air print on sizing polyester woven fabric

Compared with non woven polyester woven fabrics or knitted fabrics, the sizing and dyeing process of polyester woven fabrics is very long. Most of the auxiliaries used in spinning and weaving have been removed.

However, the auxiliaries used in dyeing and post processing may still have a small amount of residual water in the fabric and the free water it carries.

In addition, although the desizing process has undergone two thermal washing and acid pickling, the caustic soda used in Desizing may still remain within the single fiber of polyester fiber and even inside the amorphous zone.

Similarly, in the process of piling up before the fabric is finalized, free water can carry residual alkali and auxiliaries to the folded places.

At this time, the pH value of the reciprocating fold is significantly higher than that of other parts of the fabric. This is confirmed by the universal indicator, and the concentration of the auxiliaries is larger than that of other parts.

In the process of high temperature setting, the polyester chain moves violently, and OH ions can react with the disperse dye as the water molecules drill into the amorphous region.

Disperse dyes are stable under acidic conditions (pH value 5). Generally speaking, disperse dyes have the following two effects in alkaline conditions: alkaline conditions can make some dyestuff structures separate, which is reversible and reappears in neutral or slightly acidic structure.

The alkali can hydrolyze some disperse dyes. After hydrolysis, the dyes change not only the color and light, but also the affinity.

So alkali can permanently destroy some disperse dyes.

As a result, the color change of the polyester fabric woven from the top to back is too high. The pH value is too high. The hydrolysis of disperse dyes is also caused by the combined effect of the dissolving and auxiliaries on the thermal migration of disperse dyes.

Ways to avoid wind printing on polyester fabrics

If these two kinds of fabrics are dehydrated, opened and fixed in time, they will not produce wind prints.

If placed for a period of time (about 30 hours), then wind typing is easy to create.

In order to fundamentally solve the wind print, we must start with the mechanism of wind printing and minimize the factors causing wind printing.

The cause of wind printing is mainly related to dyes.

Usually, a small number of vat dyes, nvto dyes and some vinyl sulfone reactive dyes and most of the direct dyes can produce wind prints due to their poor fastness to sunlight and oxidation.

Some reactive dyes are sensitive to alkali. If the alkali is not clean after dyeing, the wind prints can easily occur when the pH value is greater than 8 (such as reactive turquoise KN G and Reactive Orange G).

The pattern was found to have wind print, while the remaining unshaped fabric folded high concentration of auxiliaries or OH - ions, only physically adsorbed on the surface of the fiber. The dye could not dissolve the amorphous region without high temperature setting AIDS, and OH - ions could not enter the amorphous zone of the fiber to react with disperse dyes.

Therefore, after washing or pickling, the high concentration auxiliaries and OH - ions have been diluted, and the wind prints can be avoided in a timely manner.