Application Of Discharge Printing Technology On Knitted Fabric

Discharge printing has always been a traditional printing process.

In the reactive dyed fabric, discharge agents are often used to discharge printing. After printing, a series of production processes are carried out through steaming, washing and drying.

You can get a strong contrast, a clear outline, no trichromatic or overlapping colors between the color and the ground color, and a strong print with strong three-dimensional sense.

This printing process has long been well grasped by people.

The principle is to make the conjugated system of some reactive dyes chromophore destroy under the condition of heat and humidity under the condition of heat and humidity, so that it can fade or change color, or directly destroy the binding between reactive dyes and cotton fiber molecules to achieve the purpose of discharging.

This is a chemical action, which is carried out in the process of steaming.

Through wet heat steaming, the reducing agent in the printing paste rapidly decomposes, releasing strong reducing compounds, resulting in the fading of reactive dyes or the loss of bonding ability with cotton fibers.

The application of discharge printing on knitted fabric is actually lagging behind that of woven fabrics.

The reason is that the knitted fabric is loose in structure and has strong elasticity in the warp and weft direction. Printing and dyeing processes must be carried out in a series of loose equipment. After discharge printing, it is especially important to prevent any chemical agents left on the printed cloth from sticking up. The processing is difficult and the defects are easily produced.

Therefore, the wet hot roasting method is used instead of the wet hot steaming method, so that the printing and steaming two processes can be converted into one continuous printing and baking process, and the chemical reaction is directly performed on the printing machine by high temperature baking.

Similarly, in the garment or garment printing industry, the vast majority of manual plate printing plants often do not have steaming conditions, and some factories even do not have the smallest steaming equipment.

Even if some factories have added a cylinder steamer, it will be more difficult to print the garment and garment garment printing.

In recent years, from the perspective of printing demand for knitted apparel at home and abroad, the discharge printing sheet on dyed fabrics has been rising linearly.

Therefore, it is necessary to apply paint in the field of garment and hand-made platen printing.

We must make breakthroughs in prescription and technology to cater for the trend of fashion printing nowadays.

In recent years, many manual plate printing factories have adopted hot wet pressing or wet hot baking instead of wet hot steaming.

Through the process practice, mastering the rules and operation methods, the discharge effect is no less than that of steaming.

The advantage of this process is that the factory does not need to buy huge steam equipment, so long as there are several high temperature press or a tunnel baking machine with several meters long to replace, the investment cost is small, and the processing speed is also faster.

The pure cotton knitted fabric cares about the net, the wet heat baking process and the matters needing attention in the round net.

In the circular net and flat net, the wet printing is mainly used in the drying room behind the printing machine for heat treatment and printing and discharge.

It is the simplest and feasible discharge method to use reactive reducing agent to dye reactive dyes and discharge pigment.

The commonly used reducing agents are carved white powder and white zinc powder.

The chemical name of white powder is formaldehyde sodium bisulfate.

Its chemical formula is nahso2. CH2O. 2H2O, which is white powder at room temperature and has stink.

Under alkaline conditions, it is stable, decomposing at more than 60 C, decomposing completely at 110, and releasing new eco hydrogen.

The chemical name of zinc for carving white powder is formaldehyde and zinc sulphate.

Its chemical formula is Zn (osoch2oh) 2. It is also a white powder at room temperature. It is a kind of chemical similar to white powder, but its stability is better than that of carved white powder. It is especially suitable for use in weak acidic medium, and has strong reducibility.

It's not easy to yellowing.

In the above prescriptions, the effect of the first prescription is better than that of the white ones.

Or the active color on the fabric is not easy to pull out completely. The disadvantage is that the handle is slightly worse.

Prescription two is characterized by a good hand feel, but the whiteness is normal.