The Principle of Microwave Heating Rapid Dyeing Technology

- May 06, 2019 -

The so-called microwave dyeing is the use of microwave heating dyeing technology. Microwave can be generally divided into meter wave, centimeter wave and millimeter wave bands, with frequencies ranging from 300 to 300,000 mHz. Microwave has been widely used in drying and other fields. The electromagnetic wave microwave with longer wavelength has been widely used in other industrial sectors and has been used as a heat source in people's daily life. In the dyeing and finishing industry, besides being used for drying, it can also be used for fixing dyes in dyeing, such as high temperature fixing of polyester dyed with disperse dyes and printing fixing, which can greatly reduce energy consumption. The principle of dyeing with microwave is that the dipole of polar molecule (e.g. water molecule) in the dye-impregnated fabric is subjected to microwave irradiation, and the dipole in the fiber is subjected to microwave high-frequency electric field, which results in repeated polarization and change of alignment direction (e.g. at 245 OmHz, there are 2.45 billion dipole rotational motions within one second). Repeated friction and heat can quickly convert the energy absorbed by electromagnetic waves into heat energy. At the same time, under the action of microwave, some dye molecules can also be induced and heated to achieve the purpose of fast dyeing and fixing. That is to say, microwave heating is to use water on the fabric to heat under induction, so as to raise the temperature of the fabric and the color paste printed on it. Therefore, the fabric (color paste) should maintain a certain amount of moisture, and the dyed (or printed) fabric is fixed when it is not dry.

microwave dyeing can be processed by fabrics or tows. It can be used not only for dyeing hydrophilic fibers (such as cellulose fibers and wool fibers), but also for dyeing hydrophobic fibers (such as polyester fibers) with appropriate additives. Reactive dyes, direct dyes and cationic dyes can be used as dyes. When dyeing, the fabric is dipped in pad dyeing solution according to the conventional method, and then guided to a sealed microwave heating chamber (reaction chamber). Under the action of microwave, the fabric is heated rapidly, which can accelerate the diffusion or fixation reaction of dyes in the fiber. The treatment after dyeing is the same as the conventional method. For example, when disperse dyes are used to dye polyester, oil-soluble dyes and disperse dyes are used to dye acetic acid fibers, microwave fixation can achieve better results. If some auxiliaries (such as urea) are added to the printing paste, the fixing speed can be accelerated and the fixing effect can be improved. Fast, high thermal efficiency, and little heat loss to the surrounding air and equipment.

Therefore, microwave dyeing has some advantages as follows: < / P >

Microwave can penetrate the heated substance instantaneously, only need to be heated for several seconds to several minutes, without preheating. Stop heating is also instantaneous, without waste heat;

2 Microwave is dielectric loss heating. Objects with large dielectric loss coefficient selectively absorb microwave, and parts without heating will not absorb microwave, thus avoiding meaningless heating;

3 Because the heated substance itself is heated and the surrounding air and devices are not heated, there will be no heat loss, so the thermal efficiency is high;

p>p>p>p> (4) Because each part of the heated object is heated at the same time, the whole object can be heated uniformly both inside and outside, which will not produce large temperature difference between the surface and inside of the object as usual conduction heating;

_can easily adjust the heating state with the power meter;

_Microwave can not only have the effect of rapid heating, but also make water molecules and dye molecules vibrate and promote dye's heating. Dissolution and diffusion. Microwave generator is a pollution-free device, but there may be some electromagnetic waves leaking from the heating device in operation, resulting in various kinds of interference. Therefore, measures should be taken to strictly control, and electromagnetic waves should be shielded by various methods.

Label: Microwave dyeing, microwave fixing, microwave fixing

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