As is known, the humidification is of fundamental importance both in printing houses that in the textile sector. In both cases, the raw material is hygroscopic, meaning able to absorb or release water vapor present in the atmosphere. This feature involves a not insignificant consequence, the product in fact change its mechanical characteristics, in particular the size (expands or shrinks according to its internal moisture), flexibility (increased humidity leads to greater flexibility), the specific weight (a greater water content increases the specific weight) and the ability to charge electrostatically.
All these phenomena can affect the production process positively or negatively, so the humidity control can create an ideal climate for a production of high quality and without waste.
As mentioned the hygroscopic products absorb or give water vapor to the surrounding environment on the basis of a simple diffusion mechanism, if the ambient humidity is greater than the material, will occur displacement of vapor from the air to the material, conversely, a material in a very humid environment relatively driest tends to release moisture to the surrounding environment. To better understand this mechanism, just think of a sponge that absorbs or releases water cyclically.
The dimensions of hygroscopic products in function of the relative humidity
Materials such as paper, cardboard or tissues are characterized by a cellular structure which can absorb moisture, for this are hygroscopic. The cells that absorb moisture swell like balloons filled with water, and shrink they are empty instead. This phenomenon involves the dilation of the material, and then the variation of size. In the case of printing this phenomenon is to be avoided because size variations between the printing of one color and the other can create problems of alignment and therefore the quality of the obtained product. In order to maintain such constant humidity with MGF nebulizers reduces the dimensional changes and thus improve the quality of the product. Similarly a yarn elongates depending on humidity and this may cause problems during processing.
The flexibility of hygroscopic products as a function of relative humidity
Same way as said the moisture contained in the paper and tissues, making them more flexible and elastic. In fact, the cells filled with water at the microscopic level are able to cushion the strains without damage, unlike a material too dry which tends to break easily and bends with difficulty. That is why it is important in the paper industry, in printing houses and textile industry exceed minimum levels of relative humidity, in order to reduce waste and breakage.
The specific weight as a function of relative humidity
Cells that constitute the paper or yarn increase their weight in function of the amount of water contained in them. Again keeping the moisture constant allows the printing houses and textile industries to meet the quality standards required and agreeded with the customer.
The reduction of electrostatic charges in the printing houses and textile industry
A final aspect to consider as deleterious in the textile printing houses is the presence of electrostatic charges, which degrade the quality of the product for several reasons. First, the charges can generate sparks with a voltage up to 25000V and then may ignite the paper or yarn, particularly synthetic ones. Spraying reduces this effect.
Another drawback caused by the electrical charges in printing processes is ink relative moving from original position (offset). This generates small inaccuracies in the press and ultimately a general deterioration of the quality of the product.
One of our customers, as documented by the images, uses from many years our misting systems to control humidity in his textile printing department, resulting in a high quality production and reduced rejects, two fundamental aspects to remain a leader in the competition world.