In printing, the use of the spray powder is to prevent the product back onto the dirty. Now many advanced printing equipment, already eliminated powder spraying device, and use three groups type drying way, namely: two groups of infrared, a group of uv. At present our domestic printing equipment, most are infrared and spray powder or only powder spraying equipment.
Usually in the production of ink layer thickness, meet the dark area is large, the operator is always hope to printing powder amount to put a few bigger, such products won't because the back onto the dirty and scrap, but often ignored powder amount should be as small as possible the problem. In fact, powder dimension can bring many hazards.
1. Powder amount is too large, machine equipment to severe wear. Production to spray powder products in at the same time, a number of powder quantity are to fly to the machine paper receiver chain, diao paper and roller teeth. Although every week maintenance time, but also may not be able to clean up all the dust, as time passes will intensify the machine of wear and tear.
2. Powder dimension, to the operator healthy also will have certain effect. Although vendors are said to human body spray powder no damage, but the operator in fine dust flying stay every day in the workshop, do not know to want how much dust in the lung.
3. Powder amount is too large, positive and negative in print, because is flour dimension, it will directly affect the class when printed opposite production. Serious when each hundreds of zhang needs cleaning a rubber cloth. The product will therefore appear unstable process, affecting both quality and affect the yield.
4. Powder amount is too large, affect the product luster. When printing some high-grade products, the operator is always hope to some degree of saturation is high ink. This product is bright-coloured printing and light, at the same time, in order to prevent the ceng dirty and increase the powder quantity. The spray powder in has not yet dry ink layer on some ink absorption, can be in colors on the form a layer of the mist, products and reduce the glossiness so.
5. Powder amount is too large, to process will have consequences, such as glazing effect, etc.
So in production, we should be in the usage of the powder spraying cause enough attention to as little as possible to spray or not spray on the back to control the purpose of ceng dirty. Production in the back by many factors of ceng dirty, the key is how to effective control.
1. To strictly control the density values. All kinds of density value, is through the pull, observe the K value, dot enlargement value and inky saturation to take the best value. In another sense, to use this method to obtain the best value (density), is also under the amount of paper ink best quantity. If we use 128 grams of Japan has the best density glossy paper value is yellow, red, and blue 1.05 1.35 1.45, black 1.70. We can keep this in the production data printing, is normally impossible ceng dirty, add a little powder spraying will be more insurance. But density too much value, even if ink layer not thick, still ceng dirty. For example, yellow, magenta 100% each dieyin and four color dark tone than previously, apparently yellow, magenta 100% each ink layer is not thick, if the yellow density values increase more than 1.30, magenta density values increase more than 1.50, beyond the paper bear the amount of ink critical value, the product is easy to back onto the dirty.
2. The reason we use spray powder is because of the large area dark products, ink layer thickness. Ink is between 35% ~ 270%, the total amount of ink than traditional practice by 125% ~ 90%, such already can ensure the dark adjustable density requirements, and also won't appear because of reduced ink too dark tone level among influence. According to relevant data demonstrate that the total of 235% and total ink ink of 360% 125% and reduce the amount of ink shown similar density value. And the actual total amount the dark ink was 235%, printing can need not spray powder or a few powder spraying can control the back onto the dirty.
3. The tear sheet is proof of the customer, is also the basis of printing. If the products and tear sheets printed out too big, the customer will not politely refuse to accept, the question is whether the tear sheet truly reflect the manuscript. Such as original and not so thick ink layer, proofing or sign when samples in order to achieve the satisfaction of customers, trying to increase the amount of ink. So will result in serious network expansion, the dot enlargement is to spread around by the center, center of the ink will exceed the amount of paper to inherit, cause not increase powder amount hard to avoid ceng dirty.
4. Ink emulsification serious can affect the product drying time. When printing ink containing a certain amount of acid aqueous, will extend the imprinting surface oxidation of conjunctival time, causing dry slow, easy to cause the back onto the dirty. Cause serious emulsification many factors of ink, but the most important still is water, and also control the load of ink. In the density of up to a certain value should use the least amount of ink and the least amount of water, this is the control ink serious emulsion best method.
5. Printing pressure light, make the ink can't normal transfer. Transfer to the paper's ink can't combined well with paper, printing ink just float on the surface of the paper, and was not strong, also can cause the back onto the dirty. So dot enlargement in normal shall, within the scope of the proper enlargement printing pressure.
To sum up, we want to do less with the spray powder spray powder or not to control the back ceng dirty, must start from the original carefully technology research, make effective process the construction plan and make suitable for printing plate making means through the original and standard tear sheets. Printing to strictly according to the digital operation, good control of all kinds of density values, pressure and wash balance, maintain a certain amount of printing speed, as appropriate, add some dry oil, reduce semi-finished products pile up high.