Printing News
The printing process about single glossy paper introduced

Because the production process of glossy paper single different, paper, there is more serious on both sides of the performance difference, the relative humidity of the outside world is very sensitive, easy occurrence curly, printing and subsequent use do a lot of influence. In this paper, through and shenzhen several enterprise technical personnel's technology exchange, made a detailed summary.
1, for single paper appear curly the cause of the problem analysis:
Due to the special requirements of single copper paper, it is both sides of the coating is different: the positive 20 grams left and right sides with (hereinafter referred to as the coating surface), when the reverse besmear only 1 g (known as not coating surface), can say single copper coating is one side of the paper, the other side is paper fibers, and fiber and coating for water coefficient of expansion of different: fiber of expansion ratio, and the expansion of the coating a smaller ratio. And both of the big water also has difference, fiber bibulous fast, coating bibulous slowly.
Paper production come out of time, because of it of moisture content in stable, fiber and paint relative balance state, paper of the surface is very smooth. When the outside environment relative humidity change (i.e. environment humidity and the water content of the paper does not match), paper will happen curly problem: environment humidity higher than paper relative humidity (such as the change of the weather: rain or snow, environment humidity will increase), paper can absorb moisture, coating surface to curly; Environment humidity under paper relative humidity, paper will lose the water, not to the coating surface curly. But if the environment relative humidity and paper relative humidity in deviation between the plus or minus 5%, general won't have too obvious curly issues. At the same time, in the printing process, if the paper is the moisture content changes (such as gravure and flexible printing paper was in excessive and dry), fiber and the balance of the coating is destroyed, also change accordingly: losing water, paper will not face to coating curly; Absorb water, to the coating surface curly.
2, printing of single copper produce curly main influence factors:
Because of the different ways of printing, single copper in Indian generation after the influence factors of curly are different. In the offset printing, produce the main factors of curly for environment temperature and humidity and paper relative humidity not match, and for gravure and flexo, besides the environment temperature and humidity and paper relative humidity outside don't match, too dry is also one of the main reasons.
Offset printing is through the oil and water don't dissolve in theory to realize the transfer of graphic, although in the printing process of water, but the water absorption ability is very low coating, basically won't affect the water content of the paper, the general won't happen curly problem. If the environment temperature and humidity and paper relative humidity match, then basically won't cause curly problem.
For gravure and flexo, besides and offset printing also will be affected by the influence of environmental temperature and humidity, because in the printing process, you will need either a drying equipment to dry ink, and dry ink at the same time, the part of the paper water evaporated. Fiber and the state of the coating is destroyed balance, so is also very easy to cause the curly problem (not coating to face curly).
3, how to avoid curly the happening of the problem:
1) and strict control of environmental temperature and humidity. Due to the environmental temperature and humidity on the single copper curly are significant, printing environment must have strict control, and always keep stable, not with the outside world and the change of the weather changes, the production workshop must be equipped with adjustment of the temperature and humidity equipment. Our company produces the single copper water general control in 4.5 5.5% between, production workshop environment temperature and humidity also have strict control: temperature 20 ± 5 ℃, humidity 50-5% RH. Therefore, if the conditions of temperature and humidity in accordance with our control standard control, normally won't happen curly problem.
2), printing conditions optimization. For gravure and flexo, if printed matter happen and curly, in can satisfy the ink dry, try to reduce the drying temperature 1-2 degrees or improve the speed of 3 to 5 m/min, and basic can reduce the degree of curly.

(Gold Printing Group)
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