In the packaging and printing industry, sometimes there are quality problems in paper, which need reasonable solutions.Whiteboard Adhesive Rubber And Paper Body Separation
Whiteboard paper is a kind of hard packaging paper, which is used for printing the packaging carton and commodity decoration lining paper of various commodities. It is often used to print all kinds of lottery tickets, children’s education pictures, etc.Whiteboard Adhesive Rubber And Paper Body Separation
Whiteboard paper can be divided into two categories: powdered whiteboard and ordinary whiteboard. According to the bottom layer, there are two kinds: gray background and white background. The specifications of white board paper include 220g / m2, 240g / m2, 250G / m2, 280g / m2 and 35og / m2.Whiteboard Adhesive Rubber And Paper Body Separation
Base paper has a great influence on the production and quality of coated paper. Therefore, there are special requirements for the composition, strength, surface properties and absorption of base paper.Whiteboard Adhesive Rubber And Paper Body Separation
① Base paper composition
The base paper of coated paper generally contains about 70% of hardwood pulp, and the rest is coniferous pulp. The tensile strength and surface strength of base paper are generally required to be high.
In order to improve the strength of base paper, in addition to improving the composition of size, sometimes measures such as appropriately improving the beating degree and surface sizing can also be taken.
② Surface properties
The surface properties of coated paper base paper are strict. The base paper shall not be too rough or too smooth. Even if the base paper is too rough after coating, the surface smoothness still can not meet the printing requirements:Whiteboard Adhesive Rubber And Paper Body Separation
if it is too smooth, the effective bonding area between the coating and the base paper is small, and the bonding strength between the coating layer and the paper surface is not enough.Whiteboard Adhesive Rubber And Paper Body Separation
③ Absorption and uniformity
The attractiveness of the base paper should be moderate, the absorption is too large, and the powder is easy to fall off after coating: the absorption is too poor, and the base paper is not firmly combined with the coating layer after coating.Whiteboard Adhesive Rubber And Paper Body Separation.
The uniformity of base paper is better, which is conducive to the uniformity of coating.Whiteboard Adhesive Rubber And Paper Body Separation
2. Control of coating performance
Coated paper must first have two characteristics: coating adaptability and printing adaptability. Coating adaptability refers to the uniform coating amount when coating. The printability is the effect of printing quality.Whiteboard Adhesive Rubber And Paper Body Separation
The concentration distribution range of the coating is relatively wide, which can be between 3o-70%. In general, the higher the concentration, the greater the viscosity and the worse the fluidity, which will affect the uniformity of coating.Whiteboard Adhesive Rubber And Paper Body Separation
② Coating amount
If the coating amount increases within a certain range, the smoothness of the paper will be improved, the dot display effect will be good, the ink absorption will be uniform, the ink will have good ink receiving performance, and the ink will be easily transferred to the coating surface, so as to improve the printing adaptability of the coated paper.
3. Development of new printing suitability improver for coated paper
Combined with the production process of coated paper, the research and development of special printability improvers for coated paper is one of the important ways to improve the printability of coated paper in the future. For example, the “printing suitability improvement additive for coated paper” developed by Hangzhou Institute of chemical industry has shown good results in use, Whiteboard Adhesive Rubber And Paper Body Separation
which has significantly improved the printing suitability of coated paper and the quality of coated paper products. Moreover, the production process of the product is reasonable, the cost is low, meets the requirements of environmental protection and has good economic benefits.Whiteboard Adhesive Rubber And Paper Body Separation
1. The ratio of pulp fiber whiteboard is made of surface pulp and each layer of bottom pulp. Therefore, the slurry is generally divided into surface slurry (surface layer), two layers, three layers and four layers. The fiber ratio of each layer of slurry is different, and the fiber ratio of each layer of slurry is different according to the quality of papermaking. In general, the basic principle of white board fiber ratio is one layer: Whiteboard Adhesive Rubber And Paper Body Separation
100% domestic (or imported) bleached chemical wood pulp; Second floor: 100% mechanical wood pulp: third floor: 30% mechanical wood pulp, 50% books and 20% gross newspaper. Four layers: 1oo% – e paper. In general, the fiber ratio of surface pulp is basically the same, while the second, third and fourth layers of pulp are determined according to specific conditions, such as raw material source, papermaking quality requirements, etc. However, proper adjustment can only be made on the premise of meeting the quality requirements.Whiteboard Adhesive Rubber And Paper Body Separation
In addition to fiber, a certain amount of filler, glue and whitening agent are added to the surface slurry of whiteboard, and an appropriate amount of filler and glue are also added to the fourth layer slurry.
2. Characteristics of Whiteboard
Because the fiber structure of whiteboard is relatively uniform, the surface layer has filler and rubber components, and the surface is uniformly coated with a certain amount of coating and multi roller calendered, the texture of the paperboard is compact and the thickness is relatively uniform. Whiteboard Adhesive Rubber And Paper Body Separation
The surface of whiteboard is generally white and smooth, with relatively uniform ink absorption, and there are few phenomena of surface de powder and hair loss, The surface strength, toughness and folding resistance of the paper are good, but the water content of whiteboard is high and has some flexibility. This will have a certain impact on printing.Whiteboard Adhesive Rubber And Paper Body Separation
At present, compared with Japan and South Korea, domestic whiteboard has reached a certain level in some quality indicators, but there is still a gap, such as ink absorption and scalability. If the surface strength of whiteboard paper is insufficient and the combination between fibers is not tight, a lot of small paper scraps will appear on the blanket soon after printing, which will affect the quality of printing products.Whiteboard Adhesive Rubber And Paper Body Separation
Solution: ① the white board paper has the phenomenon of de powder and wool, and it is required to wipe the offset blanket frequently; ② Before printing, the medium light agent and white ink shall be printed once to increase the surface strength of the paper. The chromatic printing shall be carried out after the printed matter is dry.Whiteboard Adhesive Rubber And Paper Body Separation
If the paper filler is uneven and the sizing amount is insufficient, there will also be two sheets of paper and adhesive blanket during printing. In addition, there are serious problems in papermaking quality. The whiteboard is coated evenly on the surface, and the underlying paper is loose, which often leads to the separation of the paper body in the printing process. Blind purchase and use of such a kind of low-quality whiteboard should be avoided.Whiteboard Adhesive Rubber And Paper Body Separation
When the printing pressure is too high, the paper will produce a back grinding force, which will destroy the binding force of the internal fibers of the paper. When the paper is released after printing, the rapid reduction force of the blanket and the reduction of the paper will cause the peeling of the paper (commonly known as two skins).Whiteboard Adhesive Rubber And Paper Body Separation
Solution: according to the quality and thickness of the whiteboard and the technical requirements of the equipment used, the correct pressure debugging should be carried out reasonably.Whiteboard Adhesive Rubber And Paper Body Separation
In the whole process of printing technology, it is the process of solving the contradiction between ink and paper. If you want to transfer the text coated with ink on the printing plate to the printed paper, you must apply a certain printing pressure in the process of text transfer.Whiteboard Adhesive Rubber And Paper Body Separation
People often say, “no printing without pressure.” this sentence fully shows the role of printing pressure. Generally speaking, the printing pressure is based on the premise that the printing dot is strong, the picture and text are clear, the color is bright and the shade is appropriate. On the basis of strong enough imprinting, the smaller the pressure, the better.Whiteboard Adhesive Rubber And Paper Body Separation
When printing whiteboard, the center distance between the printing plate cylinder and the rubber cylinder remains unchanged. Only the center distance between the embossing cylinder and the rubber cylinder needs to be adjusted.Whiteboard Adhesive Rubber And Paper Body Separation
When printing 250-450g / m2 white board, the center distance of the drum can be increased by 0.20-0.40mm. Specific methods: for example, when printing 400 g / m2 white board paper, the gap between the printing plate cylinder and the rubber cylinder is 3.95 mm,Whiteboard Adhesive Rubber And Paper Body Separation
The gap between the rubber cylinder and the embossing cylinder is 3.40 mm, the total package lining of the ten lining paper of the printing plate is 1 mm, and the total package lining of the rubber cylinder is 3.15 mm. If the paper changes from thick to thin, the reduced thickness is that the thickness removed from the printing plate liner is added to the rubber cylinder, Otherwise, it is added to the plate cylinder.Whiteboard Adhesive Rubber And Paper Body Separation
The surface smoothness of ordinary whiteboard is poor and rough, and the tightness of the paper is far better than that of coated paper. When printing ordinary whiteboard, pay attention to increasing the printing pressure accordingly.Whiteboard Adhesive Rubber And Paper Body Separation