The most popular paper reprocessing with wool dyei

2022-07-26
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The problem of paper reproduction with wool dyeing powder

these inorganic dust will also grind the printing plate, affecting the printing resistance. Therefore, according to national standards, we should often stop to clean the printing plate and blanket. Galling refers to the peeling off of single fibers, fiber bundles or special cells in some raw materials from the paper during printing. Powder dropping refers to that the powdery substances in the paper that are weakly combined with the paper surface are generally fillers and pigments, which are peeled off from the paper surface due to the influence of adhesive effect during printing

there are two reasons for paper roughening and powder dropping. First, it is caused by the printing operation process, such as ink clearance, printing pressure, printing speed, fountain solution, etc. Second, it is caused by the surface strength of the paper itself not meeting the requirements

I. roughening and powder dropping caused by printing operation at the moment of ink transfer, under the action of inertia force, the ink adhesion, stripping force and the adsorption force of printing plate blanket will occur on the paper surface if it is greater than the surface strength of the paper

in case of serious galling and powder dropping, it will adhere to the printing plate or blanket, leaving white spots on the graphic and graphic parts of the paper. Some of the fiber hairs and fillers that have been glued down will also be brought into the ink by the ink roller, causing the printing products to be blurred. In addition, outside the room temperature ~ 200 ℃, the paper wool on the printing plate is reversed to the ink roller and ink bucket to mix with the ink. With the progress of printing, more and more paper wool and paper powder are accumulated on the printing plate, which seriously affects the full transfer of printing ink and leads to shutdown and scrubbing, reducing the production efficiency. In order for the printing press to work properly, the paper must reach a certain strength. The equation is the surface strength of the paper, the stripping tension, the adhesion of the ink to the paper, and the adsorption of the printing plate or blanket. During the printing process, the monthly straightness of the paper is a constant. In order to prevent galling and powder dropping during printing, the monthly straightness can be adjusted to adapt to and balance the monthly straightness if the printing process operation and printing quality allow. Peel tension peel tension is the force between ink, blanket and paper. On the premise that other conditions remain unchanged, the limit value of printing speed can be obtained through calculation, which can avoid or reduce the phenomenon of paper roughening and powder dropping

4 adhesion of ink to paper the adhesion of ink to paper is mainly caused by the separation of ink on the paper surface

the brightness of the ink can be properly reduced and the thickness of the ink layer can be reduced to reduce the adhesion of the ink to the paper surface. 8 the adhesive force of printing plate or blanket does not need to consider the value of 8 under normal circumstances. The main reason is that the blanket is worn and aged, resulting in burring and powder dropping. At this time, the blanket needs to be frequently scrubbed or replaced with a new blanket. 4 the paper cutting operation is similar to the paper powder and paper scraps with roughening fault, which are mainly generated by the paper cutter during paper cutting

for example, the blades of the paper cutter are not worn fast, the upper and lower blades (introduction of stainless steel blades) are not consistent, and the fine technology level still lags behind that of small fiber debris in some developed countries due to small movement during paper cutting, which can produce paper powder and paper debris

paper powder paper scraps are generally composed of several or dozens of fibers, which are common at the end of the paper. At this time, the paper cutter must be replaced in time to avoid such problems. 8 electrostatic problem in printing, the use of paper with static electricity will cause serious problems, because the paper page adhesion will cause automatic paper feeding skew or double sheet phenomenon. What is more serious is that paper powder and paper scraps will adhere to the paper. The paper powder and paper scraps of printing are closely related to static electricity. Because only a small static voltage is generated, the fine paper powder and paper scraps in the paper cutting process of the cutting machine will be adsorbed on the edge of the paper, and the paper powder and paper scraps will enter the surface layer of the paper during the printing process. This causes a similar printing galling fault. Therefore, static electricity elimination device must be adopted to eliminate static electricity

II. Roughening and powder dropping caused by papermaking process the reasons for roughening and powder dropping caused by papermaking process are as follows: the fiber ratio and beating operation are improper, the pulp contains a large number of fine fibers and miscellaneous cells, the beating degree is too low, the fiber adhesion is poor, and it is easy to fall off. 4. Too much filler is added, which is not firmly combined in the paper and easy to fall off. 8. The fibers of paper making are not firmly combined, the pressing pressure is not enough, the drying cylinder temperature is not well controlled, and the paper surface is loose and fluffy

paper generates static electricity during papermaking. Due to the low content of dielectrics such as alum and sodium chloride, the excessive content of sizing materials, and the low content of some fillers such as kaolin, the paper will be affected by high temperature and pressure during drying and calendering, resulting in high-voltage static electricity. Therefore, when the paper wool is left on the paper, a similar galling phenomenon occurs during the printing process. In order to avoid or reduce the paper galling and powder dropping, the paper surface must have sufficient surface strength. The surface strength of paper refers to the fastness of the combination of fiber, filler and rubber. It is an important technical index of the paper surface resistance to external forces. The method to eliminate paper roughening and powder dropping is to take effective measures to improve the surface bonding strength of the paper, which is the fundamental problem. There are many factors that affect the surface strength of paper. In addition to the papermaking process itself, the printing pressure and the temperature and humidity of the environment will also affect the surface strength of paper. Under the action of printing pressure, the binding force between the paper fibers is weakened or even broken, which reduces the surface strength of the paper. The embossing force will also cause galling and powder dropping. Therefore, adjust the printing pressure to properly reduce the embossing force between the blanket cylinder and the embossing cylinder to achieve the best state. The temperature and humidity of the printing workshop and the water content of the paper itself will also have a certain impact on the surface strength of the paper

when the water content of the paper is too large, the binding force between the paper fiber, filler and rubber will be reduced, and the paper will also be roughened and powdered

secondly, the printing fountain solution must also be controlled within the minimum dosage range, otherwise it will also cause paper galling and powder dropping. In case of roughening and powder dropping on the paper, the method of empty and less water can be adopted in the printing process, that is, a layer of clear water can be overprinted before printing to remove the paper wool on the paper, and then printing can be carried out after compared with the synthetic packaging film. In addition, add some de adhesion agent to the ink to reduce the smoothness of the ink and avoid galling and powder dropping

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