Cause and treatment of the hair falling and powder

2022-08-05
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Causes and treatment of hair loss and powder removal of offset paper

paper is composed of fiber, lignin, resin, fillers, adhesives, pigments and other raw materials

the fuzzing and de dusting of paper is caused by the fact that the surface fibers are not strong and dense enough. In the process of printing, when the paper and the rubber peel off at the moment, a certain tension is formed between them due to mutual bonding. If the fiber structure of the paper is firm and dense, there will be no hair loss. On the contrary, it is easy to pull down the fibers on the surface of the paper, resulting in de dusting and hair loss

during the printing process, the offset press normally operates at a high speed of 6000 sheets/hour to 10000 sheets/hour, and the transfer of pictures and texts on the printing plate is very short. If it is invalid, please adjust the line of the limit switch (usually installed near the mobile test bench and the fixed beam) to the normal state within an instant. In this short moment, there is an extremely complex mechanical interaction between the ink on the printing plate and the paper. Due to the rapid speed of the offset press, Hubei Province will focus on cultivating and expanding the 10 new material industry chains such as high-performance metal structure, special alloys for high-end equipment, advanced optical communication materials, advanced electronic materials, new energy batteries and photovoltaic new materials, biomedical materials, advanced composite materials, new inorganic non-metallic materials, advanced high molecular materials, and new carbon materials, In order to make the ink transfer to the paper ideally, the paper must have a certain surface strength

rough paper will cause dirty plates, which will directly damage the image clarity on the printing sheet and reduce the printing quality

apart from the low surface strength of the paper, the improper selection of fillers and adhesives and the inaccurate calendering are also the reasons for the de dusting and fuzzing of the paper. In addition, it also occurs in the case of high-speed printing

the problem of hair loss and powder removal of paper is generally caused by poor product quality of paper. In addition to the suggestion that the paper manufacturers improve the quality of the products as soon as possible and require the return of the products, the operators of the printing enterprises can also take corresponding remedial measures according to the specific conditions of the printed paper:

1) due to the raw materials and manufacturing process, the paper may be de powdered and linted during the printing process, and accumulated on the surface of the blanket, thus affecting the correct transmission of the points. In serious cases, the blanket must be scrubbed every 1000 copies printed, Otherwise, the rubber blanket will be covered with powder and hair, and the gloss of the printed product will be significantly reduced. If possible, overprint a layer of white ink and clean water on the paper surface. Generally, wipe the blanket more

2) properly adjust the viscosity of the ink used, and add an appropriate amount of adhesive and diluent into the ink to reduce the viscosity of the ink, so as to improve the impact of the adhesion of the ink on the paper. Because the ink viscosity is too large, it is easy to make the paper lose hair and powder

3) adjust the printing pressure to properly reduce the stamping force between the rubber cylinder and the stamping cylinder. Or choose the appropriate printing speed and reduce the speed appropriately. In this way, after imprinting, the peel tension between the blanket and the paper can be reduced when the tolerance requirements of various motion characteristic parameters are met

4) the rubber blanket has been used for a long time, resulting in vulcanization reaction, or aging due to light, heat and wear. Especially in hot summer, the old rubber blanket is easy to become sticky if necessary, resulting in hair loss and powder removal. At this time, a layer of sulfur powder can be coated on the rubber blanket. If not, we'll have to replace the blanket with a new one

5) the paper that is prone to flake, such as offset paper, relief paper, writing paper, etc., must be dried before printing, and the paper scraps, paper powder, paper ash, dust, rags, etc. on the paper surface must be removed

the difference between offset printing and other printing methods is that water is used for offset printing, and water often causes ink emulsification, paper expansion and deformation, etc. The paper de dusting and hair loss are also directly related to offset printing water

the paper used for offset printing generally needs to be filled. In order to improve the retention rate of the added filler in the paper, the surface strength and gloss of the paper should be improved. At the same time, the paper should have a certain sizing degree. Otherwise, the paper will be weak after contacting with water, resulting in adverse phenomena such as filler falling off

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