As the main raw material for printing, paper has a great influence on the quality of product printing. Different types and batches of paper produced have different properties. In addition, the requirements for paper properties vary with product structure, characteristics, and quality requirements. Therefore, a correct understanding and understanding of certain properties of the paper is of great importance for accurately grasping the suitability of the printing process and ensuring the quality of the printed product.
First, the impact of paper on the printing quality of ink absorption The so-called paper absorbency refers to the ability of the paper to absorb ink. The paper has strong ink absorption, and the imprinting is easy to dry; on the contrary, the ink-absorbing property is weak, and the imprinting speed is slow, and inevitably, the imprinting is liable to occur. We know that the transfer of ink is accomplished by the capillary action consisting of pressure and the interweaving gap of paper fibers. That is, when the paper is pressed, the gaps of the interwoven fibers are compressed, and after the pressure disappears, the surface of the paper is restored to the original state due to the effect of elasticity, and at the same time, the ink is adsorbed, which is the process of ink layer formation. Due to the different elasticity of the fibrous tissue, various papers have different ink absorption properties. The paper with good ink absorption needs a light printing pressure, and the pressure resistance of the printing plate is high. If the paper is too loose, the fiber gap is too large, then, when the viscosity of the ink is large, it will lead to pull paper defects; the other hand, when the ink viscosity is small, it is easy to quickly infiltrate the link material, causing cross-printing phenomenon, This should be achieved by high-speed ink stickiness to suit the printability of the paper. Therefore, paper with tight paper and less ink absorbance is mostly used for color printing, so that the pigment can be prevented from falling off after the penetration of the link material in the ink, and the luster of the ink layer will affect the printing quality.
Second, the paper moisture content and PH value of the print quality of the paper's moisture content is based on the weight of water in the paper and paper weight%, generally speaking, the water content of printing paper should be controlled at 7% ± Between 1%, and the paper center and paper surrounding water content error is not more than 1% is appropriate. When the moisture content of the paper is too large, the binding force between the fibers, the filler and the rubber in the paper is likely to be reduced, which will affect the surface strength of the paper, resulting in the occurrence of de-dusting and off-paper defects after printing, thereby reducing the edge of the paper. The hardness and stiffness, so it is easy to produce positioning instability when the paper is fed, resulting in misalignment. If the moisture content of the paper is too low, the elasticity of the paper is also poor, and the printing can easily be expanded when printing dots, which means that the dot gain rate is large. In addition, static electricity and hygroscopic deformation are also prone to occur in the printing process, making overprinting of products inaccurate. The pH value of the paper is also the pH value. Normally, the PH value of the printing paper is suitable for neutrality, the acidity and alkalinity of the paper is unfavorable, and the ink that is not resistant to acid and alkali can be discolored, and the drying of the print is affected. The PH value of domestic offset paper, letterpress paper, white card, glass card and whiteboard paper is generally less than 7.0. It is partially acidic or weakly acidic. The drying speed of the print is relatively slow. Therefore, printing large area layout should pay attention to proper ink. Add dry oil to dry, so as to avoid overprinting or causing bottom quality problems. The PH value of high-grade paper and paperboard, such as coated paper and imported glass cards, is mostly above 7.0, showing weak alkalinity or alkalinity, and the imprinting drying speed is faster, which is favorable for overprinting. It is worth mentioning that, regardless of the kind of paper with the storage time, the PH value will drop.
Third, the paper's elasticity and plasticity on the print quality of the paper's elasticity and plasticity refers to the paper by the pressure after the performance of a physical performance. The elasticity of paper means that the paper is deformed under the influence of printing pressure. After the pressure is applied, the deformation disappears and the original shape is restored. Plasticity refers to the fact that after the paper is subjected to the printing pressure, it leaves traces of deformation, and the printing pressure cannot be restored to its original shape. The elasticity of the paper is related to the ability of the paper to absorb ink, because the paper is combined with the ink on the plate by pressure. When the ink is squeezed onto the surface of the fibers and the gaps in the paper, the fibers are compressed so that the air trapped between the gaps is squeezed out. After the pressure is released, due to the elasticity of the paper, part of the deformation is rapidly recovered, and the capillary action of the fibers is added. The binder in the ink is absorbed into the fibers of the paper, so the greater the elasticity of the paper, the stronger the ink absorption, and the printing ink layer will be easier to dry. On the contrary, the elasticity of the paper is too small, the ink absorption performance is poor, and the imprinting is easy. However, if the paper is over-elastic, the printed ink will lack the luster of the ink. It is also easy to produce print-through phenomenon. The plasticity of the paper is more pronounced in the letterpress printing process because the letterpress layout is convex, and the paper under the effect of pressure will produce a slight amount of protrusions on the back. This plastic deformation is exactly what the letterpress product is full of ink and the ink layer is thick. Features. In the actual production process, if there is a large elasticity of paper, the printing pressure may be appropriately increased, the ink layer thickness may be slightly thinner, and the printing effect is better. If there is a paper with a higher printing plasticity, the printing pressure should be slightly smaller, and the ink supply volume should be increased appropriately to reduce the back mark on the printed sheet to ensure the quality of the printed product.
Fourth, the paper's smoothness and thickness uniformity of the impact on the print quality Paper smoothness is high, printed on the layout of the text can be faithfully reproduced, especially the small network can be accurately restored. For paper with low smoothness, due to the depressions on the surface of the paper, it is easy to make the printing of the dots unclear, and the level of the print layout is not clear. The smoothness and thickness uniformity of the paper will have a direct effect on whether the printing pressure and the ink color can remain uniform. Therefore, the use of pressure to achieve the printing production process requires that the thickness of the paper be as uniform as possible. Of course, the smoothness is also relatively good, which is more conducive to the improvement of printing quality. However, the method of smoothness of the paper is mainly to adopt methods such as adding filler and calendering, so that the tightness of the paper is improved, and the elasticity and ink absorbability thereof are relatively decreased, so that the back of the printed product is prone to smudging. In addition, when the printing pressure is too high, it is easy to spread the ink layer and enlarge the deformation of the print. Based on these circumstances, the unevenness of the smoothness of the paper and the significant difference in the degree of rough light should be classified separately, so that when the paper with poor smoothness is printed, a clear print can be obtained by appropriately increasing the printing pressure and the amount of ink, thereby improving printing. quality.
In a word, the properties of paper are constant, and some change with time and environment and process conditions. Therefore, it is not only possible to correctly understand and understand the effects of some paper properties on the quality of printed products. Improve the printing quality of the product better, and can promote the improvement of production efficiency. (Kang Qilai) ("China Packaging News")
First, the impact of paper on the printing quality of ink absorption The so-called paper absorbency refers to the ability of the paper to absorb ink. The paper has strong ink absorption, and the imprinting is easy to dry; on the contrary, the ink-absorbing property is weak, and the imprinting speed is slow, and inevitably, the imprinting is liable to occur. We know that the transfer of ink is accomplished by the capillary action consisting of pressure and the interweaving gap of paper fibers. That is, when the paper is pressed, the gaps of the interwoven fibers are compressed, and after the pressure disappears, the surface of the paper is restored to the original state due to the effect of elasticity, and at the same time, the ink is adsorbed, which is the process of ink layer formation. Due to the different elasticity of the fibrous tissue, various papers have different ink absorption properties. The paper with good ink absorption needs a light printing pressure, and the pressure resistance of the printing plate is high. If the paper is too loose, the fiber gap is too large, then, when the viscosity of the ink is large, it will lead to pull paper defects; the other hand, when the ink viscosity is small, it is easy to quickly infiltrate the link material, causing cross-printing phenomenon, This should be achieved by high-speed ink stickiness to suit the printability of the paper. Therefore, paper with tight paper and less ink absorbance is mostly used for color printing, so that the pigment can be prevented from falling off after the penetration of the link material in the ink, and the luster of the ink layer will affect the printing quality.
Second, the paper moisture content and PH value of the print quality of the paper's moisture content is based on the weight of water in the paper and paper weight%, generally speaking, the water content of printing paper should be controlled at 7% ± Between 1%, and the paper center and paper surrounding water content error is not more than 1% is appropriate. When the moisture content of the paper is too large, the binding force between the fibers, the filler and the rubber in the paper is likely to be reduced, which will affect the surface strength of the paper, resulting in the occurrence of de-dusting and off-paper defects after printing, thereby reducing the edge of the paper. The hardness and stiffness, so it is easy to produce positioning instability when the paper is fed, resulting in misalignment. If the moisture content of the paper is too low, the elasticity of the paper is also poor, and the printing can easily be expanded when printing dots, which means that the dot gain rate is large. In addition, static electricity and hygroscopic deformation are also prone to occur in the printing process, making overprinting of products inaccurate. The pH value of the paper is also the pH value. Normally, the PH value of the printing paper is suitable for neutrality, the acidity and alkalinity of the paper is unfavorable, and the ink that is not resistant to acid and alkali can be discolored, and the drying of the print is affected. The PH value of domestic offset paper, letterpress paper, white card, glass card and whiteboard paper is generally less than 7.0. It is partially acidic or weakly acidic. The drying speed of the print is relatively slow. Therefore, printing large area layout should pay attention to proper ink. Add dry oil to dry, so as to avoid overprinting or causing bottom quality problems. The PH value of high-grade paper and paperboard, such as coated paper and imported glass cards, is mostly above 7.0, showing weak alkalinity or alkalinity, and the imprinting drying speed is faster, which is favorable for overprinting. It is worth mentioning that, regardless of the kind of paper with the storage time, the PH value will drop.
Third, the paper's elasticity and plasticity on the print quality of the paper's elasticity and plasticity refers to the paper by the pressure after the performance of a physical performance. The elasticity of paper means that the paper is deformed under the influence of printing pressure. After the pressure is applied, the deformation disappears and the original shape is restored. Plasticity refers to the fact that after the paper is subjected to the printing pressure, it leaves traces of deformation, and the printing pressure cannot be restored to its original shape. The elasticity of the paper is related to the ability of the paper to absorb ink, because the paper is combined with the ink on the plate by pressure. When the ink is squeezed onto the surface of the fibers and the gaps in the paper, the fibers are compressed so that the air trapped between the gaps is squeezed out. After the pressure is released, due to the elasticity of the paper, part of the deformation is rapidly recovered, and the capillary action of the fibers is added. The binder in the ink is absorbed into the fibers of the paper, so the greater the elasticity of the paper, the stronger the ink absorption, and the printing ink layer will be easier to dry. On the contrary, the elasticity of the paper is too small, the ink absorption performance is poor, and the imprinting is easy. However, if the paper is over-elastic, the printed ink will lack the luster of the ink. It is also easy to produce print-through phenomenon. The plasticity of the paper is more pronounced in the letterpress printing process because the letterpress layout is convex, and the paper under the effect of pressure will produce a slight amount of protrusions on the back. This plastic deformation is exactly what the letterpress product is full of ink and the ink layer is thick. Features. In the actual production process, if there is a large elasticity of paper, the printing pressure may be appropriately increased, the ink layer thickness may be slightly thinner, and the printing effect is better. If there is a paper with a higher printing plasticity, the printing pressure should be slightly smaller, and the ink supply volume should be increased appropriately to reduce the back mark on the printed sheet to ensure the quality of the printed product.
Fourth, the paper's smoothness and thickness uniformity of the impact on the print quality Paper smoothness is high, printed on the layout of the text can be faithfully reproduced, especially the small network can be accurately restored. For paper with low smoothness, due to the depressions on the surface of the paper, it is easy to make the printing of the dots unclear, and the level of the print layout is not clear. The smoothness and thickness uniformity of the paper will have a direct effect on whether the printing pressure and the ink color can remain uniform. Therefore, the use of pressure to achieve the printing production process requires that the thickness of the paper be as uniform as possible. Of course, the smoothness is also relatively good, which is more conducive to the improvement of printing quality. However, the method of smoothness of the paper is mainly to adopt methods such as adding filler and calendering, so that the tightness of the paper is improved, and the elasticity and ink absorbability thereof are relatively decreased, so that the back of the printed product is prone to smudging. In addition, when the printing pressure is too high, it is easy to spread the ink layer and enlarge the deformation of the print. Based on these circumstances, the unevenness of the smoothness of the paper and the significant difference in the degree of rough light should be classified separately, so that when the paper with poor smoothness is printed, a clear print can be obtained by appropriately increasing the printing pressure and the amount of ink, thereby improving printing. quality.
In a word, the properties of paper are constant, and some change with time and environment and process conditions. Therefore, it is not only possible to correctly understand and understand the effects of some paper properties on the quality of printed products. Improve the printing quality of the product better, and can promote the improvement of production efficiency. (Kang Qilai) ("China Packaging News")
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