Paper as the main raw material for printing, its characteristics, has a great influence on printing. Experience in production practice clearly shows that poor paper quality has a high probability of printing failures, and will inevitably adversely affect production efficiency and product quality. Therefore, it is of great significance to correctly understand and understand the printing failure caused by poor paper quality.
First, the paper wrinkles caused by uneven printing, inaccurate overprinting and ghost phenomenon and exclusion methods We know that the fibrous tissue of paper has a strong hygroscopicity, it is easy to change the water content with the environment temperature and humidity changes . Once the moisture content of the paper increases, the fibrous tissue will exhibit elongation; otherwise, the fibrous tissue will shrink. This is why paper has tight edges, curls, ruffles, and uneven paper. These paper deformations are the main cause of printing wrinkles, misprints, and ghosting failures.
The daily production practice shows that if there is too much moisture on the four sides of the paper, when the middle moisture is higher than the side moisture, a tight edge condition will be formed. In the case of tight-edged paper, wrinkles are likely to occur at the middle of printing. Curl curling is due to the difference in water content between the front and back of the paper, which causes the side of the paper with low moisture content to curl due to shrinkage. When the edge of the paper is curled, during the printing process, it is easy to cause wrinkling, misregistration, or ghosting failure because the paper is not fed or the paper edge is bent when the paper is bitten. The wrinkles caused by the curling of the paper are wrinkled, the wrinkles are generally in a large skewed shape, and the position of the wrinkles is not fixed. The exclusion method is: knocking on the curled edge to make the edge straight and firm. Ruffles also tend to cause wrinkling, misprints, or ghosting problems. The most common problem is printing wrinkle failure. The occurrence of the lotus leaf is the expression of the moisture absorption elongation of the paper edge, which makes the straight edge size of the paper edge longer than the middle part, so that the paper edge is loose and the middle is relatively flat. During the printing, the wavy paper edge is subjected to the imprinting process. The crumpling phenomenon occurs when it is squeezed, and this wrinkle generally appears on the side of the paper, and the wrinkle is most likely to occur in the trailing portion of the printed product. For the paper with flounces, the treatment method is: Hanging the paper to make the paper uniform moisture content, and maintain a relative balance with the temperature and humidity of the printing shop, so that the paper edge recovery should be smooth degree.
To maintain a good flatness of the paper, attention should be paid to control from the source of quality. First, to maintain the stability of the paper performance, the newly entered paper should not be put into use immediately. It is better to leave it for a period of time to maintain its balance with temperature and humidity. Effectiveness of putting into use is effective; Second, the temperature and humidity of the paper storage warehouse, paper cutting workshop and printing workshop must be kept in balance, and there can be no great disparity to prevent the occurrence of deformation. These are effective measures to reduce or avoid printing wrinkles, misprints, and ghosting failures.
Second, the paper surface strength caused by the powder off, pulling and peeling (delamination) printing failure phenomenon and exclusion method paper surface strength refers to the degree of binding between the paper fibrous tissue, filler and rubber, if the papermaking process is not properly mastered The surface strength of the paper is poor. During the printing process, failures such as falling, pulling, and peeling are likely to occur, and even chain quality failures such as stacking, stacking of erasers, lamination, pattern printing, and lowering of printing plate printing rate can be caused.
The main reasons for the generation of printed powder, napped and stripped papers are: the ink on the blanket is in contact with the paper surface during the imprinting process, and produces a sticking force and a peeling force on the surface of the paper, and this force increases with the printing speed. increase. Therefore, when the surface strength of the paper is not good, the faster the printing speed is, the more the paper is powdered off. After the fact that the difference in surface strength of the paper is a fact, the emergency remedial measures at the production site can only be achieved through the adjustment and control of the printing operation technology, so as to reduce or eliminate failures such as dusting, feathering and peeling. The main process measures are:
1, appropriately reduce the printing speed, reduce the sticky force and peel force when imprinting;
2, appropriate to reduce the printing pressure, reduce the impact on the paper and peel force;
3ã€Adjust the viscosity of the ink properly, add some remover or varnish to the ink to reduce the viscosity of the ink;
4. Print with as small amount of fountain solution as possible to avoid the adverse effects of “great viscosity of large ink and large inkâ€;
5. Check whether the blanket has aged sticky phenomenon. If there is such a condition, a layer of sulfur powder should be coated on the surface of the blanket. If this method is invalid, a new blanket should be replaced;
6, through the use of paper hanging machine hanging paper, through the machine rotation and blowing effect, can make some paper scraps scattered;
7, an empty imprint on the paper, so that the paper flour flakes off;
8. For paper with poor paper surface strength, adjust the layout for printing less ink absorption to ensure product printing quality.
Third, the surface of the paper caused by the acidic quality of the printing fault phenomenon and exclusion methods General requirements for printing paper is more appropriate neutral, but due to papermaking process control discomfort, such as the sizing of the presence of acidic substances in the slurry, etc., easy to cause paper Slightly acidic. Acidic paper will play a role in inhibiting the oxygen conjunctiva of the ink layer, causing the slow reaction of the ink layer of the ink. If the printing ink layer is slow-drying, on the one hand, it is easy to cause imprinting, and on the other hand, it is difficult to achieve normal overprinting and overprinting. The printing layout is also likely to be dirty, affecting product quality and reducing production efficiency. Acidic papers are of a constant nature and cannot be corrected at one time. Only through the adjustment of printing technology measures can better avoid the occurrence of printing quality problems. The main process measures are: First, adjust the drying performance of the ink, add some desiccant in the ink or use the fast-drying ink to print; second, use the "deep ink thin printing" process to print, that is, the proper hue of the ink. Deepen some of them to make the printing ink layer thinner. This will not only help the printing ink layer to dry quickly, reduce the chances of occurrence of printing and stickiness, but also make the hue of printed products meet the quality requirements. This is a common practice in the printing industry. , can receive better results.
Fourth, poor paper smoothness caused by printing quality failure and exclusion method smoothness refers to the degree of paper surface smoothness, it is also a measure of the surface roughness of the paper an indicator. The smoothness of the paper depends on the density of the fine fibers, the filler, the size, and the quality of the surface sizing. When paper with poor smoothness is printed, it can easily cause problems such as ink coloring, poor gradation of the layout pattern, large amount of ink sucked, slow drying of the print, and rapid wear of the printing plate. Paper smoothness is also a constant property and print operators cannot change their inherent properties. Therefore, for the paper with poor smoothness, the purpose of improving the printing quality of the product can only be achieved through the control of the operation process measures.
1. Appropriately increase the printing pressure to make up for the occurrence of ink coloring caused by bad contact when the paper is rough and imprinted;
2, using the "light ink thick printing" process for printing, such as printing plate products due to the large amount of ink absorption, easy to cause dark ink situation, which can be appropriate to deepen the ink hue, so that printing ink volume increased, both Can meet the printing hue requirements, but also make the printing layout saturated ink, printing quality and good results.
In summary, as the basic conditions of printing, paper has a decisive role in the quality of the product's printing quality. Therefore, the correct understanding of the nature of the paper and its relationship with the printing process, through the printing process technology Checking control and adjustment can not only prevent and avoid the occurrence of such or such print quality failures, but also effectively improve product quality and production efficiency.
First, the paper wrinkles caused by uneven printing, inaccurate overprinting and ghost phenomenon and exclusion methods We know that the fibrous tissue of paper has a strong hygroscopicity, it is easy to change the water content with the environment temperature and humidity changes . Once the moisture content of the paper increases, the fibrous tissue will exhibit elongation; otherwise, the fibrous tissue will shrink. This is why paper has tight edges, curls, ruffles, and uneven paper. These paper deformations are the main cause of printing wrinkles, misprints, and ghosting failures.
The daily production practice shows that if there is too much moisture on the four sides of the paper, when the middle moisture is higher than the side moisture, a tight edge condition will be formed. In the case of tight-edged paper, wrinkles are likely to occur at the middle of printing. Curl curling is due to the difference in water content between the front and back of the paper, which causes the side of the paper with low moisture content to curl due to shrinkage. When the edge of the paper is curled, during the printing process, it is easy to cause wrinkling, misregistration, or ghosting failure because the paper is not fed or the paper edge is bent when the paper is bitten. The wrinkles caused by the curling of the paper are wrinkled, the wrinkles are generally in a large skewed shape, and the position of the wrinkles is not fixed. The exclusion method is: knocking on the curled edge to make the edge straight and firm. Ruffles also tend to cause wrinkling, misprints, or ghosting problems. The most common problem is printing wrinkle failure. The occurrence of the lotus leaf is the expression of the moisture absorption elongation of the paper edge, which makes the straight edge size of the paper edge longer than the middle part, so that the paper edge is loose and the middle is relatively flat. During the printing, the wavy paper edge is subjected to the imprinting process. The crumpling phenomenon occurs when it is squeezed, and this wrinkle generally appears on the side of the paper, and the wrinkle is most likely to occur in the trailing portion of the printed product. For the paper with flounces, the treatment method is: Hanging the paper to make the paper uniform moisture content, and maintain a relative balance with the temperature and humidity of the printing shop, so that the paper edge recovery should be smooth degree.
To maintain a good flatness of the paper, attention should be paid to control from the source of quality. First, to maintain the stability of the paper performance, the newly entered paper should not be put into use immediately. It is better to leave it for a period of time to maintain its balance with temperature and humidity. Effectiveness of putting into use is effective; Second, the temperature and humidity of the paper storage warehouse, paper cutting workshop and printing workshop must be kept in balance, and there can be no great disparity to prevent the occurrence of deformation. These are effective measures to reduce or avoid printing wrinkles, misprints, and ghosting failures.
Second, the paper surface strength caused by the powder off, pulling and peeling (delamination) printing failure phenomenon and exclusion method paper surface strength refers to the degree of binding between the paper fibrous tissue, filler and rubber, if the papermaking process is not properly mastered The surface strength of the paper is poor. During the printing process, failures such as falling, pulling, and peeling are likely to occur, and even chain quality failures such as stacking, stacking of erasers, lamination, pattern printing, and lowering of printing plate printing rate can be caused.
The main reasons for the generation of printed powder, napped and stripped papers are: the ink on the blanket is in contact with the paper surface during the imprinting process, and produces a sticking force and a peeling force on the surface of the paper, and this force increases with the printing speed. increase. Therefore, when the surface strength of the paper is not good, the faster the printing speed is, the more the paper is powdered off. After the fact that the difference in surface strength of the paper is a fact, the emergency remedial measures at the production site can only be achieved through the adjustment and control of the printing operation technology, so as to reduce or eliminate failures such as dusting, feathering and peeling. The main process measures are:
1, appropriately reduce the printing speed, reduce the sticky force and peel force when imprinting;
2, appropriate to reduce the printing pressure, reduce the impact on the paper and peel force;
3ã€Adjust the viscosity of the ink properly, add some remover or varnish to the ink to reduce the viscosity of the ink;
4. Print with as small amount of fountain solution as possible to avoid the adverse effects of “great viscosity of large ink and large inkâ€;
5. Check whether the blanket has aged sticky phenomenon. If there is such a condition, a layer of sulfur powder should be coated on the surface of the blanket. If this method is invalid, a new blanket should be replaced;
6, through the use of paper hanging machine hanging paper, through the machine rotation and blowing effect, can make some paper scraps scattered;
7, an empty imprint on the paper, so that the paper flour flakes off;
8. For paper with poor paper surface strength, adjust the layout for printing less ink absorption to ensure product printing quality.
Third, the surface of the paper caused by the acidic quality of the printing fault phenomenon and exclusion methods General requirements for printing paper is more appropriate neutral, but due to papermaking process control discomfort, such as the sizing of the presence of acidic substances in the slurry, etc., easy to cause paper Slightly acidic. Acidic paper will play a role in inhibiting the oxygen conjunctiva of the ink layer, causing the slow reaction of the ink layer of the ink. If the printing ink layer is slow-drying, on the one hand, it is easy to cause imprinting, and on the other hand, it is difficult to achieve normal overprinting and overprinting. The printing layout is also likely to be dirty, affecting product quality and reducing production efficiency. Acidic papers are of a constant nature and cannot be corrected at one time. Only through the adjustment of printing technology measures can better avoid the occurrence of printing quality problems. The main process measures are: First, adjust the drying performance of the ink, add some desiccant in the ink or use the fast-drying ink to print; second, use the "deep ink thin printing" process to print, that is, the proper hue of the ink. Deepen some of them to make the printing ink layer thinner. This will not only help the printing ink layer to dry quickly, reduce the chances of occurrence of printing and stickiness, but also make the hue of printed products meet the quality requirements. This is a common practice in the printing industry. , can receive better results.
Fourth, poor paper smoothness caused by printing quality failure and exclusion method smoothness refers to the degree of paper surface smoothness, it is also a measure of the surface roughness of the paper an indicator. The smoothness of the paper depends on the density of the fine fibers, the filler, the size, and the quality of the surface sizing. When paper with poor smoothness is printed, it can easily cause problems such as ink coloring, poor gradation of the layout pattern, large amount of ink sucked, slow drying of the print, and rapid wear of the printing plate. Paper smoothness is also a constant property and print operators cannot change their inherent properties. Therefore, for the paper with poor smoothness, the purpose of improving the printing quality of the product can only be achieved through the control of the operation process measures.
1. Appropriately increase the printing pressure to make up for the occurrence of ink coloring caused by bad contact when the paper is rough and imprinted;
2, using the "light ink thick printing" process for printing, such as printing plate products due to the large amount of ink absorption, easy to cause dark ink situation, which can be appropriate to deepen the ink hue, so that printing ink volume increased, both Can meet the printing hue requirements, but also make the printing layout saturated ink, printing quality and good results.
In summary, as the basic conditions of printing, paper has a decisive role in the quality of the product's printing quality. Therefore, the correct understanding of the nature of the paper and its relationship with the printing process, through the printing process technology Checking control and adjustment can not only prevent and avoid the occurrence of such or such print quality failures, but also effectively improve product quality and production efficiency.
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