In the production of paper/plastic film, the printed matter is the basis of compounding, and its surface condition is the basic constraint factor of the film. Understanding the influence of the surface state of the printed matter on the film and adopting corresponding scientific and technological measures to change the original surface state of the printed matter that is not suitable for film lamination are the rational choices taken by the production management personnel to actively improve the composite quality.
First, the effect of the surface state of the printed matter on the quality of the composite 1. The surface roughness of the printing paper is determined by the thickness of the pulp fiber. The fine performance of the printing effect is represented by the number of intervals in the printing dots. The more dots in the dot, the more full and true the reduction of the detailed dots. The surface of the paper is sizing, coating, and high-gloss processing. It is in close contact with the printing plate, and has smoothness suitable for the dot spacing. It will not be uneven due to the surface of the paper, resulting in some of the dots falling or not being completely reproduced.
2. The surface state of the printed product is determined not only by the surface condition of the base paper but also by the printing effect. Offset bright resin ink is based on the reaction of unsaturated fatty acids in the molecular structure of linseed oil with oxygen in the air, and polymerizes the original straight chain structure into a network structure, thereby forming the principle of the chemical reaction process of the solid material, and drying by oxidation. The surface of the paper forms a different color ink film layer with a certain degree of hardness, adhesion and flexibility. Therefore, the surface state of the paper product after printing is determined by the two levels of the surface condition of the base paper and the state of the ink surface layer.
3. Printed ink layer due to the image of the different surface, the ink roller surface aging is different, the ink roller diameter is different, the pressure between the ink roller and the ink roller is too light and the pressure between the plate roller and the printing plate is inconsistent, or printing Affected by the printing center factors such as the deviation of the roller center of gravity, there is a layer of single primary colors printed on the actual surface, and the number of ink levels in the single-color, inter-color, and mixed-color multi-layer printing is different. The same printed matter also has inconsistencies in the depth of the ink before and after, that is, the inconsistency of the ink layer before and after printing, which not only produces the basic difference between the ink layer and the surface state of the paper, but also occurs when the composite ink has different layers due to different ink layers. Adhesive, because a single color to achieve a layer of adhesion, two layers (ink printing, paper coating) penetration, and monochrome, color, color mixing multilayer printing to achieve a layer of adhesion, multi-layer (ink printing ink Layers...paper coatings) Different penetration requirements. Under the same composite temperature and pressure conditions, the resulting surface adhesion and penetration rate will be significantly different, and its composite effect is also different; even if it is printed on one layer of a single primary color, due to the strength of the expression color, the denseness of the network points, The amount of ink will also have significant differences.
4. During the printing process, the ink layer is transferred from the printing plate to the paper, and moisture on the printing plate is also absorbed by the paper. In the same plane of the paper, the pigment particles in the ink layer appear, under the pressure of printing, into the paint, fiber in the surface of the paper, and partially increase the hardness and incompressibility of the paper. Paper with no printed area absorbs the moisture in the blank on the plate, the fibers swell, and the paper locally increases the flexibility and compressibility. This change in the softness and compressibility of different parts of the water-absorbing ink absorbs the smoothness and vacuum degree of the interface with the film, and also generates a water molecule film between the layers during the composite, which destroys the composite bond strength and transparency. .
5. In actual production, the printing ink desiccant reacts with the acid radicals of the paper. The humidity in the printing shop is relatively high, and the newly printed paper is tightly laminated on the table, and the air between the papers Can not fully flow, so that the surface of the ink ink film partial oxygen, these factors, affect the ink ink film oxidation polymerization process to proceed smoothly, so that the ink does not dry well. In order to prevent sticking and gaining time to quickly transfer to the secondary printing or the next process, printing techniques are often used to add desiccant and dusting techniques. The artificial isolation effect of this type of anti-sticking has caused great difficulties for the lamination of the film.
6. Paper has moisture absorption and dehydration functions. The opposite of the positive and negative sides in the process of moisture absorption and desorption is just the opposite. It will produce "foliage" when moisture is absorbed, curling to the reverse side, and "neutral to looseness" when dehumidified, and the surface curled to the front will be uneven. The change of surface state of the paper, which is extremely sensitive to temperature and humidity and responds quickly, is an important factor in the curling and snaking of the film.
Second, several ways to change the surface state of prints 1. After in-depth study of the composition of the paper plant fiber components and synthetic ink polymer resin, the characteristics of the link oil, the introduction of electronic technology into the film process. The use of electromagnetic shocks to change the printed surface, so that the entire area of ​​different base parts to achieve the surface tension of the close, with the same surface activity. This electronic technology is used to surface-treat printed matters, and also solves the problem of inefficiencies in the printing ink layer, such as dryness or crystallization, weakening of adhesion, evaporation of the water vapor on the surface during compounding, and separation of dust and paper wool.
2. For curling and unfolding problems affecting the smoothness of the coating film, after measuring the moisture content of the printed matter, use a mechanical or manual method to balance the water content in a space with a relative humidity of 60% to eliminate the “foliageâ€. , "tight side of the loose" phenomenon.
You can also use the technique of playing (paper) paper to disturb the corrugated or loose drums in the print and destroy the original uneven surface state. With a conscious, regular, and targeted beat pattern, a new stiffness and force dispersion line is created to guide the balance of prints through the hot press mechanism.
3. Moderately adjust the pressure, reasonably use the pressure of the pressure roller, press the pressure difference between the two ends of the roller, and the pressure difference between the pressure roller and the initial pressure (guide) roller. Therefore, the speed of the paper and the difference in the speed of all parts of the whole paper keep the speed and smoothness of the printed matter passing through the conveyor belt—the initial pressure (guide) roller mechanism—thermocompression mechanism, to ensure that the surface state of the printed matter is properly targeted. To adapt to the production conditions of the coating process and improve the quality of the composite. (Cao Hua)
Excerpted from China Packaging Yearbook 1999
First, the effect of the surface state of the printed matter on the quality of the composite 1. The surface roughness of the printing paper is determined by the thickness of the pulp fiber. The fine performance of the printing effect is represented by the number of intervals in the printing dots. The more dots in the dot, the more full and true the reduction of the detailed dots. The surface of the paper is sizing, coating, and high-gloss processing. It is in close contact with the printing plate, and has smoothness suitable for the dot spacing. It will not be uneven due to the surface of the paper, resulting in some of the dots falling or not being completely reproduced.
2. The surface state of the printed product is determined not only by the surface condition of the base paper but also by the printing effect. Offset bright resin ink is based on the reaction of unsaturated fatty acids in the molecular structure of linseed oil with oxygen in the air, and polymerizes the original straight chain structure into a network structure, thereby forming the principle of the chemical reaction process of the solid material, and drying by oxidation. The surface of the paper forms a different color ink film layer with a certain degree of hardness, adhesion and flexibility. Therefore, the surface state of the paper product after printing is determined by the two levels of the surface condition of the base paper and the state of the ink surface layer.
3. Printed ink layer due to the image of the different surface, the ink roller surface aging is different, the ink roller diameter is different, the pressure between the ink roller and the ink roller is too light and the pressure between the plate roller and the printing plate is inconsistent, or printing Affected by the printing center factors such as the deviation of the roller center of gravity, there is a layer of single primary colors printed on the actual surface, and the number of ink levels in the single-color, inter-color, and mixed-color multi-layer printing is different. The same printed matter also has inconsistencies in the depth of the ink before and after, that is, the inconsistency of the ink layer before and after printing, which not only produces the basic difference between the ink layer and the surface state of the paper, but also occurs when the composite ink has different layers due to different ink layers. Adhesive, because a single color to achieve a layer of adhesion, two layers (ink printing, paper coating) penetration, and monochrome, color, color mixing multilayer printing to achieve a layer of adhesion, multi-layer (ink printing ink Layers...paper coatings) Different penetration requirements. Under the same composite temperature and pressure conditions, the resulting surface adhesion and penetration rate will be significantly different, and its composite effect is also different; even if it is printed on one layer of a single primary color, due to the strength of the expression color, the denseness of the network points, The amount of ink will also have significant differences.
4. During the printing process, the ink layer is transferred from the printing plate to the paper, and moisture on the printing plate is also absorbed by the paper. In the same plane of the paper, the pigment particles in the ink layer appear, under the pressure of printing, into the paint, fiber in the surface of the paper, and partially increase the hardness and incompressibility of the paper. Paper with no printed area absorbs the moisture in the blank on the plate, the fibers swell, and the paper locally increases the flexibility and compressibility. This change in the softness and compressibility of different parts of the water-absorbing ink absorbs the smoothness and vacuum degree of the interface with the film, and also generates a water molecule film between the layers during the composite, which destroys the composite bond strength and transparency. .
5. In actual production, the printing ink desiccant reacts with the acid radicals of the paper. The humidity in the printing shop is relatively high, and the newly printed paper is tightly laminated on the table, and the air between the papers Can not fully flow, so that the surface of the ink ink film partial oxygen, these factors, affect the ink ink film oxidation polymerization process to proceed smoothly, so that the ink does not dry well. In order to prevent sticking and gaining time to quickly transfer to the secondary printing or the next process, printing techniques are often used to add desiccant and dusting techniques. The artificial isolation effect of this type of anti-sticking has caused great difficulties for the lamination of the film.
6. Paper has moisture absorption and dehydration functions. The opposite of the positive and negative sides in the process of moisture absorption and desorption is just the opposite. It will produce "foliage" when moisture is absorbed, curling to the reverse side, and "neutral to looseness" when dehumidified, and the surface curled to the front will be uneven. The change of surface state of the paper, which is extremely sensitive to temperature and humidity and responds quickly, is an important factor in the curling and snaking of the film.
Second, several ways to change the surface state of prints 1. After in-depth study of the composition of the paper plant fiber components and synthetic ink polymer resin, the characteristics of the link oil, the introduction of electronic technology into the film process. The use of electromagnetic shocks to change the printed surface, so that the entire area of ​​different base parts to achieve the surface tension of the close, with the same surface activity. This electronic technology is used to surface-treat printed matters, and also solves the problem of inefficiencies in the printing ink layer, such as dryness or crystallization, weakening of adhesion, evaporation of the water vapor on the surface during compounding, and separation of dust and paper wool.
2. For curling and unfolding problems affecting the smoothness of the coating film, after measuring the moisture content of the printed matter, use a mechanical or manual method to balance the water content in a space with a relative humidity of 60% to eliminate the “foliageâ€. , "tight side of the loose" phenomenon.
You can also use the technique of playing (paper) paper to disturb the corrugated or loose drums in the print and destroy the original uneven surface state. With a conscious, regular, and targeted beat pattern, a new stiffness and force dispersion line is created to guide the balance of prints through the hot press mechanism.
3. Moderately adjust the pressure, reasonably use the pressure of the pressure roller, press the pressure difference between the two ends of the roller, and the pressure difference between the pressure roller and the initial pressure (guide) roller. Therefore, the speed of the paper and the difference in the speed of all parts of the whole paper keep the speed and smoothness of the printed matter passing through the conveyor belt—the initial pressure (guide) roller mechanism—thermocompression mechanism, to ensure that the surface state of the printed matter is properly targeted. To adapt to the production conditions of the coating process and improve the quality of the composite. (Cao Hua)
Excerpted from China Packaging Yearbook 1999
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