In addition, in a mixed solvent system, if the true solvent volatilizes too quickly, not only surface tension will occur, but also the balance of the volatilization gradient of the solvent will be destroyed. As a result, the resin in the ink system is also precipitated with the absorbed pigment due to the reduction of the true solvent, resulting in hair growth. At the same time, it will also cause the pigment particles to agglomerate and affect the improvement of the flatness of the ink film surface. However, the slow evaporation of the solvent will cause the viscosity of the printing ink to rise slowly, which will cause the printing ink film to flow for a long time. As a result, the occurrence of eddy currents in the ink film is not unavoidable, causing problems such as blooming, floating color, and sagging.
The fourth is the effect of the resin on the floating color in the ink system. The variety and variety of resins are different, and the ability to wet is not the same. For a plurality of pigment compositions, since the adsorption ability of various pigments to resins is not the same, non-wetting pigments are prone to condensation, which is also a major cause of floating color.
In packaging printing ink systems, when the molecular weight and molecular weight distribution of tree shrews are different, the size and distribution of polar reactive groups will not be the same, and the differences in these distributions will cause differences in the wetting ability of the pigments. Secondly, the adsorptive capacity of various pigments on the binder is not the same. A pigment that is thin on the ink film can easily flocculate and float. In the case of small molecular weight rosin or alkyd resin inks, due to their large polarity and strong adsorptive power, the resulting adsorbed ink layers are thin, have poor dispersion stability, and are prone to flocculation and float coloration. From a theoretical point of view, in the flocculation of packaging and printing inks, the concentration of the resin in the ink grinding process should be more specifically targeted for the performance of different pigments and binders, and the polymer polymer must be forced to adsorb on the surface of the pigment. Prevents the pigment from being single and causes flocculation failure.
Poor polymer solubility in the packaging printing ink system can also cause the disadvantages of floating coloration. In general, when using several kinds of resins, they are poorly interwoven. Followed by the choice of solvent Solubility can not reach the critical value, that is, people often say that the poor mixing of the resin, coupled with the lack of affinity for the pigment is not enough, often dissolved in the volatile, it will appear floating color, hair. Even if the turbidity, floating color is eliminated under the effect of the solvent, it will appear in the solvent evaporation process. Because the volatilization of solvents and diluents destroys the balance of the resin binders, it is often said that the resin binders with poor compatibility will bring out the adsorbed pigments, resulting in the floating color of the ink ink film. Hair flowers and so on.
The fifth is the effect of packaging and printing conditions on the floating color. The dryness of the water in the north of the Yellow River in China and the long raining in the south of the Meiyu area can also cause floating color blooms after the printing of graphic arts. Whether studying in a high-humidity workshop, because the evaporation of solvents, the decrease of the surface temperature of the ink film, and the condensation of moisture during the printing process all lead to the formation of a vortex in the ink film of the packaging printing ink, the hydrophilic pigment on the surface absorbs certain moisture. As a result, agglomeration and separation of the pigment are caused. Once the water is brought into the ink layer and bound with the hydrophilic pigment particles, they tend to undergo aggregation and sedimentation and a floating color due to bridging of the non-intermolecular liquid. The occurrence of such failures is particularly evident in packaging printing inks that have a high rate of evaporation and hydrophilic solvents. This type of failure is often seen in non-professional, water-based gravure, screen, plastic, plastic intaglio, and color inkjet inks.
1.2 In printing inks, the formation of insoluble colloidal particles leads to shrinkage, and sometimes it is often confused with floating colored hair dyes. We know that the surface active material changes its concentration during the process of forming a printing ink, and it exceeds its solubility to generate a small amount of immiscible droplets that cause shrinkage. For example, excessive addition of silicone oil or excessive viscosity, easy to produce shrinkage. The difference between shrinkage holes and floating colors is that irregular, spherical, small depressions are formed on the ink film, often centered on a drop or a small piece of impurities, and a circular edge is formed around it. From the point of view of leveling of packaging printing inks, it is a special dot-like flow that is generated on the surface of the printing ink film.
Second, to prevent and remedy the floating color flower-making measures around the above ink ink film floating color of several forms of expression, carried out analysis and induction. But how can we prevent and remedy faits accomplis, and the literature is very few. For this reason, the authors described each case according to accumulated experience.
The stability of the packaging printing ink is the result of the simple interaction between the components. For example, the polarity of the solvent is different, and the adsorption of the surface of the active agent pigment is also different. For example, the order of the adsorption amount of octadecylamine in each solvent is: toluene>dichloroethane>mixed solvent. Most people think that various solvents only affect physical adsorption without affecting chemical adsorption. At the same time, it is also believed that the binder and the active agent will produce competitive adsorption on the surface of the pigment, which has been proved by junior high schools to be correct. This shows that the competitive adsorption depends on the size of the binder, the active agent and the color, and the surface affinity of the filler. If the pigment or filler is hydrophilic, the polarity of the pigment is greater in the non-polar solvent. If it is hydrophobic, in the polar solvent, the more hydrophobic substance is selected for adsorption. The physical adsorption of the surfactant does not affect the chemical attachment of the polymer, because the physical adsorption of the surfactant on the surface of the pigment and the filler is not strong, and the solvent is easily extruded from the surface of the pigment by the resin. The chemisorption surfactant formed on the surface of the pigment cannot be extruded from the surface of the pigment filler by the resin polymer. The greater the adsorption saturation of the surfactant on the surface, the greater the resistance to polymer adsorption. On the other hand, if the dispersion grinding time is slightly shorter during the ink manufacturing, the ink is not easily expelled from the pigment surface by the resin in the solvent during the manufacturing process or the ink storage, but other phenomena may still occur. To be proved by practice.
In polar solvents, ultrafine active calcium and alkyd resins can be adsorbed on the surfaces of Tiafranine and Chromium Yellow. This is because the pigment has two active sites, so it is slightly acidic active calcium and alkyd resin. Can still suck on the surface, but its rate is low, resulting in poor wetting and dispersing properties, when dispersed to 7.5 microns, the surface will have a floating color; when dispersed to 1-2 micro materials will be disappear. If thinner is added during the printing process, the floating color will flash out again to select the appropriate dispersant. Adding the wetting dispersant can not only reduce the grinding time of the pigment and filler, but also save energy and improve work efficiency.
In order to prevent the floating color of the ink, the wetting and dispersing agent should be introduced into the packaging printing ink system. Its purpose is nothing but:
1) Increase the gloss of the ink film and improve the leveling of the ink film. Can greatly improve the fineness of the pigment and filler, ensure the storage stability of the ink, prevent the flocculation particles, and improve the flatness of the printing ink film; (to be continued)
The fourth is the effect of the resin on the floating color in the ink system. The variety and variety of resins are different, and the ability to wet is not the same. For a plurality of pigment compositions, since the adsorption ability of various pigments to resins is not the same, non-wetting pigments are prone to condensation, which is also a major cause of floating color.
In packaging printing ink systems, when the molecular weight and molecular weight distribution of tree shrews are different, the size and distribution of polar reactive groups will not be the same, and the differences in these distributions will cause differences in the wetting ability of the pigments. Secondly, the adsorptive capacity of various pigments on the binder is not the same. A pigment that is thin on the ink film can easily flocculate and float. In the case of small molecular weight rosin or alkyd resin inks, due to their large polarity and strong adsorptive power, the resulting adsorbed ink layers are thin, have poor dispersion stability, and are prone to flocculation and float coloration. From a theoretical point of view, in the flocculation of packaging and printing inks, the concentration of the resin in the ink grinding process should be more specifically targeted for the performance of different pigments and binders, and the polymer polymer must be forced to adsorb on the surface of the pigment. Prevents the pigment from being single and causes flocculation failure.
Poor polymer solubility in the packaging printing ink system can also cause the disadvantages of floating coloration. In general, when using several kinds of resins, they are poorly interwoven. Followed by the choice of solvent Solubility can not reach the critical value, that is, people often say that the poor mixing of the resin, coupled with the lack of affinity for the pigment is not enough, often dissolved in the volatile, it will appear floating color, hair. Even if the turbidity, floating color is eliminated under the effect of the solvent, it will appear in the solvent evaporation process. Because the volatilization of solvents and diluents destroys the balance of the resin binders, it is often said that the resin binders with poor compatibility will bring out the adsorbed pigments, resulting in the floating color of the ink ink film. Hair flowers and so on.
The fifth is the effect of packaging and printing conditions on the floating color. The dryness of the water in the north of the Yellow River in China and the long raining in the south of the Meiyu area can also cause floating color blooms after the printing of graphic arts. Whether studying in a high-humidity workshop, because the evaporation of solvents, the decrease of the surface temperature of the ink film, and the condensation of moisture during the printing process all lead to the formation of a vortex in the ink film of the packaging printing ink, the hydrophilic pigment on the surface absorbs certain moisture. As a result, agglomeration and separation of the pigment are caused. Once the water is brought into the ink layer and bound with the hydrophilic pigment particles, they tend to undergo aggregation and sedimentation and a floating color due to bridging of the non-intermolecular liquid. The occurrence of such failures is particularly evident in packaging printing inks that have a high rate of evaporation and hydrophilic solvents. This type of failure is often seen in non-professional, water-based gravure, screen, plastic, plastic intaglio, and color inkjet inks.
1.2 In printing inks, the formation of insoluble colloidal particles leads to shrinkage, and sometimes it is often confused with floating colored hair dyes. We know that the surface active material changes its concentration during the process of forming a printing ink, and it exceeds its solubility to generate a small amount of immiscible droplets that cause shrinkage. For example, excessive addition of silicone oil or excessive viscosity, easy to produce shrinkage. The difference between shrinkage holes and floating colors is that irregular, spherical, small depressions are formed on the ink film, often centered on a drop or a small piece of impurities, and a circular edge is formed around it. From the point of view of leveling of packaging printing inks, it is a special dot-like flow that is generated on the surface of the printing ink film.
Second, to prevent and remedy the floating color flower-making measures around the above ink ink film floating color of several forms of expression, carried out analysis and induction. But how can we prevent and remedy faits accomplis, and the literature is very few. For this reason, the authors described each case according to accumulated experience.
The stability of the packaging printing ink is the result of the simple interaction between the components. For example, the polarity of the solvent is different, and the adsorption of the surface of the active agent pigment is also different. For example, the order of the adsorption amount of octadecylamine in each solvent is: toluene>dichloroethane>mixed solvent. Most people think that various solvents only affect physical adsorption without affecting chemical adsorption. At the same time, it is also believed that the binder and the active agent will produce competitive adsorption on the surface of the pigment, which has been proved by junior high schools to be correct. This shows that the competitive adsorption depends on the size of the binder, the active agent and the color, and the surface affinity of the filler. If the pigment or filler is hydrophilic, the polarity of the pigment is greater in the non-polar solvent. If it is hydrophobic, in the polar solvent, the more hydrophobic substance is selected for adsorption. The physical adsorption of the surfactant does not affect the chemical attachment of the polymer, because the physical adsorption of the surfactant on the surface of the pigment and the filler is not strong, and the solvent is easily extruded from the surface of the pigment by the resin. The chemisorption surfactant formed on the surface of the pigment cannot be extruded from the surface of the pigment filler by the resin polymer. The greater the adsorption saturation of the surfactant on the surface, the greater the resistance to polymer adsorption. On the other hand, if the dispersion grinding time is slightly shorter during the ink manufacturing, the ink is not easily expelled from the pigment surface by the resin in the solvent during the manufacturing process or the ink storage, but other phenomena may still occur. To be proved by practice.
In polar solvents, ultrafine active calcium and alkyd resins can be adsorbed on the surfaces of Tiafranine and Chromium Yellow. This is because the pigment has two active sites, so it is slightly acidic active calcium and alkyd resin. Can still suck on the surface, but its rate is low, resulting in poor wetting and dispersing properties, when dispersed to 7.5 microns, the surface will have a floating color; when dispersed to 1-2 micro materials will be disappear. If thinner is added during the printing process, the floating color will flash out again to select the appropriate dispersant. Adding the wetting dispersant can not only reduce the grinding time of the pigment and filler, but also save energy and improve work efficiency.
In order to prevent the floating color of the ink, the wetting and dispersing agent should be introduced into the packaging printing ink system. Its purpose is nothing but:
1) Increase the gloss of the ink film and improve the leveling of the ink film. Can greatly improve the fineness of the pigment and filler, ensure the storage stability of the ink, prevent the flocculation particles, and improve the flatness of the printing ink film; (to be continued)
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