Reasons for the floating color and hair growth of packaging printing ink film and prevention measures In the packaging printing process, the operator often spends a lot of time due to the color and hair dyeing of the printed graphics, and also greatly reduces the quality of printed products. This failure is mainly caused by the printing ink containing various pigments or fillers in the morning. Due to the different appearances of floating color and hair growth in the printing ink film, the author will discuss the following points according to the practice for many years, and consult with colleagues in the packaging and printing industry.
First, the ink film floating color and the performance of the form of floating color refers to the ink, once printed, the pigment in the wet ink film is horizontally layered separation. One or more of the various pigments in the JM film are concentrated on the surface and have a uniform distribution, but there is a clear difference from the color just produced from the ink factory or from the previous recipe. Flowering refers to the uneven distribution of multiple colors in the ink film of a packaged and printed ink, which is usually a stripe or honeycomb. For this reason, people often understand the vertical separation of the pigment.
In addition to floating color and hair growth, after the anilox roller is pumping ink or printing ink, the stripe-like phenomenon that can be seen on the surface of the packaging printing ink film is called silk pattern.
1.1 Causes of floating flowers. We know that in the packaging printing ink system, the composition containing two kinds of pigments or fillers may cause floating color and hair growth. The production process of the ink maker is improper or the improper operation of the packaging and printing operator also produces floating color and Hair flowers.
One is the effect of pigment settling and flocculation on floating color and hair growth. We have known for many years that floating color and hair dyeing are caused by uneven distribution of pigment on the surface of the ink film after packaging and printing. Although the reasons involved are many, the stability of pigment dispersion is very important. For example, in the ink system composed of a variety of pigments, the separation of the pigment-dispersed ink system is often caused by the excessive flocculation or sedimentation of a certain pigment, which is the reason why we often talk about floating color and flowering. Secondly, after observing the whole process of sedimentation of packaging printing ink, we learned that the role of particle size is more serious than density and floating color, which is generally called the difference in the density of pigments. Strictly speaking, it is due to the size of pigments. Caused by the role of the trail. From the perspective of China's packaging and printing ink dispersion system, the resin and solvent adsorbed by small-particle-size pigment particles are relatively much larger than large-size pigment particles, and tend to show a decrease in density. Large-particle-size pigment particles increase in density and cause pigments. The sinking of the particles; while the small particle size pigments float, constitute the floating color phenomenon of the printing ink. In this regard, in the formulation of inks, people focus on the slight control of flocculation in order to prevent the floating color of the pigment from being used as a key point. Although effective, excessive flocculation will result in precipitation and cause floating color. appear. For the sake of simplicity in production, after the 1990s, the effect of dispersants, especially coupling agents, in the ink system was very clear. The purpose of the dispersants was to achieve the best interstitial state on the surface of the pigments. The purpose is to bridging between the linking material and the pigment, so as to enhance the storage stability of the pigment and to prevent the floating color from blooming.
The second is the effect of solvents on floating color and hair growth. The ink expert Professor Yang Haiyan believes that solvent solubility in tree shive polymer and the rheology of printing ink, and the printing process, especially the formation of Momo is very important. Therefore, in order to make full use of the solvent, a multi-solvent is generally used for compatibility, ie, a true solvent and a diluent are combined. In the design of packaging printing ink formulations, the hydrogen bond between the solvent and the substrate should be similar; the solubility of the solvent is similar to the solubility of the resin in the ink system; the surface tension of the solvent is similar to the surface tension of the resin in the ink system; the density and the connection of the solvent The material density is similar; the gradient gap of the mixed solvent volatilization is similar; the true solvent and the diluent need to keep the dosage required for the packaging printing ink to adapt to the printing proportion. If we reach the above six basic conditions, we will not cause the floating color and hair growth of the printing ink film due to the solvent.
The third is the effect of surface tension gradient on the floating color. For a long time, people have neglected the cause of the surface tension gradient on the formation of ink on the ink film. We do not know that the surface tension of the printing ink film on the surface of the printing and printing ink is so poor that the tension of the upper and lower surfaces of the printing ink film is so poor that it often causes the ink film to form a vortex and flowers. . The surface of the wet ink film is affected by uneven blowing or uneven surface tension, which may cause the ink film to move in parallel and cause hair growth.
Too much solubility of the solvent will cause the viscosity of the packaging printing ink to drop rapidly, thereby accelerating the settling velocity of the pigment particles. As a result, due to the difference in the particle diameter of the pigment, the occurrence of a difference in the settlement, ie, eddy currents, will occur to the floating color. Created conditions. (To be continued)
First, the ink film floating color and the performance of the form of floating color refers to the ink, once printed, the pigment in the wet ink film is horizontally layered separation. One or more of the various pigments in the JM film are concentrated on the surface and have a uniform distribution, but there is a clear difference from the color just produced from the ink factory or from the previous recipe. Flowering refers to the uneven distribution of multiple colors in the ink film of a packaged and printed ink, which is usually a stripe or honeycomb. For this reason, people often understand the vertical separation of the pigment.
In addition to floating color and hair growth, after the anilox roller is pumping ink or printing ink, the stripe-like phenomenon that can be seen on the surface of the packaging printing ink film is called silk pattern.
1.1 Causes of floating flowers. We know that in the packaging printing ink system, the composition containing two kinds of pigments or fillers may cause floating color and hair growth. The production process of the ink maker is improper or the improper operation of the packaging and printing operator also produces floating color and Hair flowers.
One is the effect of pigment settling and flocculation on floating color and hair growth. We have known for many years that floating color and hair dyeing are caused by uneven distribution of pigment on the surface of the ink film after packaging and printing. Although the reasons involved are many, the stability of pigment dispersion is very important. For example, in the ink system composed of a variety of pigments, the separation of the pigment-dispersed ink system is often caused by the excessive flocculation or sedimentation of a certain pigment, which is the reason why we often talk about floating color and flowering. Secondly, after observing the whole process of sedimentation of packaging printing ink, we learned that the role of particle size is more serious than density and floating color, which is generally called the difference in the density of pigments. Strictly speaking, it is due to the size of pigments. Caused by the role of the trail. From the perspective of China's packaging and printing ink dispersion system, the resin and solvent adsorbed by small-particle-size pigment particles are relatively much larger than large-size pigment particles, and tend to show a decrease in density. Large-particle-size pigment particles increase in density and cause pigments. The sinking of the particles; while the small particle size pigments float, constitute the floating color phenomenon of the printing ink. In this regard, in the formulation of inks, people focus on the slight control of flocculation in order to prevent the floating color of the pigment from being used as a key point. Although effective, excessive flocculation will result in precipitation and cause floating color. appear. For the sake of simplicity in production, after the 1990s, the effect of dispersants, especially coupling agents, in the ink system was very clear. The purpose of the dispersants was to achieve the best interstitial state on the surface of the pigments. The purpose is to bridging between the linking material and the pigment, so as to enhance the storage stability of the pigment and to prevent the floating color from blooming.
The second is the effect of solvents on floating color and hair growth. The ink expert Professor Yang Haiyan believes that solvent solubility in tree shive polymer and the rheology of printing ink, and the printing process, especially the formation of Momo is very important. Therefore, in order to make full use of the solvent, a multi-solvent is generally used for compatibility, ie, a true solvent and a diluent are combined. In the design of packaging printing ink formulations, the hydrogen bond between the solvent and the substrate should be similar; the solubility of the solvent is similar to the solubility of the resin in the ink system; the surface tension of the solvent is similar to the surface tension of the resin in the ink system; the density and the connection of the solvent The material density is similar; the gradient gap of the mixed solvent volatilization is similar; the true solvent and the diluent need to keep the dosage required for the packaging printing ink to adapt to the printing proportion. If we reach the above six basic conditions, we will not cause the floating color and hair growth of the printing ink film due to the solvent.
The third is the effect of surface tension gradient on the floating color. For a long time, people have neglected the cause of the surface tension gradient on the formation of ink on the ink film. We do not know that the surface tension of the printing ink film on the surface of the printing and printing ink is so poor that the tension of the upper and lower surfaces of the printing ink film is so poor that it often causes the ink film to form a vortex and flowers. . The surface of the wet ink film is affected by uneven blowing or uneven surface tension, which may cause the ink film to move in parallel and cause hair growth.
Too much solubility of the solvent will cause the viscosity of the packaging printing ink to drop rapidly, thereby accelerating the settling velocity of the pigment particles. As a result, due to the difference in the particle diameter of the pigment, the occurrence of a difference in the settlement, ie, eddy currents, will occur to the floating color. Created conditions. (To be continued)
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