KC pearlescent pigments in letterpress printing
KC pearlescent pigments have good dispersibility, generally mixed with the ink only slightly stirring (shear stress treatment to avoid cracking, such as ball / bead mill, disperser, high-speed mixer or three-roller machine, etc.); To avoid pearlescent pigments Broken and tarnished, pearlescent pigments are usually added to the final process of ink production, and the agitation time of each batch of ink must be kept constant and as short as possible. This principle can avoid the color difference of the pigment. Because KC particles are larger than conventional ink pigments (the size of conventional pigment particles is about 0.1~1 μm), in order to ensure the printing quality and the better pearlescent printing process, different printing methods must pay attention to the following matters:
â—Ž Flexo printing:
The use of low-viscosity liquid inks (viscosity 0.1 to 1 Pa.s) is used in letterpress printing. The ink thickness is about 3 μm, and the KC has different particle sizes (usually 5 to 25 μm for printed particles). Or 10~60 μm) can be used alone or mixed with pigments with good dispersibility, high transparency and no disperse light (and the color mixture with KC cannot exceed 3% of the total weight of ink), avoid mixing with opaque pigments Loss of pearl effect.
In the case of letterpress printing, the addition of KC to the ink is about 10 to 20%, but it also adjusts itself to the desired effect; however, adding too much of the pearlescent pigment will reduce the pearlescent effect due to the overlapping of the particles. 》
[Printing ink aspect]:
1. Flow-type additives can be used to adjust and improve the surface properties of pearlescent pigments in the ink. When using solvent-based inks, pearlescent pigments are preferably pre-moistened into a paste with the same solvent (such as water, alcohol, and diluents, etc.) and dipped into the ink after impregnation for several hours (for pearlescent pigments The oil absorption is saturated, please refer to the color chart for better dispersion to avoid the pearlescent pigment gathering on the scraper.
2. In the aqueous alkaline ink system, the pH of some KC pigments is adjusted by the use of alkaline additives (eg, NH4OH) (for the KC pearlescent pigment, see the relevant information). If an alkaline thixotrope is used to adjust the viscosity in the ink, it is necessary to adjust the pigment with an acidic surface (because part of the KC pigment is acidic) in order to prevent the occurrence of pigment aggregation and unexpected ink viscosity changes.
3. The concentration of pearlescent pigments is usually between 15% and 25% of the finished ink (but because of different printing methods and effects need to adjust the amount); because the average specific gravity of 3, so try to make the ink cycle, to avoid precipitation.
4. Due to the complementary color phenomenon, do not mix KC interference color series pigments (200 series) with each other.
[Printing process]:
1. Since the KC particles are larger than traditional inks, it is necessary to pay attention to the mesh of the inking roller. If the KC particle size is 5~25 μm (average about 12 μm), the mesh size with the pearlescent pigment particle size should be corrected to 75~100/cm; if you want to use ※ larger particle size ※ 10~ For 60 μm (average about 25 μm), the mesh should be 60 bars/cm or less, and it is recommended that the solvent-based ink use a mesh depth of about 50 μm, but at this time, the ink film becomes thick and the drying temperature must be adjusted.
2. To adjust the printing speed, it is best to transfer the ink to the paper after a brief casting process, so that the pearlescent pigment and the substrate surface to maintain the best parallel arrangement.
3. Use KC pigments to achieve a better pearlescent effect, the substrate should try to use a flat, smooth surface (such as: coated paper, or special copper paper, etc.).
4. Post-printing (such as: cold, heat sealing, embossing, glazing, laminating, etc.) As long as the conventional, and embossing, embossing, etc., can make the pearl effect is more ideal.
KC pearlescent pigments in screen printing
KC pearlescent pigments have good dispersibility, generally mixed with the ink only slightly stirring (shear stress treatment to avoid cracking, such as ball / bead mill, disperser, high-speed mixer or three-roller machine, etc.); To avoid pearlescent pigments Broken and tarnished, pearlescent pigments are usually added to the final process of ink production, and the agitation time of each batch of ink must be kept constant and as short as possible. This principle can avoid the color difference of the pigment. Because KC particles are larger than conventional ink pigments (the size of conventional pigment particles is about 0.1~1 μm), in order to ensure the printing quality and the better pearlescent printing process, different printing methods must pay attention to the following matters:
â—Ž Screen printing :
The viscosity of ink in screen printing is 2~30 Pa.s, and the thickness of ink is the thickest in all printing methods, and the thickness is about 8~30 μm. It can be divided into two types: flat type and roller type screen type. The material of the plate and the manufacturing technology are important factors influencing the printing effect. The mesh can be made of natural, artificial fibers or metal filaments, and the thickness of the ink is absolutely related to the thickness of the mesh. In addition, KCs have different particle sizes (usually 5–25 μm and 10–60 μm for printed particles) and can be used alone or mixed with pigments with good dispersibility, high transparency and no disperse light (and with KC The mixed colorant should not exceed 3% of the total weight of the ink. Use to avoid mixing with opaque pigments and loss of pearlescent effect.
"In screen printing, KC is added to the ink at a rate of about 8 to 15%, but it also adjusts itself to the desired effect. However, adding too much proportion of pearlescent pigments will reduce the pearlescent effect due to the overlapping of the particles. 》 Suggestions:
[Printing ink aspect]:
1. Flow-type additives can be used to adjust and improve the surface properties of pearlescent pigments in the ink. When using solvent-based inks, pearlescent pigments are preferably pre-moistened into a paste with the same solvent (such as water, alcohol, and diluents, etc.) and dipped into the ink after impregnation for several hours (for pearlescent pigments The oil absorption is saturated, please refer to the color chart for better dispersion to avoid the pearlescent pigment gathering on the scraper.
2. In the aqueous alkaline ink system, the pH of some KC pigments is adjusted by the use of alkaline additives (eg, NH4OH) (for the KC pearlescent pigment, see the relevant information). If an alkaline thixotrope is used to adjust the viscosity in the ink, it is necessary to adjust the pigment with an acidic surface (because part of the KC pigment is acidic) in order to prevent the occurrence of pigment aggregation and unexpected ink viscosity changes.
3. The concentration of pearlescent pigments is usually between 15% and 25% of the finished ink (but due to different printing methods and effects need to adjust the amount of added); because its average weight is 3, so try to make the ink cycle, to avoid precipitation .
4. Due to the complementary color phenomenon, do not mix KC interference color series pigments (200 series) with each other.
[Printing process]:
1. Because KC particles are larger than traditional inks, in order to avoid clogging of the screen with pearlescent pigments, the mesh should use monofilament fibers as much as possible, and the mesh size should be 1.5 times that of pearlescent pigment particles (planar screen) to 2.5 times. (Roller screen), for example, pearlescent pigments with a size of 10 to 60 μm are estimated with a maximum particle size of 60 μm 1.5 or 2.5, and a mesh size of 90 μm to 150 μm is most suitable (with a large range of 150 μm Most of the pearl particles can pass.
2. To adjust the printing speed, it is best to transfer the ink to the paper after a brief casting process, so that the pearlescent pigment and the substrate surface to maintain the best parallel arrangement.
3. Use KC pigments to achieve a better pearlescent effect, the substrate should try to use a relatively flat, smooth surface (such as: copper type paper, etc.).
4. Post-printing (such as: cold, heat sealing, embossing, glazing, UV glazing, laminating, etc.) As long as the conventional, and embossing, embossing, etc., can make pearlescent effect is more ideal.
[printing order]
- Pearlescent ink will have different effects depending on the printing sequence. If the printed matter is of bright colors, you can use pearlescent ink before printing four colors to increase the saturation of the print and make it more three-dimensional. You can also use pearlescent ink after the last printing process to get the best Pearl effect.
- You can also use pearl ink to make a full base and then use half-tone printing to get a unique pearl print.
- If the printed material is of a dark color or a highly concealable color, it is recommended to print the pearlescent ink first before printing to avoid affecting the pearlescent effect.
- Because the pearlescent ink is semi-transparent, it can be used multiple times during printing; it can be added to any one printing process and it will have a unique pearlescent effect.
- On the other hand, it can be used in combination with pigments with good dispersibility, high transparency and no disperse light (the pigment mixed with pearlescent pigments should not exceed 3% of the total weight of the ink).
Source: Wenzhou Kuncai Pearlescent Pigment Co., Ltd.