The printing industry is one of the major fields of application of pearlescent pigments. Products that use pearlescent inks include packaging, publications, home decoration materials or clothing, and even ceramic products and home appliances. People's aesthetic experience naturally accepts and affirms this effect. This is the main reason why pearlescent pigments are used to improve product quality and decoration life.
The main printing methods, such as offset printing, gravure printing, flexo printing, and screen printing, can perform pearl printing. Through other surface finishing methods, such as light and sweep gold can also get a unique gloss effect. According to their specific process requirements and the characteristics of pearlescent pigments, relevant adjustments are made to the ink so that a satisfactory pearlescent effect can be achieved. In addition, attention should also be paid to coordinating relevant process parameters. Suppliers such as German Merck can be consulted.
Pearlescent pigments differ greatly from conventional pigments in terms of chemical composition and structure, as follows:
(a) The particle size is relatively large: for offset printing, for example, the grain size of ordinary coloring materials is generally 0.02 to 0.08 μm, carbon black is 0.2 to 0.7 μm, and the size of pearlescent pigments used for printing is 5 μm to 25 μm. Micron is much higher than the former. Larger grain sizes give certain difficulties in printing transfer.
(b) Lamellar structure: This structure is determined by the shape of the mica core and is the basis for the expression of the pearlescent effect. However, it caused inconvenience to the transfer of printing. In the preparation of the ink, it is impossible to apply high speed, large shear force or excessive rolling operation, otherwise the pigment will be destroyed.
(c) Surface morphology: The microscopic surface of the pearlescent pigment is composed of many grooves, giving it a rather high surface energy.
In order to avoid the above-mentioned characteristics causing trouble in the actual printing, major pearlescent pigment suppliers (such as Merck) summed up some practical and effective experiences based on years of research for printing inks and printers to adopt:
Pre-wetting of pigments: The pigment should be wetted before it is mixed into the ink. The solvent used for wetting should be compatible with the ink system. Good wetting allows the pigment to be evenly dispersed in the ink, which is the basis for obtaining high-quality pearlescent printing results. Wetting also overcomes the "dusting" of dry powders during dispersion.
Dispersion of pigments in ink: Pearlescent pigments have good dispersion ability, generally low-speed stirring can be used in low-viscosity inks, try to avoid the use of three-roller machine, high-speed mixer or ball / bead mill and other equipment, resulting in pigment breakage To lose luster, it is recommended that pigments be mixed in the final stage of ink production. When using a disperser or high-speed mixer, the stirring time for each batch should be kept constant and shortest.
Choose a good transparency of the ink media: whether it is ink color or link material, the level of transparency is an important factor affecting the pearl luster of the ink.
The distribution of pigments determines the effect: The more pearlescent pigments are distributed in the print coating, the better the uniformity is, the better the pearlescent effect will be. The other point is also important: Only when the pigment wafer is aligned parallel to the surface of the substrate Get the ideal pearl effect.
The main printing methods, such as offset printing, gravure printing, flexo printing, and screen printing, can perform pearl printing. Through other surface finishing methods, such as light and sweep gold can also get a unique gloss effect. According to their specific process requirements and the characteristics of pearlescent pigments, relevant adjustments are made to the ink so that a satisfactory pearlescent effect can be achieved. In addition, attention should also be paid to coordinating relevant process parameters. Suppliers such as German Merck can be consulted.
Pearlescent pigments differ greatly from conventional pigments in terms of chemical composition and structure, as follows:
(a) The particle size is relatively large: for offset printing, for example, the grain size of ordinary coloring materials is generally 0.02 to 0.08 μm, carbon black is 0.2 to 0.7 μm, and the size of pearlescent pigments used for printing is 5 μm to 25 μm. Micron is much higher than the former. Larger grain sizes give certain difficulties in printing transfer.
(b) Lamellar structure: This structure is determined by the shape of the mica core and is the basis for the expression of the pearlescent effect. However, it caused inconvenience to the transfer of printing. In the preparation of the ink, it is impossible to apply high speed, large shear force or excessive rolling operation, otherwise the pigment will be destroyed.
(c) Surface morphology: The microscopic surface of the pearlescent pigment is composed of many grooves, giving it a rather high surface energy.
In order to avoid the above-mentioned characteristics causing trouble in the actual printing, major pearlescent pigment suppliers (such as Merck) summed up some practical and effective experiences based on years of research for printing inks and printers to adopt:
Pre-wetting of pigments: The pigment should be wetted before it is mixed into the ink. The solvent used for wetting should be compatible with the ink system. Good wetting allows the pigment to be evenly dispersed in the ink, which is the basis for obtaining high-quality pearlescent printing results. Wetting also overcomes the "dusting" of dry powders during dispersion.
Dispersion of pigments in ink: Pearlescent pigments have good dispersion ability, generally low-speed stirring can be used in low-viscosity inks, try to avoid the use of three-roller machine, high-speed mixer or ball / bead mill and other equipment, resulting in pigment breakage To lose luster, it is recommended that pigments be mixed in the final stage of ink production. When using a disperser or high-speed mixer, the stirring time for each batch should be kept constant and shortest.
Choose a good transparency of the ink media: whether it is ink color or link material, the level of transparency is an important factor affecting the pearl luster of the ink.
The distribution of pigments determines the effect: The more pearlescent pigments are distributed in the print coating, the better the uniformity is, the better the pearlescent effect will be. The other point is also important: Only when the pigment wafer is aligned parallel to the surface of the substrate Get the ideal pearl effect.
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