The use of Gift Box Stuffing Paper pearlescent ink

The use of Gift Box Stuffing Paper pearlescent ink

The evaluation of the printing effect of pearlescent ink is generally through the visual effect of pearlescent. It is determined by the substantial reflection of brightness and color effects.

Pearlescent pigments have excellent dispersing power. Generally, light agitation is required to mix in low-viscosity printing inks. Since the pearlescent ink is a layered structure, the pearlescent pigment can only be slightly stirred when mixing with the ink to avoid damage to the pearlescent pigment. Avoid rough mechanical agitation for dispersion, such as using a three-roller, high-speed mixer, or ball/bead mill, which will damage the pigment and tarnish it. In general, the pearlescent pigments are evenly added to the printing ink in the last process of ink production. When using a disperser and a high-speed mixer, the mixing time of each batch must be kept constant and shortest, so as to avoid the color difference of each batch of products. When manufacturing high-viscosity printing inks, such as when offset printing has to use a three-roller machine, the gap between the rollers must be as wide as possible, and the stirring should be completed in the shortest time possible to avoid gloss loss due to pigment damage.

Gift Box Stuffing Paper

Note: It is necessary to use transparent connecting materials as much as possible, and avoid the use of opaque and light-scattering additives.

Pearlescent pigments help to create a rich and colorful visual experience due to their transparency, light refraction properties and light scattering properties. For some special requirements, they can be reproduced as long as they are formulated in strict accordance with the formula parameters.

The popular pearlescent pigments on the market are generally composed of mica-titanium dioxide and/or iron oxide. It is non-toxic, chemically stable and harmless to the environment. It can be used in food packaging and meets national standards. NOTE: Only emphasis is placed on removal of excess ink, cleaning of printing plates or ink delivery systems, recycling of prints and removal of accumulated printing waste.

The application and function of pearlescent pigments in various printing fields:

Pearlescent pigments used in screen printing

Through my understanding of screen printing, I feel that pearlescent pigments are relatively the most suitable for screen printing. It can be selected by selecting a screen plate with a suitable mesh size for pearlescent pigments of different sizes. The mesh should be 1.5 to 1.5 to the largest particle of the pigment. 2.5 times. Depending on the printing work, the screen type pearlescent pigments, substrates, and ink connecting materials must be selected for matching.

1. How to use pearlescent pigments in printing inks

Pearlescent pigments can be used in all screen ink systems, but it is best to use only with transparent ink binders. Well-dispersed transparent pigments can improve the coloring effect when the dosage does not exceed 3% of the finished ink.

In order to make the pigment and ink mix better, it is best to pre-wet the powdered pigment with the ink solvent. such as diluents. Then it is mixed into the ink to improve the dispersibility of the pigment. Avoid dust and ink viscosity changes in the ink.

2. Pearlescent pigments in the printing process

The most suitable screen material should be selected before printing with pearlescent pigment screen ink. Basically, pearlescent pigments of various particles can be used for screen printing. When the pearlescent pigment particles are less than 15, 400 mesh/inch can be used, that is, 180 meshes/inch. No.; when the particle is between 5-25, the mesh number can reach 355 mesh/inch, that is, No. 140; when the particle is between 10 and 60, the mesh number can reach 156 mesh/inch, or No. 61; the particle is to 200 When the screen size can reach 54 mesh/inch, that is, No. 21.

In screen printing, due to the relatively thick layer on the substrate, the drying parameters of the ink need to be strictly controlled. Due to the special morphology of pearlescent pigments, the solvent attached to its surface has greater viscosity, so its drying conditions need to be adjusted to prolong the drying time; or slightly increase the drying (curing) temperature to achieve the special required curing strength. For example, when using pearlescent pigments in color wet + wet printing, overprint drying should be used to avoid the transfer of printed colors to subsequent printing plates. So far, pearlescent pigments are usually used as spot colors after color printing. Or used in some other industries.

Pearlescent pigments and substrates

In screen printing, pearlescent pigments are available in many directions, but they are the most used in textiles.

Textile screen printing today mostly uses water-based inks. Pearlescent pigments have excellent water resistance, alcohol resistance, heat curing, solvent resistance, water wash resistance, sweat resistance, chemical dry cleaning resistance, etc., and are especially suitable for this application. Secondly, pearlescent pigments can be applied to paper, cardboard, plastic film, etc. to obtain satisfactory results.

Pearlescent pigments and finishing

Post-press processing for screen-printed products with pearlescent pigments will not adversely affect the pearlescent effect.

Post-press processing procedures such as cold, heat sealing and compounding can all be processed as usual.

Generally, pearlescent pigments have good scratch resistance, insulation, and acid and alkali resistance. The effect of pearlescent pigment printing can be significantly increased by calendering, as is the effect of buffed calico applied to textile printing. Due to the excellent chemical resistance properties of pearlescent pigments, other methods can be used, such as: water wash, stone wash or alkaline wrinkling for denim. Another interesting method is called burnt-out in the textile industry, due to the chemical resistance of pearlescent pigments, the pattern printed on the fabric with it is preserved through the acid reaction, resulting in a unique printing effect.

Selection of pearlescent pigments

The use of iridescent interference color can play a beautiful and anti-counterfeiting effect

Pearlescent pigments of different particle sizes; if you choose to use large-particle pearlescent pigments, it is best to use small-particle pigments at the same time, so that the glittering luster can be obtained without penetrating the bottom; when used together, the ratio is about the large-particle pigments; Particle Pigment = 1:3 or 1:4.

Note: When using different particles of iridescent interference color pearlescent pigments to be mixed, only a series of glossy varieties can be used to match, such as Ir. 249 with Ir. 201, etc., otherwise the interference color pearl effect will be lost.

Pearlescent pigments can show richer colors when mixed with different color inks.

Selection of wire mesh

Monofilament screen is more suitable for pearlescent printing, because it is not easy to block the screen; choose a screen with a thickness of T; choose a suitable mesh size to avoid blocking; usually, the mesh size should be 1.5 ~ 1.5~ of the maximum pigment size used 2.5 times. Below we give the corresponding selection of wire mesh based on Iriodin pearlescent pigment from Merck, Germany.

Requirements for the selection of connecting materials

It is as colorless and transparent as possible, otherwise it will lose its pearlescent luster; it has good wettability and bonding with the substrate; it has good bonding with pearlescent pigments; it has good abrasion resistance.

Preparation of ink

According to different printing materials and gloss requirements, the concentration of pearlescent pigments is between 8~15%:

1. Pre-wetting: very critical, it is related to the dispersibility and trial printing performance of pearl powder, and must be carried out in strict accordance with the following procedures:

1. Prepare a suitable solvent

2. Measure about 30% of the weight of the pearlescent powder, add it into the weighed pearlescent powder, and stir slowly. The process is as follows: the stirring seems to have no effect, the stirring resistance gradually increases, and the pearlescent powder forms into small balls. , the color becomes darker; continue stirring, the small balls are broken into smaller particles, and the stirring resistance is significantly reduced, and the stirring becomes easier; finally, the pearlescent powder becomes a granular mixture of uniform size, and the color becomes dark. Let stand for 20 to 30 minutes; stir and mix the above mixture with the connecting material evenly. Note: Do not use dispersing equipment with large shear force such as three-roll mill. For drying adjustment, it is necessary to select the appropriate drying temperature according to different ink layer thicknesses and printing speeds.

Pearlescent pigments are used in flexographic printing

Flexographic printing inks are classified as low-viscosity liquids. There are solvent-based, water-based and light curing (UV) three. Pearlescent pigments are available for all three inks. However, a binder with higher transparency should be selected to configure the ink to avoid loss of pearlescent effect.

When configuring color ink, only the dispersibility is good, and the transparent colorant can be mixed with the pearlescent pigment, generally no more than 20% of the weight of the pearlescent pigment. Too heavy tones will affect the pearlescent effect. Because pearlescent pigments have a unique optical interference function only in the ink layer with abundant light, and too much colored pigments cause a large amount of light scattering to be lost.

Pre-wetting: In order to make the pearlescent pigment in the best state in the ink, it is recommended to pre-moisten the pigment with the ink solvent (such as water, alcohol, thinner) equivalent to 30% of its weight, and then mix it into the ink. This procedure avoids the occurrence of floating dust and viscosity changes of the finished ink when manufacturing the ink, so that the pearlescent pigment and the ink can achieve the best mixing state.

The content (weight ratio) of pearlescent pigment is about 15~25% of the finished ink.

The ink needs to be thoroughly and carefully stirred before printing, so that the pigment is evenly dispersed in the ink without flocculation or precipitation. In long-form printing, try to use a circulating ink supply device to avoid sedimentation.

Generally, suitable ink additives are used to avoid foaming and prevent pigment precipitation.

If you need to add colorants to color, it should be based on visual observation.

Before printing, the ink viscosity needs to be adjusted according to the substrate, printing speed and drying conditions. Usually in water-based ink, for smooth paper or plastic film, the appropriate viscosity is 40~60 seconds (DIN4 viscosity cup 23 degrees), for rougher kraft cardboard, corrugated cardboard or gray cardboard, use low Viscosity ink, such as 25~35 seconds (DIN4 viscosity cup 23 degrees).

It is very important to choose a suitable photosensitive resin sheet. For pearlescent printing, I recommend the following varieties: HOF, PLB, PLS, POF and UVB of Sele, FA, FAH and FAR of BASF's "Nyloflex".

There are many kinds of anilox rollers used in flexographic printing, including traditional steel anilox rollers and laser-engraved ceramic anilox rollers. The choice of anilox roller is determined by the substrate and the desired thickness of the ink layer. Tests show that laser-engraved porcelain rollers work best in flexographic printing with pearlescent pigments, especially for water-based ink transfer. The technical parameters of flexographic printing must be coordinated with the particle size of pearlescent pigments.

The particle size matching relationship between the anilox roller and the pigment.

The printing effect depends on how much ink is transferred to the substrate. Thick ink layers result in a pronounced gloss effect. Therefore, it is recommended that solvent-based inks use anilox rollers with ink orifices as deep as 50. The best printing effect can be obtained by adjusting the printing speed. The ink is best able to maintain a short cast after transfer to the substrate to keep the pigments in an optimal parallel arrangement with the substrate surface.

About substrates

There are many types of substrates that can be used, including corrugated cardboard, white cardstock, label stock, light and heavyweight paper, paper towels, kraft cardstock and plastic film. The choice of substrate has a great influence on the printing effect. Substrates with smooth, flat surfaces achieve the best pearlescent results.

Post-press processing

Pearlescent pigments have no adverse effect on the post-press processing of flexographic printing products.

The post-printing process can be handled as usual. Cold, heat sealing, embossing, calendering and laminating can be carried out without special adjustment. Calendering and embossing may increase the pearlescent effect because they arrange the pigments better.

There are also pearlescent pigments that have good scratch resistance, insulation, and acid and alkali resistance.

Pearlescent ink is used in gravure printing

Low viscosity liquid inks are mainly used in gravure printing. Pearlescent pigments can be used in solvent-based or water-based inks, but a binder with high transparency should be selected to avoid loss of pearlescent effect.

When preparing color ink, only the dispersibility is good, and the transparent colorant can be mixed with the pearlescent pigment, which generally does not exceed 20% of the weight of the pearlescent pigment. Too heavy tones will affect the pearlescent effect. . Because pearlescent pigments can only have special optical interference functions in the ink layer with abundant light. Excessive amounts of other colored pigments cause a large amount of light scattering to be lost.

Pre-wetting: We do nanoscale microscopic observation on the surface of pearlescent pigments, and we can find that there are many extremely fine capillary structures distributed. And thus lead to relatively large surface energy. In order to make the pearlescent pigment in the best state in the ink, it is recommended to pre-wet the pigment with an ink solvent (such as water, alcohol, thinner) equivalent to 30% of its weight, and then mix it into the ink. This procedure avoids the occurrence of floating dust and viscosity changes of the finished ink when manufacturing the ink, so that the pearlescent pigment and the ink can achieve the best mixing state.

The content (weight) of pearlescent pigment is about 15~30% of the finished ink

The ink needs to be thoroughly and carefully stirred before printing, so that the pigment is evenly dispersed in the ink without flocculation or precipitation. In the long printing process, try to use the circulating ink supply device to avoid sedimentation.

It is recommended to use suitable ink additives to avoid foaming and prevent pigment precipitation.

If you need to add colorants to color, it should be based on visual observation.

Before printing, the ink viscosity needs to be adjusted according to the substrate, printing speed and drying conditions. Usually the appropriate viscosity for solvent-based inks is 14~25 seconds (DIN4 viscosity cup 23 degrees), for water-based inks (such as decorative paper inks), it needs to be higher, until 40 seconds (DIN4 viscosity cup 23 degrees) formula)

Pearlescent pigments in gravure printing

Both etched and engraved plates can use pearlescent pigments. Tests have shown that the best results are achieved with a cylinder-type plate using a taper-shaped inking hole with an opening angle of about 120 degrees. When the particle size of the pigment is large (the average particle size is greater than 25), it is recommended to use an etching roller, because its special hole shape allows a large amount of ink to pass through, which positively supports the pearlescent effect of pearlescent pigment printing.

The parameters of the plate cylinder and the pigment particle size need to match each other. It is recommended to prepare plate cylinders with reference to the data in the table.

In addition, ordinary solvent-based ink is suitable for plate rollers with an opening angle of 120 degrees, and water-based inks are suitable for plate rollers with an opening angle of 140 degrees.

For corrosive printing plates, the mesh-to-wall ratio is preferably 10:1 or higher, but not lower than 6:1.

The printing effect is determined by how much ink is transferred to the substrate. The thickness of the ink layer results in a more pronounced pearlescent effect. Therefore, solvent-based inks are recommended to use ink holes with a depth of about 50.

The best printing effect can be obtained by adjusting the printing speed. It is best to have a short casting process after the ink is transferred to the paper, so that the pearlescent pigments have the best parallel arrangement with the surface of the substrate.

Pearlescent pigments and substrates and finishing

There are many kinds of substrates to choose from, ranging from PVC in the wallpaper industry to coated paper, cardboard or heavyweight paper, kraft cardboard, paper towels, plastic films, fabrics, etc. in the packaging and labeling industry.

The choice of substrate has a great influence on the printing effect. Substrates with smooth, flat surfaces achieve the best pearlescent results.

Pearlescent pigments are used in offset printing

Pearlescent Pigments in Printing Inks

Ordinary offset printing ink is a high-viscosity ink, which makes it difficult to disperse coarse-grained pearlescent pigments. Therefore, it is best to use specially developed pearlescent offset inks. Compared to traditional offset inks, pearlescent inks should have a slightly lower viscosity.

Pearlescent offset printing requires the use of detackifiers or thickeners to adjust the ink viscosity according to the printing conditions and substrates. To obtain the best printing effect, special printing rubber sheets must be used. Due to the structure of the pearlescent pigment offset printing ink. It is necessary to increase the ink supply. Continuous-tone pearlescent effects can also be printed by screen, but it is important that the pigment particles match the number of screen lines. Tests have shown that screening in the field and 60 lines/cm can be