Application of pearlescent pigments in ink and paper printing

Pearlescent Pigments are special-effect pigments that produce a pearly, soft, shimmering luster. Their core principle is the interference effect of light. Their primary component is mica flakes coated with one or more layers of high-refractive metal oxides (such as titanium dioxide and iron oxide). When light strikes these parallel flakes, it undergoes reflection, refraction, transmission, and interference, resulting in a dazzling pearlescent color and metallic luster.

1. Unique Advantages of Pearlescent Pigments in Printing
2. Magnificent Optical Effects: They can produce metallic luster, pearly soft luster, and angular color shift (color changes when viewed from different angles) that are unattainable with conventional four-color printing, greatly enhancing the visual appeal of products.
3. Environmentally Friendly and Safe: Most pearlescent pigments are mica-based and non-toxic, complying with safety regulations for food packaging and toys (e.g., EU 10/2011, FDA CFR 21). 3. Excellent Durability: It exhibits excellent heat resistance, light resistance, weather resistance, and chemical stability, adapting to a variety of printing processes and post-processing requirements.
4. It replaces more expensive processes: Printing with pearlescent inks can simulate effects such as hot stamping and metal foil embossing, but at a lower cost, with higher efficiency, and can achieve large-area printing.

 ---Application in Ink Systems

Pearlescent pigments must be evenly dispersed in a specific binder to create an ink for printing. Depending on the printing method, the ink system must be adjusted accordingly.

1. Offset Ink:

 Features: Offset printing is an indirect printing method, resulting in a thin ink layer. Pearlescent pigment particles must be small (typically less than 25μm) and exhibit good dispersibility and flowability to prevent buildup and smearing.

Applications: Commonly used in high-end book covers, business cards, greeting cards, gift boxes, etc., to create a delicate pearlescent effect.

2. Gravure Ink: 

Features: Gravure inks offer a thick, dense ink layer and strong tinting strength, making them ideal for creating pearlescent effects. Larger particle sizes can be used to create a more intense shimmer. Solvent-based gravure inks dry quickly and are suitable for high-speed printing.

Applications: Widely used in flexible packaging (such as food and cosmetic bags), labels, wallpaper, and decorative materials.

3. Flexographic Ink:

Features: Water-based flexographic inks, in particular, are particularly environmentally friendly. Dispersion and stability of pearlescent pigments in water-based systems are key challenges, requiring the addition of appropriate additives to prevent sedimentation and agglomeration. 

Applications: Carton outer packaging, food packaging, self-adhesive labels, etc.

4. Screen Printing Ink:

Features: Screen printing ink produces the thickest ink layer, which best highlights the three-dimensional effect and intense metallic luster of pearlescent pigments. Almost all particle sizes of pearlescent pigments, from fine to coarse, can be used.

Applications: High-end electronic product casings, cosmetic bottle caps, greeting cards, art prints, textile printing, etc.

5. uv ink:

Features: UV-curable inks are solvent-free, cure quickly, and offer excellent performance. Pearlescent pigments have excellent compatibility and transparency in UV systems, producing very pure and vivid interference colors.

Applications: High-end tobacco and alcohol packaging, credit cards, membership cards, book covers, etc.