The Science Behind Ink: Composition, Chemistry, and Applications

omposition, Chemistry, and Applications

Ink varieties

Ink is present everywhere from school textbooks, cookbooks to our favourite pen, but did you know that it has a unique composition and goes through a lengthy process until it can serve its final purpose? 

In this article, the ZEBRA team collected all the information you need to know about the various types, properties and production of ink.

COMPOSITION

This is a complex mixture, containing a variety of substances such as resins, solvents, alcohol, lubricants, carbon, pigments, dyes, aniline, dextrine, glycerine, fluorescents and other materials.

PIGMENTS

Pigments are finely ground solid particles that provide color and opacity to ink. Generally, pigments are defined as coloured, black, white, or fluorescent organic or inorganic solids that cannot dissolve in, or be affected by the substrate or vehicle they are incorporated into.

Pigments are responsible for the visual appearance. They help in covering the underlying surface by blocking light transmission. They can improve the lightfastness and resistance to fading of the product. Derived from carbon-based compounds, organic pigments offer a wide range of vibrant colors. Made from minerals or metals, inorganic pigments provide excellent lightfastness and stability. 

Metallic pigments include metallic flakes or powders, such as aluminum or bronze, which add shimmer or metallic effects. Specialty pigments are unique pigments with special properties, such as fluorescent or phosphorescent pigments.

Zebra pen with premium ink

SOLVENTS

Solvents are generally in liquid form, and are used to dissolve, extract or suspend other materials, usually without chemically changing either the solvents or the other material.

Solvents dissolve pigments to make a homogenous mixture to create dissolving pigments. By adjusting viscosity they control the flow and thickness. Facilitating drying means solvents evaporating during the drying process, allowing the ink to adhere to the surface.

Common solvents used in production:

  • Water: Widely used as a solvent in water-based types, it is environmentally friendly and suitable for various applications.
  • Alcohols: Ethanol, isopropanol, and other alcohols are often used in solvent-based products, providing quick drying and compatibility with different surfaces.
  • Ketones: Solvents like acetone and methyl ethyl ketone (MEK) are employed in specialized inks for their fast evaporation rate and solvency power.
  • Glycols: Propylene glycol and ethylene glycol are used in certain inks to control drying time and prevent clogging in inkjet printers.
Ballpoint pen with blue ink

ADDITIVES

There are several types of additives used in the manufacturing of ink. Viscosity modifiers are additives like thickeners or rheology modifiers that adjust the flow properties and viscosity. Wetting agents are substances that reduce the surface tension, enabling better spreading and adhesion on the substrate. 

Anti-foaming agents are additives that prevent the formation of bubbles or foam during manufacturing and printing processes. UV stabilizers protect it from degradation caused by exposure to ultraviolet light, enhancing its colorfastness. Drying accelerators are additives that promote faster drying by facilitating solvent evaporation. pH modifiers are used to adjust the pH level, ensuring optimal performance and stability.

Examples of common additives and their functions:

  • Cellulose derivatives: Improve flow and prevent sedimentation.
  • Dispersing agents: Aid in the dispersion and stability of pigments in the product.
  • Biocides: Inhibit microbial growth to prevent spoilage and maintain shelf life.
  • Crosslinkers: Enhance adhesion and durability on various substrates.
  • Defoamers: Eliminate foam or air bubbles that may hinder the printing process.
  • Optical brighteners: Additives that improve the brightness and whiteness.

CHEMISTRY

Pigment clusters are broken down into individual particles through mechanical means and dispersion agents. Proper dispersion ensures consistent color, stability, and prevents clogging.

DRYING MECHANISMS

  • Evaporation: Solvent-based products dry by solvent evaporation.
  • Oxidation: Some products dry through a chemical reaction with oxygen.
  • Absorption: On porous substrates it dries by being absorbed and solvent evaporation.
  • Factors: Drying time is influenced by solvent composition, formulation, environmental conditions, and substrate properties.

Ink components can chemically interact with substrates, affecting adhesion, penetration, and degradation. Chemical interactions affect performance, durability, resistance to fading, water, light, and chemical exposure.

Emulsion: The suspension of liquid in a liquid. As of today, this is the 4th generation ink formulated by ZEBRA Pen. Though “hybrid” products have been introduced to the writing instrument market, none of the formulations have produced the full emulsion type properties now offered in the emulsion refill from Japan.

Emulsion ink

APPLICATIONS

It has various applications as it became part of our daily lives.

Printing ink
Close up of plotter ink tanks with color marks in printing shop or publishing agency

PRINTING TECHNOLOGIES

  • Offset printing: Balanced viscosity, tack, and drying time for sharp image reproduction.
  • Flexographic printing: Fast-drying type with low viscosity for high-speed printing.
  • Gravure printing: High-viscosity for precise product transfer in fine detail.
  • Digital printing (Inkjet): Compatible with specific printheads, precise droplet formation, and quick drying.

WRITING

  • Ballpoint pens: Low viscosity for smooth ball movement and controlled flow.
  • Fountain pens: Suitable viscosity and flow for capillary action and controlled flow.
  • Gel pens: High viscosity and thixotropic properties for smooth writing and vibrant colors.
  • Markers: Quick-drying, good adhesion, and resistance to smudging or bleeding.
  • Factors affecting flow and performance: Viscosity, surface tension, drying time, pigment particle size, and composition.

SPECIALTY TYPES

There are various inks that differ from what people most commonly use. These are present in different professions and art forms allowing creative freedom.

  • Security type: Invisible, UV-visible, or magnetic inks for anti-counterfeiting measures.

    Unique applications and requirements:
     Special features, authentication codes, or color-changing properties.
  • Conductive type: Silver, carbon, or graphene-based product for printed electronics.Unique applications and requirements: Good conductivity, adhesion, and flexibility for electronic applications.
  • Ceramic type: High-temperature stable product for printing on ceramics or glass.Unique applications and requirements: Compatibility with high-temperature firing processes and adherence to non-porous surfaces.

ABOUT PRODUCTION

Ink is a complex mixture carrying a variety of substances. There are many types on the market, and they all have their own unique characteristics. Although there are many varieties, the applications are fairly similar. It forms part of our everyday life. At ZEBRA, we aim to create good quality, long lasting pens that can help you with your work or your personal tasks.

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