Organic pigments used in the printing ink industry
Product Details
Organic pigments are a class of colored organic compounds that are insoluble in water and the mediums used (such as oils and solvents). They typically exist as highly dispersed microparticles, adhering to the surface of an object or mixed within the object through binders or film-forming substances, thereby coloring the object.
Main Categories and Typical Representatives
Organic pigments are diverse and can be mainly classified into the following categories according to their chemical structure:
Azo Pigments: This is the largest category in terms of production volume and variety, accounting for approximately 59% of the total organic pigments. Colors are primarily yellow, orange, and red, such as the common benzidine yellow and permanent orange.
Phthalocyanine Pigments: These are the second largest category in terms of production volume, accounting for approximately 24%. They are mainly bright and highly stable blues and greens, such as phthalocyanine blue and phthalocyanine green, widely used in high-grade inks and coatings.
Lake Pigments: These are produced by converting water-soluble dyes (such as acid dyes and basic dyes) into insoluble pigments using precipitants. They offer bright colors and low cost, such as golden red and iridescent cyan.
High-Performance Organic Pigments (HPP): These pigments possess excellent lightfastness, heat resistance, and migration resistance. Typical examples include quinacridones (providing magenta, purple, etc., such as Pigment Violet 19), dioxazines (providing bright purple, such as Permanent Violet RL), and isoindolineones (providing excellent yellow).
Main Application Areas
Organic pigments, due to their vibrant colors, strong tinting strength, and high safety, have a wide range of applications:
Printing Inks: This is the largest application area, accounting for approximately 60% of organic pigments.
Paints/Coatings: Used in automotive paints, architectural coatings, and industrial anti-corrosion coatings.
Plastics/Rubber: Used for coloring plastic products, synthetic fiber pulp, and rubber tires.
Other Applications: Art pigments (such as watercolors and oil paints), cosmetics, stationery (crayons and colored pencils), and electronic materials (such as LCD color filters).
Core Characteristics of Organic Pigments
In addition to the advantages and disadvantages mentioned above, organic pigments also possess some key physical and chemical properties that determine their application performance:
Particle size and distribution: The size of pigment particles (typically in the nanometer to micrometer range) directly affects their color, tinting strength, hiding power, transparency, and weather resistance. For example, smaller particle size generally results in higher transparency and stronger tinting strength, but may reduce weather resistance.
Specific surface area: Smaller particle size leads to a larger specific surface area and stronger surface adsorption, which affects the pigment's dispersibility and rheological properties in the medium.
Crystal form: Organic pigments with the same chemical structure may exist in multiple different crystal forms (polymorphs). Different crystal forms may have drastically different colors, stability, and application properties. For example, phthalocyanine blue has multiple crystal forms such as α, β, and γ, among which the β crystal form is a stable green-blue color.
Surface treatment: To improve the pigment's dispersibility and stability in the medium or to impart special functions (such as easy dispersibility, hydrophobicity, etc.), pigment particles are usually surface-treated (e.g., by adding surfactants, resin coatings, etc.). Treated pigments are called easily dispersible pigments or pre-dispersible pigments.
Chemical stability: This refers to the pigment's ability to resist the attack of chemicals such as acids, alkalis, oxidants, and reducing agents. This is crucial for applications such as coatings and plastics used in special environments.
In summary, organic pigments are a class of colorants with rich colors, adjustable properties, and good environmental friendliness. In practical applications, it is necessary to comprehensively weigh the advantages and disadvantages based on specific needs (such as required brightness, durability, cost, processing conditions, etc.) and pay attention to core characteristics such as particle size and crystal form in order to select the appropriate variety.