PAINTS & COATINGS

solid particle, insoluble, organic, inorganic

list down 4 characteristics of pigments.

CMPA

According to ____ a pigment is a solid particle, can be organic or inorganic, it's insoluble, does not dissolve to the vehicle or film forming polymer, and can keep its crystal structure.

Pigment

it does not dissolve to the vehicle or film forming polymer.

Pigment

can keep its crystal structure.

Pigment

It goes in as a solid crystal and stays a solid crystal forever.

Extenders

Modify physical properties of paint, such as gloss, hardness, viscosity as well as the cost.

Functional Pigments

Provide specialized protective functions like anti-corrosion barriers or chemical inactivation.

Biological Pigments

Distinct from industrial pigments and are often dyes that color living animal and vegetable tissues.

Qualities of Pigment

Appearance, Colour, Tinctorial Strength, Particulate Nature, Insolubility, Opacity, Transparency, Durability, Chemical Stability, Heat Stability.

Appearance

Should provide visual effect, mainly colour and opacity. The pigment must fight: Insolubility, light fastness, Weatherability, Chemical resistance.

Colour

Depends on the chemical structure of pigment. The pigment hue is mainly dependent on the pigmented surface selective absorption and reflection of various lights wavelength.

Colour

comes from electrons in the molecule jumping to higher energy levels when they absorb specific wavelengths of light. The wavelengths not absorbed are the colour you see. E=E2−E1=hcλ.

Fluorescent Colour

They take invisible Ultraviolet (UV) light from the sun, absorb its high-energy rays, down-convert that energy internally, and spit it back out as visible light. They are fluorescent dyes dissolved into resin.

Colour Organic Compound

An organic molecule to have color, it must possess a chromophore. Chromophore requires conjugation. Alternating single and double bonds create electron highways.

Colour Organic Compound

Conjugated Straight-chain structure works perfectly; however, it is chemically fragile. Paint chemists rely on aromatic compounds, specifically benzene rings. Auxochromes fine-tune absorption.

Auxochromes Camp A

Electron Donors: Alkoxy (—OR), hydroxy (—OH), alkyl, arylamino groups.

Auxochromes Camp B

Electron Acceptors: Nitro (—NO2), carboxylic acids (—COOH), esters (—COOR), sulfones (—SO2).

Colour Inorganic Compound

Most inorganic pigments are made from transition metals with d-orbitals. Inorganic pigment is usually Metal ion + Oxygen or Sulfur. Mechanisms: d-d Transitions, Charge Transfer.

Tinctorial Strength

Measurement of a pigment’s coloring efficiency. High tinctorial strength means potency, lower production costs, higher profit margins.

Organic Pigment High Tinctorial Strength

High conjugation, planarity, electron donors increase efficiency.

Inorganic Pigment High Tinctorial Strength

Mixed-valence states yield high strength; trapped cations yield low strength.

Tinctorial Strength Particle Size

Smaller particle size increases tinting power.

Particulate Nature

True solid pigments come in crystalline or amorphous forms. If they dissolve, they lose pigment status.

Solvent Soluble Dyes

Water-insoluble colorants designed to dissolve in organic solvents. Characteristics: Insolubility, Transparency, Heat & Light Resistance.

Solvent Soluble Dyes Application

Plastics & Polymers, Inks & Coatings, Fuels & Lubricants, Waxes & Candles.

Vat Dyes

Insoluble dyes requiring reduction to leuko form, absorption, and oxidation to restore insoluble color.

Vat Dyes Characteristics

Maximum fastness, complex application, material compatibility. Applications: Denim, Military Uniforms, Workwear.

Insolubility

Golden rule of pigments: they must remain solid and insoluble. Problems: Blooming, Plate out, Bleeding, Recrystallization.

Pigment Blooming

Organic pigment dissolves slightly, migrates to surface forming haze. Prevention: Pigment selection, temperature optimization, environmental controls.

Pigment Plate Out

Pigment deposits on equipment surfaces. Prevention: Optimize lubrication, add cleaning fillers, switch pigment treatments, adjust equipment temperature.

Pigment Bleeding

Colorant dissolves out and migrates. Prevention: Use inorganic pigments, high molecular weight organics, barrier coats, fixing agents.

Pigment Recrystallization

Pigment dissolves during high temperature and reforms into larger altered crystals. Rosin or polymer coatings

Additives

Low-level ingredients that nevertheless exert a massive, disproportionate impact on the paint's performance and stability.

Spiral Formulation Trap

Additives can trigger a chain reaction of fixes.

Stripped-Back Philosophy

Because of this spiral trap, a paint's recipe can become bogged down with excess chemicals.

Paint Extenders

Primary, bulky ingredients used to add volume, thickness, and durability to paint.

Paint Additives

Specialized, chemical ingredients used in small amounts to fine-tune specific performance traits, like drying time, mildew resistance, or flow.

Extenders Purpose

To bulk up the paint, reduce costs, and improve properties like scrub resistance and sheen.

Additives Purpose

To enhance or modify specific application and performance properties.

Extenders Quantity

High volume.

Additives Quantity

Low volume.

Extenders Common Types

Calcium carbonate (chalk), clay, silica, and talc.

Additives Common Types

Defoamers, mildewcides, UV absorbers, and flow/leveling agents.

Anti-Corrosive Pigment Enhancers

Materials added to boost the rust-protecting performance of primary anti-corrosive pigments like zinc phosphate, often used to partially replace expensive prime pigments to save on costs.

Kelate, Albarex , and Alcophor 827

Anti-Corrosive Pigment Enhancers Examples

Antisettling Agents

Pigments are heavy solids suspended in liquid resin; antisettling agents build a temporary internal structure to keep pigments suspended.

Antisettling Agents Chemical Strategies

Soya-Lecithin, Modified Hydrogenated Castor Oils, Modified Montmorillonite Clays, Pyrogenic Silicas.

Driers

Metallic soaps of organic acids that dissolve smoothly into paint resins to accelerate crosslinking.

Driers Function

Oxygen Absorption, Radical Generation, Cross-Linking (Curing).

Cobalt Drier, Surface Drier

The most powerful catalyst on earth. It drives rapid surface crosslinking. If used alone, it leaves the under-film wet and mobile, causing the surface to buckle and wrinkle in thick coats.

Lead Drier, Through Drier

The traditional champion of uniform, deep drying throughout the entire thickness of the film. Heavily restricted or banned in modern paints due to severe toxicity and tendency to stain black when exposed to atmospheric sulfides.

Zirconium Drier, Through Drier

The premier modern, non-toxic replacement for lead. It ensures uniform deep-drying without the regulatory or toxicity issues.

Manganese Drier, Mixed Drier

The runner-up to cobalt, contributing to both surface and through-drying. Its massive flaw is color: it shifts from light brown to dark brown, ruining clean whites. Adding too much actually hurts drying.

Calcium Drier, Auxiliary Drier

Ineffective on its own. When paired with cobalt/lead systems, it stabilizes the active metals, prevents lead from precipitating on storage, and stops alkyd "blooming".

Aluminium Drier, Through Drier

A specialized non-toxic option. It cannot simply be swapped into an old formula; the resin vehicle must be custom synthesized to work with it, yielding excellent color and exceptional hardness.

Electrical Properties Additives

Modifying the paint's electrical resistance is vital for transport safety and automated industrial spray booths.

Electrical Properties Additives Roles

Antistatic Transport Safety, Electrostatic Spray Optimization.

Insecticidal Additives

Turn a flat wall coating into an active pest control surface, primarily deployed in specialty zones like ships' holds to eradicate cockroaches or on wood structures to stop boring insects.

Insecticidal Additives Limitation

Rarely popular for general household flying pests as consumers despise flies dropping lifeless directly from the ceiling into their dinner plates.

Ultraviolet Absorbers

Molecules that act like chemical sunblock, absorbing destructive short-wavelength UV rays and safely converting that energy into harmless heat before it can tear the resin apart.

HALS (Hindered Amine Light Stabilizers)

Radical scavengers that trap and neutralize free radicals created by UV light, preventing under-film chalking and ensuring clear coats remain crystal clear for decades.