How to get the Best From Your Carbon Black PNW Coatings Society October 2014

Agenda Review of Carbon Black Fundamentals Dispersion Process and Optimization Process Wetting Dispersion Stabilization Correct Carbon Black Product Dispersant types Examples Summary

Review of Carbon Black Fundamentals

Four Fundamental Properties of Carbon Black Fineness Particle Size Distribution Structure Aggregate Size/Shape Distribution Porosity Pore Size Distribution Surface Activity Surface Functionality Distribution

Properties of Carbon Black - Primary Particle Size Measured directly by Electron Microscope or indirectly by tint test, ISA, NSA A wide distribution of particle sizes within a product, but similar particle size within an aggregate Birla Carbon make blacks with mean particle sizes from 8 nm to 100 nm Raven 410 100 nm Conductex 7055 Ultra 42 nm Raven 5000 Ultra II 8nm Raven 1255 21 nm

Surface area and its influence Smaller particle diameter generally leads to high surface area Surface area typically measured by nitrogen absorption (ASTM D6556) or iodine titration (ASTM D1510) Birla Carbon’s carbon blacks have surface areas ranging from 25- 580+ m2/g High surface area is the single biggest predictor of color performance (masstone and tint) Higher surface area increase viscosity and conductivity and UV protection High surface area lower dispersibility

Carbon Blacks

Structure – Oil Absorption Number (ASTM D2414) Oil Absorption Number, primarily influenced by aggregate size/shape, may be influenced by porosity The amount of oil to reach a peak torque, results given as cubic centimetres of oil per 100 g carbon black

Effect of Structure on Performance Higher structure (OAN) leads to Slightly lower blackness and tint strength Better dispersibility Higher viscosity and vehicle demand Higher electrical and thermal conductivity

Porosity and its Influence Porosity is caused by oxidation in the reactor and is controlled by residence time Indicated by a difference between Nitrogen Surface Area (NSA) & Statistical Thickness Surface Area (STSA) High porosity gives an increase in Conductivity Viscosity Moisture pick up High porosity Enables a low loading in conductive applications Decreases gloss

Surface Activity and its Influence Property describing the interaction of a carbon black surface with its surroundings Furnace carbon blacks can be chemically surface treated after production to mimic channel blacks Increase of surface activity by an increased number of acid groups leads to improved dispersion Improves wetting of the carbon black by most vehicle systems Reduces viscosity in liquid systems Reduces conductivity Carbon Black as produced Post treatment adds oxygen groups to the surface Oxidation 950 OC No Oxygen

Measurement of Surface Activity Volatile (Mass loss at 950 °C) Usually indicative of oxygen function groups, sometimes influenced by moisture, sulfur and toluene extract pH (ASTM D1512) Generally assumed to indicate surface acidity by oxygen functional groups, often strongly influenced by sulfur levels Oxygen Content Direct measure of bulk oxygen XPS Analysis Measure of surface composition by atomic type, and some qualitative information on oxygen functionalities

Oxygen Functionality – Volatile All of these functionalities can be present on the surface in different amounts, currently we do not control which species are on the surface of the carbon black Increasing Acidity Carboxyl Phenol Aldehyde Lactone Quinone Anhydride Ether

Dispersion Optimization

Stages of Dispersion Process Premixing Grinding Depends on Premixing Grinding Letdown

Correct Carbon Black Product For full color coatings, a high surface area product, which gives a jet color and blue shade For tint applications, there is a tradeoff between strength and blue shade. Higher tint products giver a browner shade, lower strength products give a blue shade.

Full Color Performance

Tint Color Performance

Dispersant Choice Surfactants Low molecular weight dispersing agent which can modify the properties between the pigment and resin solution by lowering their interfacial tension. Polymeric Dispersants Higher molecular weight dispersing agents, composed of anchoring groups and polymeric chains that stabilize dispersions via a steric stabilization mechanism.

Surfactants Can be Classified by Head Group Type Anionic – negative charge Sodium dodecylsulfate (SDS) also called sodium lauryl sulfate (C12H25)OSO3Na Good for basic pigment surfaces Cationic – positive charge Cetyltrimethylammonium bromide (CTAB) (C16H33)N(CH3)3Br Good for acidic pigment surfaces Nonionic – No charge Octaethylene glycol monododecyl ether (C12H25)(OCH2CH2)8OH Good for neutral pigment surfaces Zwitterionic – both postive and negative charge (on different parts of the molecule) Phosphatidylcholine (as seen in lecithin)

Surfactants Can be Classified by Tail Type Saturated Unsaturated Monounsaturated Polyunsaturated

Phosphatidylcholine Structure Red - choline and phosphate group Black – glycerol Green - unsaturated fatty acid Blue - saturated fatty ac

Polymeric Dispersants Polymeric dispersants are at least a two-component structure which combines the following requirements: Specific Anchor Groups The dispersant must be capable of being strongly adsorbed into the carbon black surface via the anchoring groups. Polymer Chains The dispersant must contain polymeric chains that give steric stabilization in the required solvent or resin system.

Effect of Dispersant Choice : Leather Coating

Effect of Dispersant Choice : WB Automotive

Effect of Dispersant Loading: WB Automotive

Effect of Dispersant Loading: SB Automotive

Summary The first stage in getting the best from your carbon black, is choosing the right carbon black initially Tailor dispersant and resin chemistry to optimize performance Ladder study to optimize loading

Further Information : Thank you MSDS, brochures and other information is available at birlacarbon.com The International Carbon Black Association website carbon-black.org also contains useful health and safety information including a users guide