Introduction of Basic of Paint Technology

About Paint, its composition, properties etc.

1. INTRODUCTION OF PAINT BASIC CHEMISTRY

2. Polymeric Coatings Coatings are materials that are applied to a surface which form a continuous film in order to beautify and/or protect the surface. Paint: Pigmented surface coating Varnish: Coating that lacks a pigment Lacquer: Thermoplastic solution paints or varnishes, term also used for all clear wood finishes Enamel: Glossy Thermoplastic , thermosetting paints

3. Paint Cross Section

4. Other Coatings Varnish : A film former, commonly Low cost Natural resin , dissolved in a solvent, which normally doesn’t contain a stain. Purpose is to protect wood Stain: A mixture of organic dyes dissolved in solvent. Made to penetrate wood and stain in. Does not protect Enamel : Glossy, thermoplastic Or thermosetting paint.

5. 5 Basic Composition of Solvent based Paint Solvents (Liquids) Pigments Additives Resins (Binder)

6. Types of Pigmented Paint

7. Solvents Dissolve film former Reduce viscosity for ease of application Control rate of cure Low molecular weight organic chemicals Examples include aliphatic, aromatic, and chlorinated hydrocarbons; alcohols; ketones; esters; glycol ethers; and water.

8. Pigment 1. Decorate, color, and hide 2. Protect Barrier Galvanic Inhibitive 3. Provide consistency 4. Provide film thickness 5. Control vehicle penetration into substrate

9. 9 Prime Pigments Titanium Dioxide (TiO 2 ) Provides excellent hiding power and whiteness Available as a solid (powder) or liquid (slurry) Titanium dioxide is the world's primary pigment for providing whiteness, brightness and opacity. White

10. Pigment : Extenders and others Extenders provide no colour to a film, but their use is an inexpensive method of improving adhesion, ease of sanding, film strength and opacity. Calcium carbonate (whitewash) Aluminum silicate (clay) Magnesium silicate (talc) Barium sulphate ( barytes ) Silica Anticorrosive Pigment provide no color to a film, but their use as Sacrificial , barrier / Preventive method improving Saltspray resistance Or Water resistance . Zinc Phosphate (whitewash) Strontium Chromate (Yellow) Micacious Iron Oxide ( Red / Grey) Basic Lead Silicate ( white ) Zinc Dust

11. Resin (binder) Principal ingredient Holds paint together and to the substrate Establishes chemical and physical properties Defines coatings generic type A "Vehicle" that turns to a "Solid" (nonvolatile )

12. Organic Coatings The resin is a carbon based polymer (urethanes, epoxies, alkyds, acrylics, etc ) R C C R R R R R

13. Inorganic Coatings The resin is not a carbon based polymer Most utilize some type of silicate binder Si O O O O Si O O Zn Zn Zn Zn O

14. Type of Curing in Modern Coating Resins Solvent evaporation Oxidation Chemical reaction Catalyzed film former Thermoplastic Thermoset Emulsion - water based

15. How does paint dry? When paint dries, a thin polymer film is formed that adheres to the surface and suspends the pigments. Paint dries by a number of different mechanisms: Solvent evaporation Rust proof paints/ Thermoplastic Paints Heating (thermosetting) By chemical Reaction Automotive or Industrial Paint Alkyd Amino/ Acrylic Amino/Acrylic Isocyanate Oxidation Drying oils, artistic paints Linseed oil

16. 16 Resins Types: Latex, Alkyd, Epoxy, Acrylic Binds or glues ingredients (pigments and additives) of paint together Resin provides adhesion to the substrate Resin provides durability & resistance properties: U-V resistance Moisture resistance Chemical resistance Stain resistance Acid Alkali resistance Block resistance

17. 17 Alkyd Resin Technology ALKYD (Oil-Based) A synthetic resin made by reacting Polyol and fatty acids Soya bean, linseed, tung -oil oil commonly used Benefits of alkyds: Superior brushing characteristics Excellent flow and leveling Good adhesion Used in Trivial rust preventative paint Low Cost

18. 18 Latex Resin Technology LATEX (water-based) Synthetic polymers Main resins 100% Acrylic Styrene Acrylic Vinyl-Acrylic Acrylic Copolymer Vinyl Acetate Ethylene

19. 19 QUALITY Latex paint benefits include: * Ease of application * Yellowing resistance * Chalk resistance * Washability * Good flow & leveling * Excellent adhesion * Scrub resistance * Water clean-up Latex Resin Technology

20. Evolution of Solvent-borne Acrylic Coatings 1950’s 1970’s 1960’s 1980’s 1990’s 2000’s Molecular Weight 10 3 10 4 10 5 10 6 Lacquers 25 % solids 75 % solvent Super-Solids Enamels 75 % solids 25 % solvent High-Solids Enamels 50 % solids 50 % solvent

21. 21 Acrylic vs. Alkyd Paints The paint on the left half of each board is acrylic, the paint on the right half, an alkyd.  The colors of the paints were identical when applied.  After 5 years of weathering, the appearance of the alkyds has changed dramatically.  All have lost gloss, faded, and chalked.  The acrylic paints, in contrast, have proven remarkably durable with good color retention.

22. Thermosetting Binders: Epoxy and Polyurethane Resins Epoxy resins are two-component paints formulated from epoxide functionalized monomer and (usually) amine hardeners. Reaction of diisocyanates with diols generates polyurethane coatings whose structure/properties can be varied widely. Polyurethanes afford superiour abrasion and chemical resistance, as well as a fast, low-temperature cure.

23. Methods for applying polymeric Coatings Powder Spray coatings Electrocoating Fluidized Bed Dip coating Spray coating Spin coating

24. 24 Gloss/Sheen Levels • Gloss or Sheen of paint refers to reflectivity or how shiny the dry paint film is. • Gloss is measured at 20 ° for full gloss ranges. • Gloss is measured at 60 ° for flat to gloss ranges. Sheen is measures at 85 ° between flat to eggshell • Some paint manufacturers use different terms to define products between flat and semi-gloss: silk, suede, satin, velvet, eggshell, low sheen, low luster, pearl, etc.

25. 25 Gloss/Sheen Levels Term Gloss @ 60° Sheen @ 85 Flat 0-5 0-5 Velvet/Low Luster 5-10 5-15 Eggshell 10-20 15-25 Low Sheen 20-30 Semi-Gloss 55-70 Gloss 75+ •

26. Solvent-Related Surface Defects Orange peel patterns result from high film viscosity and/or surface tension gradient induced flow. Solvent popping results from rapid solvent evaporation and an inability of the coating to flow.

27. Aesthetic Properties of Dried Film Coatings Opacity Extent of substrate coverage, as determined by pigments, extenders and other occlusions in the film. Dependent on refractive index of fillers relative to the polymeric binder. Surface Finish Gloss is a function of surface irregularity, as determined by the film formation process and dispersion of pigments/fillers. Color Inorganic and organic colourants that are soluble or dispersed in the film (may or may not provide opacity).

28. Mechanical Properties of Dried Film Coatings Properties : Hardness Impact (& Chip) Resistance Flexibility Abrasion Resistance Solvent Resistance Adhesion Tests : Indentation, Scratch (Pencil) Drop tests, Stone chip Tester Elongation, Bend Taber Abrasion MEK ( methylethylketone ) double rub Scraping, Crosscut Adhesion

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