Paint & paint systems
- Paint composition
- Generic types of paint
- Paint systems
- Application equipment
- Application techniques
- Paint defects
- Calculations
- Technical data sheet
- Metallic coating-thermal spray
- Metallic coating-hot dip galvanizing
- Fire protective coatings
- Special coatings
- IOGP Definitions of Paint and Surface Treatment
Paint composition
Introduction
1. Paint consists of:
A. Liquid: Vehicle / Varnish
| B. Dry: Powders / Pigments
| C. Chemicals: Additives
|
(FROSIO’s grouping: Binder, Pigments, Extenders, Solvents, and Additives)
2. Composition of paints
A. Binder Natural Resins:
Synthetic Resins:
| B. Pigments
| C. Extender
|
D. Solvent
|
E. Additive
|
Binders
Decides the properties of paint
- Describes the type of paint/coating (generic type)
- Binds pigments and extenders within the solid film
- Provides adhesion to the substrate and cohesion, flexibility in the film
- Provides the water, chemical, solvent and UV resistance
Organic vs. Inorganic Coating
The classification organic versus inorganic coating refers to the binder.
What is an Organic coating?
- Coating based on a binder that is carbon based e.g. made from oil
- For example, epoxy, polyurethane, polyester
What is an Inorganic coating?
- Coating based on a binder that is not carbon based, typically silicate
- Usually pigmented with metallic zinc
- In general, inorganic binders are electrically conductive
- For example, Zinc alkyl silicate, Zinc alkali silicate
Types of binders
Synthetic resins:
| Natural resins:
|
Modified binders
A modified binder may contain more than one binder:
- Epoxy Mastic
- Vinyl Epoxy
A binder may be modified chemically by attaching new molecule groups to their molecules:
- Styrene modified alkyd
- Urethane modified alkyd
- Epoxy ester
Solvents
Purpose in the paint
- Must dissolve the binder
- Gives lower viscosity
- Gives application properties for brush, roller, spray
- Once the paint has been applied, there is no more need for the solvent
Solvents – examples
- White Spirit
- Xylene
- Ketones
- Esters
- Glycol ethers
- Alcohols
- Reactive solvents e.g. styrene
Solvent vs. Thinner
Solvent
- Raw material used when making paints and thinners
- Dissolves the binder completely (forms a solution)
Thinner
- Commercial products
- Used to lower the viscosity (and for cleaning the equipment)
- May be made up by a single solvent or of a mixture of solvents
The paint is supplied with the correct viscosity
- The paint is supplied at its optimal viscosity for being applied
- Thinning is usually only required to adjust the viscosity to suit application method and temperatures
- Use only the thinner named in TDS
- Excessive thinning should be avoided
Addition of thinner
Evaporation rate and solubility of a thinner will influence paint’s:
- Drying time
- Film-forming properties
- Quality of the film
Most paints are ready to be applied as supplied by the manufacturer.
Never add an unknown thinner to paint, it may cause issues with drying, application and durability
Volatile / Non-volatile
Paint’s “Solid Content” means the ingredients which do not evaporate. Commonly referred to as Solids by Volume (%)
Paint’s “VOC” (Volatile Organic Compound) tell us how many grams of volatiles there are in one litre of paint
Solid content: WFT vs. DFT
When applied in the same WFT, the paint with the higher solids content will give a higher DFT (and thus needs fewer coats or gives better protection)
Pigments
Colour Pigments
- Natural or synthetic pigments
- Organic or inorganic pigments
- Give colour to the film
- Hide the substrate / previous coats (opacity)
- Almost all colours consist of a blend of pigments
- A colour can be changed or adjusted by altering the pigment blend
Active / Reactive Pigments
Takes an active role in ensuring that the paint performs as expected:
- Anticorrosive
- Zinc-phosphate
- Zinc-dust
- Antifouling
- Cuprous oxide
Barrier pigments
- Flake-shaped pigments
- Tend to align themselves parallel to the substrate
- Reinforces the film
- Increase the pathway between the surface and the substrate (barrier effect)
- Often made from aluminium, glass, mica or micaceous iron oxide (MIO)
Inhibitive pigments and Cathodic Protective pigments
- Inhibitive pigments:
- Zinc Phosphate
- Pigments with cathodic protection effect:
- Metallic zinc
Extender Pigments
Naturally occurring minerals:
- Dolomite
- Talc (Talcum powder)
- Chalk (Calcium Carbonate)
- Clay (China Clay)
- Reinforce and give body to the film
- Improves hardness
- White / grey in colour
- Very little influence on colour of the film (poor opacity)
Pigment Volume Concentration – PVC
An expression of how much of the dry paint film is made up of pigments. This may affect several of the paint’s properties, such as abrasion resistance, flexibility, gloss, etc.
Additives
Examples
- Wetting agent
- Anti-foam
- Anti-settling
- Anti-skin
- Anti-sagging
- Levelling agent
- Catalysts
- UV-absorbers
Many types
- Production enhancers
- improve manufacturing
- Storage facilitators
- storage stability
- Application aids
- easier application
- Appearance improvers
- better gloss
- Service life
- resist fouling
- Gå til avsnitt
- Introduction
- Binders
- Solvents
- Pigments
- Additives
