"introduction to epoxies" by hubert monteiro, royce international

Dr. Hubert A. MonteiroTechnical Director

Royce International

What are Epoxy resins?

A family of thermosetting resins which have the following chemical group:

When reacted with a hardener(or curing agent), they set to a hard mass which does not melt or dissolve in solvents.

Hardeners are typically amine or anhydride based chemistry.

In what forms are Epoxies and Hardeners supplied?

LiquidsSolidsSolutionsSemi-formulated pastes

What are the advantages of Epoxies?

• Bonds strongly to most materials including metals, concrete, glass, ceramics, stone, wood, leather. Exceptions are plastics materials like polyethylene, polypropylene, Teflon, etc.

• Excellent resistance to chemicals and solvents.• Very good electrical insulating properties.• Outstanding mechanical strength including

tensile, compressive, flexural and modulus.• Very little shrinkage on curing, thus providing

good dimensional stability.

What are the limitations of Epoxies?Limited pot life when resin and hardener

are mixed.Cured systems have poor resistance to

U.V. Thus, outdoor exposure over time tends to yellow and chalk coatings and electrical insulators can begin to “track”.

Limited temperature resistance:Ambient cure: 150-250°FHeat cure: up to 360° F

Resins and Hardeners need to be handled with care in sensitive individuals to prevent dermatitis or rash.

Industries in which Epoxies are utilized

• Coatings, Paints and Lacquers.• Civil Engineering and Construction.• Aerospace and Industrial Composite.• Electrical & Electronics (i.e. casting,

impregnation, insulation, laminates, potting, etc).

• Adhesives and Sealants.• Recreational and Sporting Equipment (i.e. golf

shafts, skies, snowboards, tennis racquets).• Foundries and tooling (i.e. automotive).

Epoxy Coatings

Epoxy Coatings

Solvent Free Solvent Containing

Water based

Liquid Solid Powder Coatings

AmbientCure

Water SolubleAnodicCathodicElectrodeposition

WaterDispersible

HeatCure

Coating Applications

• Civil Engineering• Construction• Flooring• Industrial Maintenance• Marine• Powder Coatings• Can/Coil/Packaging• Automotive

Epoxies for Civil Engineering and Construction Applications

Coatings Solvent-free lining of concrete and steel tanks, Water-based coatings for concrete. Powder coatings for rebars.Mortars Self-leveling and trowellable floors Pothole repair for roads and airfields. Grouting of heavy machinery.Bonding

Bonding of prefabricated elements in bridges and other structures. Bonding new to old concrete. Bonding external reinforcement to concrete.Injection Systems Grouting and repair of concrete cracks.

Epoxy Mortars vs. Cement ConcreteMechanical Units Epoxy Mortar CementProperties (Filler: Binder=4.1) ConcreteCompressive Kg/cm² 800 – 1200 300-500Strength

Tensile kg/cm² 150-250 40-60Strength

Flexural kg/cm² 250-400 50-80Strength

Modulus of kg/cm² 1.6 x 10⁵30 x10⁵

Elasticity

Elongation % 0.1 0.02At Break

Coefficient of °C¯¹ 2.5x10⁵1.2x10¯⁵

Expansion

Epoxies for Electrical Applications

• Ambient cure potting, casting and encapsulation of small low voltage components.

• Battery sealing compounds.• Joints and termination in electrical cables and gas

seals in telecommunication cables.• High voltage insulators and bushings.• Switch gear parts in circuit breakers.• Current and potential measuring transformers.• Impregnation of large rotating machines (VPI

process).• Resin-rich mica-paper tapes and resin-poor tapes

for insulation of coils in large rotating machines.

Epoxies for Electronic Applications

• Transfer molding compounds for encapsulating of semiconductors.

• Liquid casting resins for potting active and passive components.

• Brominated resins for base laminates for printed wiring boards.

• Conductive solders for mounting heat sensitive components.

• Dip-coating and conformal coatings for components and assemblies.

Advantages of CompositesHigh Strength to Weight Ratio

Material Strength toWeight Ratio

Aluminum 0.8Steel 1.0Titanium alloy 1.0Glass/ Epoxy 2.86Carbon/Epoxy 3.8Aramid (Kevlar)/Epoxy 5.09

Epoxies for ReinforcedPlastic Applications

• Filament winding• Pultrusion• Hand lay-up• Resin transfer moulding (RTM)• Vacuum bag/ pressure bag moulding• “Prepreg” processing Autoclave processing under pressure Flat laminates.

DDS Hardener for Aerospaceand Electronics Applications

4,4’DDS Normal grade for solution prepregs and

laminates.4,4’ DDS MicroMicropulverized grade for hot melt prepregs

and laminates.3,3’ DDSAerospace composite applications.

Epoxy Resins

Diglycidyl ether of Bisphenol A Diglycidyl ether of Bisphenol FEpoxy NovolacLong chain aliphatic diglycidyl ethersCycloaliphatic epoxy resinsMultifunctional resinsBrominated epoxy Resins

Epoxy Hardeners

Aliphatic amines/ adductsCycloaliphatic amines /adductsPolyaminoamides /AmidoaminesPhenalkaminesAromatic aminesFormulated anhydridesBF₃ and BCL ₃ adducts with amines

Choice of Hardener

ToxicityEase of mixing with the resinViscosityMixing proportion – Tolerance to variationsPotlifeConditions of applicationCure Time & Temperature

Factors related to Processing

Choice of Hardener

Factors related to cured system

Heat Deflection TemperaturePhysical, mechanical, electrical propertiesThermal stability (class of insulation)Chemical resistanceLight stabilityCost

AcceleratorsTertiary amines BDMA DMP-10 DMP-30

Imidazoles 1-methyl imidazole 2-methyl imidazole EMI-24 Phenols Phenol Nonyl phenol Cardanol Salicylic acid