Epoxy Materials
.A Family of thermoset polymers
Epoxy resins (polyepoxides), are a class of reactive prepolymers and polymers which contain epoxide (Epoxy) groups
Most common epoxy resins are produced from a reaction between epichlorohydrin (ECH) and bisphenol-A (BPA). though the latter may be replaced by other raw materials (such as aliphatic glycols, phenol and o-cresol novolacs) to produce specialty resins.
The epoxy resins can be obtained in either liquid or solid states.
Cross-linked Epoxy
Epoxy resins may react many functional groups to go through cross-linking reaction which is commonly referred to as Curing.
Cross-linking may be with themselves (through catalytic homopolymerisation), or with a wide range of co-reactants which are often referred to as Curing Agents
Epoxy curing agents when reacted with epoxy resin create a 3-D crosslinked system that can be formulated with exceptional performance properties making them ideally suited for use in a variety of industrial applications
Epoxy Curing Agents
The type of curing agent influences the curing
characteristics
:For Example
....
Dry Time
Pot Life
as well as the final thermoset performance
:For Example
....
Appearance
Mechanical Resistance
Chemical Resistance
.of an epoxy resin system
Epoxy Curing Agents
,Following
:We will review some of the epoxy hardeners
Cashew Nutshell Liquid (CNSL) Technology
A renewable oil is naturally obtained from the cashew nutshell as a by-product of cashew and it is non-food chain.
CNSL is approx. 25 % of the cashew kernel by weight.
The primary component of CNSL is cardanol, a natural phenolic compound with a long unsaturated fatty side chain.
Phenalkamine
Phenalkamine Structure & Properties
Phenalkamine
Phenalkamine Curing Agents are different in some values like:
- Solid content
- Viscosity
- Color
- Amine Value
- AHEW
Phenalkamide
- Phenalkamide technology can be used in many applications where polyamide technology currently prevails to bring a new level of performance, reliability, application latitude, and cost savings.
- General protective coatings, for example, that require good color stability and long overcoatability can avoid having separate summer and winter versions by using a phenalkamide based converter package.
- The overall system will have fast cure, low temperature cure, and excellent corrosion protection without the need for tertiary amines or anticorrosive pigments.
- A single formula’s broader application latitude gives coating manufacturers protection from summer converter packages being used erroneously in low temperature conditions, and simplifies finished product and raw material inventory management.
Phenalkamide
For Example these two different products have different appearance that affects the color of the dry film. The lighter hardener is more expensive obviously!
Phenalkamines for Top Coats
Cardanol based curing agent for use in floor coatings
- Very low color and nice film appearance
- Fast cure
- Excellent water resistance
- Balanced mechanical properties
- Good self-leveling properties
- Excellent weatherability
- Ideal for floor top coats
- Good replacement for cycloaliphatic amines
Phenalkamines for Cathodic disbondment
- Low viscosity, solvent-free phenalkamine
- Very iast cure and bond strength development
- Excellent...
- Cathodic disbondment performance
- Corrosion protection
- Chemical resistance
- Specialty product ior heavy-duty and flooring applications
Chemical Resistance
- NX-5594 has Excellent resistance to:
- Petrochemicals: gasoline, jet fuel, diesel, ethanol, xylene, methanol, toluene
- Acids: sulfuric acid, hydrochloric acid
- Alkali, salts, and distilled water
:Conclusion
we have reviewed various curing agents for epoxy resin.
The most suitable curing agent must be selected according to
the use conditions, application, workability, and other factors.
Only the curing agents for epoxy resin are discussed in this
issue; in practical use, however, they are mixed with diluents, coupling agents, fillers, and other agents to improve the curing properties and workability.
