This image was created with artificial intelligence – marked under Art. 50 of the AI Act, Regulation (EU) 2024/1689. It is a placeholder until the company's photos arrive.Epoxy resins (EP)
Discover why epoxy resins (EP) are used so frequently in industry and engineering – explained concisely and clearly.
Epoxy resins belong to the group of thermosets
Epoxy resins in industrial use
Epoxy resins are thermosetting synthetic resins with high mechanical strength, pronounced adhesion and very good chemical resistance. They are used wherever components must be designed to be permanently load-bearing, dimensionally stable and resistant to media.
In the cured state, epoxy resins form a close-meshed polymer network. This provides high compressive and flexural strength, low shrinkage during curing and a stable bond to metals, plastics and mineral substrates. As a result, epoxy resins are suitable both for structural applications and for coatings, potting and bonding applications.
Typical industrial fields of application are mechanical and plant engineering, electrical engineering, mould making and chemical apparatus engineering. Depending on the formulation, properties such as toughness, temperature resistance or electrical insulation can be specifically adjusted.
A material classification in the context of engineering plastics is often made together with other reactive resin systems. For orientation within the portfolio, it is advisable to start via engineering plastics.
Properties of epoxy resins
Epoxy resins are characterised by a combination of high mechanical load capacity, very good adhesion and pronounced chemical resistance. These properties remain largely stable even under continuous stress.
Mechanical strength
Cured epoxy resins achieve high compressive, tensile and flexural strengths. The material shows a low tendency to creep and is suitable for load-bearing or dimensionally stable components.
Chemical resistance
Epoxy resins are resistant to oils, greases, fuels and many acids and alkalis. This makes them suitable for applications in chemically stressed environments.
Thermal properties
Heat deflection resistance is typically between 80 °C and 180 °C depending on the system. Special high-temperature formulations allow higher service temperatures.
Adhesion and surface bonding
Epoxy resins adhere very well to metals, plastics, glass and mineral substrates. This property makes them particularly suitable for coatings, bonds and potting applications.
Compared with other engineering plastics, epoxy resins are among the materials with the highest combination of strength, adhesion and media resistance.
Areas of application of epoxy resins
Epoxy resins are used in numerous industrial areas where high mechanical strength, permanent adhesion and chemical resistance are required. The combination of these properties enables both structural and protective applications.
Mechanical and plant engineering
In mechanical engineering, epoxy resins are used for coating components, for potting components and for producing dimensionally stable tools and fixtures. They increase resistance to oils, coolants and mechanical stress.
Electrical engineering and electronics
In electrical engineering, epoxy resins are used for insulating materials, circuit boards, potting compounds and protective coatings. They provide electrical insulation, protection against moisture and high dimensional accuracy.
Mould and tool making
Epoxy resin systems are used in model, mould and tool making, in particular for prototypes, casting moulds and negative moulds. The low shrinkage during curing supports precise moulding.
Chemical apparatus engineering
Due to their chemical resistance, epoxy resins are used for linings, coatings and components that are permanently exposed to aggressive media.
The selection of suitable resin systems is often made in conjunction with other engineering plastics in order to tailor material properties specifically to the respective application.
Processing and curing of epoxy resins
Epoxy resins consist of a resin and a hardener, which are combined in the specified mixing ratio before processing. The properties of the cured material depend directly on the correct dosage, the processing temperature and the curing time.
Mixing ratio
The mixing ratio of resin and hardener is defined specifically for each system. Deviations lead to altered strength, incomplete curing or reduced chemical resistance.
Pot life and processing window
The pot life describes the period during which the mixed epoxy resin remains workable. It varies depending on the formulation, batch size and ambient temperature and determines the available processing window.
Curing
Curing takes place at room temperature or with the application of heat. Post-curing with heat increases in many cases the final strength, temperature resistance and chemical resistance of the material.
Processing techniques
Epoxy resins are cast, spread, laminated or applied as a coating. The choice of technique depends on component geometry, layer thickness and the desired surface quality.
For processing, supplementary materials and auxiliary materials from the field of engineering plastics are often used in order to specifically adjust processes and component properties.
Advantages and limitations of epoxy resins
Epoxy resins offer a balanced combination of strength, adhesion and chemical resistance. At the same time, there are material-typical limits that should be taken into account when selecting materials.
Advantages of epoxy resins
- High mechanical strength and rigidity
- Very good adhesion to metals, plastics and mineral substrates
- Low shrinkage during curing
- Good chemical resistance to many media
- Good electrical insulating properties
Limitations
- Limited temperature resistance compared with high-performance plastics
- More brittle fracture behaviour under sudden loading
- Longer curing times at room temperature
- Sensitivity to UV radiation without suitable additives
Compared with thermoplastic engineering plastics, epoxy resins are dimensionally stable and permanently cross-linked after curing, but are less suitable for applications with high dynamic loading or repeated reshaping.
Selection and application criteria for epoxy resins
The selection of a suitable epoxy resin system depends on the technical requirements of the respective application. Decisive factors are mechanical load, thermal stress, chemical influences and processing-related framework conditions.
Mechanical requirements
For load-bearing or dimensionally stable components, high compressive, tensile and flexural strengths are relevant. Under dynamic loading, the toughness of the resin system plays a central role.
Temperature and media resistance
The permissible service temperature as well as contact with chemicals, oils or moisture determine the choice of resin formulation. Special systems offer increased temperature or media resistance.
Processing and curing
Pot life, curing conditions and possible post-curing with heat influence the manufacturing process. These criteria are particularly relevant for series production and large components.
Component geometry and layer thickness
The geometry of the component as well as the planned layer thickness affect heat development, curing and surface quality. This determines the selection of suitable casting, laminating or coating systems.
As part of material selection, epoxy resins are often assessed together with other engineering plastics in order to weigh up functional, economic and processing-related aspects.
Distinction from other resin systems
Epoxy resins belong to the reactive synthetic resins and are often assessed in direct comparison with polyester, vinyl ester and phenolic resins. Each system has specific property profiles that determine its field of application.
Epoxy resins and polyester resins
Epoxy resins offer higher mechanical strength, better adhesion and lower shrinkage during curing. Polyester resins are more cost-effective and are used primarily where lower requirements are placed on strength and dimensional accuracy.
Epoxy resins and vinyl ester resins
Vinyl ester resins lie between polyester and epoxy resins in terms of strength and chemical resistance. Epoxy resins generally show higher adhesion and better long-term stability.
Epoxy resins and phenolic resins
Phenolic resins are suitable for high temperature and fire protection requirements. Epoxy resins, by contrast, offer better mechanical properties and greater processing versatility.
The choice of the suitable resin system is often made in direct comparison within the group of engineering plastics, taking into account mechanical, thermal and economic requirements.
Frequently asked questions about epoxy resins
What are epoxy resins?
Epoxy resins are reactive, thermosetting synthetic resins that cure through the chemical reaction of resin and hardener. After curing, they form a dimensionally stable, high-strength polymer network.
What are epoxy resins used for in industry?
Epoxy resins are used in mechanical and plant engineering, in electrical engineering, in mould making and in chemical apparatus engineering. Typical applications are coatings, potting compounds, bonds and dimensionally stable components.
What properties characterise epoxy resins?
Epoxy resins offer high mechanical strength, very good adhesion to different substrates, low shrinkage during curing and pronounced chemical resistance.
How does the curing of epoxy resins take place?
Curing takes place by mixing resin and hardener in the specified ratio. Depending on the system, the material cures at room temperature or with the application of heat.
How do epoxy resins differ from other resin systems?
Compared with polyester or vinyl ester resins, epoxy resins offer higher adhesion, lower shrinkage and very good long-term stability. Classification is often made by comparison within the group of engineering plastics.
What should be considered when selecting an epoxy resin system?
Essential criteria are mechanical load, temperature requirements, chemical influences and the processing-related framework conditions such as pot life and curing.