PEKK (polyetherketoneketone) is becoming increasingly important as a high-performance material in industrial surface technology. As an alternative to PEEK in particular, the polymer offers an impressive combination of mechanical robustness, chemical resistance and thermal resilience – while at the same time significantly reducing the processing temperature. Buser Oberflächentechnik AG uses PEKK specifically to reliably coat components even when other processes reach their physical limits. Whether for aerospace, food technology or electronics – PEKK coatings open up new fields of application. 

PEKK vs PEEK – key advantages of the polymer at a glance 

As a high-performance representative of polyaryletherketones, PEKK offers a wide range of technical properties that are in no way inferior to those of PEEK – and in some areas are even superior. Especially in industrial coating, PEKK scores with clear advantages in processing, dimensional stability and chemical resistance.  

Gentler process temperatures and substrate protection 

A decisive advantage of PEKK over PEEK lies in the thermal load during the coating process. PEKK requires a process temperature that is around 70 °C lower than PEEK – a significant difference that is particularly important for temperature-sensitive substrates. This means that components can also be coated that would not be compatible with the heat exposure of conventional PEEK processing. The lower thermal load also reduces the risk of material stresses or structural changes in the component itself. 

Very low shrinkage stress for complex geometries 

Another advantage of PEKK is its significantly lower shrinkage stress compared to PEEK. While PEEK can develop stresses of up to 1.5% during cooling, this value is only around 0.005% for PEKK. This property is particularly important for coating complex geometries, thin-walled structures or functional components with tight tolerances. PEKK enables a stress-free, uniform layer without distortion – even with complex shapes. 

Mechanical & chemical performance values at top level 

PEKK offers high mechanical strength, with tensile strengths of up to 140 MPa and moduli of elasticity of over 4 GPa. In many cases, this puts it on a par with or even slightly above PEEK. Its chemical resistance is also excellent: PEKK remains structurally stable even after prolonged exposure to aggressive media such as toluene, MEK or steam and hardly loses any of its mechanical performance. 

Thermal stability, fire protection and electrical insulation 

With a continuous service temperature of 250-260 °C and a glass transition temperature of around 160 °C, PEKK is one of the most thermally resilient coating materials. In contrast to many other plastics, PEKK meets the UL 94 V-0 fire protection standard without additives and is also approved for applications in accordance with FAR 25.853 (e.g. aircraft interiors). 

The PEKK coating process at Buser Oberflächentechnik AG 

The technical advantages of PEKK only come into their own with a precisely coordinated coating process. We process PEKK using state-of-the-art powder coating technology – specifically optimized for demanding industries.  

Kepstan®-based powder coating: Process and parameters 

At Buser Oberflächentechnik, PEKK is used in the form of high-quality Kepstan® powder – an industrially proven PEKK polymer. The application is carried out as an electrostatic powder coating, in which the material is applied evenly to the component and then baked on. Due to the significantly lower curing temperatures compared to PEEK, the thermal load level remains low, which increases process reliability with sensitive substrates. At the same time, the process enables very precise control over layer thicknesses, which is particularly advantageous for functional surfaces. 

Quality assurance: coating thickness, absence of pores, adhesion 

Buser Oberflächentechnik AG places the highest value on consistent coating quality. Using state-of-the-art testing methods, the applied PEKK layers are checked for defined layer thicknesses, even distribution and complete absence of pores. Particular attention is paid to the adhesive strength: PEKK shows excellent adhesion to a wide variety of substrates. This results in functional, resilient and durable coatings – even for extreme conditions of use. 

Technical characteristics: PEKK vs PEEK in detail 

In direct comparison with PEEK, PEKK not only shows comparable material properties, but even superior ones in many areas. This makes the high-performance plastic particularly interesting for applications where mechanical stress, thermal stability and dimensional stability are crucial.  

Strength, rigidity and abrasion resistance 

PEKK impresses with its high mechanical strength and extremely robust surface behavior. The most important key figures at a glance: 

• Tensile strength: approx. 120-140 MPa (comparable to or higher than PEEK) 
• E-modulus: 3.6-4.4 GPa → high rigidity, dimensionally stable even under load 
• Compressive strength: up to 180 MPa 
• Abrasion & wear resistance: very high, ideal for moving components or surfaces subject to sliding 

These values make PEKK coatings a reliable solution for applications subject to high mechanical stress.  

Thermal limit values and long-term service temperature 

PEKK also withstands high temperatures over the long term and exhibits stable behavior over a wide range of applications: 

• Continuous service temperature: 250-260 °C 
• Glass transition temperature (Tg): approx. 160-165 °C 
• Melting point: around 340 °C (similar to PEEK, but can be processed with lower energy input) 
• Self-extinguishing: UL 94 V-0 (without additives), meets aviation standard FAR 25.853 

Dimensional stability and moisture absorption 

An often underestimated advantage of PEKK compared to other technical polymers is its excellent dimensional stability – even under changing environmental conditions. 

• Water absorption (24 h, 23 °C): < 0.1 % (PEEK: approx. 0.5 %) 
• Shrinkage stress on cooling: < 0.005 % (PEEK: up to 1.5 %) 

This means that components with a PEKK coating remain dimensionally stable, even under high humidity, temperature fluctuations or many years of use. This reduces maintenance costs, extends service life and improves functionality.  

Typical fields of application for PEKK coatings 

The outstanding properties of PEKK open up a wide range of applications. In many industries, PEKK successfully replaces metals, PVDF or other high-performance plastics and is particularly suitable where conventional materials reach their limits.  

Aerospace 

In the aerospace industry, every gram is crucial – and at the same time, the highest demands are placed on fire protection, temperature resistance and mechanical reliability. PEKK meets these requirements with ease: 

• Weight savings of up to 60% compared to aluminum 
• Complies with FST guidelines (Flame, Smoke, Toxicity) such as FAR 25.853 
• Temperature and dimensionally stable coating of structural parts, connecting elements or insulators 

Thanks to the excellent coating quality, PEKK coatings are even used on components used in space missions.  

Chemical, oil & gas industry 

Extremely corrosive media, high temperatures and continuous mechanical stress – PEKK is made for these environments. Typical areas of application: 

• Pump and valve components 
• Tank linings and process lines 
• Connecting elements that have to withstand long-term chemical exposure 

PEKK coatings retain their structural integrity and mechanical function even after prolonged exposure to aggressive chemicals such as toluene or MEK.  

Automotive & e-mobility 

The automotive industry is under pressure to innovate: lighter vehicles, higher voltages in e-drives, increasing demands on thermal and electrical insulation. PEKK offers answers: 

• High tracking resistance → ideal for HV components 
• Temperature-resistant up to over 250 °C 
• Abrasion-resistant, chemical-resistant protective coatings for motor compartments, sensors or connector housings  

Electronics & high-voltage insulation 

PEKK offers a perfect property profile for insulating coatings on printed circuit boards, busbars or electric motors: 

• High dielectric strength 
• Dimensionally stable coating for thin-walled or complex components 
• Resistant to moisture, leakage currents and thermal cycles 

Medical and food technology 

PEKK is not only physiologically safe, but also approved for direct food contact: 

• FDA & EU Regulation 10/2011 compliant 
• Sterilizable (autoclaving, irradiation) 
• Non-stick, easy to clean, resistant to cleaning agents and disinfectants 

PEKK is therefore also suitable for applications in laboratories, food processing or medical devices where hygiene and chemical exposure come together. 

Regulatory compliance & sustainability of PEKK polymers 

In addition to technical performance data, legal requirements and environmental aspects are becoming increasingly important when selecting suitable coating materials. PEKK meets the highest standards in this respect – both in terms of health protection as well as sustainability and regulatory safety. 

FDA & EU 10/2011 approval for food contact 

The PEKK used at Buser is approved for direct contact with food by both the US Food and Drug Administration (FDA) and in accordance with European Regulation (EU) No. 10/2011. It therefore offers a safe solution for applications in food processing, packaging and medical technology, where materials frequently come into contact with sensitive substances. 

Typical advantages in the food environment: 

• No migration of harmful substances 
• Non-stick surface – easy to clean 
• Resistant to cleaning agents and disinfectants 
• Sterilizable (e.g. by autoclave or gamma irradiation) 

REACH/RoHS, halogen-free and PFAS-free 

PEKK meets current environmental and safety requirements at EU level – it is also 

• REACH-compliant: free from SVHC (substances of very high concern) 
• RoHS-compliant: no use of banned heavy metals or flame retardants 
• Halogen-free & PFAS-free: no fluorine-containing additives or persistent compounds 

These properties make PEKK not only safe to process and use, but also future-proof in terms of regulatory developments. At the same time, the durability of the coating improves the ecological balance: fewer replacements, lower material consumption, reduced maintenance cycles. 

PEKK as a PVDF alternative 

In many industrial sectors, PVDF (polyvinylidene fluoride) has established itself as a resistant material for chemically aggressive environments. However, PVDF reaches its limits at higher temperatures, mechanical stress and electrical insulation. PEKK offers a future-oriented solution here – with comparable chemical resistance, but significantly improved performance in several key areas. 

Chemical resistance 

Both PVDF and PEKK are characterized by very good resistance to a wide range of chemicals – such as acids, bases, solvents and oils. However, PEKK offers additional advantages here: 

• High dimensional stability even after prolonged exposure to chemicals 

• No significant embrittlement with aggressive media (e.g. toluene, MEK) 

• Better retention of mechanical properties under chemical stress 

PEKK offers more reliable long-term performance than PVDF, particularly in safety-relevant applications such as pipeline construction, reactor environments or sealing systems. 

Temperature and wear behavior 

In contrast to PVDF, whose service temperature typically ends at approx. 120 °C, PEKK remains permanently stable up to 260 °C – without deformation or degradation: 

Property	PEKK	PVDF
Continuous service temperature	250–260 °C	approx. 120 °C
Melting point	approx. 340 °C	approx. 177 °C
Abrasion resistance	very high	medium
Mechanical strength	high	rather limited
Insulation behavior	excellent	good, but material-dependent

Especially for moving parts, friction-intensive applications or combined thermal and chemical loads, PEKK has the edge. 

Cost-benefit analysis 

While PVDF is currently cheaper to purchase, PEKK has a significantly longer service life and therefore reduces follow-up costs: 

• Fewer replacement cycles 
• Lower maintenance costs 
• Higher process reliability and functional stability 

In systems with long downtimes or safety-critical components, the investment in PEKK coatings can therefore quickly pay for itself. 

Conclusion & decision-making aid: When is PEKK the right choice? 

PEKK is more than just an alternative to PEEK – it is a strategic material choice for demanding applications where thermal, chemical and mechanical resilience are required in equal measure. Thanks to its gentle coating process, high dimensional stability and regulatory safety, PEKK is ideal for all industries in which conventional plastics or metals reach their limits. 

PEKK is particularly recommended if … 

• the component is temperature-sensitive and requires a low process temperature. 
• complex geometries or thin-walled structures require a stress-free coating. 
• mechanical stress, friction or abrasion must be permanently compensated. 
• chemical resistance at high temperatures and with aggressive media is crucial. 
• regulatory requirements such as FDA, EU or aviation approvals must be met. 
• a sustainable, halogen-free and PFAS-free material with a long service life is required. 

With PEKK, Buser Oberflächentechnik AG is expanding its portfolio with a high-performance polymer that opens up new applications and specifically improves existing solutions.