Excellent heat resistance, strength and stiffness
Polyamide Resin

Overview and Features
Leona Leona

What is LEONA™?

LEONA™ is Asahi Kasei's family of PA66 (polyamide 66, nylon 66) resins.

PA66 is short for polyamide 66—the chemical name—and also known as nylon 66 . PA66 is engineering plastic featuring excellent heat resistance and mechanical strength. PA 66 is crystalline thermoplastic resin. 

Asahi Kasei is responsible for every step in the manufacturing process for PA66 polymers in house, starting from intermediates such as acrylonitrile, adiponitrile, hexamethylenediamine, and adipic acid. 

We offer a wide range of product grades suitable for many different purposes spanning many industrial sectors—making us both Asia's No. 1 manufacturer* of PA66 resin and the No. 1 manufacturer in the Japanese market*, supplying PA66 resin primarily to Japanese automakers and meeting a broad spectrum of customer needs. 

*Source: Based on global market sales volume and Japanese market sales volume from Fuji Keizai's 2023 Engineering Plastics Market Outlook and Global Strategy.


Key Features of LEONA™

LEONA™ is Asahi Kasei's family of PA66 resins. These products are classified as engineering plastics featuring outstanding heat resistance and mechanical strength

Classification of plastics and positioning of polyamide resin LEONA™

LEONA™ PA66 resin is crystalline thermoplastic, exhibiting a good balance of several key properties, including the following. 

Heat resistance

LEONA™ PA66 resins have a high melting point (265°C) in general-purpose engineering plastics and boast excellent heat resistance. 

Comparison with non-crystalline resins
Comparison with non-crystalline resins
Comparison with crystalline resins (non-reinforced)
Comparison with crystalline resins (non-reinforced)

Mechanical properties 

LEONA™ PA66 resins feature excellent strength and rigidity. The high toughness and excellent impact resistance of these materials are valuable features. These properties are derived from the molecular structure of PA66 resins, which feature tightly interwoven polymer chains with hydrogen bonds acting between molecules; the water absorption of these materials allows them to exhibit water-absorption-induced plasticity (with water molecules occupying amorphous sites). 

These properties make LEONA™ materials an effective alternative to metals.

Hydrogen Bonding and Coordination of Water Molecules in Polyamide 66 Resin
Hydrogen Bonding and Coordination of Water Molecules in Polyamide 66 Resin

Electrical insulation

LEONA™ PA66 resins feature excellent electrical insulation and tracking resistance. These properties are derived from the absence of benzene rings in the molecular structure of PA66 resins, which are thus resistant to carbonization.  

Comparison of electrical properties (for 30% glass-fiber-reinforced material) 
Comparison of electrical properties (for 30% glass-fiber-reinforced material) 

Resistance to oil and organic solvents 

LEONA™ PA66 resins feature excellent resistance to non-acid chemicals, organic solvents, lubricant oils, and similar substances. 

Chemical resistance of polyamide 66 resin LEONA™
Chemical resistance of LEONA™ resins (Source: Based on Asahi Kasei data, selected by chemical-resistance performance) 

Optional fillers for strength reinforcement

LEONA™ PA66 resins has high intermolecular cohesion and do not become brittle even when compounded with fillers.

The cohesion is defined as the cohesive energy density which is the cohesive energy divided by the molar volume. A comparison among polymers shows that the cohesive energy density of polyamide is much higher than that of other polymers (see figure).

Plastics are often compounded with glass fiber (GF), mineral fillers, and other additives to improve material strength, etc. However, large amounts of such additives can cause brittleness and a drop in strength and impact resistance. Therefore, there is a maximum limit to the amount of fillers added to plastics, and the limit varies depending on the type of plastic.

As mentioned above, polyamide has a high cohesive energy density, so it does not become brittle even when reinforced with a high filler content and can be reinforced with a larger amount of fillers to enhance various performance characteristics.

Cohesive energy density of each polymer (non-reinforced) (Created from Yoshifumi Araki (2018) "Industrial Materials" Nikkan Kogyo Shimbun)
Cohesive energy density of each polymer (non-reinforced) (Created from Yoshifumi Araki (2018) "Industrial Materials" Nikkan Kogyo Shimbun)

Reasons for choosing LEONA™


Fully in-house production—from raw ingredients to finished products—ensures stable supply 

Asahi Kasei is the only manufacturer in Asia producing PA66 resins entirely in-house, from intermediates to finished products. Indeed, we are among a handful of firms worldwide producing our own adiponitrile, from which we make hexamethylenediamine; we also produce adipic acid from cyclohexanol made by our own proprietary method (the cyclohexane method). From these intermediates, we make LEONA™ PA66 resins. Our fully in-house production process minimizes external disruptions to reduce supply instability. 

Production flow from raw materials to resin for LEONA™ polyamide resin
Production flow from raw materials to resin for polyamide 66 resin LEONA™

As Japan's No. 1 manufacturer of PA66 resins,
we offer an extensive lineup of material grades  

As Asia's No. 1 manufacturer* of PA66 resins and the No. 1 manufacturer in the Japanese market*—supplying resins primarily to Japanese automakers—Asahi Kasei leverages decades of experience to develop a wide range of material grades for the automotive industry and many other industrial sectors for many different purposes. Our extensive lineup of product grades serves a broad variety of customer needs. With 37% of the entire Japanese market, Asahi Kasei is Japan's No. 1 supplier*

*Source: Based on global market sales volume and Japanese market sales volume from Fuji Keizai's 2023 Engineering Plastics Market Outlook and Global Strategy.


Technical support

With offices in many countries around the world, Asahi Kasei supports our customers on a global basis.
Moreover, our “resin CAE technology” service—Asahi Kasei's in-house design-simulation expertise—is available to support customers in the product design and development stages. 

→ Click here for details on Asahi Kasei's technical support 



leona automotive leona E&E
LEONA™ products have been selected as materials for a vast array of automotive components by automotive OEMs around the world. The excellent heat resistance and mechanical properties of LEONA™ resins have led to these materials being adopted for products including: cylinder head covers to prevent spattering of engine oil; brackets and mounting components used to install vibration-reduction devices for engine units; guides for engine timing chains and cases to prevent oil spattering; oil pumps for engine brakes and other vehicle components; cooling pumps and pipes for batteries and other vehicle subsystems; bases and retention brackets for door mirrors; and smart-key housings. In recent years, Asahi Kasei has supported the transition to electric vehicles by stepping up proposals for resin products to serve as end plates for lithium-ion battery modules and components in various types of thermal-management systems.
Electrical and electronic
The excellent tracking resistance of LEONA™ resins, as well as their suitability for laser marking and related processes, has earned these products an extensive track record of adoption as materials for a variety of components, including connectors, magnetic switches, motor end caps, and solar-cell connector nuts. Asahi Kasei also offers a variety of materials for smartphone cases and other components of advanced communication systems.
Applications spanning a wide range of uses and objectives 
The fatigue resistance, attractive appearance, and other excellent properties of LEONA™ resins have led to these materials being chosen for a broad spectrum of products, including tanks for warm water washing toilet seats, water meter cases, home-improvement hardware such as crescents for installing windows and sliding doors, and industrial tools such as solenoid valves and decelerators. We also offer in-house expertise in resin CAE technology to help design resin replacements for metallic components.

Grade Proposal

Asahi Kasei is proud to offer an extensive lineup of LEONA™ polyamide resin grades featuring a variety of polyamide resins blended with fillers and other additives.

For the standard PA66 series, we offer standard, heat resistant, glass-fiber (GF) reinforced, low warpage/low wear, impact resistant, high viscosity/fatigue resistant, sliding, and Flame retardance grades.

Beyond the PA66 family, we also offer grades based on PA66/6I—a compound blended with semi-aromatic polyamide 6I—and grades based on 66+6I polymer alloys, as well as grades based on low-water-absorption PA612 and grades based on PA610, which features low water absorption and is derived from plant matter.

As a newly developed material, flame retardants that do not contain halogens or red phosphorus are used, and the PA66+6I flame retardant grade LEONA™ SN series, which has excellent appearance and high strength when absorbing water, etc., is used for unpainted exteriors. PA6+6I grade LEONA™ SU series with excellent moldability and strength is available. We are also developing extrusion grades that can be applied to EV cooling pipes, pipes, and tubes.


Product Data/Tips for Use *Handling Precautions

Precautions for handling LEONA™

The content of this document is based on materials, information, and data available at this time, and may be revised based on new findings. Please note that these are provided as information and are not guaranteed. Therefore, when using our products, please take full consideration of the usage environment, design, etc., and use them at your own risk after judging that there is no problem with the product.

1. Handling Precautions

The following items are the main points of care for handling the LEONA™ itself supplied to your company. Please use it for safe handling of LEONA™.
A separate material safety data sheet has been prepared for handling precautions for LEONA™. Please contact us and we will send it to you. We request that your company investigate the safety of additives, etc. that your company uses other than LEONA™.

(1) Precautions for safety and health
Care should be taken to avoid contact with the eyes, skin, and inhalation of gases generated when LEONA™ dries or melts. Also, avoid direct contact with hot resin. It is recommended to install a local exhaust system and wear protective equipment (protective glasses, protective gloves, etc.) for each work such as drying and melting.

(2) Precautions regarding combustion
LEONA™ is flammable and should be handled and stored away from heat and sources of ignition. If it burns, it may generate toxic or suffocating gas. Extinguishing can be done with water, foam or dry chemical.

(3) Notes on disposal
LEONA™ can be disposed of by incineration or landfill, but when disposing of it, please entrust it to an authorized industrial waste disposal company or local public body in accordance with the "Waste Disposal and Public Cleansing Law". Also, when incinerating by yourself, please use incineration equipment and follow laws and ordinances such as the Air Pollution Control Law. When incinerated, toxic gases such as carbon monoxide and suffocating gases may be generated.

(4) Notes on storage
Absolutely avoid resin contamination and moisture absorption. Store in a cool, dry place and start molding immediately after opening. Do not pierce the product bag or let it get wet. Also, do not return spilled resin to the product bag. It is a combustible material (synthetic resins) designated by the Fire Service Act, and should be handled in accordance with municipal ordinances. (Fire extinguishing facility, indoor storage facility, etc.)

(5) Notes on molding
The optimum resin temperature for molding LEONA™ is 270 to 310°C. If it is lower than this, there is a risk of local degradation of physical properties due to non-uniform plasticization. On the other hand, if it is higher than this, there is a risk of gas generation due to decomposition or poor appearance such as silver. However, there are some exceptions such as FR200 and FR370, so be sure to refer to individual catalogs before molding. Also, do not allow LEONA™ to stay in the molding machine cylinder for a long time in a molten state. Doing so may cause the resin to decompose, resulting in discoloration or deterioration of the molded product. In that case, once replace the inside of the cylinder with polyethylene, etc., and then perform molding.

2. Usage

  • ・Do not use LEONA™ for embedding in the body or for direct contact with bodily fluids or infusion fluids.
  • ・When using for other medical purposes, please be sure to contact us in advance.
  • ・Do not use for applications that come into contact with food, such as food packaging containers.
  • ・Please contact us for details.
  • ・If you are considering using our products for other special purposes, please contact us and we will discuss them individually.
  • ・Please contact our person in charge for details on the compatibility of each grade with the Electrical Appliance and Material Control Law, UL standards, CSA standards, etc.


Please be aware of industrial property rights when using this product.

Please contact us to ask any questions, discuss any concerns, and request samples.

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