Biomass filler, good mechanical and sliding properties
CNF Nanocomposite Materials CNF-reinforced thermoplastics

Overview and Features
CNF-reinforced thermoplastic resins CNF-reinforced thermoplastic resins

What is CNF-reinforced thermoplastics?

CNF-reinforced thermoplastics are composite products that combine Asahi Kasei’s highly heat-resistant cellulose nanofibers (CNFs) with various types of engineering plastics—such as polyamide (PA) and polyacetal (POM)—to yield lightweight materials boasting excellent reworkability*(*excellent reworkability: the ability to be reworked or regrinded by using sprues, runners and so on, with good retention of mechanical properties)

To date, Asahi Kasei has developed two families of CNF-reinforced thermoplastics: PA/CNF composite materials combining highly heat-resistant CNFs with various PA, and POM/CNF composite materials combining highly heat-resistant CNFs with POM. These materials are ideal for fabricating sliding components, where the unique properties of CNF composites allow components to be made with smaller sizes, thinner walls, and lighter weights.

*As defined by UL 746A, regrind refers to a noncontaminated product or scrap from molding, such as sprues or runners that have been reclaimed by shredding, repalletizing, and granulating for use in-house.

CNF-reinforced thermoplastics gear

Key features and technologies of Asahi Kasei’s CNFs

The CNFs developed by Asahi Kasei are biomass fibers containing cotton-linter constituents that are miniaturized via sophisticated techniques to sizes as small as nanometer scales.

Key Features

High heat resistance / Biomass fiber / Excellent reworkability / Low specific gravity / Low friction coefficient and low abrasion / High elasticity / Low linear expansion coefficient / High gas-barrier strength 

As indicated by the figure below, Asahi Kasei’s CNFs can reinforce resins by serving as biomass fillers with higher heat resistance than conventional CNFs. These materials boast low specific gravity (1.5 g/㎤).
 Other superior properties of these materials include high elasticity, a low linear expansion coefficient, a low friction coefficient, low abrasion, and high gas-barrier strength.

旭化成のCNF原料の耐熱性(従来品との比較)
Heat resistance of CNFs (Asahi Kasei’s CNFs vs. conventional CNFs)

Technologies for nanodispersing CNFs

Because CNFs are extremely hydrophilic, they tend to clump together when blended into resins. This has often prevented CNFs from achieving their full potential as reinforcing additives.

Asahi Kasei is developing technologies for nanodispersing CNFs in a variety of resins, ensuring a single, consistent manufacturing process from CNF production to CNF composites.

CNF composite materials

01

PA/CNF composite materials

PA/CNF composite materials combine Asahi Kasei’s heat-resistant CNFs with various types of PA. Key features of these materials include good sliding properties, good rigidity at both low and high temperatures, low specific gravity, and excellent reworkability compared to non-reinforced PA or PA/GF. PA/CNF composites are well-suited for use in fabricating sliding components with smaller sizes, thinner walls, and lighter weights.

Feature 1:  High heat resistance and mechanical properties retention after using regrind
Asahi Kasei’s heat-resistant CNFs exhibit relatively low thermal degradation, fiber rupture and high mechanical properties retention after using regrind. Compared with conventional CNF, injection-molded products are less prone to coloration and have a superior appearance during molding (see figure below).

heat resistance and material recyclability

CNF regrind properties Tensile modulus retention

Feature 2: High rigidity and good dimensional stability
Asahi Kasei’s PA/CNF composite materials exhibits high specific flexural elasticity, high flexural modulus in the normal temperature range of 23°C to high temperature 80°C, and low coefficient of linear expansion compared to non-reinforced polyamide and glass fiber (GF) reinforced polyamide.  

High stiffness and dimensional stability

Feature 3: Good sliding properties
Asahi Kasei’s PA/CNF composite materials have low friction coefficients, exhibit low abrasion, and are less likely to abrade friction partners (such as metals).
Because CNF nanocomposite materials are less likely than glass-fiber-reinforced materials to abrade the metal surfaces over which they slide, these materials eliminate the need to treat those metal surfaces with special surface-processing steps.

Sliding properties

Biomass plastic PA610/CNF composite
PA610 is a biomass engineering plastic containing polymers that are 60% plant-derived. Blending PA610 with 10% CNF reinforcers yields a composite with 65% plant-derived content. By using PA610 as the base polymer, the biomass raw material ratio is further increased, while still possessing the excellent reworkability, rigidity, dimensional stability, and sliding properties of PA/CNF as explained above.

For more information on the plant-derived polyamide (PA) 610 LEONA™ BG series of products, click here.

 

02

POM/CNF composite materials

POM/CNF composite materials combine Asahi Kasei’s highly heat-resistant CNFs with POM. Key features of these materials include good sliding properties, good rigidity at high temperature, minimal shrinkage, a low coefficient of thermal expansion, and good creep properties at high temperature as compared to general POM. POM/CNF composite materials are well-suited for use in fabricating sliding components with smaller sizes, thinner walls, and lighter weights.

Feature 1: Superior sliding properties against surfaces made of metal or of the same material
POM has good mechanical properties, and exhibits superior friction and abrasion characteristics, making it a popular choice for fabricating gears and other sliding components. Also, CNFs are less likely than glass-fiber-reinforced materials to abrade metal partner surfaces in sliding components. Thus, POM/CNF composite materials combine good mechanical properties with improved sliding behavior.
Moreover, even when used as sliding components against surfaces of the same material—a situation that is commonly understood to yield poor performance—POM/CNF components have low friction and low abrasion and operate silently, as indicated in the figure below. For this reason, choosing POM/CNF materials not only downsizes product, but also may allow multiple materials to be replaced by a single material.

Characteristics of CNF reinforced POM resin

Excellent sliding properties (against metal and between the same materials)

Feature 2: Molding processing characteristics (irregular shape extrusion molding)
CNF-reinforced POM resin obtained using our unique CNF dispersion technology enables profile extrusion molding of POM, which was previously difficult.
Conventionally, POM was considered to be a resin that was not suitable for profile extrusion molding, but our CNF-reinforced POM resin exhibits unique viscosity characteristics and molding shrinkage suppression capabilities, making it suitable for complex profile extrusion molding.
The molded products have a good appearance, excellent dimensional accuracy, and excellent sliding properties, making them suitable for use in sliding parts such as rails.

CNF強化POM樹脂 異形押出品

Special shaped extrusion products (molded by Excel Tokai Co., Ltd.)

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

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sustainability
How Asahi Kasei’s engineering plastics help to achieve carbon neutrality.
 Asahi Kasei Group is adopting policies to accelerate progress toward carbon neutrality.
We introduce our approaches to realize circular economy through our engineering plastics.
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