FlatFiber: Pioneering Polymer Reinforcement through State-of-the-art Technology

TAGS:  Automotive     Cost Efficiency    

This is a sponsored article by Nittobo.

For years, the use of flat fibers has played a pivotal role in strengthening plastics, elevating their resilience and longevity. Now, introducing FlatFibers, an innovative progression from Nittobo. In contrast to traditional alternatives, these fibers feature an elliptical cross-section, representing the forefront of FlatFiber technology. Their distinctive shape provides:

• better tensile strength,
• minimal warpage, and
• sleek surface finishing

By overcoming the constraints associated with conventional fibers, particularly polyamides, FlatFibers usher in a new era of plastic reinforcement.

Nittobo's breakthrough in FlatFiber technology marks a revolutionary departure from conventional, circular-profiled fibers. The game-changing element is its unique oval cross-section. Unlike traditional fibers, FlatFiber not only addresses warpage issues but also preserves the intrinsic strength of the fiber.

Furthermore, its ability to seamlessly integrate with polyamides guarantees flawless surface quality and the absence of imperfections commonly associated with regular fibers. The outcome? An exceptional composite material that harmonizes durability and aesthetics, enabling industries to enhance their product offerings.

In this article, we will examine the standout characteristics and potential uses of Nittobo's FlatFibers, which surpass the capabilities of traditional fibers and represent the future of reinforced plastics.

Contrasting FlatFiber with Traditional Fibers: An Overview of Benefits

Advanced performance of FlatFiber

Nittobo's FlatFiber represents a breakthrough in polymer reinforcement, distinguished by its innovative design and exceptional qualities. Analyzing the presented data, we can identify its unmatched attributes when compared to traditional fibers.

  
A Comparison Between Conventional Fibers (L) and Nittobo’s FlatFibers (R)

Improved dispersion and uniformity

Traditional fibers frequently cluster, resulting in uneven distribution. In contrast, FlatFiber, with its distinctive 1:4 aspect ratio and fiber dimensions of 7 x 28 μm, guarantees optimal dispersion. This uniform distribution maintains consistent strength throughout the material, effectively eliminating weak points.

Check out the physical properties of Nittobo’s FlatFibers and conventional fibers that are compared in the table below:

Property Name/Conditions		Unit	Method	Conventional Fiber Chopped Strand			Flat Glass Fiber Chopped Strand
Shape and flat ratio		-	-	-			Ratio 4 (1:4) FlatFiber
Fiber diameter		μm	-	11			7 x 28
Processing temperature		°C	-	235	250	265	235	250	265
Flexural strength	Molding direction	MPa	ISO	141	161	140	171	204	174
	Transverse direction			106	109	108	148	174	157
Flexural modulus	Molding direction	GPa		6.1	7.6	6	7.3	9.3	7.3
	Transverse direction			4.9	4.9	4.7	6.5	8.1	7.1
Charpy impact (notched)	Molding direction	kJ/m2		15	17	14	19	24	23
	Transverse direction			15	15	17	19	25	24

Physical Properties of Nittobo’s FlatFibers Compared to Conventional Fibers

Minimized warpage and shrinkage

Warpage and shrinkage pose considerable challenges in polymer reinforcement. Notably, FlatFiber operates effectively within the processing temperature range of 235 °C to 265 °C, like conventional fibers. However, its optimized design enables a notable reduction in both shrinkage and warpage.

Glass Flakes and Mica Fillers Reduce Warpage at the Cost of the Physical Properties of the Composite; Nittobo FlatFibers Reduce Warpage without Sacrificing Physical Properties
Traditionally, fillers in the form of powders or flakes have been employed to reduce warpage in composites, often at the cost of compromising their structural integrity. Common fillers such as mica and glass flakes provide only modest reinforcement owing to their non-fibrous composition. In contrast, FlatFibers not only alleviate warpage but also augment the reinforcing properties of conventional fibers.

Improved surface quality

The surface quality of a product serves as a visible marker of its overall quality. FlatFiber provides products with a superior and smoother surface finish, a critical factor in industries that prioritize aesthetics. For instance, the surface roughness of polyamide 6 reinforced with 50% FlatFiber is on par with that of polyamide 6 reinforced with 30% traditional fibers.

Enhanced impact resistance

The durability of polymer products significantly affects their longevity. In assessments of Charpy impact tests, conducted at various temperatures and in both molding and transverse directions, FlatFiber consistently demonstrates superior performance compared to its conventional counterpart. Specifically, at a processing temperature of 250 °C, FlatFiber exhibits an impact resistance of 24 kJ/m² (in the molding direction) and 25 kJ/m² (in the transverse direction), surpassing the 17 kJ/m² and 15 kJ/m² achieved by conventional fibers.

To substantiate this assertion, Nittobo's FlatFiber 4 underwent testing in two orientations, 0°, and 90°, and was compared to conventional fibers. A mold was created using an injection molding machine (SUMITOMO 75MT) at injection temperatures of 235 °C, 250 °C, and 265 °C. Mold temperature and Charpy impact measurements were recorded for both materials and are depicted in the bar graph below.

Anisotropy of Physical Property

Depending upon Temperature

Anisotropy of Physical Property by Direct Injection; Physical Property Depending on Temperature

Exceptional flexural strength and modulus

Strength and rigidity represent vital performance criteria for reinforced polymers. At an operating temperature of 250 °C, FlatFiber excels with a remarkable flexural strength of 204 MPa in the molding direction and 174 MPa in the transverse direction. In comparison, conventional fibers deliver 161 MPa and 109 MPa, respectively.

Furthermore, when it comes to the flexural modulus, FlatFiber stands out with impressive values of 9.3 GPa in the molding direction and 8.1 GPa in the transverse direction, surpassing the conventional fiber's 7.6 GPa and 4.9 GPa. These results unequivocally establish its superiority. These claims were substantiated through experimentation involving a 100 mm x 100 mm mold created through the injection molding process, utilizing a resin with a 60/40 weight ratio.

	Flexural Modulus (GPa)	Flexural Strength (MPa)

Anisotropy of Physical Property by Direct Injection; Physical Property Depending on Temperature

Achieving cost efficiency with FlatFiber technology

Nittobo's FlatFibers offer a significant advantage when it comes to cost optimization. Thanks to their extended retention of residual fibers compared to traditional fibers, they maintain exceptional strength even when recycled in compounding machines. This, in turn, enables compounders to achieve a higher regrind material ratio, providing an ideal opportunity to reduce costs while upholding quality standards.

By harnessing FlatFiber technology, the transition from the more expensive polyamide 66 to the cost-effective polyamide 6 is made possible, all while maintaining superior performance. This strategic shift not only lowers material expenses but also positions FlatFiber-reinforced polyamide 6 as a competitive alternative to premium polymers like PEEK and PEI, offering a combination of quality and cost-efficiency.

Nittobo’s FlatFiber Technology for Automobiles

In the realm of automotive engineering, there is a growing trend toward utilizing unconventional materials to replace traditional metals with lightweight alternatives. One particularly promising combination involves the integration of metals with plastics, particularly those reinforced with fibers.

Carbon Fiber Reinforced Plastics (CFRP) represent a potential replacement for metals due to their impressive strength-to-weight ratio. However, CFRP cannot be seamlessly combined with metal due to the risk of a significant problem - stray current corrosion, which is a result of the conductive properties of metal. On the contrary, Glass Fiber Reinforced Plastics (GFRP) are made from non-conductive materials, making them immune to stray current corrosion when combined with metals.

The union of metals and fiber-reinforced plastics, however, is not without its challenges. The most critical issue encountered is the delamination of the interface between the metal and plastics, stemming from the shear stress caused by differences in the Coefficient of Linear Thermal Expansion (CLTE).

Particularly, the CLTE in the transverse direction is substantially lower, leading to the potential occurrence of significant shear stress. FlatFiber reinforced plastics, which exhibit a smaller disparity in CLTE between the machine direction (MD) and transverse direction (TD), offer improved reliability and durability in addressing this concern.

Automotive parts using FlatFiber technology

FlatFiber reinforced plastics stand out due to their superior abrasion resistance compared to conventional materials. These are being contemplated for use in sliding applications such as Electric Power Steering (EPS) gears and more.

The exceptional performance of FlatFiber reinforced plastics hold a promise for a wide range of automotive applications. It extends to:

• engine components,
• front-end modules,
• under-the-hood parts,
• powertrain components like EPS gears, chassis elements, as well as interior and exterior components.

Furthermore, it finds utility in advanced driver-assistance systems (ADAS) such as sensors and electrical equipment like connectors and fuse boxes.

Other Applications

Consumer Electronics — In the realm of consumer electronics, FlatFiber offers an enticing blend of aesthetics and durability. Manufacturers incorporate this technology to enhance surface finishes and bolster impact resistance. The result is consumer gadgets that not only look great but also withstand the rigors of daily use.


Industrial Equipment — Nittobo's FlatFiber plays a pivotal role in the industrial landscape, ensuring that machinery components exhibit consistent strength and improved heat resistance. This is particularly vital for elements like gears and structural components, ultimately contributing to enhanced durability and optimal performance in industrial settings.


Building and Construction — The construction industry harnesses the structural integrity of FlatFiber. Its remarkable property of reduced shrinkage ensures that construction materials, such as panels and claddings, maintain their shape over time. This characteristic leads to the creation of sturdy and long-lasting infrastructure, serving the needs of both builders and occupants.


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