Flexfill TPE 96A

Flexfill TPE (thermoplastic elastomer) is a highly flexible 3D printing filament, unique in its properties compared to TPU materials. It is a high quality 3D printing material with very good printing, surface and mechanical properties. It has two types of hardness, 90A and 96A, and constitutes a great bet of Fillamentum to expand the possibilities in the market of flexible filaments.

Unlike the Flexfill TPU (thermoplastic polyurethane), which has a glossy finish, the TPE has a matt and soft finish, which is pleasing to the touch and not sticky, which helps to achieve a perfect finish, dirt resistant and washable.

Image 1: Piece printed with Flexfill TPE 96A Light Gray. Source: Fillamentum

The first difference that exists compared to other flexible filaments is their chemical resistance, which achieves a high resistance against a wide range of substances such as water, acids, alkalis or alcohols even at high temperatures. In addition, it is abrasion resistant, has a low degree of moisture absorption and very low gas permeability.

It has a good quality thanks to maintaining its dimensional stability with a high adhesion between layers, which gives it a great resistance to tearing and a low chain that gives it that matte finish.

It is a recyclable filament, which practically does not give off odors and is free of Bisphenol A (BPA). It contains no restricted substances, and is safe for food contact applications (although it is not FDA certified, as it does have TPE 90A), with the skin or with the mucous membrane. It is also a material that can be used for the production of electrical and electronic equipment. To ensure that the final product meets the requirements, it must be tested in accordance with the relevant regulations. These regulations set out the test conditions, which are based on the intended use of the printed object.

In addition, the base polymer in the case of TPE are polyolefins, instead of TPU polyurethane. This involves different properties, which are summarized below in the comparison table between the different materials with some flexibility that exist.

	TPE 70A  Filaflex	TPE 82A  Filaflex	TPE 90A  Flexfill	TPU 92A  Flexfill	TPU 93A Smartfil	TPE 96A  Flexfill	TPU 98A  Flexfill
Tensile strength (MPa)	32	45	5	49	40	5	53.7
Elongation at break	900 %	600 %	250 %	-	-	150 %	318 %
Absorción  humedad					-
Chemical resistance	Solvent Acetone Fuel	Solvent Acetone Fuel	Water Acid Alcohol Alkali	Polish Oil	Polish Oil Solvent	Water Acid Alcohol Alkali	Polish Oil
Contact food and skin	Not recommend.	Not recommend.	Certificate	Not recommend.	Not recommend.	Reliable	Not recommend.
Permeability gases					-

Table 1: Comparison of properties of the flexible filament range

On a theoretical level, it is determined that the TPU (Thermoplastic Polyurethane) is obtained thanks to the modification of a TPE (Thermoplastic Elastomer), resulting in a material with less flexibility. For practical purposes, however, two types of materials are considered as totally independent today. Until now, the differentiation rule was established, which evidenced that a TPE was always flexible, and a semi-flexible or rigid TPU. Today, this differentiation has become meaningless due to the great development of variants in TPE and TPU materials, and very flexible TPE filaments (with Shore hardness 70A, 82A and 90A) and semi-flexible as 96A are found.

Therefore, when defining what material is needed for an application with a material with a certain flexibility, it will be necessary to analyze the sum of two totally different vectors from which will result the correct choice or resulting vector. On the one hand, the hardness of the material itself (normally compared on a Shore A scale) and, on the other, the type of material (TPE or TPU), with differences in its intrinsic properties.

The printing of very flexible materials is essential to be done with a direct extrusion system, although in some cases it could be with a bowden system if the filament was 2.85 mm. Instead, filaments such as TPU 92A, 93A and 98A or TPE 96A can be printed on any extrusion system (bowden or direct) and on any diameter (1.75 mm or 2.85 mm).

Image 2: Pieces printed with Flexfill TPE 96A Light Gray, Sky Blue and Signal Red. Source: Fillamentum

After several months of intensive testing, Fillamentum has determined that both the TPE 90A and the TPE 96A will only be manufactured in 1.75 mm diameter to ensure maximum printing success (both with direct extruder and bowden), since the bowden extruder tests in 2.85 mm did not achieve completely successful results due to the intrinsic properties of the material, as there were non-reversible deformations.