Cologne, September 3, 2020 – LANXESS is expanding the range of applications of extrusion blow molding: Continuous fiber-reinforced thermoplastic composites of the Tepex brand can also be integrated in the production process. In a feasibility study, experts at the specialty chemicals company demonstrated that components made of polyamide 6 can be manufactured with blow molding technology while receiving local reinforcement with Tepex at points subject to heavy loads. The investigations were performed on a state-of-the-art and close-to-production blow molding machine at the technical center of the High Performance Materials business unit (HPM) in Dormagen. “The components show an outstanding adhesion, which allows utilization of Tepex’s tremendous strength and rigidity,” explains Arthur Rieb, blow molding specialist at HPM.

The process can be used to locally boost the mechanical performance of blow-molded components, for instance in areas that are subject to high mechanical stress due to impact loads or high pressure. “In addition, it is suitable for the manufacture of blow-molded structural components, for example hollow sections for car body reinforcement. Extensive use of Tepex can be a key factor in reducing weight and material use because the basic wall thickness of the component can be decreased,” Rieb explains. Based purely on thermoplastic systems, the hollow parts are easy to recycle, thus making it easier to establish closed-loop material cycles.

Blow molding step determines cycle time

When manufacturing such hollow parts, a tubular parison is extrudedfirst of all. At the same time, a heated and plasticized Tepex insert isplaced in the blow molding tool. The parison is then inflated in thetool, thus also forming the Tepex section. This results in a componentwith a defined shape and local Tepex reinforcement. “The forming ofTepex is integrated in the blow molding process. Therefore, the resultis a one-step overall process with short, economically efficient cycletimes that are typical of blow molding,” adds Rieb.

Simplified process

Previously, manufacturing components of this kind involved thesubsequent welding of a two- or three-dimensional Tepex insert ontothe blow-molded hollow part. The overall process in the first case hastwo stages, while that in the second case has three due to thepreceding Tepex forming. “Therefore, our process makes thingsmuch simpler,” says Tilmann Sontag, expert in lightweight design atHPM’s Tepex Automotive Group. “In addition, the fabricreinforcement makes the plasticized Tepex material much easier tohandle than tapes that are unidirectionally reinforced with continuousfibers. This enables a stable and safe production process.”

Fully consolidated material bond

The continuous fibers in Tepex are fully pre-impregnated with plastic.Consequently, the pressure during blow molding is sufficient toconsolidate the material so that no air pockets are formed. “The resultis a material bond with excellent adhesion between the blow moldingmaterial and Tepex. Even low blow molding pressures are enough toform Tepex into critical 3D geometries such as hemispheres with tightradii,” says Sontag.

Wide range of blow moldable polyamides

HPM has developed a wide product range of high-viscosity compounds based on polyamide 6 and 66 with and without glassfiber reinforcement. These materials can also be used for the new process/material combination. For instance, the range includes very soft, impact-resistant product variants such as the unreinforced polyamide 6 compounds Durethan BC700HTS DUSXBL and Durethan BC550Z DUSXBL. Materials of this kind are extremely suitable for Tepex-reinforced tanks or other hollow parts where the application also requires high impact resistance and flexibility, for example. By contrast, the glass fiber-reinforced product types tend to be the material of choice for lightweight structural components.

With Tepex, too, a wide range of product types are available for the process – for instance material variants that are reinforced with continuous-fiber fabrics or laminates made of glass, aramid, orcarbon fibers. The matrix of composites is also capable of variation. In addition to polyamide 6 or 66, for instance, it can also consist of polyolefins such as polypropylene or polyethylene.

HiAnt – comprehensive customer service

LANXESS HPM business unit has combined its expertise in material, application, procedural and technological development under the brand HiAnt so that it can support customers at all stages of component development. The service encompasses everything from concept design, material optimization and the calculation of component characteristics by means of simulation tools right through to processing, component testing and the start of series production.

More information about LANXESS products and developments, technologies and services for blow molding and Tepex can be found at blow-molding.lanxess.com and bond-laminates.com.