current information about innovative solutions.

Low-Emission and Heat-Resistant

New Developments. A low-emission polypropylene compound and a masterbatch specially developed for fiber-reinforced structural components meet the current requirements of the automotive industry. The new developments help reduce odor in auto interiors and produce engine components that can withstand even the highest temperatures.

 

The requirements of the automotive industry continue to increase and higher priority is being given to ecology and economy in this sector. There is a growing demand for products to be designed quickly and flexibly to meet the needs and wishes of the OEMs. This challenges the plastics processing industry to achieve the required mechanical properties with lightweight components, while satisfying high quality criteria at the same time. As a result, masterbatch and compound producers are faced with new tasks.

 

For example, the polypropylene (PP) material previously used in air ducting significantly exceeds the new emission limits for vehicle interiors. To comply with the requirements for an improved vehicle interior climate, the Grafe Group based in Blankenhain, Germany, has developed a low-emission PP compound for extrusion blow molding in collaboration with a major German OEM. In this project, it was necessary to take into account the comprehensive additional requirements and standards of the OEM and process technology for air ducts and channeling used in auto manufacture.

 

Emission and Odor

Today, plastics account for about one-fifth of the materials used in cars (Fig.1). The wide variety of applications demonstrates that these materials can meet the diverse requirements thanks to their high flexibility, light weight, and ease of processing. Polypropylene (PP), in particular, is a material with a steadily rising share in the auto market.

 

Thermoplastic components in motor vehicles must be tailored individually and specifically to the requirements of the OEM. Here, the masterbatch and compounding industry can have a crucial influence on subsequent product quality, including the emission and odor behavior of the material. In all areas of life, humans are exposed to odors and emissions of anthropogenic origin. Reaction to odors has increased in the course of time. Some we find pleasant, while others are a nuisance to our life. Often, concerns about possible harmful health effects are an important consideration.

 

Against this background, a tier 1 supplier tailored PP formulations for vehicle air ducts and channeling to the comprehensive requirements of the OEM in several development stages. The challenge in developing these compounds was to strike the right balance between emissions and stability.

 

When plastic components are used in auto interiors, volatile constituents can sometimes be released. The emission behavior of a material is influenced by several factors, such as its properties and history, e.g. processing parameters. Other factors include the air exchange rate and atmospheric humidity, as well as other particles in the room, such as dust. To make emission behavior measurable and comparable, the OEMs specify guidelines and standards. The emission values and odor ratings of components and assemblies in a motor vehicle are determined under varying climatic conditions. Important standard tests in this area are VW 50180 and VDA276-1. In these tests, the organic emissions of vehicle interior components are measured in a test chamber. VDA 270 describes tests to determine the odor behavior of materials at different temperatures.

 

Low-emission Material

This newly developed low-emission PP compound (Fig.2) for blow molding and injection molding applications in motor vehicles provides the industry with a low-emission PP grade for automotive interiors. Its heat aging stability as per VW 44045 was verified in a number of tests. The process-optimized formulation generates additional optimization potentials for processability, cycle time, and odors. With the aid of suitable additive packages developed in-house and the use of specially selected carbon black grades, the PP compound meets the specific application requirements for heat aging resistance, low emissions, neutral odor, and process reliability. The requirements and standards of the OEMs are satisfactorily fulfilled.

 

In comparison with the PP materials previously used for air ducting, which no longer comply with the new emission limits for vehicle interiors, the newly developed, low-emission PP compound offers advantages such as

  • low emission: meets OEM specifications and the efficiency and cost-effectiveness requirements of modern serial production processes,
  • odor-optimized: material has a neutral odor after processing,
  • process-optimized: formulation of the PP compound permits better and gentler processing, lower emissions and faster cycles, and
  • customer-specific: individually tailored to the technological and commercial requirements of the customer.

 

Further Developments

Besides the low-emission PP compound, other innovative products have been developed for automotive production. One example is HP Masterbatch Composite. This product offers excellent long-term thermal stability, wide design freedom and a strong fiber/polymer bond for fiber-reinforced structural components used in interior, exterior and powertrain applications. One specification that had to be met here was an efficient masterbatch addition rate of less than 3%. Even very high temperature stresses in the engine compartment cannot cause significant damage to the structural components produced with this masterbatch over the lifetime of the vehicle.

 

Kunststoffe international (03/2012)

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