The car has become a second home for many people today, because they spend a lot of time on the road. However, because more emissions relative to the space are present in vehicle passenger compartments than is usual at the workstation in the office, the limit values for the concentration of organic substances in the air inside the car, such as solvents and formaldehyde, should be significantly below the values accepted in buildings.
Particularly for the gaskets that are used in passenger compartments of vehicles, where a clean, allergy-free room climate without odour irritation should prevail, Cologne-based Sonderhoff Chemicals ensures that its gasket products are free of volatile organic compounds (VOC) and substances that contain solvents.
When solvents or liquid fuels evaporate, VOCs in large quantities are dissipated into the ambient air. Less apparent is the distribution of various associated substances that are not firmly bound in the products. These substances can slowly dissipate into the air from the product surface and can be continuously resupplied to the surface from the interior of the product. For example, this applies for residual solvents and monomer components in plastics, auxiliary substances, such as softeners, anti-oxidation agents, additives, stabilizers, and catalysts – they are present in many paints, glues, and sealants. Due to their variety, VOCs cannot be assigned to a uniform health hazard. Their toxicity extends from non-hazardous, to impairment of immunity, to toxic. They can cause eye, ear, throat, and skin irritations or induce allergic effects. However, for most VOCs, to this point there is a lack of detailed and well-founded scientific findings relative to the effects on health. Consequently VOC burdens should be avoided or at least reduced to the extent possible.
Although occupational exposure limits (OELs) in accordance with the new German Hazardous Substance Ordinance (GefStoffV) apply for workplaces where hazardous substances are handled, these limits do not apply for vehicle passenger compartments, or for apartments and offices. The OEL is the temporally weighted average concentration of a substance, such as gas, vapour, or a suspended substance in the respiratory air at the workplace, at which acute or chronic health impairment on the part of employees is not expected. In 2007, the German Federal Environmental Agency (UBA) issued “Recommendations for indoor air”, which however to this point only have a “recommending” character.
Automobile manufacturers are increasingly demanding low emissions for the vehicle interior as well
Sonderhoff, as system supplier to a wide variety of industries, has been further developing low emission polyurethane-based foam gaskets for ten years, the results are the so-called low-emission gaskets. These gaskets are particularly demanded by customers in the automobile industry and by manufacturers of air filters for room air systems. For example, the low emission gaskets from Sonderhoff are used in vehicles for door modules, for interior door trim, window openers, speaker gaskets, for door/rear ventilation, and for leak-free seating of micro pollen filters in the air conditioner.
The topic of low emission also arrived in the automobile industry some time ago. Due to the specifications of the EC Commission to reduce CO2 emissions by 20% by the year 2020, now the automobile manufacturers are not only building lower-pollution engines. They are also placing increased focus on the plastics installed in the passenger compartment in their emissions considerations. Since 2004, Ford has been advertising the allergy-tested passenger compartment; as one of the first auto manufacturers with a special TÜV certificate. More than 100 materials were analyzed, e. g. all surfaces with which vehicle occupants can come into contact during the trip, such as steering wheel covers, belts, gear shift, and buttons. Also the air quality was precisely examined relative to concentration of organic substances, such as solvents and formaldehyde. For example, pollen filters for allergy-free cars must retain at least 98% of pollen to get the TÜV seal. But pollen is not the only substance that can cause problems for persons with allergies during a car trip. Dyes, plastics, solvents, or nickel can be found in many fabrics and trim elements and not infrequently are the triggers for respiratory difficulties or contact allergies. From the medical perspective, the stress potential through VOCs for the growing number of persons with allergies (more than 25% in Germany) is increasingly acknowledged.
Sonderhoff develops foam gaskets for the low emission requirements of the automobile manufacturers and their suppliers
In addition to Ford, also Daimler, BMW, and GM/Opel impose rigorous requirements on the plastics installed in the vehicle and are increasingly requiring low emission plastics with low VOC and FOG values. For example, in its test guideline DBL 5452, Daimler prescribes strict limit values for polyurethane-based foam-moulded soft-elastic foams. In the guideline the VOC limit value is specified at 100 µg, and the FOG limit value is specified at 250 µg per 1 gram of polyurethane. The Sonderhoff low emission foam gasket systems satisfy these limit values for soft-elastic open-pore polyurethane foams that are applied as sealing profiles with low pressure mixing and dosing systems from Sonderhoff in the process on the parts, recently certified by an accredited independent test institute.
The emission values are determined by independent institutions in accordance with the German standard VDA 278 (Standard of the German Association of the Automotive Industry: Thermal Desorption Analysis of Organic Emissions for the Characterization of Non-Metallic Materials for Automobiles Current Version, October 2011). Herein, evaporation of volatile organic components at low temperatures is measured in the form of the VOC value, and evaporation of non-volatile components is measured at high temperatures, expressed by the FOG value (derived from the word “fogging”). Even if binding limit values do not yet exist for the total of VOCs present in the passenger compartment, VOCs in the air can cause what is referred to by experts as the fogging effect. Fogging is a physical effect that cannot be wholly prevented. Soot, dust or aerosol particles move through the air from a warm area into colder zones where they precipitate. In the extreme case fogging of the windshield can impair the driver’s traffic safety.
Plastics, and thus gaskets as well, must emit no harmful pollutants, even at extreme temperatures, as often prevail in vehicle interiors exposed to direct sunlight in summer. Minimization of emissions is achieved via the selection of raw materials. In the case of low emission foam gaskets, this means that volatile components, such as propellants, oils, stabilizers or softeners that are included under the designation VOC are not used by Sonderhoff. Thus the low emission sealing products from Sonderhoff also contribute to reduced pollution in the automobile.
