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Development of Improved Environment-friendly Low-VOC DURACON®
Staff in charge of development in front of the showroom
Recently, the term “VOC” may be used with respect to the environmental problem. This is the standard abbreviation for Volatile Organic Compounds, which is the general term for “organic chemical substances that are readily emitted into the air at normal temperature and pressure”. Among these substances, formaldehyde and toluene, in particular, are considered leading causes of so-called sick building syndrome, and are thus regulated in the building sector based on World Health Organization (WHO) guidelines. These regulations are also being extended to other industrial areas, such as the automotive industry, office automation, and electronic devices.
In order to meet current social demands, we at POLYPLASTICS have developed many products in “DURACON®” polyacetal resin with significantly reduced VOC emissions. Over the last several years, these products have been used in a wide range of applications, especially automotive components. The following pages introduce comments from researchers who have been involved in the development of these newly improved products.
What process led to the development of low-VOC “DURACON®”?
Recently, residential and office buildings have been made much more airtight while various new building materials have been incorporated. As a result, readily volatile and vaporizable chemical substances (i.e. VOCs) accumulate in buildings, irritating the eyes, heads and throats of occupants, in what has become known as “sick building syndrome”. Extensive research into this problem has been carried out by WHO and many other institutions to identify which chemical substances - such as formaldehyde and toluene are causing this syndrome, and to set guidelines for safe concentration levels. In response to these guidelines, indoor VOC concentrations are legally regulated in the building sector.
The VOC issue is not confined to buildings. Research at universities and public laboratories has also raised questions about vehicle cabin environments. Accordingly, automotive manufacturers have taken positive measures to counter the problem by seeking to reduce VOC emissions from paints, adhesives, leather, and resin components in car interiors.
“Vehicle Cabin VOC reductions” has become a key subject throughout the automotive industry. In 2005, the Japan Automobile Manufacturers Association, Inc. (JAMA) presented “Voluntary Approach to Vehicle Cabin VOC Reduction (JAMA Report No. 98)”, in which it was stated that “vehicle cabins be considered as part of our living space and, for new models coming to market from 2007, should meet the regulations for the 13 substances designated by the guidelines on indoor VOC concentrations issued by the Ministry of Health, Labour and Welfare”.
To be concrete, this policy stipulates that research should be undertaken throughout the industry to “establish a dedicated method for testing vehicle cabin VOCs in consideration of the way of the use of vehicle cabin and vehicle cabin environments differing from those in a buildings” and “since VOCs in vehicle cabins are a mixture of chemicals emitted from various components, to advance research in cooperation with component and material manufacturers”.
DURACON®, our main product, is widely used in vehicle cabins as the raw material for various components. The prime constituent of this resin is formaldehyde and, if it decomposes for any reason, has been proved to emit formaldehyde. For a long time, we have been studying how best to improve the resin quality to reduce odors due to formaldehyde emission at the molding site, and keeping the mold clean. Based on these efforts, we have addressed the requirements of automotive manufacturers to treat VOCs as a critical issue concerning our health and the environment, and have concentrated our energy on developing products that alleviate the VOC issue.
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| An air-conditioner blowport | A combination switch | A shift lever |
What kind of difficulties did you have to deal with during the development?
As mentioned before, we have been dealing with quality improvements such as reducing formaldehyde emissions at the DURACON® molding stage.
However, automobile manufacturers require a reduction in VOC emissions when the cars are in use. Therefore it is hard for us to sufficiently control the VOC issue. Since formaldehyde is a gas, it decomposes with age during storage after molding, while its volume increases through decomposition of the resin. Consequently, the emission volume largely depends on the shape of the molded products, molding conditions, and storage conditions after molding, etc. On the other hand, because the method of measuring formaldehyde and the target values set by each automotive manufacturer vary, we had a huge hurdle to surmount to satisfy all of these different requirements.
The first difficulty was how to measure VOCs. Though JIS A1901 specified a method for building materials, it was unclear for car interior components. We frequently needed to exchange information with automotive manufacturers to check many points, such as the component's manufacture, period of time between assembly in a car until measurement, ambient temperature at the time of measurement, use or otherwise of an air-conditioner, and the VOC collecting system.
The second difficulty was how to reduce formaldehyde emissions while maintaining the original benefits of DURACON®: excellent mechanical properties, fatigue resistance, creep strength*, friction and wear resistance, heat resistance, and ease of molding. In addition, it was necessary to ensure quality sufficient to bear the severe temperatures involved during the molding of certain components. The primary necessity was to find a high-performance additive to adsorb the formaldehyde. Suitable additives should have no adverse effect on the resin characteristics, good affinity to the resin, and neither ooze nor stick to the mold under any conditions. We continued our research for a solution with repeated examinations and an exhaustive range of test conditions. Eventually in 2004, we concluded, “This must be the one.” Our testing naturally included consideration for the safety, acceptability, and availability of the additive itself.
After this prolonged effort, our low-VOC DURACON® was created. In comparisons using an identical testing method, we succeeded in reducing the formaldehyde level to about one tenth that of conventional DURACON®.
How have users evaluated the low-VOC DURACON®?
How will you deal with environment problems in the future?
Our DURACON® has always had an excellent reputation for its ease-of-use and excellent moldability. The improved low-VOC DURACON® has earned a high reputation among users, as it is far superior to its competitors.
In order to develop this product, we continued our research by considering how to solve the inevitable formaldehyde problem that arises from polyacetal resin to improve the molding site and working environment, as well as considering what to improve so that our clients continued to feel safe using our additive. The original purpose behind its development was a reduction in vehicle cabin VOC emissions. However, this product has tremendous potential in other applications, such as OA machinery and equipment. At present, there is a trend towards smaller personal computers, copying machine, projectors, and many other OA and home-use equipment, which results in higher temperatures inside these devices. Replacing the polyacetal resin conventionally used inside these devices with our low-VOC DURACON® will afford better protection for the indoor environment. We hope that use of our low-VOC product will extend to such areas.
(*Creep strength: creep refers to the increased strain on an object over time when force is continuously applied to it. In general, the lower the strain, the better the creep strength).