In the late 1960s/early 1970s, polysulfide sealants dominated the European industry from the get-go once the 2-stage sealing system for insulating glass was developed. The fundamental chemistry for this is over 180 years old by now, while the manufacturable elastomers are approximately half as old. Nowadays, 2-C polysulfide sealants are mostly utilized for insulating glass. However, due to their lack of chemical reactivity, they are also used as sealing masses in aircraft and automotive construction as well as for “water” proofing around gas stations to prevent petrol from seeping in.
Their immediate and early triumph in insulating glass has two reasons: On the one hand, the industry (and especially American raw material producers) was in search of new applications after this chemistry was replaced as missile fuel in the mid-1950s. And on the other hand, an application was found that offered the insulating glass manufacturer not only an easily applicable sealant but also provided a broad tolerance range for mixing the particular A and B components. In the late 1990s, polysulfide sealants dominated the insulating glass industry with a market share in Europe of more than 90%. From the 1980s to the 2000s, this market was sustained and controlled by 4 raw material manufacturers from the USA, Japan, Germany, and Russia. Today, only 2 are left and still deliver significant amounts to the insulating glass sealant industry.
That reflects on the development and use of the corresponding insulating glass sealants throughout recent years in Europe. As a result, the market share of polysulfide sealants has decreased noticeably in favor of polyurethane sealants, based on the sealings for windows, such as behind UV-protective frames, in Europe. The market share of silicones is primarily limited to the open and unprotected edge, which is mostly part of glass facade constructions. However, when gas-tightness plays a minor part, silicones are occasionally (or in certain countries) used as secondary sealants in IG units for windows.
In the USA, polysulfides – despite their prior widespread use – have been largely replaced by (reactive) hot-melts, whose operators appreciate their swift and easy use. First of all, decisive for the respective market penetration are the respective national standards and laws, along with offers of the machine and sealant manufacturers. Then, the price/performance ratio decides either for a sealant or against it. For many years, developers have been quite restricted since polysulfide polymers are expensive to manufacture in comparison and only have very few options in terms of variants for the insulating glass market. In contrast to polyurethane, polysulfide sealants have another massive disadvantage. This sealant’s UV/water resistance can only be achieved with immense efforts and high costs while the new standards increasingly require these properties.
In Russia, the replacement of polysulfide sealants has manifested as well – albeit through other very economical mercaptan groups (polymercaptan polymers or PUSH polymers). Here, a polyurethane backbone receives SH groups, which results in appropriate sealants. This chemistry is also relatively old, seeing as it was introduced in the USA during the mid-1960s. This product class is currently experiencing a comeback due to its low manufacturing costs. That is particularly true for the Russian market, which has its effect on the global market share of polysulfide sealants.
Simply put, in Europe the trend shifts from polysulfide to polyurethane, in the USA it shifts from polysulfide towards (reactive) hot-melt and polyurethane, and in Russia from polysulfide towards polymercaptan polymers.
In China – or Asia, in general –, it is quite difficult to conduct an accurate market analysis. A great number of local sealant suppliers are present there, while their products are mostly silicone-based, with some of them still being on the basis of solvents. European sealant qualities are rarely demanded and usually only when high-quality machines are in use. However, the Asian machine manufacturers have caught up with the competition in Europe, which shows in the current trend of buying both machines and sealants locally.
During the next few years, it remains to be seen which legal restrictions will be issued and if environmentally conscious measures and manufacturing are going to prevail.
IGK rises to these global trends with its product portfolio that has grown in recent years.
Dr. Randolf Karrer
