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Our modern lifestyles desire the development of sophisticated and advanced applications. A special material like silicones commands versatility in the most cost effective way and meet the requirements, according to Angelica Buan, who also highlights China’s hold on the silicones global market.
The world’s increasing wants and needs inevitably create new markets for new applications.
Silicones, or polysiloxanes, are versatile polymers of silicone and oxygen with carbon, hydrogen, or occasionally, other elements. Silicones can be classified as fluids, elastomers or resins. The solidification process of all heat-activated cure thermosets, including silicone rubber, is caused by a chemical reaction called vulcanisation, or cure. Silicones possess physical and chemical properties that allow their use in a multitude of diverse applications from personal care items for our skin and hair to industrial applications such as automotive lubricants and polishes, as well as sealants and protective coatings for construction.
Medical applications for silicones are also quite diverse: from artificial tears, to burn treatment and wound care, as coatings for tablets and capsules, for implants, and in the treatment of blood handling equipment.
According to a new report by US research firm IHS, global demand growth for silicone fluids will grow about 4%, driven primarily by the cosmetics, toiletries, and medicinal/pharmaceutical applications.
For silicone elastomers, which are critical to the growing construction and automotive industries, a stronger demand growth at 7% a year is expected, whereas for silicone resins, which are also tied to the construction industry, a more modest growth of 3% a year is expected.
Global demand for silicones will increase from 1.7 million tonnes in 2012 to 2.4 million tonnes in 2018, which represents an average annual growth rate of nearly 6% from 2012-2018, says IHS.
China – over the top with silicones
Meanwhile, a robust demand for silicones in China, combined with an improving economy, is driving market growth for these versatile polymers. But even so, aggressive capacity expansion of silicone production by China since 2009 is generating significant global excess capacity that is impacting profitability and growth and is driving less profitable producers or operations to rationalise their production.
China is expected to build additional capacity, equivalent to nearly 20% of the 2012 global demand, through 2016. This excess capacity is causing prices to fall, according to the author of the IHS Chemical Economics Handbook: Silicones report, Aida Jebens.
Now the largest producer of silicones in the world, China owns nearly 40% of global silicone production capacity. This feat was made possible by the start-up of several world-scale silicones manufacturing plants built since the mid-2000s, noted the IHS report. Some of these plants are joint ventures with foreign companies such as US-based Dow Corning and German firm Wacker Chemie.
According to IHS, further capacity additions are scheduled to come on stream in China through 2016 that will see China’s share of the global capacity rise to 50%. In comparison, no significant capacity additions occurred in the other regions in the last five years and none is expected through 2016.
With the increased domestic supply of silicones, China’s consumption of silicones has grown very rapidly in a short period of time — consumption rates of the product increased 25% a year from 2002-2012, enabling China to surpass the traditional demand powerhouses of the US and Western Europe.
“As economies improve and consumers in developing countries like China expand their disposable incomes,” Jebens said, “the demand for personal care items and automobiles, which are produced using silicone components, increase. Likewise, improving economic conditions drive more construction, which is heavily dependent upon silicone-based materials.”
China’s projected consumption growth for silicones will slow, although it will still grow at close to 10% a year, pulling the overall global growth rate close to 6% a year from 2012-2018, said Jebens.
As the most dominant player in the market, any major shifts in either Chinese demand or production capacity will have significant implications for the global silicones market.
IHS expects above-average growth may also occur in Central and Eastern Europe, Central and South America, and the Middle East and Africa, although consumption levels in these regions are still fairly low. Consumption in North America and Western Europe is expected to increase between 3%-3.5% a year, while Japan’s market will grow only slightly.
Besides Dow Corning and Wacker Chemie, the largest manufacturers of silicones, in terms of capacity, are US-based Momentive Performance Materials (which recently filed for bankruptcy and is undergoing restructuring), Shin-Etsu Chemical (Japan), and Bluestar Silicones (France).
Performance-level LSRs
Liquid silicone rubber (LSR) is a silicone rubber that has the same structure, with a lower viscosity, and provides an edge over solid silicone rubber in many ways.
LSRs come in a variety of forms, including self-adhesives; faster curing grades for larger, thicker parts; self-lubricating formulas to reduce friction on surfaces that need to be slippery; and liquid fluorosilicone elastomers. Advantages to using LSR include minimal waste; faster cycle times; flashless technology; no secondary operations and limited likelihood of cross-contamination.
Thus, it is no surprise that LSR is a strong growth driver for silicones and is expected to reach US$17.2 billion by 2017, according to a report by research firm Global Industry Analysts (GIA).
US research firm Freedonia, in its 2012 study, says that LSR is increasingly valued for its ease of processing, flexibility, and ability to form high precision parts.
Among other factors, advancements in equipment and materials are spurring the market for LSR to develop further. The shift in usage results from OEMs finding solutions to substituting chemical polyisoprene with LSR. While LSR is mostly adaptive to the requirements of the medical market, it also renders use for automotive, military, consumer, and space applications.
Wacker Chemie showcased its heat-resistant solid silicones for the automotive and household appliances at the recently staged Chinaplas in Shanghai.
Its Elastosil R756, R416/70 and R416/70 are heat and coolant resistant, making them suitable for manufacturing components that are constantly exposed to high temperatures, such as tubing or seals placed near the engine or exhaust pipe or vehicles or gaskets for oven doors with pyrolytic self-cleaning features.
Wacker’s platinum-cured LSR 3022/60 features very low compression set, thus making it suitable for making seals for cooling systems in cars. Its resilience also ensures leak-tightness in the seal groove.
Wacker says that standard silicone elastomers are not exactly ideal as sealants in the hot areas of engine cooling circuits, because some of the key properties deteriorate once they come into contact with a coolant of over 100°C.
Injection moulding LSRs
Due to their good physical properties and chemical resistance, LSRs are giving standard plastics a run for their money. Furthermore, compared to high-consistency silicone rubber (HCR) and other elastomers, LSRs can withstand extreme temperatures from –55°C to 200°C.
In spite of the higher cost for LSRs, which is about three to five times as much as TPEs and TPUs, the products are finding uses in injection moulding applications.
Said Joyce Meng, Global Product market Manager of Dow Corning’s Xiameter LSR brand, “Liquid silicone rubber has evolved from a very specific need to produce silicone rubber parts and products more efficiently and economically.” She added that Xiameter RBL-9200 Series LSRs are setting new standards for processing speed and end-product quality. LSRs in the series can be used for end products such as kitchenware, baby/infant care products, electrical insulation, keypads, grommets, gaskets and seals.
Dow Corning teamed up with moulding machine manufacturer Maplan to demonstrate the processing benefits of its Xiameter RBL-9200 series at the International Rubber show in the US last year. Maplan was using its MHF200L/200EDITION machine to inject the LSR into a beverage cup mould from M.R. Mold & Engineering Corp.
Unlike plastics, which are injected at high temperatures and cooled inside the mould, elastomers are injected at lower temperatures and cured by heating the mould. Thus, LSR moulds can be more difficult to clean and maintain. LSRs also require special treatment, such as uniform distributive mixing. In addition, the material must be maintained at a constant temperature up until it is pushed into the heated cavity and vulcanised.
One way moulders are standardising LSR moulding is with the use of cold runners. Besides reducing waste, a standard cold runner system can reduce cycle and setting times. Finished parts are immediately available for use or in assembly processes.
Furthermore, LSR’s excellent adhesion to plastics and metals, allows it to be the ideal material for two-shot and over-moulding injection moulding of LSRs – also known as multi-shot or assembly injection moulding.
Two-shot moulding allows for the combination of two materials – one with a cold runner and the other with a hot runner – directly in the same mould, thereby saving expensive assembly steps while allowing for the integration of multiple functional features in one ejected, finished part. This process makes consistency possible.
LSRs in healthcare
Medical grade LSRs are also being used extensively in the healthcare sector, primarily for advantages such as transparency, easy sterilisation and biocompatibility as well as resistance to UV and stains. LSR also has a soft feel similar to that of skin, allowing it to be used in devices that contact the body.
In comparison to latex rubber, which poses allergy risk to sensitive end-users, and PVC, which contains health-hazardous phthalates, LSR is found to be safe.
In fact, Food and Drug Administration (FDA) standard-approved LSR is ideal for use in implantable devices.
LSR also works particularly well for parts with intricate geometries and smooth surfaces that require high precision, including liquid feeding bottles and catheters.
One company that is broadening its speciality LSR products is Bluestar Silicones. It recently introduced its Bluesil ESA products for medical electronics, designed to bond to most plastics and metals. The product line offers deep-section cure with no released by-products, dielectric properties, thermal management and corrosion resistance.
“It’s an exciting time at Bluestar Silicones,” says Karen O’Keefe, Healthcare Market Manager. “We are investing in new products, new markets and continuous improvements in our new plant to deliver the highest quality silicone solutions to the healthcare and medical market.” The products are manufactured in a clean room environment at Bluestar Silicone’s new 226,000-sq-ft facility in the US.