  A
Historical Review of Silicones
Silicones
are industrially produced compounds derived from the element
silicon. Although silicon is the second most common element
in the earth’s crust, its high affinity for oxygen
means that it is only found in compounds with oxygen, namely
as the silicates and silicon dioxide that make up minerals
and sand. Elemental silicon was discovered at a relatively
late stage because of the very high silicon-oxygen bond energies.
In 1823, the chemist Jöns Jakob Berzelius obtained amorphous
silicon by reducing silicon dioxide with carbon in the presence
of iron. When hydrochloric acid was added to dissolve the
iron, the reaction mixture was found to contain silicon in
powder form. However, it was to be more than 100 years before
this newly discovered element would embark on its triumphal
march. For a long time, the main stumbling block preventing
the production of metallic silicon chunks was the high melting
point of 1410 °C. Nor was there a suitable process capable
of producing silicon in large quantities.
Not until the discovery
and widespread use of electricity was it possible to generate
the high heat of fusion of silicon
or an economic process for its manufacture. Despite these
difficulties, a number of chemists were researching the chemistry
of silicon in the 19th century. They were hoping to develop
a chemistry of silicon to rival that of carbon.
Discovery
of Silicones
It
was the English chemist F. S. Kipping who, at the start
of the 20th century, really dedicated himself to silicon
chemistry. He synthesized a large number of Si-C compounds
that do not occur naturally. His products were mostly
resinous products that would not crystallize and would
not distill. The first silicones had
been discovered!
Kipping’s first syntheses
concerned chloro-organosilanes, which he would hydrolyze.
By analogy with chloroalkyl
compounds, he expected hydrolysis to yield the corresponding
alcohols. However, the hydrolysis products, silanols,
spontaneously condensed to larger units, with the release
of hydrogen chloride gas. At that time, none was intererested
in either the properties or the applications of these
compounds and so Kipping did not pursue the matter
any further.
The
Breakthrough in Silicones
In
the early 1940s, the USA started researching and testing
the properties of silicones to help with the war effort.
Initial interest focused on their hydrophobic properties
and protective action against static electric discharges.
Consequently, the first silicone product was a paste
that protected electrical sparking equipment in airplanes.
The producer was Dow Corning. It processed silicone
precursors obtained from General Electric. At GE in
1940, Eugene G. Rochow discovered a synthesis route
for chloromethylsilanes that utilized silicon and chloromethane
(methyl chloride) as its starting reagents. Independently
and at the same time, the German chemist Richard Müller
discovered a similar synthesis route, now called the Müller-Rochow
synthesis.
From then on, there was no stopping
silicones. It was now possible to produce silicone precursors
cheaply.
From then on, the goal was to incorporate specific
organic groups to expand the silicones’ range
of applications.
The
Discovery of Silicone Chemistry in Germany
A
prominent figure in this regard was S. Nitzsche,
who devised a silane synthesis
for the company. The first round-the-clock silane furnace
started operating in Burghausen in 1949. WACKER chemists
then set about modifying the silicone backbone with methyl,
phenyl, vinyl, amino
and other functional groups to expand the range
of applications of the new
polymers.
Today, WACKER is a world leader in
silicones. It sets trends in the fields of research,
analysis and
environmental
protection.
A chronological overview of WACKER’s
rise is presented in the following table.
Chronicle
of WACKER SILICONES
 |
|
| 1913 |
Foundation
of the Consortium für elektrochemische Industrie
GmbH |
| 1914 |
Foundation
of Wacker Chemie AG on October 13 |
| 1947 |
Start of silicones research in Burghausen |
| 1949 |
First silane furnace comes on stream in Burghausen
(see photo above) |
1950 |
First pilot plant for silicones
Silicone fluids and resins developed
Work starts on optimizing the direct synthesis of chloroethylsilanes |
| 1951 |
Expansion of silicone production
Product range extended to include impregnating agents
for the textiles industry, release agents for the
rubber industry, antifoams and emulsions |
| 1953 |
First masonry protection
agents launched
Start of HTV rubber production
Sales of silicones reach DM 2.1 million
|
| 1955 |
The first RTV rubbers developed
Synthesis route found for phenylsilanes
|
| 1957 |
Expanson of silicones production, construction of
distillation towers and tank farms for silanes
Product range now numbers 200
Sales of silicones reach DM 7.8 million
|
| 1960 |
Development work starts on silicone joint sealants
sold under the brand name ELASTOSILâ
First combination resins for the coatings
industry |
| 1967 |
Sales of silicones reach DM 37.8 million |
| 1969 |
Direct synthesis switched to the fluid-bed process
Pure silane distillation comes on stream
WACKER Chemical Corp. New York acquires a 33 % holding
in SWS Silicones Corp. Adrian/Michigan, USA
|
| 1970 |
New generation of addition-curing silicone rubbers
Start of pyrogenic silica production HDKâ in Kempten, Germany |
| 1971 |
WACKER Mexicana: Start of silicones production |
| 1972 |
New silicone plants for synthesis and distillation
in Burghausen; extended in 1974 |
| 1976 |
Methanolysis plant comes on stream |
| 1977 |
Foundation of Bayplan, a Bavarian company specializing
in masonry protection |
| 1978 |
Silicone rubber in the ascendancy
The decisive component HDK® is now also produced in Burghausen |
| 1981 |
Start of silicones production at WACKER Quimica do
Brasil Ltda |
| 1982 |
Substantial expansion of capacity of silicone plants |
| 1983 |
WACKER Chemical East Asia, Tokyo: Production of RTV-
and HTV silicone
rubbers |
| 1985 |
WACKER holding in WACKER-Stauffer Silicones Corp.
increased to 50 % |
| 1987 |
Foundation of WACKER Silicones Corp., Adrian, Michigan,
USA, as 100 % subsidiary
Foundation of Drawin Vertriebs GmbH, Ottobrunn, Germany,
for small-scale silicones sales
Creation of the WACKER silicone prize for outstanding
research achievement in organosilicon chemistry
|
| 1988 |
Restructuring: silane, silicone and silica activities
amalgamated into the Silicones Division
In Burghausen, industrial plants for methylsilicone
resins and phenylsilanes come on stream
|
| 1990 |
Silicones in high-tech SEMICOSILâ in
electronics, POWERSILâ in
the power transmission and distribution industry, silanes
for pharmaceutical syntheses |
| 1991 |
Silicones production starts at Wacker-Chemie Italia
SpA.
Start of hot-rubber compounding in WACKER Quimica Iberica
|
| 1993 |
Quality management system certified to ISO EN 9001 |
| 1997 |
Production of LC pigments starts
Sales of the Silicones Division: DM 1.4 billion
Employees: 3,000
100 % acquisition of SILMIX SpA, Italy
Wacker Silicones celebrates 50 years
|
| 1998 |
In Japan, silicones production is concentrated at
the Akeno site |
1.1.
1998 |
Wacker
Silicones Corporation, Adrian, USA, a wholly owned subsidiary
of Wacker Chemie AG, Munich, and Kelmar Industries,
Duncan, South Carolina, USA, agree to found a joint venture
for specialty silicones
Founded in 1988, Kelmar Industries, which has 66 employees
and focuses on the production and marketing of textile
auxiliaries based on silicones, posts sales of around
USD 30 million in fiscal 1996/1997 |
| 1998 |
On November
27, 1998, Wacker-Chemie signs a contract to acquire the
Nünchritz plant (in Saxony) of Hüls AG for
the benefit of the Silicones Division |
| 1999 |
Asahi Chemicals
Industry Co.Ltd., (Asahi Kasei) in Tokyo, Japan, and
Wacker-Chemie sign a 50/50 joint venture agreement on
September 17, 1999, to develop, manufacture and market
silicone products. The new company is called Wacker Asahikasei
Silicone Co., Ltd, and is headquartered in Shinjuku-ku,
Tokyo |
| 2000 |
Shanghai Technical Center. The technical service center, a joint project with Wacker Polymer Systems, officially opened its doors. This center will support the expansion of Wacker activities in Asia’s rapid-growth silicone markets – particularly in the construction sector.
In June 2000, an innovation and advisory center for silicone applications in the cosmetic industry was opened in Burghausen. |
| 2001 |
WACKER SILICONES launched a range of silicone rubber in pellet form. |
| 2002 |
The expansion project at the Nünchritz site in Germany (begun in 2001) continued on schedule in 2002. |
| 2003 |
On March 10, 2003, a symbolic groundbreaking ceremony launched the expan-sion of the monomer plant. |
| 2004 |
Sika AG, based in Baar, Switzerland, acquires WACKER's structural silicone sealants and adhesives business.
A new silicone-emulsion production facility goes on stream in Shanghai, China |
| 2005 |
WACKER and Dymatic set up a joint venture in Shunde (China) for the manufacture and marketing of silicone products used in the textile, leather and fiber industries. |
| 2006 |
WACKER enters into a joint venture with Dow Corning to manufacture silicone precursors in Asia. |
|
