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定義
本品は、スチレンとブタジエンからなる共重合体である。
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解説
スチレン-ブタジエンゴム, 略称SBR．スチレンとブタジエンの共重合体である．合成ゴムとしてもっとも多量につくられ，一般的に使われる種類である．工業的には乳化重合法によってつくられ，スチレンを23.5％ 含むものが普通である．カーボンブラックやシリカで補強したものは，天然ゴムに近い強度をもち，耐老化性，耐熱性がすぐれている．重合方法，スチレン含有量の大小などにより，コールドラバー，ホットラバー，ハイスチレンゴムなどに分類されている．森北出版「化学辞典（第2版）
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化粧品の成分用途
不透明化剤
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主な用途／役割
ブタジエンとスチレンとを重合させて得られる合成ゴム。布、プラスチックフィルム、紙、発泡体のようなフレキシブルなものを接着する接着剤、木材用水系高分子イソシアネート系接着剤に使用される。
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化学的特性
solid or viscous liquid, depending upon the degree of polymerisation
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使用
Molded or extruded into toys, packaging, appliances, communication cassettes, dinnerware and serviceware.
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調製方法
SBR is prepared mainly by emulsion and solution polymerization
in a free-radical process with a mercaptan, such as
dodecylmercaptan, which is used as a chain-transfer agent
to control molecular weight. In the emulsion process, a soapstabilized
water emulsion of styrene and butadiene is polymerized in continuous reactors to form SBR elastomer.
“Cold” SBR is produced at a temperature of 5–10°C, and
“hot” SBR at about 50°C . Solution SBR is typically
made in hydrocarbon solution with an n-butyllithium initiator.
The major differences between emulsion and solution
styrene–butadiene are in the linearity and molecular-weight
distribution of the polymer chains. In nonpolar solvents, the
tendency is to produce block copolymer, but random copolymers
are formed in polar solvents. SBR can be vulcanized
similar to natural rubber but generally requires less sulfur and
is more accelerated because of its lowunsaturation.
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危険性
Questionable carcinogen.
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健康ハザード
Styrene Butadiene Rubber is prepared in large quantities for tire treads and other, similar uses. The properties, molecular weight, and percentage of monomer can all be controlled in the polymerization process. Hazards of the SBR industry have been identified and related mostly to the monomers and additives. Contact dermatitis and leukemia have been associated with solvent and additive use but not with the actual polymer itself (Checkoway et al., 1984; Kilpikari, 1982). Epidemiological studies in the industry have not revealed a significant increase in disease or causes of death (Matanoski and Schwartz, 1987; Meinhardt et al., 1982). The hazards of the butadiene and styrene monomers were discussed previously.
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安全性プロファイル
An eye irritant. Questionable carcinogen. When heated to decomposition it emits acrid smoke and irritating fumes. See also POLYMERS, INSOLUBLE.
