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Microbeads are plastic microspheres that are widely used in cosmetics as exfoliating agents and personal care products such as toothpaste, as well as biomedical and health science research, microscopy techniques, fluid visualization and fluid flow analysis, and process troubleshooting.〔(Paint and Coatings Industry Magazine, January 1st, 2010 : Opaque Polyethylene Microspheres for the coatings applications )〕 They are most frequently made of polyethylene but can be of other petrochemical plastics such as polypropylene and polystyrene.〔(【引用サイトリンク】url=http://www.5gyres.org/microbeads/ )〕 In the United States, microbeads are defined as less than five millimeters in its largest dimension. Microbeads are commercially available in particle sizes from 10 µm to 1000 µm (1 mm). Low melting temperature and fast phase transitions make this material especially suitable for creating porous structures in ceramics and other materials. Microbeads pose an environmental hazard when disposed of in waste water. Because they pass through sewage treatment plants without being filtered out, their disposal has resulted in plastic particle water pollution. Several jurisdictions have regulated the use of microbeads. ==Types== Fluorescent polyethylene microspheres are commonly used to run blind tests on laboratory and industrial processes, in order to develop proper methods and minimize cross-contamination of equipment and materials. Microspheres that appear to be invisible in the daylight can be illuminated to display a bright fluorescent response under UV light. Colored polyethylene microspheres are used for fluid flow visualization to enable observation and characterization of flow of particles in a device. Colored microspheres can also be used as visible markers in microscopy and biotechnology. Sphericity and particle size uniformity create a ball-bearing effect in creams and lotions, resulting in a silky texture and spreadability. Exceptional smoothness and roundness also provides lubrication. Colors add visual appeal to cosmetic products.〔(Solid Polyethylene Microspheres for effects in color cosmetics ) Cosmetics and Toiletries.com, April 2010〕 Black polyethylene microspheres can have magnetic or conductive functionality, and have uses in electronic devices, EMI shielding and microscopy techniques. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Microbead」の詳細全文を読む スポンサード リンク
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