エチルセルロース

化学的特性white to slightly yellowish powder

化学的特性Ethyl celluloses are low density polymers (1070–1180 kg.m–3) with solubilities depending on the degree of ethylation; usually commercial grade contains 44–48% ethoxyl functional groups. Solid masses of ethylcellulose exhibit low absorption of moisture, excellent dimensional stability and low temperature toughness and impact resistance. Chemically they are less resistant towards acids than cellulose esters but much more resistant to alkalis. They can be processed by injection molding. Because ethylcellulose is soluble in a wide variety of solvents, it provides a wide variety of varnish formulations. Benzylcelluloses yield plastics with excellent dielectric properties and chemical stability.

解説エチルセルロース,セルロースのヒドロキシ基をエチルエーテル化したもの．アルカリセルロースに硫酸ジエチルまたは塩化エチルなどのエチル化剤を一般に不均一系で反応させる．グルコース単位当たり3個あるヒドロキシ基のうち，エーテル化されたものの数で表す置換度により，溶解性，軟化温度などの諸性質が異なる．低置換度(0.8以下)のものはアルカリに可溶，置換度0.8～1.3のものは水溶性で，高置換度になるにつれて，アルコールなどの極性溶媒や無極性溶媒に可溶になり，置換度2.4～2.5において他種類の溶媒に可溶となる．この溶媒可溶性，ほかの樹脂との相溶性，安定性，耐水性，耐薬品性にすぐれることから，塗料，プラスチック，フィルムなどに広く利用されている．

用途エチルセルロース,セルロース誘導体の一種で，プラスチック，ラッカー，ワニス，接着剤，透明シートに使われている。広い温度にわたって強度と可撓性を保持する熱可塑性プラスチックであり，押出成形や射出成形で成形される。コットンリンターや木材パルプを水酸化ナトリウムと反応させてアルカリセルロースとし，その水酸基を塩化エチルによってエーテル化して作る。置換度によって諸性質が異なり，高置換度になるにつれて多種類の溶媒に可溶となる。

使用ethyl cellulose is a binder, film former, and thickener. It is used in suntan gels, creams, and lotions. This is the ethyl ether of cellulose.

製造方法Ethyl cellulose is prepared by reacting cellulose with caustic to form caustic cellulose, which is then reacted with chloroethane to form ethyl cellulose. Plasticgrade material contains 44-48% ethoxyl. Although not as resistant as cellulose esters to acids, it is much more resistant to bases. An outstanding feature is its toughness at low temperatures.

Ethylcellulose is prepared by treating purified cellulose (sourced from chemical-grade cotton linters and wood pulp) with an alkaline solution, followed by ethylation of the alkali cellulose with chloroethane as shown below, where R represents the cellulose radical: RONa + C2H5Cl→ROC2H5+NaCl The manner in which the ethyl group is added to cellulose can be described by the degree of substitution (DS). The DS designates the average number of hydroxyl positions on the anhydroglucose unit that have been reacted with ethyl chloride. Since each anhydroglucose unit of the cellulose molecule has three hydroxyl groups, the maximum value for DS is three.