Method for recovering aromatic diols and aliphatic diols

Abstract

To provide a method for obtaining aromatic diols and aliphatic diols from an aromatic-aliphatic copolymerized polycarbonate resin, then highly separating the aromatic diols and the aliphatic diols, and efficiently recovering diols which are recyclable as a raw material for an optical resin, have high purity and are excellent in a color tone.SOLUTION: A method for recovering aromatic diols and aliphatic diols hydrolyzes an aromatic-aliphatic copolymerized polycarbonate resin in the presence of a metal hydroxide aqueous solution and produces aromatic diols and aliphatic diols, distributes the aromatic diols produced by the hydrolysis into the metal hydroxide aqueous solution, then filters a decomposed liquid, and separates the metal hydroxide aqueous solution containing the aromatic diols and the aliphatic diols.SELECTED DRAWING: None

Claims

1. A method for recovering aromatic diols and aliphatic diols, characterized by hydrolyzing an aromatic-aliphatic copolymer polycarbonate resin solution dissolved in an organic solvent in the presence of an aqueous metal hydroxide solution to produce aromatic diols and aliphatic diols, dissolving the aromatic diols produced by the hydrolysis in the aqueous metal hydroxide solution and precipitating the aliphatic diols by distilling off or cooling the organic solvent, and then filtering off the decomposition solution to separate the aqueous metal hydroxide solution containing the aromatic diols from the aliphatic diols, wherein the aromatic diols are of the following formula (1), and the aliphatic diols are at least one aliphatic diol selected from the group consisting of adamantanediol, norbornanedimethanol, pentacyclopentadecanedimethanol, decalin-2,6-dimethanol, 2,2-bis(4-hydroxycyclohexyl)propane, spiroglycol, and isosorbide. 【Chemistry 1】 (In the formula R １ ~R ４ Each of these independently represents a hydrogen atom, a C1-C20 alkyl group, a C1-C20 alkoxyl group, a C6-C20 cycloalkyl group, a C6-C20 aryl group, a C6-C20 cycloalkoxyl group, and a C6-C20 aryloxy group. X is a single bond or a unit represented by the following formula (A). 【Chemistry 2】 (In the formula R ５ ~R １４ Each of these independently represents a hydrogen atom, a C1-C20 alkyl group, a C1-C20 alkoxyl group, a C6-C20 cycloalkyl group, a C6-C20 aryl group, a C6-C20 cycloalkoxyl group, and a C6-C20 aryloxy group. n represents an integer from 4 to 10.

2. A method for recovering aromatic diols and aliphatic diols according to claim 1, wherein formula (1) is the following formula (4). 【Transformation 3】 (In the formula R １５ ~R ２０ Each of these independently represents a hydrogen atom, a C1-C20 alkyl group, a C1-C20 alkoxyl group, a C6-C20 cycloalkyl group, a C6-C20 aryl group, a C6-C20 cycloalkoxyl group, and a C6-C20 aryloxy group.

3. The method for recovering aromatic diols and aliphatic diols according to claim 2, wherein formula (4) is the following formula (5). 【Chemistry 4】

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