- METHOD FOR PRODUCING 1,2,4,5-CYCLOHEXANETETRACARBOXYLIC DIANHYDRIDE
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An object of the present invention is to provide a method for producing 1,2,4,5-cyclohexanetetracarboxylic dianhydride, which is capable of stably achieving a high dehydration rate. The method for producing 1,2,4,5-cyclohexanetetracarboxylic dianhydride of the present invention is a method for producing 1,2,4,5-cyclohexanetetracarboxylic dianhydride by subjecting 1,2,4,5-cyclohexanetetracarboxylic acid to a dehydration reaction in a slurry state in the presence of a dehydrating agent, wherein an average particle size of the 1,2,4,5-cyclohexanetetracarboxylic acid is 20 μm or more.
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Paragraph 0153-0155
(2020/02/15)
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- Synthesis method for 1,2,4,5-cyclohexanetetracarboxylic dianhydride
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The invention provides a preparation method for 1,2,4,5-cyclohexanetetracarboxylic dianhydride. The method comprises the following steps: preparing pyromellitic acid ester by reacting pyromellitic acid with an esterification reagent; synthesizing hydrogenated pyromellitic acid ester by adding the pyromellitic acid ester with hydrogen in a fixed bed reactor; obtaining the 1,2,4,5-cyclohexanetetracarboxylic dianhydride by synthesizing the hydrogenated pyromellitic acid ester in strong acids and organic solvents. Compared with a traditional production process, the esterification reaction of the invention has high efficiency, the service life of a catalyst is prolonged, continuous production of hydrogenation reaction is realized, and a process route is shortened. The method has the advantagesof simple operation, high production efficiency and low cost and the like. The content of metal ions (sodium, potassium, iron, calcium, aluminum, and zinc) of the obtained 1,2,4,5-cyclohexanetetracarboxylic dianhydride contains is equal to or less than 1 ppm, and meets requirements of electronic grade products.
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Paragraph 0085; 0086
(2018/06/04)
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- Electronic grade hydrogenation of pyromellitic acid dianhydride preparation method (by machine translation)
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The invention discloses a preparation method of electronic grade hydrogenated pyromellitic dianhydride. The method comprises the following steps: adding commercially available pyromellitic dianhydride with the purity greater than or equal to 98.0%, deionized water and a noble metal catalyst into an autoclave; feeding hydrogen into the autoclave and simultaneously carrying out a hydrolysis reaction and a catalytic hydrogenation reaction; carrying out aftertreatment after the reactions so as to obtain crude hydrogenated pyromellitic dianhydride; decoloring and refining crude hydrogenated pyromellitic dianhydride with deionized water and activated carbon so as to obtain hydrogenated pyromellitic dianhydride with the purity greater than or equal to 99.5%; finally, carrying out a dehydration reaction on hydrogenated pyromellitic dianhydride by using acetic anhydride so as to obtain electronic grade hydrogenated pyromellitic dianhydride with the purity greater than or equal to 99.85%. According to the method, the purity of prepared hydrogenated pyromellitic dianhydride can reach above 99.85%, and the content of single metal ions (such as sodium, potassium, calcium, iron, copper, aluminum and the like) in prepared hydrogenated pyromellitic dianhydride is respectively less than 1ppm. Thus, electronic grade hydrogenated pyromellitic dianhydride can be widely applied to the field of photoelectronics, micro-electronics and other high and new technologies.
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Paragraph 5-7
(2018/02/04)
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- POLYIMIDE RESIN
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A polyimide resin contains repeating structural units represented by formulas (1) and (2), wherein the content of the repeating structural unit represented by formula (2) relative to the total of the repeating structural unit represented by formula (1) and the repeating structural unit represented by formula (2) falls within a specific range and the content of the divalent group represented by the following structural formula (B1) falls within a specific range: X1 represents a tetravalent group containing an alicyclic hydrocarbon structure and having a carbon number of from 4 to 22. X2 represents a tetravalent group containing an aromatic ring and having a carbon number of from 6 to 22. R1 and R2 each independently represent a divalent organic group, and the content of the divalent group represented by the following structural formula (B1) relative to the total of R1 and R2 is from 80 to 100 mol %:
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- Compounds, polymers, resin compositions and nonlinear optical devices
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The present invention provides, as heteroaromatic compounds made functional so as to be used for nonlinear optical materials, compounds represented by the following general formula (1), and also provides polymers obtained from these and nonlinear optical parts comprising such polymers. In the formula, Ar1 and Ar2 each represents a divalent aromatic group; R1, R2 and R3 each represents an atom or a group independently selected from a hydrogen atom or an alkyl group and an aromatic group; X1 represents a monovalent organic group; n represents an integer of 2 to 12; and Z1 and Z2 each represents a group independently selected from electron attractive functional groups.
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- Dicylcohexyl-3,4,3'4'-tetra-carboxylic acid or dianhydride thereof and polyamide-acid and polymide obtained therefrom
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A polyimide obtained from a polyamide-acid or polyamide-acid ester prepared by reacting dicyclohexyl--3,4,3?,4?-tetracarboxylic acid or dianhydride with a diamine is excellent in transparency, heat resistance and mechanical properties, said polyimide being able to be obtained at a lower temperature, and particularly suitable for an orientation film used in liquid crystal display device.
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