DE117148C

DE117148C -

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Publication number: DE117148C
Application number: DENDAT117148D
Authority: DE

Description

KAISERLICHESIMPERIAL

PATENTAMT.PATENT OFFICE.

Das vorliegende Verfahren bezweckt die Herstellung von Chromgelb aus Bleioxydhydrat unter Zuhülfenahme des elektrischen Stromes.The present process aims at the production of chrome yellow from lead oxide hydrate with the help of the electric current.

Bei den bisher gebräuchlichen Verfahren erfolgte ' die Bildung des Chromgelbs zumeist durch Fällung wässeriger Bleisalzlösungen mit Alkalidichromat unter Zusatz von freier Säure, schwefelsauren Salzen und dergl. Es ist bekannt, dafs hierbei die Farbe, Lebhaftigkeit und sonstige physikalische Beschaffenheit des Niederschlages hauptsächlich von den Umständen abhängt, welche bei der Fällung obwalteten. Geringfügige Unterschiede in der Temperatur, der Lebhaftigkeit des Umrührens, der Concentration der Lösungen und dergl. verursachten bei ganz oder nahezu gleicher empirischer Zusammensetzung eine verschiedene Farbe und verschiedene physikalische Beschaffenheit des erhaltenen Productes. Die gröfste Schwierigkeit hierbei bildete die Herstellung der tief orangefarbigen und rothen Töne. Hierzu kommt noch die Empfindlichkeit besonders der hellen, citronenfarbigen Nuancen 'gegen Verunreinigungen der Rohmaterialien und die dadurch bedingte Nothwendigkeit der Verwendung völlig reiner Ausgangsmaterialien; ferner die zur Herstellung guter Erzeugnisse erforderliche kostspielige Essigsäure, welche bei . den bekannten Verfahren zumeist verloren ging, der Zeitverlust, welcher mit der Vorbereitung des Processes verbunden war, etc. Alle diese Umstände machten das sonst so beliebte und beständige Chromgelb zu einer relativ theuren und darum nur für besondere Zwecke verwendbaren Malerfarbe.In the processes used up to now, the chrome yellow was mostly formed by precipitation of aqueous lead salt solutions with alkali dichromate with the addition of free acid, sulfuric acid salts and the like. It is known that the color, liveliness and other physical properties of the precipitate mainly on the circumstances depends on which prevailed during the felling. Slight differences in temperature, liveliness of stirring, the concentration of the solutions and the like. Caused at completely or almost the same empirical composition a different color and different physical nature of the product received. The greatest difficulty here was the production the deep orange and red tones. Added to this is the sensitivity in particular the light, lemon-colored nuances' against contamination of the raw materials and the necessity of using completely pure raw materials; also the expensive acetic acid required for the production of good products, which is used in . the known procedures were mostly lost, the time lost with the preparation of the trial, etc. All these circumstances made the otherwise so popular and constant chrome yellow to a relatively expensive and therefore only usable for special purposes Paint.

Die Verwendung von Bleioxydhydrat als Ausgangsmaterial bei der Herstellung von Chromgelb beseitigt die vorerwähnten Uebelstände. Bleioxydhydrat ist auf elektrolytischem Wege leicht, rein und wohlfeil erhältlich, indem man Bleianoden in einem geeigneten Elektrolyten, dessen Anion Blei löst, also in Nitrat-, Acetat- etc. Lösungen der Einwirkung des elektrischen Stromes aussetzt. Die erhaltene Bleilösung wird mit Alkali gefällt, das Bleioxydhydrat gewaschen und weiterhin auf Chromgelb verarbeitet.The use of lead oxide hydrate as a starting material in the manufacture of Chrome yellow eliminates the abovementioned problems. Lead oxide hydrate is on electrolytic Ways easily, purely and cheaply obtainable by placing lead anodes in a suitable Electrolytes, the anion of which dissolves lead, i.e. in nitrate, acetate etc. solutions of the action of the electric current. The lead solution obtained is precipitated with alkali, the Washed lead oxide hydrate and processed further on chrome yellow.

Dieses Product zeichnet sich durch hervorragende Eigenschaften aus, welche der Chromgelberzeugung sehr zu statten kommen. Dasselbe besitzt eine sehr bedeutende Reactionsfähigkeit, setzt sich mit Chromaten, Dichromaten etc. sofort und in der Kälte glatt um, ist in der vorerwähnten Weise aus Werkblei in ausreichender Reinheit leicht, in ununterbrochenem Betriebe und wohlfeil erhältlich und kann, den Umständen, unter welchen es gefällt wurde, entsprechend, in beliebiger physikalischer Structur vom feinsten schwammigen Gefüge bis zum grob krystallinischen Pulver erhalten werden. Bei der Umsetzung des derart hergestellten Bleioxydhydrates mit Dichromaten gehen die physikalischen Eigenschaften des ersteren auf das erzeugte Chromgelb über. Die elektrolytische Herstellung der Bleilösung, aus welcher nachträglich durch Alkalizusatz das Bleioxydhydrat ausgefällt wird, gestattet, je nach der Zeitdauer, innerhalb welcher die Lösung dem Elektrolysirtroge entnommen wird, eine beliebige Concentration derselben mitThis product is characterized by excellent properties, which are the generation of chrome yellow very come in handy. It has a very great ability to react, reacts with chromates, dichromates etc. immediately and smoothly in the cold, is light in the above-mentioned manner from lead in sufficient purity, in uninterrupted manner Establishments and cheaply obtainable and can, the circumstances under which it was precipitated, accordingly, in any physical structure of the finest spongy Structure can be obtained up to the coarsely crystalline powder. When implementing the such The physical properties of the lead oxide hydrate produced with dichromates go down of the former to the generated chrome yellow. The electrolytic production of lead solution, from which the lead oxide hydrate is subsequently precipitated by adding alkali, permitted, depending on the period of time within which the solution is removed from the electrolysis tray, any concentration thereof with

Claims

Ease to manufacture. The concentration and temperature at which the lead oxide hydrate is precipitated determines the physical nature of the latter. Concentrated, cold-precipitated solutions give a spongy, flaky lead oxide hydrate; warm, dilute solutions give a crystalline product when they are precipitated with alkali. In this way it is possible without difficulty to achieve any desired gradation of the physical properties of the lead oxide hydrates and the chrome yellow produced from them. When carrying out the process in continuous operations, lead is first brought into solution electrolytically using suitable salt solutions (nitrates, acetates, etc.). If alkali salts are used as the electrolyte, the amount of alkali required to precipitate the lead oxide hydrate is formed on the cathode at the same time. This is followed by the precipitation of the lead oxide hydrate from the lead solution formed and the regeneration of the electrolyte, which is reduced by the proportion of water decomposed during the passage of the current. In the case of precipitation with alkali, care must be taken that by varying the concentration and temperature that physical quality of the lead oxide hydrate is obtained which corresponds to the chrome yellow to be produced. The lead oxide hydrate freed from the electrolyte, washed and suspended with water is then treated with the appropriate amount of chromates or dichromates and the usual coprecipitating agents (sodium sulfate, etc.) are all orange; it is therefore necessary to ensure the presence of a small amount of free acid if yellow nuances are to be obtained. In the case of the production of orange or red products, the production is even simpler in that, as mentioned, the free amount of alkali always required to produce orange precipitates forms automatically during the double conversion between lead oxide hydrate and alkali dichromate. The rule here is that flocculent lead oxide gives light tones, while crystalline ones are particularly advantageous for the production of darker and red nuances. Patent-Α ν Proverbs:

1. Process for the production of chrome yellow, characterized in that lead oxide hydrate with chromates or dichromates and the other usual partial coprecipitation or solvents (sodium sulfate, acetic acid, etc.) are added.

2. An embodiment of the method according to claim i, characterized by the electrolytic Dissolution of lead, subsequent precipitation of the lead oxide hydrate and conversion of the latter into chrome yellow the method described in claim ι.