DE1132332B - Process for the production of light-colored synthetic resins, which are soluble in organic solvents, by condensation of ketones with aldehydes - Google Patents

Description

It is known that resin-like condensation products can be produced by the condensation of aliphatic ketones with formaldehyde to manufacture. When using large amounts of alkaline condensing agents, one obtains dark-colored infusible resins. These hitherto known resins are, however, lacquer technology completely useless.

It is also known that very light-colored, easily soluble and meltable synthetic resins can be produced in good yield arise when the alkaline condensation of aliphatic ketones with aldehydes, such as formaldehyde, the ketone is first precondensed at a low temperature, the reaction mass then with acid added and heated to about 70 to 80 ° C, whereupon alkali is added as quickly as possible and during the main condensation now taking place a sufficient amount of further aldehyde is added to complete the formation of the resin. The color number of the resins produced by this process is at 50% solution in toluene at about 10 to 20, measured in the Hellige comparator.

It has now been found that light-colored synthetic resins which are soluble in organic solvents can be produced by condensation of ketones with aldehydes in the presence of alkaline catalysts by 1 mol of an aliphatic ketone and 1.5 to 2.5 mol of formaldehyde are heated to 50 to 75 ° C, then 0.1 mole of an alkaline condensing agent per mole of aliphatic ketone in such portions admits that the temperature of the reaction mixture does not rise above 98 ° C, and the condensation completed by heating to about 90 ° C for another half hour.

For the preparation of these resins, the procedure is as follows: Aliphatic ketones, such as acetone, methyl ethyl ketone, methyl propyl ketone or diethyl ketone and formaldehyde are heated to about 50 to 75 ⁰ C. At this temperature, the alkaline condensing agent is added in such a way that the temperature of the reaction mixture does not rise above 98.degree. There is a gentle reflux of the starting components. The addition of alkali is continued, and after about half of the alkali has been added, the resin precipitates in the form of a very light mass. The condensation is now continued at 90.degree. C. for about another half an hour. After cooling, the raw resin cake is washed out until it is free of alkali. The raw resin is dehydrated, expediently at the end with switching on a vacuum, and then drained into tubs in a known manner and smashed.

The production of the condensation products can process for the production of bright,

soluble in organic solvents

Synthetic resins by condensation

of ketones with aldehydes

Applicant:
Rheinpreussen Aktiengesellschaft

for mining and chemistry,
Homberg (Ndrh.), Baumstrasse 31

Dipl.-Chem. Dr. Friedrich Josten,

Utford via Moers,

Wilhelm Haferkamp, Moers-Hochstrasse,

and Herbert Sarres, Orsoy, Pelden,

have been named as inventors

can also be carried out continuously under the conditions according to the invention.

The color number of the resins produced in this way is about 2 to 7. The melting point of these new ketone resins is 75 to 85 ° C, the acid number is 0.

Since these resins are mainly used in nitrocellulose lacquers, the progress made is in terms of the color number is important. It has been found that larger amounts of alkali than are required for the invention are not desired, as they lead to dark-colored products. Will be lesser Amounts of alkali than those given for the invention are used, the reaction does not work until resin formation.

example

663 liters of methyl ethyl ketone and 1600 l 3O% formaldehyde solution are heated to about 75 ° C. in a reaction vessel equipped with a stainless steel stirrer. At this temperature, about 70 liters of sodium hydroxide solution, which contains 440 g of NaOH per liter, are added in such a way that a temperature of 98 ° C. is not exceeded. After about 35 l of sodium hydroxide solution have been added, a very light resin cake suddenly precipitates out of the clear solution. To complete the reaction of the p _H -value is for retention of at least 13, the remaining

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Add amount of alkali and keep the temperature at about 93 ° C for another 30 minutes. Now will the reaction mixture is cooled to about 30 to 40 ° C., the resin precipitating as a viscous mass at the bottom of the reaction vessel. The mother liquor It is drained off over the resin cake and the resin is washed free of salt several times with condensed water. Any residues of alkali that may be present are neutralized by acid. The resin is stirring and Dehydrated using superheated steam, the last amounts of water being expedient by application removed by vacuum.

Claims (2)

Patent claims: 1. Process for the production of light-colored synthetic resins which are soluble in organic solvents by condensation of ketones with aldehydes in the presence of alkaline catalysts, characterized in that 1 mol of an aliphatic Ketones and 1.5 to 2.5 moles of formaldehyde heated to 50 to 75 ° C, then 0.1 mole of an alkaline condensing agent per mole of aliphatic ketone in such partial amounts admits that the temperature of the reaction mixture does not rise above 98 ° C and the Condensation is completed by heating to about 90 ° C for another half hour. 2. The method according to claim 1, characterized in that that the reaction is carried out continuously. Considered publications:
U.S. Patents Nos. 2,570,389, 2,395,414,
2237325, 1683 535. © 209 617/442 6.62