Patent GB-447954-A (GB)
Title: Improvements in or relating to the treatment of rubber
IPC: C08K11/00
Filed: 1935-10-05
Abstract: The resistance of rubber stocks to age is improved by the addition to the mix of the reaction product of an alkali metal upon a ketone-amine condensate.  The condensation product is prepared in a known manner, and is preferably washed with an alkaline solution and freed from water before being allowed to react with the alkali metal. The reaction preferably takes place in an inert atmosphere such as nitrogen and at a temperature above the melting point of the alkali metal.  The excess of alkali metal is removed by treatment with alcohol and water at the end of the reaction.  In an example, diphenylamine and acetone are reacted in the presence of ferrous iodide, the product washed with caustic soda, dried, and then heated in an atmosphere of nitrogen with metallic sodium at 150 DEG  C. for 3 hours.  The nitrogen is bubbled upwards through the resin to effect a complete mixing with the alkali metal.  The excess of sodium is removed with alcohol and water, the product washed and added directly to a rubber mix. Other ketones mentioned which may be used are methyl ethyl ketone, ethylidene acetone, phorone, methyl propyl ketone, diethyl ketone, cyclohexanone, dimethyl ketone, diacetone alcohol, dipropyl ketone, and benzophenone.  Other amines mentioned are tolylamine, xylylamine, diphenylamine, naphthylamine, dinaphthylamine, and phenyl alpha- and beta-naphthylamine.  The ketone-amine condensation products prepared according to the process of Specification 395,322 may also be used.  It is stated that the products of the present invention possess a higher viscosity than the untreated ketone amine condensation products, due probably to a molecular rearrangement having occurred.  The anti-agers of the present invention may be used in any type of rubber stock, whether natural, reclaim or synthetic, or whether in solid form or in the form of latex.  The term rubber includes guttapercha, balata, synthetic rubber and rubber isomers.  Examples are given to show the efficiency of the product both as an antiager and as a preventive of cracking on repeated flexing.ALSO:The resistance of rubber stocks to age is improved by the addition to the mix of the reaction product of an alkali metal upon a ketone-amine condensate.  The condensation product prepared in known manner is allowed to react with an alkali metal in an inert atmosphere, preferably after a preliminary wash with an alkaline solution followed by removal of moisture.  An example is given of the preparation of an anti-oxidant by the action of sodium on an acetone-diphenylamine condensation product.  A list of a number of alternative ketones and amines which may be condensed and then reacted with alkali metal is given.  The anti-agers of the present invention may be used in any type of rubber stock, whether natural, reclaim or synthetic, or whether in solid form or in the form of latex.  The term rubber includes guttapercha, balata, synthetic rubber and rubber isomers. Examples are given to show the efficiency of the product both as an anti-ager and as a preventive of cracking on repeated flexing.