Patent GB-249113-A (GB)
Title: Improvements in the vulcanisation of rubber substances
IPC: C08L7/00
Filed: 1926-03-08
Abstract: 249,113. Grasselli Chemical Co., (Assignees of Williams, I., and Burnett, W. B.). March 13, 1925, [Convention date]. Drawings to Specification. Aldehyde-amine condensation products.- Rubber substances are vulcanized with the aid of the products obtained by condensing two or more (up to twenty) molecular proportions of an alpha-#-saturated aldehyde (i.e. an aldehyde in which the a and # atoms are linked by a single bond) with one molecular proportion of a primary amine. Suitable amines are aniline, n-butylamine, ethylamine, and o-tolydiguanide, and propionaldehyde, n-butyraldehyde and heptaldehyde are examples of suitable aldehydes. The properties of the rubber obtained by vulcanizing at 140‹ C. with accelerators prepared from different proportions of aldehyde and amine are tabulated for the following condensation products :-heptaldehyde with n-butylamine; and n-butyraldehyde with aniline, o-tolyldiguanide, and n-butylamine. Curves illustrating some of the data are also given, and it is shown that the accelerating function of the products increases with increasing proportions of aldehyde to maxima which are usually between 3 and 7 molecules of aldehyde to one of amine. The Specification as open to inspection under Sect. 91 (3) (a) describes also the manufacture of condensation products which may be used as accelerators in the vulcanization of india-rubber by causing one molecular proportion of any amino-body to react with two or more (up to twenty) molecular proportions of any aldehyde under conditions wherebv water is eliminated. Suitable amines and aldehydes, in addition to those mentioned above, are ethylamine, ethylene diamine, o-toluidine, methylamine, and diethylamine, and acetaldehyde, crotonaldehyde, citral, acetaldol, and cinnamic aldehyde. Polymerized aldehydes, e.g. para- and meta-aldehydes may also be used. The condensation may be carried out in the presence or absence of acids or acidic substances, e.g. acetic, propionic, n-butyric, stearic, oleic, salicylic, picric, hydrochloric, phosphoric or sulphuric acids, zinc chloride, or acid anhydrides or acid halides. The amount of acid used is preferably between 0.05 and 0.3 molecular proportions for each molecular proportion of amine used, and the acid may be provided by using a portion of the amine in the form of a salt. Inert solvents may also be present. The products obtained by condensing primary amines in the presence of organic acids with alpha-#-saturated aliphatic aldehydes give the best results as vulcanization accelerators. The condensation of heptaldehyde (2 molecules) with n-butylamine in the absence of a condensing agent is described in an example, and the products obtained with varying molecular proportions of aldehyde, up to 15, are tabulated for propionaldehyde and aniline, and crotonaldehyde and ethylaniline in addition to the products mentioned, above. The properties of the following condensation products, obtained without condensing agents, are also described, the numbers in brackets giving the molecular proportions of aldehyde to amine : acetaldehyde-aniline (5 : 1), n-butyraldehyde-guanidine (5: 1), n-butyraldehyde-ethylamine (5: 1), n-butyraldehyde-diethylamine (5 : 1), n-butyraldehyde ethylaniline (5 : 1), n-butyraldehyde-methylamine (10: 1), n-butyraldehyde-ethylene-diamine (10: 1), nbutyraldehyde-ethylamine (15 : 1), heptaldehydeethylamine (5 : 1), heptaldehyde-o-tolyldiguanide (5: 1), acetaldol-ethylamine (5: 1), acetaldol-nbutylamine (5 : 1), acetaldol-o-tolyldiguanide (5 : 1), crotonaldehyde-aniline (5: 1) and citralo-tolyldiguanide (5: 1). As an example of the use of an acidic condensing agent, the preparation of n-butyraldehyde-aniline (5: 1) in the presence of butyric acid is described, and tables, showing the effect of varying quantities of acid on the progress of the reaction and on the tensile strength of the rubber vulcanized by the product are given. The products obtained by replacing butyric by stearic and sulphuric acids, and by condensing heptaldehyde (3 molecules) with nbutylamine in the presence of n-valeric acid, are also described. The aldehyde may also be used in excess of the amount desired in the product, the excess being removed by distillation. In examples of this modification, the condensation of n-butyraldehyde with aniline or o-toulidine in presence of n-butyric or acetic acid is described. The effect of using acid condensing agents is also shown 'by tabulating the properties of rubber vulcanized with the following condensation products :-butyraldehyde-aniline, in presence of n-butyric, acetic or propionic acid; heptaldehyde with o-tolyldiguanide or ethylamine, in presence of oenanthylic acid: propionaldehyde with aniline, in presence of propionic acid; and heptaldehyde with n-butylamine, in presence of valeric acid. This subject-matter does not appear in the Specification as accepted, but is in part claimed in Specification 263,853.