Patent GB-413296-A (GB)
Title: Improvements in or relating to the manufacture of vulcanised rubber
IPC: C08K5/00
Filed: 1932-11-10
Abstract: Vulcanization accelerators for incorporation in india-rubber compositions comprise condensation products, other than salts, obtained by reaction of a compound of the guanide or guanidine class with an accelerator of the disulphide class.  Such products are obtainable also by the action of the guanidine or guanide upon the disulphide formed in situ from the corresponding thiol accelerator in presence of an oxidizing agent such as iodine, sodium hypochlorite or atmospheric oxygen.  The following examples of the production of the accelerators are given.  (1) p  Diphenylguanidine (1 mol.) and mercaptobenzothiazole (1 mol.) are dissolved in toluene and an excess of a solution of sodium hypochlorite is slowly added with cooling; the mixture is well shaken for several hours and then heated under reflux for 2--3 hours and filtered hot; the toluene is then evaporated off and the residue boiled with water and washed with dilute hydrochloric acid to remove uncombined diphenylguanidine and then with dilute caustic soda to remove uncombined mercaptobenzothiazole; the product is assumed to be of the constitution <FORM:0413296/IV/1> Diphenylguanidine (2 mols.) and 2 : 2<1>-dibenzthiazyldisulphide (1 mol.) are boiled in toluene for 1\ba1/2\be hours under reflux and the precipitated salt is filtered off; the filtrate is then evaporated and the residue is washed and extracted with hot water.  (3) Diphenylguanidine (2 mols.) is similarly condensed with tetramethylthiuramdisulphide (1 mol.).  (4) Diphenylguanidine (2 mols.) is similarly condensed with tetraethylthiuramdisulphide (1 mol.).  (5) Diphenylguanidine (2 mols.) is similarly condensed with dipentamethylenethiuramdisulphide (1 mol.).  (6) Diphenylguanidine (2 mols.) is similarly condensed with di-isopropylxanthogen disulphide (1 mol.).  (7) Diphenylguanidine (2 mols.) is similarly condensed with dithiofuroyldisulphide (1 mol.).  (8) Diphenylguanidine is similarly condensed with dithiofuroic acid which is oxidized in the course of the reaction.  (9) Diphenylguanidine (2 mols.) is similarly condensed with dibenzoyldisulphide (1 mol.).  A table is also given showing the time required for incipient vulcanization at temperatures of 100--160 DEG  C. with the use of 1 per cent of the various accelerators obtained in accordance with the above examples.  The first Provisional Specification includes also an example of the preparation and use of a condensation product from 2 : 2<1>-dibenzthiazyldisulphide (1 mol.) and di-o-tolylguanidine (2 mols.).  Dipentamethylenethiuram disulphide is obtained by oxidation of piperidine-pentamethylenedithiocarbamate, e.g. with iodine. Di-isopropylxanthogen disulphide is similarly obtained by oxidation of potassium isopropylxanthogenate.  Dithiofuroyl disulphide is similarly obtained by oxidation of dithiofuroic acid.  Dithiofuroic acid is obtained by interaction of furfural with ammonium polysulphide.ALSO:Vulcanization accelerators for incorporation in indiarubber compositions comprise condensation products, other than salts, obtained by reaction of a compound of the guanide or guanidine class with an accelerator of the disulphide class.  Such products are obtainable also by the action of the guanidine or guanide upon the disulphide formed in situ from the corresponding thiol accelerator in presence of an oxidizing agent such as iodine, sodium hypochlorite or atmospheric oxygen.  The following examples of the production of the accelerators are given.  (1) Diphenylguanidine (1 mol.) and mercaptobenzothiazole (1 mol.) are dissolved in toluene and an excess of a solution of sodium hypochlorite is slowly added with cooling; the mixture is well shaken for several hours and then heated under reflux for 2-3 hours and filtered hot; the toluene is then evaporated off and the residue boiled with water and washed with dilute hydrochloric acid to remove uncombined diphenylguanidine and then with dilute caustic soda to remove uncombined mercaptobenzothiazole; the product is assumed to be of the constitution <FORM:0413296/V/1> (2) Diphenylguanidine (2 mols.) and 2 : 21-dibenzthiazyldisulphide (1 mol.) are boiled in toluene for 1 1/2 hours under reflux and the precipitated salt is filtered off; the filtrate is then evaporated and the residue is washed and extracted with hot water.  (3) Diphenylguanidine (2 mols.) is similarly condensed with tetramethylthiuramdisulphide (1 mol.).  (4) Diphenylguanidine (2 mols.) is similarly condensed with tetraethylthiuramdisulphide (1 mol.).  (5) Diphenylguanidine (2 mols.) is similarly condensed with dipentamethylenethiuramdisulphide (1 mol.).  (6) Diphenylguanidine (2 mols.) is similarly condensed with di-isopropylxanthogen disulphide (1 mol.).  (7) Diphenylguanidine (2 mols.) is similarly condensed with dithiofuroyldisulphide (1 mol.).  (8) Diphenylguanidine is similarly condensed with dithiofuroic acid which is oxidized in the course of the reaction. (9) Diphenylguanidine (2 mols.) is similarly condensed with dibenzoyldisulphide (1 mol.).  A table is also given showing the time required for incipient vulcanization at temperatures of 100-160 DEG  C. with the use of 1 per cent of the various accelerators obtained in accordance with the above examples.  The first Provisional Specification includes also an example of the preparations and use of a condensation product from 2 : 21-dibenzthiazyldisulphide (1 mol.) and di-o-tolylguanidine (2 mols.).  Dipentamethylenethiuram disulphide is obtained by oxidation of piperidine-pentamethylenedithiocarbamate, e.g. with iodine. Di-isopropylxanthogen disulphide is similarly obtained by oxidation of potassium isopropylxanthogenate.  Dithiofuroyl disulphide is similarly obtained by oxidation of dithiofuroic acid.  Dithiofuroic acid is obtained by interaction of furfural with ammonium polysulphide.