Patent GB-586973-A (GB)
Title: Improvements relating to plasticized synthetic rubber and methods of making the same
IPC: H01J23/07
Filed: 1944-08-02
Abstract: Synthetic rubbers, such as copolymers of butadiene with acrylonitrile or styrene, are plasticised by preparing a mixed emulsion of a synthetic rubber and an unsaturated hydrocarbon material boiling above 160 DEG  C. and preferably above 190 DEG  C. at 12 mms. Hg., and containing at least 40 per cent of hydrocarbons soluble in concentrated or fuming sulphuric acid, co-coagulating the emulsion and removing the precipitated coagulum.  The preferred unsaturated hydrocarbons which have empirical formul  of C3H4 and a molecular weight of 300-1000 and an iodine number of 20-60, preferably of 40-60, are derived from the refining of mineral oils, particularly those obtained from the residues after treatment with sulphuric acid or selective solvents such as furfural, phenol, cresol, dichlordiethyl ether or mixtures of liquid SO2 with various organic solvents including benzol.  These residues are neutralized if necessary and then distilled at 12 mms. Hg., the fraction boiling above 160 DEG  C. and below about 360 DEG  C. being utilised, such materials are known under the trade name of "Naftolen."  Unsaturated hydrocarbons with the above properties derived from cracked petroleums, petroleums with a naturally high content of unsaturates, asphaltic petroleums, coal tar and pine tars are also suitable.  The unsaturated hydrocarbon is preferably heated to 80 DEG  C. and an emulsifying agent such as a sodium or potassium salt of oleic, stearic or palmitic acid, a sulphonate salt or alcohol added and the mixture rapidly stirred into hot water to produce an emulsion. Stabilizing agents such as ammoniacal casein may be added if desired. This emulsion is mixed with the synthetic rubber emulsion and the mixture coagulated with acetic acid or aluminium sulphate solution preferably by pouring the desired solution into a suitable coagulator, removing as much water as possible and then forcing the coagulum through small apertures to facilitate washing.  The product may be dried at 170 DEG  C. for 24 hours.  From 3-90 parts of hydrocarbon may be used to each 100 parts of synthetic rubber. Natural rubber latex may be added to the synthetic rubber at the coagulating stage to produce an especially tacky product.ALSO:Synthetic rubbers, such as polymers of chloroprene and copolymers of butadiene with acrylonitrile or styrene, are plasticized by preparing a mixed emulsion of a synthetic rubber and an unsaturated hydrocarbon material boiling above 160 DEG C. and preferably above 190 DEG C. at 12 mms Hg., and containing at least 40 per cent. of hydrocarbons soluble in concentrated or fuming sulphuric acid, co-coagulating the emulsion and removing the precipitated coagulum.  The preferred unsaturated hydrocarbons which have empirical formulae or C3H4 and a molecular weight of 300-1000 and an iodine number of 20-60, preferably of 40-60, are derived from the refining of mineral oils, particularly those obtained from the residues after treatment with sulphuric acid or selective solvents such as, furfural, phenol, cresol, dichlordiethyl ether or mixtures of liquid SO2 with various organic solvents including benzol.  These residues are neutralized if necessary and then distilled at 12 mms Hg, the fraction boiling above 160 DEG C. and below about 360 DEG C. being utilised, such materials are known under the trade name of "Naftolen."  Unsaturated hydrocarbons with the above properties derived from cracked petroleums, petroleums with a naturally high content of unsaturates, asphaltic petroleums, coal tar and pine tars are also suitable.  The unsaturated hydrocarbon is preferably heated to 80 DEG C., and an emulsifying agent such as a sodium or potassium salt of oleic, stearic or palmitic acid, a sulphonate salt or alcohol added and the mixture rapidly stirred into hot water to produce an emulsion.  Stabilizing agents such as ammoniacal casein may be added if desired.  This emulsion is mixed with the synthetic rubber emulsion and the mixture coagulated with acetic acid or aluminium sulphate solution preferably by pouring the desired solution into a suitable coagulator removing as much water as possible and then forcing the coagulum through small apertures to facilitate washing. The product may be dried at 170 DEG C. for 24 hours and used for tyre treads, mechanical goods and oil resistant hose.  From 3-90 parts of hydrocarbon may be used to each 100 parts of synthetic rubber. Natural rubber latex may be added to the synthetic rubber at the coagulating stage to produce an especially tacky product.