Patent GB-575541-A (GB)
Title: Improvements in or relating to the plasticising and softening of rubber and synthetic rubber-like materials
IPC: C08K5/372
Filed: 1943-12-09
Abstract: Synthetic rubber-like materials such as vinyl chloride polymers, chloroprene polymers, polymerized diolefines, isobutylene polymers, copolymers of diolefines and olefines, and organic polysulphides are plasticised by means of a thiodipropionic acid ester having the following structural formula <FORM:0575541/IV/1> in which R and R1 are the same or different alkyl (including alicyclic) arylalkyl or aryl groups.  In the case of alkyl groups, the carbon chain should preferably not exceed 6 carbon atoms in length.  In an example for the preparation of a thiodipropionic acid ester, 1 mol. of b b , thiodipropionitrile is stirred and refluxed for five hours with 10 mols. of n-butanol and 2 mols. of concentrated sulphuric acid. Excess butanol is removed under reduced pressure, and after neutralization, washing and drying the resulting dibutyl thiodihydroacrylate is distilled in vacuo.  In an example, ditetrahydrofurfuryl thiodihydroacrylate is prepared by refluxing .6 mol. of b b , thiodipropionic acid, 1.32 mols. of tetrahydrofurfuryl alcohol and .01 mol. of sulphuric acid with sufficient toluene to keep the boiling point of the mixture below 145 DEG  C. until the acid strength of the reacting solution becomes less than N/10 ; then cooling, neutralizing, washing, drying and redistilling the product. The plasticiser may be added during the rolling process (in general, 5-50 per cent being used), the heated mixture being incorporated till a satisfactory sheet is formed.  When two or more rubber-like materials are to be mixed, the tougher is preferably first treated with sufficient plasticiser to render it about as soft as the softer component. Other substances which may be added include channel black, zinc oxide, sulphur, stearic acid, phenyl b -naphthylamine, benzothiazyl disulphide, zinc chloride di-o-tolylguanidine reaction product, pigments and dyes.  The compositions may be calendered, extruded, moulded or used in the production of waterproof fabrics. Specification 531,721 is referred to.ALSO:Rubber and synthetic rubber-like materials are plasticised by means of a thiodipropionic acid ester having the following structural formula:- <FORM:0575541/V/1> in which R and R1 are the same or different alkyl (including alicyclic) arylalkyl or aryl groups.  In the case of alkyl groups, the carbon chain should preferably not exceed 6 atoms in length. The synthetic rubber-like materials may be vinyl chloride polymers, chloroprene polymers, polymerized diolefines, isobutylene polymers, copolymers of diolefines and olefines, organic polysulphides, polyacrylic and polyvinyl copolymers such as the copolymers of butadiene with acrylonitrile or styrene and the like. In an example for the preparation of a thiodipropionic acid ester, 1 mol. of b b 1 thiodipropionitrile is stirred and refluxed for 5 hours with 10 mols of n-butanol and 2 mols of concentrated sulphuric acid. Excess butanol is removed under reduced pressure and after neutralisation, washing and drying the resulting dibutyl thiodihydrocrylate is distilled in vacuo.  In a second example ditetrahydrofurfuryl thiodihydracrylate is prepared by refluxing .6 mol of b b 1 thiodipropionic acid, 1.32 mols of tetrahydrofurfuryl alcohol and .01 mol of sulphuric acid with sufficient toluene to keep the boiling point of the mixture below 145 DEG  C. until the acid strength of the reacting solution becomes less than N/10 , then cooling, neutralising, washing, drying and redistilling the product. The plasticizer may be added during the rolling process (for natural rubber about 1-10 per cent by weight is sufficient, but in the case of synthetic materials over 50 per cent may be required) the heated mixture being incorporated till a satisfactory sheet is formed. When two or more rubber-like materials are to be mixed the tougher is preferably first treated with sufficient plasticizer to render it about as soft as the softer component.  Other substances which may be added include channel black, zinc oxide, sulphur, stearic acid, phenyl b -naphthylamine, benzothiazyl disulphide, zinc chloride-di-o-tolylguanidine reaction product, pigments and dyes. The compositions may be calendered, extruded, moulded or used in the production of waterproof fabrics.  Specification 531,721 is referred to.