Patent GB-715314-A (GB)
Title: Plasticizing agents for rubber
IPC: C08K5/37
Filed: 1950-12-27
Abstract: The invention comprises compositions of a synthetic rubber-like butadiene polymer or a vulcanisate thereof and a pentasubstituted thiophenol or derivative thereof of the general formula R-S-X wherein R stands for C6Cl5 or C6Cl4.alkwhere "alk" represents an alkyl group and X stands for hydrogen, -ZnSR, -CO.SR, a radical of the type R3CO where R3 is an aliphatic or aromatic group, a radical of a sulphonic or thiocarbamic acid, -SnR (n = 1 or 2) a lower cyanoalkyl group (alkyl = C1 to C4) or the group <FORM:0715314/IV (a)/1> wherein R1 is hydrogen or alkyl and R2 is hydrogen, alkyl or aryl.  By "synthetic rubber-like butadiene polymers" are meant polymers of butadiene or its homologues such as isoprene and dimethylbutadiene as well as copolymers of these compounds with other polymerisable compounds such as styrene or acrylonitrile.  The plasticising agents may be used in combination with wetting agents.  The plasticising effect may result at temperatures of 80 to 95 DEG C. and upwards. Other plasticising agents of the above formula specifically mentioned are tetrachloromethyl- or ethyl-thiophenols, dipentachlorophenyl di- and tri-sulphides, the zinc salt of pentachlorothiophenol, S-benzoylpentachlorothiophenol and other S-aryl derivatives from aliphatic mono- and dicarboxylic acids, other (including halogen-substituted) aromatic acids such as aryl derivatives from acetic acid, propionic acid, fatty acids from the oxidation of petroleum hydrocarbons, stearic acid, oxalic acid, and 2, 5-dichlorobenzoic acid; pentachlorothiophenyl phthalic acid monomethyl ester, formaldehyde bis-pentachlorophenyl mercaptal, benzaldehyde-bispentachlorophenyl mercaptal, N-phenyl-S-pentachlorophenyl thiourethane, hexamethylene-di-(S-pentachlorophenyl-thiourethane), di-S-pentachlorophenyl-di-thio-carbonic ester, di-S-pentachlorophenyl-thio-oxalic ester, S-pentachlorophenyl-thio-acetonitrile, and pentachlorothiophenyl naphthalene carboxylic ester.ALSO:The Specification comprises thiophenols and their derivatives of the formula R-S-X in which R stands for C6C5l-, or C6Cl4alk.-, where "alk." represents an alkyl group, and X stands for hydrogen or the group -ZnSR, -CO-SR, a radical of the type R3CO (where R3 is an aliphatic or aromatic group), a radical of sulphonic or thiocarbamic acids, -SnR (n = 1 or 2), a lower cyanoalkyl group (alkyl = C1 to C4), or the group <FORM:0715314/IV (b)/1> wherein R1 is hydrogen or alkyl, and R2 is hydrogen, alkyl or aryl.  The chains of the alkyl radicals may be interrupted by hetero atoms and the aryl radicals may be substituted. The thiophenols are prepared by reacting penta-substituted thiophenols containing as substituents five chlorine atoms or four chlorine atoms and one alkyl group with alkali metal disulphides in the presence of an organic solvent containing at least one alcoholic hydroxyl group.  Reaction temperatures between 70 DEG  C. and 140 DEG C., preferably 80-100 DEG  C., are suitable, and the reaction is preferably effected under anhydrous conditions.  For quantitative reaction of the substituted thiophenol the alkali metal must be employed in at least 2.7 times the theoretical amount.  Suitable solvents are alcohols, e.g. methanol ethanol, propanol, butanol, ethylene glycol, butylene glycol, or mono-ethers of di- and polyhydroxy alcohols.  From the alkali- and alkaline earth metal salts of the penta-substituted thiophenols are obtained the disulphides by reaction with oxidizing agents, e.g. hydrogen peroxide, sodium hypochlorite, chlorine, potassium ferricyanide or air (in alkaline solution).  The trisulphides are obtained by reacting the penta-substituted thiophenol with sulphur dichloride. The zinc salts are obtained by reacting the sodium salts of the pentasubstituted thiophenols with ammoniacal zinc chloride solution. From the penta-substituted thio phenols there are also prepared the acyl compounds (by reaction with acyl chlorides or anhydrides), the thioacetals (by reaction with aldehydes and ketones in the presence e.g. of hydrochloric acid or zinc chloride), the thiourethanes (by fusion with isocyanates), and the alkyl ethers (by reaction with alkylating agents, e.g. dialkyl sulphates).  Reaction of the penta-substituted thiophenols may also be effected with compounds containing reactive halogen atoms, e.g. cyanogen chloride or bromide, chloro-acetonitrile, chloracetic acid or its esters and 2-chloro-benzothiazole.  In examples there are prepared (1) pentachlorothiophenol by reaction in methanol of hexachlorobenzene, sodium sulphide, and sulphur followed by precipitation with sulphur dioxide. Pentachloro-alkyl-benzenes, e.g. pentachlortoluene or ethyl benzene may be reacted similarly; (2) di-pentachlorophenyl-disulphide by oxidation of an alkaline solution of pentachloro-thiophenol with potassium ferricyanide, air, hydrogen peroxide or sodium hypochlorite; (3) bis - pentachloro - phenyl - trisulphide from pentachloro-thiophenol and sulphur dichloride; (4) the zinc salt of pentachloro-thiophenol; (5) S - benzoyl - pentachloro - thiophenol from pentachloro-thiophenol and benzoyl chloride.  S-acyl derivatives from aliphatic mono- or dicarboxylic acids, other (including halogen-substituted) aromatic acids, e.g. from acetic acid, propionic acid, fatty acids of about C8 to C12 from petroleum hydrocarbon oxidation, stearic acid and oxalic acid, are obtained similarly. Further examples illustrate compositions of the products with natural and synthetic rubber (see Groups IV (a) and V).  Additional compounds specified are S - acetyl - and S - 2,5 - dichloro-benzoyl-pentachloro-thiophenols, pentachlorothiophenyl phthalic acid-monomethyl ester, benzenesulphonic acid - pentachlorothiophenyl ester, formaldehyde bis - pentachlorophenyl mercaptal, benzaldehyde - bis - pentachlorophenyl mercaptal, N - phenyl - S - pentachlorophenyl thiourethane, hexamethylene-di - (S - pentachlorophenyl thiourethane), di-S - pentachlorophenyl - di - thio - carbonic ester, di - S - pentachloro - phenyl - thio - oxalic ester, S - pentachloro - phenyl - thio - acetonitrile and pentachloro-thiophenyl naphthalene carboxylic ester.ALSO:The invention comprises plasticizing rubber with a pentasubstituted thiophenol or derivative thereof of the general formula R-S-X wherein R stands for C6Cl5- or C6Cl4 alk.- where "alk." represents an alkyl group and X stands for hydrogen, -ZnSR, -COSR, a radical of the type R3CO where R3 is an aliphatic or aromatic group, a radical of a sulphonic or thiocarbamic acid, SnR (n=1 or 2), a lower cyanoalkyl group (alkyl=C1 to C4) or the group <FORM:0715314/V/1> wherein R1 is hydrogen or alkyl, and R2 is hydrogen, alkyl or aryl.  The plasticizing agents may also be incorporated into the latex as obtained from the trees or into the stabilized latex.  They may be used in combination with wetting-agents. Quantities of 0.1 to 0.5 per cent. based on the rubber content are suitable.  Plasticization temperatures of 80 to 150 DEG C. are mentioned.  Particularly suitable for application to latex are the free mercaptans, the di- and trisulphides, the S-acyl derivatives and the zinc salts. Examples describe determinations of the plasticity after given times of smoked sheets masticated at temperatures of from 120 DEG C. to 150 DEG C. with (6) pentachlorothiophenol and 1.2.4-trichlorothiophenol; (9) S-benzoyl-pentachlorothiophenol and the zinc salt of the pentachlorothiophenol; (10) S-acetyl-pentachlorothiophenol, S-2.5-dichlorobenzoyl-pentachlorothiophenol, di-pentachlorophenyl disulphide, di-pentachlorophenyl trisulphide, and pentachlorothiophenylphthalic acid monomethyl ester; (11) benzene sulphonic acid pentachlorothiophenyl ester, formaldehyde-bispentachlorophenyl mercaptal, benzaldehyde bispentachlorophenyl mercaptal; (12) ethyl-tetrachlorophenyl mercaptan and its zinc salt, N-phenyl-S-pentachlorophenyl thio-urethane, hexamethylene di-(s-pentachlorophenyl thio-urethane), di-S-pentachlorophenyl-di-thio-carbonic ester, di-S-pentachlorophenyl-thio-oxalic ester, and S-pentachlorophenyl-thio-acetonitrile.  Also mentioned are pentachlorothiophenyl propionic ester, esters of pentachlorothiophenol with fatty acids from the oxidation of petroleum hydrocarbons, pentachlorothiophenyl oleic ester pentachlorothiophenyl naphthalene carboxylic ester, butyl-cyclo-hexyl- and iso-octyl-tetra-chloro-thiophenols.  The preparation of the plasticizing agents is described (see Group IV (b)).  They are also suitable for the plasticization of synthetic rubber-like butadiene polymers (see Group IV (a)).