Patent GB-582700-A (GB)
Title: Improvements in and relating to the concentration of aqueous dispersions of neoprenes
IPC: C08C1/08
Filed: 1944-09-25
Abstract: A process for concentrating a neoprene in aqueous dispersion wherein the neoprene particles are negatively charged, which dispersion contains from 0-2.5 per cent based on the weight of the dispersed phase of an alcohol or ketone or a mixture of the two, having a water solubility of about 1 to 20 per cent, comprises adding to such dispersion an amount of water-soluble alginate determined by the formula A=KB (3-C) (70-D), where A is the amount of the alginate in parts by weight, B is the amount of the aqueous phase in parts by weight, C is the amount of the alcohol or ketone or mixture thereof in per cent of the dispersed phase, D is the amount of the dispersed phase in per cent of the dispersion, and K is a coefficient whose value is within the range 0.00002 to 0.00010.  The alginate is preferably the ammonium, sodium or potassium salt and is used in 0.5 to 1.0 per cent aqueous solution.  The particles of neoprene in the dispersion are charged negatively by adding any water-soluble salt having an anionic solubilising group such as the ammonium, sodium or potassium salt of oleic, abietic, alkyl naphthalene sulphonic, dinaphthyl methane sulphonic, and long-chain alkyl sulphuric acids. The alcohols or ketones which are preferably cyclohexanol, n - butanol, n - octanol, methylcyclohexanol, methyl - cyclohexanone, n - hexanol, benzyl alcohol, methyl butyl ketone and diethyl ketone may be added either before, during or after polymerization of the chloroprene.  In an example, chloroprene is polymerized with sulphur to give a 50 per cent dispersion in the presence of 2 per cent of cyclohexanol resin, caustic soda, ammonium persulphate, C-cetyl betaine and dinaphthylmethane sodium sulphonate.  Diethanolamine was added and the dispersion creamed with the calculated quantity of ammonium alginate solution.  After standing two layers separated, the lower being a dispersion containing 60 per cent solids.  In another example, the ammonium alginate is mixed with the salts of the sulphation product of a mixture of straight-chain primary aliphatic alcohols with an average chain length of 13 carbon atoms.  Other surface active agents which may be used include sodium dibutyl dithiocarbonate and the alkalis.  In a further example, the process was rendered continuous by constantly removing the denser portion by a centrifuge.  The process is preferably carried out at a temperature of 15-30 DEG  C., higher quantities of reagents being required above 25 DEG  C.ALSO:A process for concentrating a neoprene in aqueous dispersion wherein the neoprene particles are negatively charged, which dispersion contains from 0-2.5 per cent. based on the weight of the dispersed phase of an alcohol or ketone or a mixture of the two, having a water solubility of about 1 to 20 per cent., comprises adding to such dispersion an amount of a water soluble alginate determined by the formula A= KB(3-C) (70-D) where A is the amount of the alginate in parts by weight, B is the amount of the aqueous phase in parts by weight, C is the amount of the alcohol or ketone or mixture thereof in per cent. of the dispersed phase, D is the amount of the dispersed phase in per cent. of the dispersion, and K is a coefficient whose value is within the range 0.00002 to 0.0001.  The alginate is preferably the ammonium, sodium or potassium salt and is used in 0.5 to 1.0 per cent. aqueous solution.  The particles of neoprene in the dispersion are charged negatively by adding any water soluble salt having an anionic solubilising group such as the ammonium, sodium or potassium salt of oleic, abietic, alkyl naphthalene sulphonic, dinaphthyl methane sulphonic and long chain alkyl sulphuric acids. The alcohols or ketones which are preferably cyclohexanol, n-butanol, n-octanol, methyl cyclohexanol, methyl-cyclohexanone, n-hexanol, benzyl alcohol, methyl butyl ketone and diethyl ketone may be added either before, during or after polymerisation of the chloroprene.  In an example, chloroprene is polymerized with sulphur to give a 50 per cent. dispersion in the presence of 2 per cent. of cyclohexanol, resin, caustic soda, ammonium persulphate, C-cetyl betaine and dinaphthylmethane sodium sulphonate. Diethanolamine was added and the dispersion creamed with the calculated quantity of ammonium alginate solution.  After standing two layers separated the lower being a dispersion containing 60 per cent. solids.  In another example, the ammonium alginate is mixed with the salts of the sulphation product of a mixture of straightchain primary aliphatic alcohols with an average chain length of 13 carbon atoms, other surface active agents which may be used include sodium dibutyl dithiocarbamate and the alkalis. In a further example the process was rendered continuous by constantly removing the denser portion by a centrifuge.  The process is preferably carried out at a temperature of 15-30 DEG C., higher quantities of reagents are required above 25 DEG C.