Patent GB-436944-A (GB)
Title: Production of powdered substances
IPC: B29B9/00
Filed: 1934-03-22
Abstract: Substances which are difficult to disintegrate such as chlorinated rubber and cellulose esters and ethers are obtained in finely powdered form by first forming a dispersion of a non-solvent, e.g. water in a solution of the substance, gradually adding more non-solvent in the presence of a hydrophilic colloid, e.g. ammonium or potassium oleate, until the phase is inverted, i.e. a dispersion of the solution in the non-solvent is obtained, removing the solvent without breaking the dispersion, and separating the finely divided substance from the non-solvent.  The solvent may be removed by evaporation or by introducing a liquid in which the material is insoluble but in which the solvent and non-solvent are soluble.  In an example, a solution of 25 parts of chlorinated rubber in 45 parts of benzene containing 1 part of oleic acid is mixed with 50 parts of water to obtain an emulsion of the water in the solution, the emulsion containing potassium oleate.  The emulsion is then gradually diluted with 100 parts of water and the phase is inverted.  The inverted emulsion is warmed with constant stirring until all the benzene is evaporated and the suspension is flocculated by the addition of dilute acetic acid and the precipitate is filtered, washed and dried.  In another example 220 parts of the inverted emulsion are added gradually with constant stirring to 400 parts of cold alcohol and the precipitate is filtered off.  In another example, 10 parts of benzyl cellulose are dissolved in 45 parts of benzene containing 1 part of oleic acid.  50 parts of water containing ,2 parts of ammonia is slowly stirred in drop by drop to produce first a dispersion of the water in the solution and finally a dispersion of the solution in water.  The dispersion is diluted with a further 100 parts of water and the dilute dispersion is added drop by drop to 320 parts of alcohol.  The precipitated benzyl cellulose powder is filtered off and dried by exposure to the air. Other examples are given.  Specifications 414,862, 416,056, and 418,068, [all in Group V], are referred to.ALSO:Substances which are difficult to disintegrate such as chlorinated rubber and cellulose esters and ethers are obtained in finely powdered form by first forming a dispersion of a non-solvent, e.g. water in a solution of the substance, gradually adding more non-solvent in the presence of a hydrophilic colloid, e.g. ammonium or potassium oleate, until the phase is inverted, i.e. a dispersion of the solution in the non-solvent is obtained, removing the solvent without breaking the dispersion, and separating the finely divided substance from the non-solvent.  The solvent may be removed by evaporation or by introducing a liquid in which the material is insoluble but in which the solvent and non-solvent are soluble.  In an example, a solution of 25 parts of chlorinated rubber in 45 parts of benzene containing 1 part of oleic acid is mixed with 50 parts of water to obtain an emulsion of the water in the solution, the emulsion containing potassium oleate.  The emulsion is then gradually diluted with 100 parts of water and the phase is inverted.  The inverted emulsion is warmed with constant stirring until all the benzene is evaporated and the suspension is flocculated by the addition of dilute acetic acid and the precipitate is filtered, washed and dried.  In another example 220 parts of the inverted emulsion are added gradually with constant stirring to 400 parts of cold alcohol and the precipitate is filtered off.  In another example, 10 parts of benzyl cellulose are dissolved in 45 parts of benzene containing 1 part of oleic acid.  50 parts of water containing ,2 parts of ammonia is slowly stirred in drop by drop to produce first a dispersion of the water in the solution and finally a dispersion of the solution in water.  The dispersion is diluted with a further 100 parts of water and the dilute dispersion is added drop by drop to 320 parts of alcohol.  The precipitated benzyl cellulose powder is filtered off and dried by exposure to the air. Other examples are given.  Specifications 414,862, 416,056, and 418,068 are referred to.ALSO:Substances which are difficult to disintegrate such as chlorinated rubber and cellulose esters and ethers are obtained in finely powdered form by first forming a dispersion of a non-solvent, e.g. water in a solution of the substance, gradually adding more non-solvent in the presence of a hydrophilic colloid, e.g. ammonium or potassium oleate, until the phase is inverted, i.e. a dispersion of the solution in the non-solvent is obtained, removing the solvent without breaking the dispersion, and separating the finely divided substance from the non-solvent.  The solvent may be removed by evaporation or by introducing a liquid in which the material is insoluble but in which the solvent and non-solvent are soluble.  In an example, a solution of 25 parts of chlorinated rubber in 45 parts of benzene containing 1 part of oleic acid is mixed with 50 parts of water to obtain an emulsion of the water in the solution, the emulsion containing potassium oleate.  The emulsion is then gradually diluted with 100 parts of water and the phase is inverted.  The inverted emulsion is warmed with constant stirring until all the benzene is evaporated and the suspension is flocculated by the addition of dilute acetic acid and the precipitate is filtered, washed and dried.  In another example, 220 parts of the inverted emulsion are added gradually with constant stirring to 400 parts of cold alcohol and the precipitate is filtered off.  In another example, 10 parts of benzyl cellulose are dissolved in 45 parts of benzene containing 1 part of oleic acid.  50 parts of water containing .2 parts of ammonia is slowly stirred in drop by drop to produce first a dispersion of the water in the solution and finally a dispersion of the solution in water.  The dispersion is diluted with a further 100 parts of water and the dilute dispersion is added drop by drop to 320 parts of alcohol.  The precipitated benzyl cellulose powder is filtered off and dried by exposure to the air. p  Other examples are given.  Specifications 414,862, 416,056, 418,068, and 418,069, are referred to.