Patent GB-886811-A (GB)
Title: Method of making a latent-foaming polymeric composition
IPC: B29C44/34
Filed: 1958-11-28
Abstract: Latent foaming polymeric compositions are obtained by supplying a homogeneously heat plastified mass of a vinyl aromatic polymer derived from a predominant amount of at least one monovinyl compound of the benzene series 0,05 to 0,3 gram molecular proportion of a volatile organic compound selected from saturated aliphatic hydrocarbons and perchlorofluorocarbons of boiling point not above 95 DEG  C. and mol. wt. at least 58 under super atmospheric pressure and a temperature between 160 DEG  and 280 DEG  C., advancing the mass towards an extrusion orifice, cooling and blending the mass during the advance to a uniform temperature, extruding into a zone of atmospheric pressure and immediately contacting with an inert coolant to cool to below 50 DEG  C., and which may then be heat treated to improve the foaming characteristics.  Such treatment is at a temperature of 50 DEG  to 75 DEG  C. for 2 to 180 minutes.  Specified polymers are those derived from styrene, vinyl toluene, vinyl xylene, ethyl vinyl benzene, isopropyl styrene, ar ethyl vinyl toluene, di tert. butyl styrene, and chloro-, dichloro-, bromo-, or fluoro-styrene; or isopolymers of 99,9% to 99,99% of one or more of such compounds and 0,1% to 0,01% of divinyl benzene, ethyl divinyl benzene, divinyltoluene or divinylxylene; or copolymer of one or more aromatic vinyl compounds with either an alkenyl aromatic compounds, e.g. a -methyl styrene, p-methyl, a -methyl styrene or a -ethyl styrene; or with acrylonitrile, methyl methacrylate, acrylic or methacrylic acid.  Specified volatile compounds are butane; n-iso- and neo-pentane; hexanes; heptanes; trichloro fluoro-; dichloro difluoro and chlorotrifluoro-methane; sym tetrachloro difluoroethane; 1 chloro 1, 1, 2, 2, 2, pentafluoro ethane; 1 chloro 1, 2, 2, 3, 3, 4, 4 hepta fluoro cyclobutane; and 1, 2, dichloro, 1, 2, 3, 3, 4, 4, hexafluoro cyclobutane and may be used singly or in admixture.  0,02% to 5%, relative to the polymer, of additive, e.g. plasticizer, lubricants (white mineral oil) dyes, light stabilizers, antioxidants and flame proofers (acetylene tetrabromide) can also be included. Specification 695,826 is referred to.ALSO:Latent foaming polymeric compositions are obtained by supplying a homogeneously heat plastified mass of a vinyl aromatic polymer derived from a predominant amount of at least one monovinyl compound of the benzene series and 0,05 to 0,3 gram molecular proportion of a volatile organic compound selected from saturated aliphatic hydrocarbons and perchlorofluorocarbons of boiling point not above 95 DEG C and Mol. wt. at least 58 under super atmospheric pressure and a temperature between 160 DEG  and 280 DEG C., advancing the mass toward an intrusion orifice, cooling and blending the mass during the advance to an uniform temperature, extruding into a zone of atmospheric pressure and almost immediately contacting with an inert coolant to cool to below 50 DEG C., and which may then be heat treated to improve the foaming characteristics.  Such treatment is at temperatures of 50 DEG  to 75 DEG C. for 2 to 180 minutes.  The compositions may be prefoamed before final foaming and may contain 0,02% to 5%, relative to the polymer of plasticizers, lubricants e.g. white mineral oil, dyes, light stabilizers, auti-oxidants and flame proofers e.g. acetylene tetrabromide.  Specification 695,826 is referred to.