Patent GB-1030013-A (GB)
Title: Production of granular expandable thermoplastic compositions
Inventor: DAUMILLER GUENTHER
IPC: C08J9/16
Filed: 1963-03-12
Abstract: A granular thermoplastic composition comprises an intimate mixture of (A) at least one substantially halogen free polymer or copolymer derived from aromatic or cycloaliphatic vinyl compounds, (B) at least one polymer or copolymer of vinyl chloride or vinylidene chloride, (C) 2-20% of a gaseous or liquid expanding agent, the weight of (A) being at least 1 1/2 times that of (B) and the chlorine content of the composition being 8-25%. Copolymers (A and (B) may contain up to 30 and 40% respectively of units other than those specified above. In addition to (A) and (B) the composition may contain up to 20% of other polymers and copolymers. Other additives may be: flame retardants, e.g. SbO3, 1,2,5,6,9,10-hexabromocyclododecane, hexabromocyclohexane and tris - (2,3 - di - bromopropyl) phosphate; flame retardant activators, e.g. dicumyl peroxide; plasticizers, e.g. polyvinyl pyrrolidone, hydroxyethyl cellulose, BaSO4 and CaHPO4; organic and inorganic fillers and colouring matter.  The composition may be formed by polymerizing the monomer precursors of (A) in aqueous suspension, adding the monomer precursors of (B) and polymerizing them.  The first polymerization may be carried out at 50-120 DEG  C. in the presence of 0.1-2.0% catalysts, e.g. dibenzoyl peroxide, lauroyl peroxide or azodiisobutyronitrile and 0.0573.0% plasticizers. 0.1-3.0% of catlyst may be added before the second polymerization at 30-80 DEG  C.  The expanding agent may be added prior to, during or after the second polymerization.  In an alternative method polymers (A) and (B) in a plasticized state may be mixed with the other additives in an extruder at 60-220 DEG  C. and the resulting solidified composition may be granulated. (A) may be derived from acrylonitrile, acrylic esters, methacrylic esters, acrylamide, maleic esters, itaconic esters, divinyl benzene or butadiene in addition to styrene, a -methyl styrene, o- and p-vinyl toluene and vinyl cyclohexane. Polyvinyl cycloaliphatic compounds may be derived by hydrogenation of polyvinyl aromatic compounds. Copolymers (B) may be partially derived from acrylonitrile, maleic esters, acrylic esters, vinyl acetate, vinyl ethers or vinyl ketones; (C) may boil between 20 and 80 DEG  C. and may be a pentane, hexane, cyclopentane petroleum fraction, CH2Cl2, benzene, acetone, ethyl acetate, propane butane or vinyl chloride. 4-12% may be used.  In addition to (A) and (B) polymers and copolymers may be present which are derived from: acrylonitrile, itaconic esters, maleic esters, methacrylonitrile or acrylamide. In examples (1-3, 9-15) polymer (A) is derived from styrene and acrylonitrile (1), methylacrylate (11, 12), 2,5-dichlorostyrene (13), divinyl benzene (14), vinyl alcohol (14, 15) and vinyl toluene (15 and 21).  Polymer (B) is derived by polymerization in the presence of (A) of vinylidene chloride (1), vinyl chloride (2, 3, 9-15), acrylonitrile (1, 9, 10) and dimethyl maleate (3, 14, 15).  Polymeration was carried out in water suspension (1-3, 9, 10, 14, 15) and under nitrogen (1, 9, 10).  Other additives are: blowing agents, pentane (1, 3, 9, 10, 14, 15), hexane (2,12 and 13), ethanol (3, 14, 15) and butane (11-13); polyvinylpyrrolidone (1, 9, 10); catalyst, azodiisobutyronitrile and benzoyl peroxide (2, 3, 11-13, 15); plasticizers, sodium carboxymethyl cellulose (2, 11-13) and stearic acid (3, 14, 15); polyvinyl alcohol (3); and flame retardants, SbO3 (3, 14, 15) and sodium phosphate (3, 14, 15).  In examples (4-8, 16-20) (A) is derived from styrene (4-6, 8, 16-20), acrylonitrile (6), butadiene (6, 17) and vinyl cyclohexane (7).  (B) is derived from vinyl chloride (4-8, 16-19, 20a, 20b), vinylidene chloride (7, 20c), vinyl isobutyl ether (20a), vinyl acetate (20b) and ethyl acrylate (20c). Granules of (A) and (B) are mixed and extruded optionally into water (4-7, 16-20).  Additives are: blowing agents: hexane (4, 16), pentane (5, 6, 8, 17-20), ethyl acetate (5, 6, 18-20), acetone (7), petroleum (b.p. 35-45 DEG  C.) (7) and propane (17); SbO3 (4-6, 16-19, 20a, 20b); a chloroparaffin (8); hexachlorocyclododecane (20c); polyvinylpyrrolidone (7); ferrocene (8); polybutylacrylate (19) and manganese acetylacetonate (20c).  In Example (21) styrene and o-vinyl toluene are copolymerized in the presence of benzoyl peroxide, azodiisobutyronitrile, sodium acetate, and hydroxyethylcellulose.