Patent GB-980229-A (GB)
Title: Production of microporous hydrocarbon polymers
IPC: C08L23/02
Filed: 1962-12-18
Abstract: A solid hydrocarbon polymer having interconnecting pores is produced by heating a solid thermoplastic hydrocarbon polymer and 25-90% of a water soluble anionic surface-active agent to a temperature such that they become miscible, cooling the solution to give a reticular solid surrounded by surface active agent and removing the surface active agent by extraction with a liquid in which it is soluble but the polymer is not.  Polymers may be homo- and copolymers of a -olefines containing 2-8 carbon atoms and optionally having aryl substituents. Mixtures may be used. Monomers specified include ethylene, propylene, butadiene and styrene.  Surface active agents may be alkali metal salts of: carboxylic acids of 12-18 carbon atoms, sulphonic acids, sulphocarboxylic esters, amino-aliphatic sulphonic acids or sulphuric acid/aliphatic alcohol monoesters.  The salts may be solids.  They may be obtained by hydrolysis of natural fats as in commercial soap flakes.  Compounds specified include: sodium dibutyl-naphthalene sulphonate, sodium di-(2-ethylhexyl) sulphosuccinate, sodium N - methyl - N - oleyltaurate, and sodium monolaurylsulphate.  The initial mixture may be formed in the dry state or by dissolving either or both components in a solvent which is subsequently evaporated. The hot homogeneous phase may be rolled into sheets or moulded or extruded into shape. It may be cross-linked by the presence of a peroxide.  The homogeneous phase may be cooled to ambient temperature or up to 75 DEG  C. to achieve separation.  It may be cross-linked by high energy radiation on cooling.  Solvents specified are water, alphatic ketones, ethers and alcohols.  They may be heated.  The solvent and surface active agent may be recovered from the leaching liquid by evaporation or spray drying.  The product may be mixed with wood flour, diatomaceous earth, carbon black, silica, glass fibres, asbestos fibres, cotton fibres, metal powder and ion exchange resin.  It may be used in cigarette filters, colour absorbents, heat insulators, battery separators, electrodes and conductors and to coat paper, cloth, metals, wood, wire and threads. In Example (1) polyethylene is mixed with sodium di-(2-ethylhexyl) sulphosuccinate and cross-linked with dicumyl peroxide.  In Example (5) a mixture of polyethylene, polybutadiene and sodium di-(2-ethylhexyl) sulphosuccinate or sodium N-methyl-N-oleyl-taurate is cross-linked with dicumyl peroxide. In Example (6) polythene mixed with soap flakes or sodium di-(2-ethylhexyl) sulphosuccinate is cross-linked by high energy radiation and the surface active agent removed by washing with dilute H2SO4, water and methanol. Specifications 818,963, 831,126 and 937,100 are referred to.ALSO:Surfaces such as cloth, paper, wood and metal sheets are coated with a porous-forming composition comprising a solid thermoplastic hydrocarbon polymer and 25-90% of a water soluble anionic surface active agent, the surface active agent being subsequently extracted to form interconnecting pores.  The composition is produced by heating the components to a temperature at which they become miscible.  On cooling this gives a reticulated solid surrounded by the surface active agent.  This is extracted with a liquid in which it is soluble but the polymer is not.  The product may be used to make, for example, gloves, thermal clothing, underwear, and battery separators.  Polymers specified are homo- or co-polymers of a -olefines containing 2-8 carbon atoms and optionally having aryl substituants, e.g. ethylene, propylene, butadiene and styrene.  Mixtures of polymers may be used.  Surface active agents may be alakli metal salts of: carboxylic acids having 12-18 carbon atoms, sulphonic acids, sulphocarboxylic esters, amino aliphatic sulphonic acids or sulphuric acid alkyl esters.  Compounds specified include: sodium, dibutylnaphthalene sulphonate, sodium di-(2-ethylhexyl) sulphosuccinate, sodium N-methyl-N-oleyl-taurate, and sodium monolaurylsulphate.  The polymer/surface active agent mixture may be cross linked with peroxides at high energy radiation. The surface active agent may be extracted with water or aliphatic alcohols, ketones or ethers which may be heated.  Specifications 818,963, 831,126, and 937,100 are referred to.