Abstract:
In the manufacture of polymer suspensions, good spacetime yields, a narrow particle size distribution and good polymer properties are obtained in a relatively uncomplicated apparatus which includes a plurality of reactors having a length/diameter ratio of at least 4, the first reactor standing vertically and the others approximately horizontally. Plug flow of the polymerization mixture is maintained in the reaction zones provided by the reactors. In the first such zone, up to 10% of the polymerization is carried out, with agitation, preferably at a stirring energy per unit volume of 0.1 to 5 kWm.sup.-3. Wall encrustation is substantially prevented, particularly in the second reaction zone, through the use of smooth, non-metallic surfaces in the zone.
Abstract:
A polypropylene molding composition having an excellent impact strength at a temperature down to -60.degree. C and simultaneously a good hardness contains from 70 to 90% by weight of a polypropylene, 2 to 10% by weight of an ethylene propylene copolymer and 8 to 25% by weight of a polyethylene and is distinguished by a melt index MFI 230/5 lower than that of the polypropylene contained therein and simultaneously higher by the coefficient 1.3 to 7.0 than that of a polypropylene prepared in the presence of the same catalyst as the molding composition and having the same RSV.
Abstract:
A sinterable, finely divided molding material and the preparation thereof are described. The molding material is composed of a vinyl chloride (graft) copolymer, at least one anionic and/or nonionic emulsifier and, if appropriate, small quantities of additives.The vinyl chloride (graft) copolymer contains 95 to 70% by weight of polymerized units of vinyl chloride, 5 to 30% by weight of polymerized units of an alkyl acrylate having 3 to 10 carbon atoms, 0 to 7% by weight of polymerized units of ethylene and 0 to 15% by weight of polymerized units of vinyl acetate.The molding material is suitable for the production of flexible, sintered moldings, in particular separator plates, for electric cells.
Abstract:
A process is described for the preparation of a polymer which contains, besides polymerized units of vinyl chloride, 30 to 60% by weight, relative to the polymer, of polymerized units of an acrylate, if appropriate together with copolymerizable monomers. The acrylate is firstly polymerized in aqueous emulsion with addition of a monomer containing at least 2 ethylenically unsaturated, non-conjugated double bonds in the presence of a fatty acid salt and in the presence of an alkane- or alkylarylsulfonate. Polymerization in aqueous suspension is then carried out in which vinyl chloride, customary polymerization auxiliaries, a precipitant for the emulsifiers used in the emulsion polymerization, and water are initially introduced, and the acrylate dispersion produced by emulsion polymerization is subsequently added. Polymers of high bulk density and good free-flowing properties which can easily be demonomerized are thus obtained. Mixed with vinyl chloride homopolymers, moldings having good impact resistance and surface quality are obtained with good processability.
Abstract:
Preparations of insoluble colorants, especially pigments, are obtained by distributing the colorant in molten polypropylene wax having a viscosity of 0.5 to 5 Pa.s, determined at 170.degree. C., and an isotactic proportion of 40 to 90% by weight. These preparations are easily dispersible in polyolefins and especially useful for dyeing polypropylene in the mass.
Abstract:
A coating composition essentially consisting of a polypropylene having a crystalline fraction of from 20 to 60 % by weight and a melt viscosity of from 5,000 to 200,00 cP at 170.degree. C is applicable by a roll coater. The coatings have a high elasticity, toughness and good adherence on the support and are sealable.
Abstract:
Essentially amorphous polyolefines of medium molecular weight are prepared by polymerization of .alpha.-olefines in the presence of a Ziegler supported catalyst. This catalyst consists of the reaction product of the chloride and/or alcoholates of the tetravalent titanium and of an alcoholate and/or a magnesium compound containing hydroxyl groups and of an aluminiumorganic compound containing chlorine, in which the proportion Al : Cl is 4:1 to 0.8:1. The polymerization is carried out at a temperature of from 100.degree. to 160.degree.C.
Abstract:
A molding composition which is essentially composed of a mixture of at least two polymers based on vinyl chloride and at least one water-soluble surfactant is described. One of the polymers is a sinterable vinyl chloride/alkyl acrylate copolymer which can contain, in addition, polymerized units of vinyl acetate and ethylene. At least one further polymer is a vinyl chloride polymer which can contain up to 5% by weight of polymerized units of vinyl acetate and ethylene. The molding composition is suitable for the production of sintered, porous, flexible moldings, in particular separator compartments for electric cells.
Abstract:
A process is described for preparing vinyl chloride polymers. The polymerization is carried out in an apparatus the inside walls and internal fitments of which have been coated with a reaction product which forms on reacting certain silanes with inhibitors for free-radical polymerizations and which contain in the molecule at least one aromatic or at least one quinonoid ring and at least one hydrogen atom which is bonded to an oxygen, sulfur or nitrogen atom with subsequent reaction with water, drying and heat treatment.The wall-deposit formation observed with the new process is markedly smaller, in particular after several polymerization batches, than in the case of known processes.
Abstract:
The process is described for the continuous suspension polymerization of vinyl chloride in aqueous phase, in which the polymerization mixture is subjected, in 2 zones, to treatment employing different process parameters in respect of final conversion, dwell time, number of theoretical cascade stages and stirrer power applied. This procedure gives, at good space-time yields, very uniform products which have a narrow particle size distribution, a high bulk density, good flow and a low speck count. In spite of using standard kettle material, only a very low formation of deposit on the kettle walls is observed.