Abstract: The present invention refers to the production of a polyester-type polymer and more particularly to the solid phase condensation of a polyester. The invention presents a process for manufacturing polyester which comprises at least the following steps: a) esterifying of transesterifying a carboxylic diacid or a carboxylic acid diester with a diol, b) prepolymerizing the esterification or transesterification product in liquid phase until an average degree of polymerization between 10 and 50, preferably between 20 and 45, c) preparing a dispersion of the prepolymer in a non-solvent of diol and non-swelling of the prepolymer liquid, the prepolymer being present in the dispersion in the form of solid particles having diameters under 2 mm and crystallized, with a crystalline lamella thickness under 17 nm, d) polymerizing in dispersed solid phase, e) recovering solid particles. The accomplishment of a dispersed solid phase polymerization permits improving the reaction kinetics.

Abstract: The solid catalytic component according to the invention is obtained bya) treatment of a catalytic component support with ZrCl.sub.4 or HfCl.sub.4 in the gas phase, followed by ab) treatment with a solution or suspension of a compound capable of grafting a group containing the cycloalkadienyl skeleton to the Zr or Hf contained in the support. Polymerization of olefins in the presence of such a catalytic component results in polymers with low polydispersities, which polymers are obtained with high productivities.

Abstract: A catalyst support consisting essentially of a mixture of silica and magnesium chloride, said support having a porous structure and containing less than 100 micromoles of hydroxyl groups per gram of support; the process of making such support by heating such mixture at a temperature below about 720.degree. C. in the presence of a dehydrating agent, and catalysts consisting essentially of such support and at least one active component.