Versalis S.p.a.

Eni S.p.a.

Romano Lima

Alessandro Casalini

Paolo Mariani

Michela Agnoli

Massimo Merlini

Davide Santi

Davide De Santi

Antonio Palumbo

Giovanni Rivici

The present invention relates to an aqueous emulsion comprising: a) from 50% to 60% of an organic phase dispersed in an aqueous phase, said organic phase containing a mixture including from 24% to 30%, calculated with respect to the final emulsion, of ethylene-vinyl acetate copolymers and/or polyalkyl(meth)acrylates, indicated in the present description as polymeric component, and a high-boiling organic solvent, or a mixture of said solvents; b) a primary emulsifier at a concentration higher or equal to 0.1% and lower than or equal to 3% by weight, calculated with respect to the final emulsion; c) from 37% to 47% of an aqueous phase; wherein the ratio between said polymer component and said organic solvent in the final aqueous emulsion is at least 1/1 and where the organic solvent and any polymer of the polymeric component have a Hildebrand solubility parameter &#x3b4; such that, the difference (&#x3b4;&#x3b4;) is lower than 2 in absolute value for any polymer of the polymeric component.

Aqueous emulsions containing ethylene-vinyl acetate copolymers, preparation process thereof and their use as anti-gelling additives of crude oils

Process for the preparation of a nitrile rubber comprising: &#x2014;subjecting at least one &#x3b1;,&#x3b2;-unsaturated nitrile, at least one conjugated diene and, optionally, one or more further copolymerizable monomers, to emulsion polymerization, in the presence of at least one alkyl thiol containing from 12 to 16 carbon atoms and at least three tertiary carbon atoms and having the sulfur bound to one of said tertiary carbon atoms, at a pH ranging from 7 to 10, preferably from 8 to 9, obtaining a latex; &#x2014;subjecting said latex to coagulation, in the presence of at least one metal sulfate selected from magnesium, sodium, potassium, preferably magnesium, at a temperature higher than or equal to 30&#xb0; C., preferably ranging from 40&#xb0; C. to 60&#xb0; C., obtaining a coagulated nitrile rubber: &#x2014;subjecting said coagulated nitrile rubber to washing with water, in the presence of at least one inorganic base, selected from sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, lithium hydroxide, preferably potassium hydroxide, at a pH higher than or equal to 10, preferably ranging from 11 to 12. The nitrile rubber thus obtained is capable of giving vulcanizable elastomeric compositions having a high vulcanization rate and a good vulcanization yield. Furthermore, said elastomeric compositions cause a low fouling of the molds and can consequently be advantageously used in injection molding processes.

Process for the preparation of nitrile rubbers

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Russi, Italy

Romano Lima